To see the other types of publications on this topic, follow the link: Self-healing polymers.
Dissertations / Theses on the topic 'Self-healing polymers'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Self-healing polymers.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Burattini, Stefano. "Self-Assembled Healing Polymers." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525124.
Full text
2
Ahammed, Ballal. "MOLECULAR DYNAMICS SIMULATION OF SELF-HEALING POLYMERS." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1564686567714321.
Full text
3
Ling, Zichen. "ION EFFECTS ON SELF-HEALING POLY(ACRYLIC ACID) AND POLY(METHACRYLIC ACID) GELS." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1556767022932537.
Full text
4
Sarrazin, John Cody. "Ultrasonic repair of polymers fundamentals and modeling for self-healing /." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/sarrazin/SarrazinJ0509.pdf.
Full textAbstract:
Although current research focuses within self-healing materials are advancing, most pursuits are passive systems, unlike the active biological systems they aim to mimic. In this paper an active method utilizing ultrasonic energy is explored. Ultrasonic inspection has served as an effective means toward nondestructive damage detection for decades. Also, a recent method called time-reversed acoustics allows for the redirection of acoustic waves back towards the source. The active healing method utilizes ultrasonic nondestructive damage detection to locate and categorize damage, and then provide coordinates for the redirection of an amplified ultrasonic energy to heal the material. First, the temperature change as a result of ultrasonic treatment was measured, and then a variety of dogbone samples were tensile tested, including virgin samples, damaged samples, and damaged but ultrasonically treated dogbone samples. The ultrasonic treatment increased the ultimate stress of the ultrasonically treated dogbone samples, which was a result of increased crystallinity. The crystallinity was confirmed with differential thermal analyses. The ultrasonic influence of material temperature and effect of ultrasonically treated damaged samples versus just untreated damaged samples were replicated with finite element models as a means to predict future application and use.
5
Everitt, Daniel Thomas. "Self-healing agents for application in fibre-reinforced polymers." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707746.
Full text
6
Castellucci, Matt. "Resistive heating for self-healing materials based on ionomeric polymers." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/33920.
Full textAbstract:
Self-healing materials have received considerable development in the last decade. Recent
results have demonstrated healing in polymeric materials via a chemical reaction using a
healing agent or response to thermal treatment.
The goal of this research is to develop a new composite material, for application in wire
insulation, that can detect damage and heal itself using resistance heating. The composite
material is composed of a conductive network embedded in a polymer matrix. The conductive
network is used for damage detection and resistive heating. A matrix material is
used that melts when heated and flows to fill damage. External electronic circuitry is used
to implement a damage detection algorithm and apply current for resistive heating. Surlyn
8940 is chosen as the polymer matrix and carbon fibers are selected for the resistive heating
elements. Methods for melt processing Surlyn are developed and used to produce Surlyn
films and composite samples where carbon fiber is embedded in a Surlyn matrix. A finite
element model of the resistive heating process is developed to predict the temperature
distribution.
Thermal imaging is used to characterize resistive heating while optical microscopy and
tensile testing are used to characterize healing. Damage detection using capacitive measurements
is demonstrated and characterized. The self-healing composite is placed on top
of another conductive material such as in the wire insulation application. Capacitance
measurements are made using the conductive network inside the composite is used as one
electrode and the wide conductor as the second electrode.Master of Science
7
Chen, Hsieh. "Polymers and colloids in flows : from dynamics to self-healing." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/80894.
Full textAbstract:
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 161-182).
Polymers and colloids are important building blocks of life as well as many modern technologies. Driven by ow, polymers and colloids can express very complex yet interesting behavior. This thesis aims at a fundamental understanding of the dynamical properties of dierent polymer-colloid mixtures in flows using computer simulations. A special motivation comes from the blood clotting process. Our blood is a complex uid made of polymeric proteins and colloid-like cells. Controlled by ow, a blood-clotting protein (the so-called von Willebrand factor or vWF) can change shapes from a compact structure to an extended morphology. This polymeric protein later on forms composites with the colloidal cells (platelets) and completes the initial blood-clotting task. In this thesis, we build minimalist simulation models trying to capture the essential physics behind blood clotting. We first examine the behavior of single polymers in passive owing colloidal suspensions. Our results show that the presence of colloids has a pronounced eect on the unfolding and refolding cycles of collapsed polymers (which is believed to be a good model for vWF), but has negligible effects for non-collapsed polymers. Further inspection of the conformations reveals that the strong ow around the colloids and the direct physical compression exerted on the collapsed polymers diffusing in between colloidal shear bands largely facilitate the initiation and unraveling of the collapsed chains. We believe these results are important for rheological studies of (bio)polymer- (bio)colloid mixtures, and give insight on the activation of von Willebrand factor in owing cell suspensions. We then study interacting polymer-colloid mixtures in flows. In blood clotting, the formation of plug, which is essentially a polymer-colloid (vWF-platelet) composite, is believed to be driven by shear ow, and contrary to our intuition, its assembly is enhanced under stronger flow conditions. Here, inspired by blood clotting, we show that polymer-colloid composite assembly in shear flow is a universal process that can be tailored to obtain dierent types of aggregates including loose and dense aggregates, as well as hydrodynamically induced log-type aggregates. The process is highly controllable and reversible, depending mostly on the shear rate and the strength of the polymer-colloid binding potential. Our results have important implications for the polymer-colloid binding potential. Our results have important implications for the assembly of polymer-colloid composites, an important challenge of immense technological relevance. Furthermore, flow-driven reversible composite formation represents a new paradigm in non-equilibrium self-assembly. We also study binary colloidal mixtures and self-associating polymers, both of which are very relevant to blood clotting. Platelet margination refers to the phenomenon that for flowing red blood cell and platelet mixtures in vessels, the platelets will migrate to vessel walls. Using a simple binary colloidal suspension model, we show that the nonhomogeneous red blood cell distribution as well as the shear dependent hydrodynamic interaction is key for platelet margination. We believe this separation process is important not only in the biophysics of blood clotting, but also in applied science such as drug delivery or coatings. Catch-bonds refer to the counterintuitive notion that the average bond lifetime has a maximum at a nonzero applied force. They have been found in several ligand-receptor pairs including vWF/platelet GP1b-alpha. Here we use coarse-grained simulations and kinetic theory to demonstrate that a multimeric protein, with self-associating domain pairs, can display catch-bond behavior in ow. Our biomimetic design shows how one could build and tune macromolecules that exhibit catch-bond characteristics. We finally include an appendix that describes an unrelated project that is to solve for the block copolymer propagator in polymer field theory using Lattice Boltzmann method originally developed for hydrodynamics. Comparing to the conventional pseudo-spectral method, the Lattice Boltzmann approach is slightly inaccurate yet has many extra benefits including the optimal parallel computing eciency and the ability for grid refinements and arbitrary boundary conditions.
by Hsieh Chen.
Sc.D.
8
Specht, Steffen [Verfasser], and Joachim [Akademischer Betreuer] Bluhm. "Modeling of Self-healing Polymers and Polymeric Composite Systems / Steffen Specht ; Betreuer: Joachim Bluhm." Duisburg, 2018. http://d-nb.info/1152210637/34.
Full text
9
Cui, Xiaoyu. "POLYCATION REINFORCED SULFONATED SYDIOTACTIC POLYSTYRENE GELS& SELF-HEALING LATEX CONTAINING POLYELECTROLYTE MULTILAYERS." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1495204173832965.
Full text
10
Park, Jong Se. "Self-healing composites using thermally remendable polymers and electrical resistive heating." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1973896491&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
11
Fleet, Elliot J. "Inkjet printing of self-healing polymers for enhanced composite interlaminar properties." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7098/.
Full text
12
Schleder, Gabriel Ravanhani. "Intrinsic self-healing nanocomposites : computational simulations." reponame:Repositório Institucional da UFABC, 2017.
Find full textAbstract:
Orientador: Prof. Dr. Jeverson Teodoro Arantes JuniorDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2017.
Uma estrutura que pode autorregenerar em condições ambiente é um desafio enfrentado atualmente e é uma das áreas mais promissoras na ciência de materiais inteligentes. O presente projeto visa a utilização de métodos teóricos para o estudo das propriedades estruturais e funcionais de nanocompósitos intrinsecamente autorregenerativos, permitindo estratégias mais eficientes para o desenvolvimento de novos materiais. As simulações são baseadas na Teoria do Funcional da Densidade (DFT). Estudamos os componentes isolados que constituem o nanocompósito funcional: diarilbibenzofuranona (DABBF), SHP e nanopartículas de (óxido de) níquel. Estudando a formação da DABBF contra a reação da arilbenzofuranona (ABF) e O2 (auto-oxidação), vemos que a reação de formação sem barreira da DABBF é preferida à auto-oxidação porque existe um processo de transferência de carga que resulta no superóxido fracamente ligado. Realizamos um estudo sistemático por meio de cálculos ab initio para investigar a reação de clusters de Ni13 com moléculas de O2. Avaliamos dinamicamente o efeito sobre as propriedades estruturais, eletrônicas e magnéticas e compreendemos o mecanismo de quimissorção do oxigênio (primeiro estágio da oxidação). Finalmente, estudamos as interações entre os oligômeros do SHP e as nanopartículas, levando ao nanocompósito autorregenerativo. Sugerimos como trabalhos futuros simular as interações entre todos esses materiais levando ao nanocompósito autorregenerativo por meio de uma abordagem multiescala via métodos DFT e de dinâmica molecular (MD).
A structure that can sustain self-healing repair under standard conditions is a challenge faced nowadays and is one of the most promising areas in smart materials science. The present project aims at the use of theoretical methods for the study of structural and functional properties of intrinsically self-healing nanocomposites, allowing improved design strategies for novel materials. The simulations are based on Density Functional Theory (DFT). We studied the isolated components that constitute the functional nanocomposite network: diarylbibenzofuranone (DABBF), SHP, and oxidated nickel nanoparticles. Studying DABBF bond formation against arylbenzofuranone (ABF) and O2 reaction (autoxidation), we see that the barrierless DABBF bond formation is preferred over autoxidation because there is a charge transfer process that results in the weakly bonded superoxide. We performed a systematic study by means of ab initio calculations to investigate Ni13 clusters reaction with O2 molecules. We evaluate dynamically the effect on structural, electronic, and magnetic properties and understand the oxygen chemisorption (first oxidation stage) mechanism. Finally, we study the interactions between SHP oligomers and the nanoparticles, leading to the selfhealing nanocomposite. We suggest as future work simulating the interactions between all these materials leading to the self-healing nanocomposite through a multiscale approach via DFT and molecular dynamics (MD) methods.
13
Embaye, Natnael B. "Mechanism of self-healing of amplified spontaneous emission in the dye-doped polymer disperse orange 11 dye in PMMA polymer." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Fall2007/N_Embaye_111907.pdf.
Full text
14
Kothari, Jehan. "Synthesis and Thermal Analysis of Hexamethylene Diisocyanate/Polyurea Formaldehyde Core/Shell Self-Healing Microcapsules." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504803190656406.
Full text
15
Imperiale, Vita. "Design and formulation of a bespoke self-healing agent for repair of multifunctional fibre reinforced polymers." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.582821.
Full textAbstract:
The aim of this investigation was to design a bespoke self-healing agent (SHA) formulation in order to achieve a fully autonomous healing functionality, which provides effective and timely in-situ repair of FRP composite laminates. The preliminary phase of the design process consisted of the identification of the SHA requirements, the choice of epoxy resins as the most suitable chemistry and, finally, the selection of the best candidate species, amongst the many commercially available. Numerous formulations were then generated by the combination of the above components. Therefore, an initial downselection process, with chemical and physical properties characterisation was necessary to consider only a limited number of formulations for mechanical properties characterization. A Mode I fracture toughness test was considered as a means of final selection, the adhesive function being one of the most important functional requirements. Finally, the recovery of residual compressive strength after impact (CAI) was used as a validation method, which was able to demonstrate and quantify the self-healing recovery within a FRP laminate. A very low viscosity epoxy based formulation with a slightly higher fracture toughness than the host composite matrix and good degree of reactivity was selected as having the best overall performance. Adhesion, as a function of time and temperature, was further assessed in this formulation. It was demonstrated that a certain degree of load bearing ability can be achieved after limited reaction extent with full recovery of load bearing ability after 6 hours at 25°C. An ageing assessment of SHA demonstrated that after seven days exposure to 60°C the formulation possessed excellent adhesive properties. The novel integration of a two-part SHA, with the components segregated within different hollow glass fibres for a fully autonomous process, required the development of a suitable manufacturing and design of the FRP laminate. The damaged and self-healed samples achieved 93% of the strength relative to the initial pristine configuration. Besides an increase in the failure load, self-healing generated a significant change in the stress-strain characteristics, which restored a degree of linearity up to failure, and a reduction in the differential strains (and hence increased buckling resistance). The bleeding of the SHA from storage in the HGF to effect healing can be implied from ultrasonic C-scan analysis, where images of self- healing samples possessed fragmented and less defined delamination contours compared to the image of damaged samples without SHA within hollow glass fibres. This investigation has demonstrated that a fully autonomous recovery of a significant proportion of compressive strength in a CFRP is possible via self-healing. For the first time it has been demonstrated that a bespoke multi-component SHA is able to bleed from embedded HGF, self-mix and react to allow recovery of up to 93% of compressive strength, notwithstanding the presence of remaining damage within the CFRP laminate
16
Zhang, Hongji. "Matériaux polymères à mémoire de forme et autoréparables contrôlés par la lumière via un effet photothermique." Thèse, Université de Sherbrooke, 2014. http://savoirs.usherbrooke.ca/handle/11143/5337.
Full textAbstract:
Au cours des dernières décennies, le concept de « matériaux intelligents » a suscité un intérêt en croissance rapide en raison de l'apparition de plusieurs nouveaux types de matériaux polymères qui sont capables d'accomplir une fonction désirée en réponse à un stimulus spécifique de façon prédéterminée et contrôlée. Deux exemples représentatifs sont les polymères à mémoire de forme (SMPs) et les polymères autoréparables or réparables par un stimulus (SHPs). Ils sont sujets de cette thèse. D'une part, les SMPs sont des matériaux qui ont la capacité de mémoriser une forme spécifique. Après avoir été déformés et fixés à une forme temporaire, ils peuvent récupérer la forme originale et permanente sous l'effet d'un signal stimulant comme la chaleur, la lumière ou un champ électrique. Bénéficiant de la mise en œuvre relativement facile, les SMPs sont une alternative intéressante aux alliages à mémoire de forme bien établis; et ils ont trouvé un large éventail d'applications potentielles allant des implants pour la chirurgie non-invasive aux actionneurs sensibles aux environnements. D'autre part, les SHPs sont des matériaux qui sont capables de réparer des dommages mécaniques (fissures ou fractures) par eux-mêmes ou avec l'aide d’un stimulus externe. Leur développement a un grand intérêt pour améliorer la sécurité, prolonger la durée de vie et réduire le coût de l'entretien des matériaux. Sauf quelques matériaux souples (certains gels et élastomères) qui sont guérissables de façon vraiment autonome, la plupart des SHPs nécessitent l'intervention d'un stimulus comme c’est le cas pour les SMPs. L'objectif principal de cette thèse est de développer de nouveaux SMPs et SHPs contrôlables par un rayonnement lumineux. La stratégie que nous avons utilisée est basée sur l'ajout d'une petite quantité de nanoparticules d'or (AuNPs ) ou de nanotiges d'or (AuNRs) dans un SMP ou SHP pour absorber la lumière visible ou proche infrarouge. L’idée est d’utiliser la chaleur dégagée par les nanoparticules lors de l’absorption de la lumière due à la résonance plasmonique de surface (SPR) pour contrôler les transitions de phase dans les polymères et, par conséquent, de dicter leurs processus de mémoire de forme ou de guérison. Bien qu’un effet photothermique est à l'origine de ces processus, tous les avantages de l'utilisation de la lumière comme stimulus sont conservés, tels que l'activation à distance et le contrôle spatiotemporel. Plusieurs travaux de recherche ont été réalisés au cours de cette thèse, dont les résultats, nous l'espérons, peuvent constituer une contribution de base faisant l'utilisation d’AuNPs et AuNRs une technologie de plate-forme pour le développement des SMPs et SHPs contrôlables par la lumière.
En ce qui concerne les SMPs, nous avons d’abord préparé un nouveau matériau nanocomposite AuNP-polymère à base d’oligo(ε-caprolactone) ramifié et réticulé. En faisant usage de chauffage localisé induit par la lumière, nous avons prouvé que la lumière visible peut être utilisée pour activer un processus de récupération de forme de manière sélective spatialement, et pour réaliser plusieurs formes intermédiaires sur-demande. En outre, nous avons constaté qu'en ajustant l'intensité de la lumière laser ou la quantité d’AuNPs, l'élévation locale de la température dans le matériau peut être importante et atteindre une amplitude prédéterminée sans influence défavorable sur ses environs. Cette caractéristique intéressante permet d'utiliser le même SMP pour des applications couvrant un large domaine de températures environnantes. De plus, dans cette étude, nous avons démontré comment l'énergie libérée dans un processus de récupération de forme contrôlé par la lumière peut être utilisée pour accomplir un travail mécanique.
Sur la base du projet précédent, nous avons ensuite fait la première démonstration que la polarisation de la lumière peut également être utilisée pour contrôler l'effet de mémoire de forme ainsi que le processus de récupération de forme. À cette fin, nous avons conçu et préparé un SMP anisotrope contenant des AuNRs orientés par étirage de films de poly(alcool de vinyle) (PVA). L'idée est que la quantité de chaleur dégagée par les nanotiges d’or lors de l'exposition à la lumière proche infrarouge, est déterminée par l’absorption de photons qui, pour un matériau anisotrope, est dépendante de la polarisation de la lumière incidente. Nous avons montré qu’en effet, changeant la direction de polarisation du laser incident par rapport à la direction d'étirage du film tout en conservant toutes les autres conditions inchangées, permet de contrôler le degré d'élévation de température dans le matériau, ce qui détermine le processus de récupération de forme. En découvrant ce nouveau moyen de control, cette étude a élargi la boîte à outils pour les SMPs contrôlables par voie optique.
Sur le côté SHPs, notre motivation d’exploiter l'approche photothermique est d'aborder la question difficile de la guérison de matériaux mécaniquement forts et dues. En général, une force mécanique élevée (ou une grande dureté) d'un matériau entrave sa capacité d’auto-guérison ou guérison induite par des stimuli en raison du manque de mobilité de chaînes du polymère, sachant que cette mobilité est cruciale pour la diffusion du polymère dans une région fracturée conduisant à la cicatrisation. Nous avons proposé la stratégie consistant à utiliser l'effet photothermique pour provoquer la transition de phase « fusion – cristallisation » pour la réparation. Dans une première étude, par le chargement d'une très petite quantité d’AuNPs dans deux polymères cristallins, le poly(oxyde d' éthylène ) (PEO, T[indice inférieur m~]63 °C) et le polyéthylène de basse densité (LDPE , T[indice inférieur m~]103 °C), nous avons réussi une guérison optique très rapide et efficace, fusionnant deux morceaux de polymère en contact en un seul avec des propriétés mécaniques bien récupérées. Nous avons confirmé le mécanisme de guérison basé sur la fusion des chaînes cristallisées lors de l’exposition à la lumière, suivie de la cristallisation lors du refroidissement après l'extinction du laser. Cette cristallisation des chaines ayant diffusé à travers les surfaces de coupe a pour effet de les fusionner pour la guérison. En plus de l'activation à distance et la capacité de cicatrisation rapide, nous avons aussi démontré le control spatial de la guérison optique car elle a lieu uniquement dans les régions fracturées exposées au laser.
Après avoir appris comment utiliser l'effet photothermique découlant de la SPR d’AuNPs pour réaliser le control des processus de mémoire de forme et de guérison dans des polymères séparés, nous avons continué notre effort pour développer des matériaux qui possèdent les deux fonctions de mémoire de forme et de guérison commandées par la lumière. La réalisation d’un tel matériau est aussi une tâche difficile en raison de l'incompatibilité structurelle entre les SMPs et SHPs, puisque la structure de réseau réticulé nécessaire pour le mémoire de forme réduit généralement la mobilité de chaînes requise pour la guérison. Grâce aux connaissances générées par nos recherches, nous avons proposé un design de matériau consistant à réticuler chimiquement un polymère cristallin (PEO) chargé d’une petite quantité d’AuNPs. Notre étude a montré que ce matériau polymère acquise l’effet de mémoire de forme contrôlable par la lumière et la guérison optique rapide dus au même effet de chauffage localisé induit par un laser. En effet, l'effet photothermique peut activer le processus de récupération de la forme du matériau en élevant sa température au-dessus de la T[indice inférieur m] de la phase cristalline et, dans le même temps, permet la cicatrisation de fissures par l'intermédiaire de fusion des chaînes cristallisées sous exposition au laser et la cristallisation ultérieure lors du refroidissement après l’éteinte du laser. De plus, nous avons démontré que ces deux fonctions peuvent être exécutées de manière séquentielle sur le même matériau, sans interférence entre elles. La mise en œuvre simultanée des deux fonctions distinctes dans un seul matériau peut élargir les applications possibles de SMPs et SHPs.
Par la suite, nous avons appliqué la stratégie établie avec des polymères cristallins aux hydrogels polymères. Il est connu depuis longtemps qu’il est très difficile d’obtenir des hydrogels mécaniquement robustes pouvant être réparés par effets de stimuli. Nous avons conçu et préparé un hydrogel hybride en chargeant une petite quantité d’AuNPs dans un hydrogel formé par copolymérisation du N, N-diméthylacrylamide (DMA), de l'acrylate de stéaryle (SA) et du N, N'- méthylène bisacrylamide (MBA). La force mécanique de cet hydrogel est donnée par une réticulation chimique qui coexiste avec une réticulation physique due aux chaînes latérales d’alkyles hydrophobes cristallisées. Encore une fois, par le contrôle de la transition de phase de « fusion-cristallisation » des chaînes SA à l'aide d'un laser, l'hydrogel hybride montre à la fois la fonction de mémoire de forme contrôlé par la lumière et la fonction de guérison optique efficace. Une grande contrainte à la rupture supérieure à 2 MPa a été obtenue pour un hydrogel coupé en deux et puis réparé par la lumièr.
La dernière, mais non la moindre, contribution portée par l’étude dans cette thèse est une découverte que nous avons faite sur les SHPs. Nous avons observé que l’hydrogel de PVA physiquement réticulé, étant préparé par la méthode de congélation/décongélation, peut s’auto-guérir à la température ambiante sans l’utilisation d’un stimulus ou d'un agent de guérison. Cette découverte est importante étant donné que cet hydrogel est biocompatible et un matériau largement utilisé pour des applications. Notre étude a montré que la clé pour obtenir une guérison autonome efficace de l'hydrogel de PVA ayant une force mécanique relativement élevée est d'avoir une quantité suffisante de groupements hydroxyle libres sur les chaînes de PVA pour ponts-hydrogène et une bonne mobilité de chaîne assurant la diffusion du polymère à travers les surfaces de coupe.
17
Micheel, Mathias [Verfasser], Benjamin [Gutachter] Dietzek, and Peter [Gutachter] Gilch. "Photophysical characterization of dynamically linked polymers for self-healing applications / Mathias Micheel ; Gutachter: Benjamin Dietzek, Peter Gilch." Jena : Friedrich-Schiller-Universität Jena, 2019. http://d-nb.info/1206605219/34.
Full text
18
Stopler, Erika Brooke. "CARBON NANOTUBE REINFORCED DYNAMIC MATERIALS SYNTHESIZED BY REVERSIBLE ADDITION FRAGMENTATION CHAIN TRANSFER (RAFT) POLYMERIZATION." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1564680997583507.
Full text
19
Yan, Tingzi [Verfasser], Thomas [Akademischer Betreuer] Thurn-Albrecht, Wolfgang [Akademischer Betreuer] Paul, and Sebastian [Akademischer Betreuer] Seiffert. "Self-assembly, rheological properties and self-healing studies of supramolecular polymers in the bulk state / Tingzi Yan. Betreuer: Thomas Thurn-Albrecht ; Wolfgang Paul ; Sebastian Seiffert." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2015. http://d-nb.info/1089085486/34.
Full text
20
Chen, Hao. "Exploring Advanced Polymeric Binders and Solid Electrolytes for Energy Storage Devices." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/406053.
Full textAbstract:
Intermittent electricity generation from renewable energy sources, such as wind energy, ocean energy, and solar energy, has significantly intensified the demand for high-energy-density, high-power, and low-cost energy storage devices. In this regard, tremendous efforts have been devoted to the development of electrode materials, electrolytes, and separators of energy-storage devices to address the fundamental needs of emerging technologies such as electric vehicles, artificial intelligence, and virtual reality. Polymer materials are ubiquitous in fabricating these energy storage devices and are widely used as binders, electrolytes, separators, and other components. However, binders, as an important component in energy-storage devices, are yet to receive sufficient attention. Polyvinylidene fluoride (PVDF) has been the dominant binder in the battery industry for decades despite several well-recognized drawbacks, i.e., limited binding strength due to the lack of chemical bonds with electroactive materials, insufficient mechanical properties, and low electronic and lithium-ion conductivities. The limited binding function cannot meet the inherent demands of emerging electrode materials with high capacities such as silicon anodes and sulfur cathodes. Polymers are also used as electrolyte matrices because they offer the advantages of low cost, lightweight, easy processability, excellent mechanical deformation, and better interfacial contact and compatibility with electrodes. However, the practical implementation of solid polymer electrolytes has been hindered by several challenging issues including low ionic conductivity, low ion transfer number, high-voltage instability, and lithium dendrite growth. Because of the increasingly growing demand for higher performance of energy storage devices, it is necessary to develop novel polymeric binders and solid electrolytes with advanced functionalities to help improve the operation of the currently existing energy storage systems.
In the first study, we synthesized a novel self-healing poly(ether-thioureas) (SHPET) polymer with balanced rigidity and softness for the silicon anode. The as-prepared silicon anode with the self-healing binder exhibits excellent structural stability and superior electrochemical performance, delivering a high discharge capacity of 3744 mAh g−1 at a current density of 420 mA g−1, and achieving a stable cycle life with a high capacity retention of 85.6% after 250 cycles at a high current rate of 4200 mA g−1. The success of this work suggests that the proposed SHPET binder facilitates fast self-healing, buffers the drastic volume changes and overcomes the mechanical strain in the course of the charge/discharge process, and could subsequently accelerate the commercialization of the silicon anode.
Binders could play crucial or even decisive roles in the fabrication of low-cost, stable, and high-capacity electrodes. This is especially the case for the silicon (Si) anodes and sulfur (S) cathodes that undergo large volume change and active material loss in lithium-ion batteries during prolonged cycles. In the second study, a hydrophilic polymer poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was explored as a dual-functional aqueous binder for the preparation of high-performance silicon anodes and sulfur cathodes. Benefiting from the dual functions of PMVEMA, i.e., the excellent dispersion ability and strong binding forces, the as-prepared electrodes exhibit improved capacity, rate capability, and long-term cycling performance. In particular, the as-prepared Si electrode delivers a high initial discharge capacity of 1346.5 mAh g-1 at a high rate of 8.4 A g-1 and maintains 834.5 mAh g-1 after 300 cycles at 4.2 A g-1, while the as-prepared S cathode exhibits enhanced cycling performance with high remaining discharge capacities of 711.44 mAh g-1 after 60 cycles at 0.2 C and 487.07 mAh g-1 after 300 cycles at 1 C, respectively. These encouraging results suggest that PMVEMA could be a universal binder to facilitate the green manufacture of both anodes and cathodes for high-capacity energy storage systems.
Stable and seamless interfaces among solid components in all‐solid‐state batteries (ASSBs) are crucial for high ionic conductivity and high rate performance. This can be achieved by the combination of functional inorganic material and flexible polymer solid electrolytes. In the third study, a flexible all‐solid‐state composite electrolyte is synthesized based on oxygen‐vacancy‐rich Ca‐doped CeO2 (Ca-CeO2) nanotube, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and poly(ethylene oxide) (PEO), namely Ca-CeO2/LiTFSI/PEO. Ca-CeO2 nanotubes play a key role in enhancing ionic conductivity and mechanical strength while the PEO offers flexibility and assures the stable seamless contact between the solid electrolyte and the electrodes in ASSBs. The as‐prepared electrolyte exhibits high ionic conductivity of 1.3 × 10−4 S cm−1 at 60 °C, a high lithium ion transference number of 0.453, and high‐voltage stability. More importantly, various electrochemical characterizations and density functional theory (DFT) calculations reveal that Ca-CeO2 helps dissociate LiTFSI, produces free Li-ions, and therefore enhances ionic conductivity. The ASSBs based on the as‐prepared Ca-CeO2/LiTFSI/PEO composite electrolyte deliver high‐rate capability and high‐voltage stability.
Offering high energy density and high safety, all-solid-state lithium-sulfur batteries (ASSLSBs) have emerged as one of the most promising next-generation energy storage systems. However, there are a series of barriers to their practical applications, including insufficient sulfur utilization, low ionic conductivity and unstable interfaces. In the fourth study, we adopt acetamide to construct a deep eutectic system to suppress electrode passivation, and therefore address the issues of sulfur utilization, and improve the ionic conductivity of the solid polymer electrolytes. Furthermore, we establish a lithium bis(trifluoromethanesulfonyl)imide - lithium oxalyldifluoroborate (LiTFSI-LiDFOB) dual-salt system to facilitate the establishment of a stable and uniform passivation layer, a favorable interface on lithium anode, to prevent lithium dendrite formation and the polysulfide shuttling. Consequently, the as-prepared ASSLSBs deliver a high initial discharge specific capacity of 1012 mAh g-1 at 0.05 C and a stable capacity of 234.84 mAh g-1 after 1000 cycles at 0.1 C. This work suggests that the simultaneous adoption of the deep eutectic system and dual-salt electrolyte could accelerate the practical applications of ASSLSBs.
In summary, the high performance of the as-prepared silicon anodes demonstrates potential for addressing the challenges for next-generation anodes by designing self-healing polymers and aqueous hydrophilic polymers. Moreover, the success of the aqueous hydrophilic polymer in lithium-sulfur batteries suggests that such a binder system can be extended to other high-capacity energy storage materials that suffer from severe volume changes. As for the polymer electrolytes, the design of functional inorganic/polymeric composite electrolyte presents a promising strategy to resolve the stubborn barriers (i.e., insufficient contact at the interfaces and ionic conductivity) of ASSBs. Additionally, combining the merits of the deep eutectic system and the dual-salt system, long-term cycling stability and high capacity retention of ASSLSBs can be achieved. These polymeric binders and electrolytes can be further optimized to realize high performance for various energy storage systems.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
21
Chai, Qinyuan. "Synthesis and Characterization of Ionically Crosslinked Networks." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367939178.
Full text
22
Döhler, Diana Verfasser], Wolfgang H. [Akademischer Betreuer] Binder, and Ulrich Sigmar [Akademischer Betreuer] [Schubert. "Crosslinking approaches towards self-healing polymers : “click”-crosslinking and supramolecular clustering ; [kumulative Dissertation] / Diana Döhler. Betreuer: Wolfgang H. Binder ; Ulrich S. Schubert." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2015. http://d-nb.info/1077768176/34.
Full text
23
Sandmann, Benedict [Verfasser], Ulrich Sigmar [Gutachter] Schubert, and Norbert [Gutachter] Moszner. "Design and application of functional polymers : from self-healing materials via hard tissue composites to methacrylate tougheners / Benedict Sandmann ; Gutachter: Ulrich Sigmar Schubert, Norbert Moszner." Jena : Friedrich-Schiller-Universität Jena, 2016. http://d-nb.info/1177614049/34.
Full text
24
ZHANG, HUAN. "EFFECTS OF SOLUTION COMPOSITION (SALTS, PH, DIELECTRIC CONSTANT) ON POLYELECTROLYTE COMPLEX (PEC) FORMATION AND THEIR PROPERTIES." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1543848436422118.
Full text
25
Simonin, Léo. "Silicone supramoléculaire : un nouveau concept permettant l'auto-cicatrisation." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS149/document.
Full textAbstract:
Les silicones auto-cicatrisants de façon autonome (sans stimulus externe) présentent de faibles propriétés mécaniques, limitant leur utilisation industrielle. L’objectif de cette étude était de dépasser cette limitation. Nos travaux se sont intéressés aux copolymères segmentés PDMS-urée constitués de blocs souples (SS) et rigides (HS). Tout d’abord, nous avons étudié la relation entre la structure des bis-urées et les propriétés macroscopiques. Nous avons ainsi montré que la symétrie des HS gouverne la rigidité de ces matériaux. Toutefois, la présence de HS symétriques inhibe la cicatrisation du matériau. Puis, nous avons développé un nouveau concept permettant d’accélérer leur cinétique de cicatrisation. Un stoppeur de chaine macromoléculaire a été ajouté à la formulation de ces silicones thermoplastiques, créant un défaut dans l’assemblage supramoléculaire, conduisant à des clusters organiques plus petits et plus dynamiques. Néanmoins, contrairement aux plastifiants, la chute du module de Young observée par rapport à la matrice est limitée. D’ailleurs, nous reportons la synthèse d’un copolymère PDMS-urée avec un module de traction de 1MPa dont 90% de la contrainte à rupture peut être récupérée après cicatrisation pendant 24h à 25°C. Ce concept a aussi été adapté à un thermoplastique commercial (GENIOMER80). Enfin, notre défi a été d’optimiser la balance entre rigidité et autocicatrisation. Dans ce contexte, nous avons synthétisé de nouvelles matrices plus rigides, ainsi que des additifs avec des groupements associatifs de plus grande énergie cohésive. Nous avons alors pu repousser la limite de rigidité accessible aux silicones auto-cicatrisants de façon autonome (3MPa)Autonomous self-healable (without external stimulus) silicones exhibit too low mechanical properties restricting their use in industry. The aim of this study was to overcome this limitation. We focused our work on segmented PDMS-urea copolymers made of soft (SS) and hard segments (HS). First the investigation of the relationship between the bis-urea chemical structure and the macroscopic properties was made. Results shown that, the symmetry of HS governs materials rigidity. Moreover, with a too symmetrical HS, the material does not exhibit self-healing abilities. We have developed a new concept improving the healing efficiency of these materials. The idea was to add to the formulation of these silicone thermoplastics a macromolecular chain stopper. The new additive creates a defect in the supramolecular assembly which leads to smaller and more dynamic H-bonding clusters and hence a faster healing kinetic. Unlike plasticizers, this additive deteriorates the tensile modulus only marginally. We therefore report a stress at break recovery of 90% after 24 hours at room temperature for a PDMS-urea copolymer with a tensile modulus of 1MPa. The concept was also extented to a commercial thermoplastic (GENIOMER80). Finally, our last challenge was to manage the balance between rigidity and chains dynamics allowing self-healable materials with good mechanical properties. In this context we have synthesized new matrixes with higher HS percentage and additives with stickers with higher cohesive energy. These new syntheses have led to an improvement of the rigidity limit reachable by the autonomous self-healable silicones (3MPa)
26
Cho, Szu-Hao. "FACILE AND FAST FABRICATION OF FUNCTIONAL THIN FILMS VIA POLYELECTROLYTE LAYER-BY-LAYER ASSEMBLY." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1597419056509933.
Full text
27
Solouki, Bonab Vahab. "Polyurethane (PU) Nanocomposites; Interplay of Composition, Morphology, and Properties." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1542634359353501.
Full text
28
Ford, Kevin J. "Characterization of self-healing composite materials." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4704.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xiv, 148 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 122-129).
29
Owen, Christopher Cooper. "Magnetic Induction for In-situ Healing of Polymeric Material." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/79682.
Full textAbstract:
The field of self-healing materials is growing dramatically due to the obvious in- centive of having structural materials with the ability to repair damage. Some polymers have demonstrated the ability to heal from damage autonomously[12, 26], when exposed to heat[1], or when punctured[5, 9]. The goal of this research is to develop a "proof-of-concept" polymer composite that has the ability to heal when exposed to an alternating magnetic field.
Several types of magnetic particulate were inspected for use in the production of polymer composite test samples. The types of particulate used in sample production were two supplies of γ-Fe₂O₃, one supply of α-Fe₂O₃, and one supply of Ni-Zn Ferrite. Surlyn 8940 was selected as the bulk polymer due to its self-healing qualities[9]. A method for melt mixing the particulate with the polymer in various volume fractions was developed and an SEM was used to study the dispersion of the particulate.
Once the polymer composite samples were made, various tests were conducted to characterize the samples in order to determine what effects the particulate had on the prop- erties of the bulk polymer. These tests included differential scanning calorimetry (DSC), rheology, conductivity, and magnetic response. Once the samples were characterized, tests were performed to study the composite polymers ability to heat and heal. These tests included healing microscopy, induction heating, and tensile testing. From this study, it was found that the addition of particulate to the bulk polymer does alter the properties by increasing viscosity and electrical conductivity.
However, the addition of particulate does not change the melt temperature, but allows the magnetic hysteresis loop of each composite sample to be revealed through magnetic testing. Through healing microscopy and tensile testing, the polymer composites were found to heal when heated, but at a higher temperature than the pure bulk polymer samples. Each type of polymer composite also heated to varying degrees through magnetic induction. Due to the ability of the polymer composite to heal and heat, a "proof-of-concept" has been provided for a magnetically healing polymer composite.Master of Science
30
Tsinberg, Anait. "Evaluation of novel autonomous self-healing polymer composite." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45355.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
"September 2008."
Includes bibliographical references (p. 61-63).
Autonomous self-healing materials offer a novel ability to self-repair damage caused by fatigue or fracture. Applications in many industries, from medical to aerospace, suffer from formation of microcracks, which often result in catastrophic failure of the product when the cracks remain undetected. A self-healing material capable of microcrack elimination would improve the safety of such products, as well as extend their lifetime. This paper presents several recently developed autonomous self-healing designs of polymer composites. The commercialization potential of the designs is explored. Potential applications in four industries are identified, and the helicopter blade is selected as the most likely application to succeed in introducing the novel material into the market. The helicopter market is evaluated based on demand, growth, stability, and ease of entry. Intellectual property landscape is presented and competitors are identified. A combination business strategy of research and development and intellectual property licensing is recommended for entry into the helicopter market.
by Anait Tsinberg.
M.Eng.
31
Latnikova, Alexandra. "Polymeric capsules for self-healing anticorrosion coatings." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2012/6043/.
Full textAbstract:
The present work is devoted to establishing of a new generation of self-healing anti-corrosion coatings for protection of metals. The concept of self-healing anticorrosion coatings is based on the combination of the passive part, represented by the matrix of conventional coating, and the active part, represented by micron-sized capsules loaded with corrosion inhibitor.
Polymers were chosen as the class of compounds most suitable for the capsule preparation. The morphology of capsules made of crosslinked polymers, however, was found to be dependent on the nature of the encapsulated liquid. Therefore, a systematic analysis of the morphology of capsules consisting of a crosslinked polymer and a solvent was performed. Three classes of polymers such as polyurethane, polyurea and polyamide were chosen. Capsules made of these polymers and eight solvents of different polarity were synthesized via interfacial polymerization. It was shown that the morphology of the resulting capsules is specific for every polymer-solvent pair. Formation of capsules with three general types of morphology, such as core-shell, compact and multicompartment, was demonstrated by means of Scanning Electron Microscopy. Compact morphology was assumed to be a result of the specific polymer-solvent interactions and be analogues to the process of swelling. In order to verify the hypothesis, pure polyurethane, polyurea and polyamide were synthesized; their swelling behavior in the solvents used as the encapsulated material was investigated. It was shown that the swelling behavior of the polymers in most cases correlates with the capsules morphology. Different morphologies (compact, core-shell and multicompartment) were therefore attributed to the specific polymer-solvent interactions and discussed in terms of “good” and “poor” solvent. Capsules with core-shell morphology are formed when the encapsulated liquid is a “poor” solvent for the chosen polymer while compact morphologies are formed when the solvent is “good”. Multicompartment morphology is explained by the formation of infinite networks or gelation of crosslinked polymers. If gelation occurs after the phase separation in the system is achieved, core-shell morphology is present. If gelation of the polymer occurs far before crosslinking is accomplished, further condensation of the polymer due to the crosslinking may lead to the formation of porous or multicompartment morphologies. It was concluded that in general, the morphology of capsules consisting of certain polymer-solvent pairs can be predicted on the basis of polymer-solvent behavior. In some cases, the swelling behavior and morphology may not match. The reasons for that are discussed in detail in the thesis.
The discussed approach is only capable of predicting capsule morphology for certain polymer-solvent pairs. In practice, the design of the capsules assumes the trial of a great number of polymer-solvent combinations; more complex systems consisting of three, four or even more components are often used. Evaluation of the swelling behavior of each component pair of such systems becomes unreasonable. Therefore, exploitation of the solubility parameter approach was found to be more useful. The latter allows consideration of the properties of each single component instead of the pair of components. In such a manner, the Hansen Solubility Parameter (HSP) approach was used for further analysis. Solubility spheres were constructed for polyurethane, polyurea and polyamide. For this a three-dimensional graph is plotted with dispersion, polar and hydrogen bonding components of solubility parameter, obtained from literature, as the orthogonal axes. The HSP of the solvents are used as the coordinates for the points on the HSP graph. Then a sphere with a certain radius is located on a graph, and the “good” solvents would be located inside the sphere, while the “poor” ones are located outside. Both the location of the sphere center and the sphere radius should be fitted according to the information on polymer swelling behavior in a number of solvents. According to the existing correlation between the capsule morphology and swelling behavior of polymers, the solvents located inside the solubility sphere of a polymer give capsules with compact morphologies. The solvents located outside the solubility sphere of the solvent give either core-shell or multicompartment capsules in combination with the chosen polymer.
Once the solubility sphere of a polymer is found, the solubility/swelling behavior is approximated to all possible substances. HSP theory allows therefore prediction of polymer solubility/swelling behavior and consequently the capsule morphology for any given substance with known HSP parameters on the basis of limited data. The latter makes the theory so attractive for application in chemistry and technology, since the choice of the system components is usually performed on the basis of a large number of different parameters that should mutually match. Even slight change of the technology sometimes leads to the necessity to find the analogue of this or that solvent in a sense of solvency but carrying different chemistry. Usage of the HSP approach in this case is indispensable.
In the second part of the work examples of the HSP application for the fabrication of capsules with on-demand-morphology are presented. Capsules with compact or core-shell morphology containing corrosion inhibitors were synthesized.
Thus, alkoxysilanes possessing long hydrophobic tail, combining passivating and water-repelling properties, were encapsulated in polyurethane shell. The mechanism of action of the active material required core-shell morphology of the capsules.
The new hybrid corrosion inhibitor, cerium diethylhexyl phosphate, was encapsulated in polyamide shells in order to facilitate the dispersion of the substance and improve its adhesion to the coating matrix.
The encapsulation of commercially available antifouling agents in polyurethane shells was carried out in order to control its release behavior and colloidal stability.
Capsules with compact morphology made of polyurea containing the liquid corrosion inhibitor 2-methyl benzothiazole were synthesized in order to improve the colloidal stability of the substance. Capsules with compact morphology allow slower release of the liquid encapsulated material compared to the core-shell ones.
If the “in-situ” encapsulation is not possible due to the reaction of the oil-soluble monomer with the encapsulated material, a solution was proposed: loading of the capsules should be performed after monomer deactivation due to the accomplishment of the polymerization reaction. Capsules of desired morphologies should be preformed followed by the loading step. In this way, compact polyurea capsules containing the highly effective but chemically active corrosion inhibitors 8-hydroxyquinoline and benzotriazole were fabricated.
All the resulting capsules were successfully introduced into model coatings. The efficiency of the resulting “smart” self-healing anticorrosion coatings on steel and aluminium alloy of the AA-2024 series was evaluated using characterization techniques such as Scanning Vibrating Electron Spectroscopy, Electrochemical Impedance Spectroscopy and salt-spray chamber tests.In Anlehnung an den Selbstheilungsmechanismus der menschlichen Haut entwickeln wir ein innovatives Verfahren zur Funktionalisierung von Korrosionsschutzbeschichtungen, um auch diese in die Lage zu versetzen Beschädigungen selbstständig „auszuheilen“. Dazu werden winzige Mikro- und Nanobehälter mit aktiven Substanzen (z. B. Korrosionshemmstoffen, Versiegelungsmitteln, Bioziden etc.) befüllt und anschließend in eine Korrosionsschutzbeschichtung eingebettet. Kommt es nun im Zeitablauf zu korrosionsauslösenden Beschädigungen der Schutzbeschichtung (z. B. durch Kratzer oder Risse) werden an der Defektstelle die eingebetteten Behälter zerstört und aktiv wirkende Gegensubstanzen freigesetzt. Dadurch wird die verletzte Stelle sofort wieder verschlossen und die Korrosionsgefahr eliminiert. Der entscheidende Vorteil derart funktionalisierter Schutzbeschichtungen ist ihre aktive Rückkopplung mit dem Korrosionsauslöser: Die aktive Schutzsubstanz wird nur an der Defektstelle und nur in der zur Korrosionsvermeidung erforderlichen Menge freigegeben. Somit werden eine länger anhaltende Wirkdauer sowie eine deutlich höhere Nachhaltigkeit der Beschichtungen ermöglicht. Dieses „intelligente Verhalten“ der neuen aktiven Korrosionsschutzbeschichtungen ist nur dank ihrer innovativen Mikrostruktur möglich. Die winzigen Mikro- und Nanobehälter beinhalten nicht nur aktive Substanzen in ihrem Inneren sondern besitzen auch eine intelligent konstruierte Hüllenstruktur, deren Durchlässigkeit sich je nach Art des Korrosionsauslösers ändert. Wird die eingekapselte aktive Substanz freigesetzt, fängt diese sofort an gegen die korrosionsverursachenden Einflüsse zu wirken. Ist die Gefahr beseitigt verringert sich die Durchlässigkeit der Behälterhülle wieder. Diese bedingte Reversibilität zwischen geschlossenem und geöffnetem Zustand des Behälters sorgt für einen sehr sparsamen Verbrauch der aktiven Substanz und für die stark verbesserte Schutzwirkung darauf basierender Antikorrosionsbeschichtungen. Diese Arbeit befasst sich mit dem Aufbau polymerer Kern-Schale-Mikrokapseln, die entsprechende Korrosionsinhibitoren und Biocide enthalten. Der Morphologie wird für zahlreiche Lösungsmittel und Polymere mit Hilfe der Hansen-Löslichkeitsparameter in guter Übereinstimmung mit elektronenmikroskopischen Experimenten beschrieben. Die Wirkungsweise in technischen Beschichtungen wird quantifiziert anhand von elektrochemischer Impedanzspektroskopie, Rastervibrationssondenmessungen und industrienahen Testverfahren.
32
Wang, Xufeng Materials Science & Engineering Faculty of Science UNSW. "Application of single-part adhesives as healing agent in self-healing composites." Awarded by:University of New South Wales. Materials Science and Engineering, 2007. http://handle.unsw.edu.au/1959.4/32233.
Full textAbstract:
The aim of this study was to develop a new single-part healing system for self-healing composites. The self-healing approach to composite repair has been developed in the last two decades and means that a damaged area can be repaired by material already housed within the structure. The background and development of self-healing has been reviewed. The two main self-healing mechanisms are discussed. To date only two part self healing systems have been examined. These require diffusion of the separate constituents to a single location in order to effect cure and restore strength. Single part adhesives do not have this disadvantage and are therefore very attractive. Several candidate single-part adhesive or resin systems were considered and discussed according to the critical requirements of a self-healing system. A series of experiments was undertaken to evaluate the possibility of candidate adhesive systems being effective for self-healing by focusing on the determination of storage stability and bonding efficiency. The results of storage stability testing showed that the stability of cyanoacrylate and polyurethane adhesives was poor. However silane and polystyrene cements showed good storage stability. Very low bonding efficiency was achieved with polystyrene cement but a 22% strength recovery was obtained with the silane 3-[tris(trimethylsiloxy)silyl]-propylamine. Suggestions for further research into single-part healing systems are also given.
33
Dunn, Simon Craig. "A novel self-healing shape memory polymer-cementitious system." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/54194/.
Full textAbstract:
The polymer model is incorporated into a simulation for the entire material system which is based on a beam idealisation and in which a strong discontinuity approach is used to simulate cracking. It is shown that this model is able to accurately simulate the experiments carried out on the LatConX system.
34
Van, den Dungen Eric T. A. "Self-healing coatings based on thiol-ene chemistry." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1274.
Full textAbstract:
Thesis (PhD (Chemistry and Polymer Science)--University of Stellenbosch, 2009.The work presented in this dissertation describes the development of self-healing coatings based on thiol-ene chemistry. The approach was to synthesize capsules with thiol and ene compounds separately encapsulated. These capsules were embedded in various coating formulations and upon the formation of a crack with a razor blade, these capsules ruptured. This caused the healing agent to flow into the crack via capillary action and the thiol-ene healing mechanism was initiated. This resulted in recovery of the damaged coating and provided continued protection to the substrate. Pentaerythritol tetrakis(3-mercaptopropionate) (TetraThiol), 1,6-hexanediol diacrylate (DiAcrylate) and 1,6-hexanediol di-(endo, exo-norborn-2-ene-5-carboxylate) (DiNorbornene) are the thiol and ene compounds used in this study. Kinetic experiments indicated that both TetraThiol-DiAcrylate and TetraThiol-DiNorbornene monomer pairs undergo rapid polymerization and form a network within minutes upon exposure to UV radiation and with the addition of a photoinitiator. The TetraThiol-DiNorbornene monomer pair also showed a high rate of polymerization without the addition of a photoinitiator and/or exposure to UV radiation. Styrene-maleic anhydride (SMA) copolymers and chain-extended block copolymers with styrene (P[(Sty-alt-MAh)-b-Sty]) were synthesized via Reversible Addition-Fragmentation chain Transfer (RAFT)- mediated polymerization. These copolymers were used as surfactant in miniemulsification for the synthesis of core-shell particles with TetraThiol as the core material. It appeared that P[(Sty-alt-MAh)-b-Sty] block copolymers, sterically stabilized via the addition of formaldehyde, provide optimal stability to the core-shell particles. DiNorbornene is encapsulated via miniemulsion homopolymerization of styrene and well-defined, stable nanocapsules were obtained. TetraThiol and DiAcrylate microcapsules were synthesized via in-situ polymerization of urea and formaldehyde. Microcapsules with a particle size of one to ten micrometers and with a very smooth surface were obtained. These microcapsules and nanocapsules were embedded in poly(methyl acrylate) (PMA), styrene-acrylate and pure acrylic films and the self-healing ability of these coatings, after introduction of a crack with a razor blade, was assessed.
35
Yamin, Inbar (Inbar S. ). "The role of self-healing coatings on soft polymer fibers." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98556.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 32).
Mussel byssal threads exhibit unique self-healing mechanical properties. This study designed a synthetic system modeled after the byssal thread structure in order to isolate the origins of their unique self-healing mechanical properties. PDMS fibers were coated with metal-coordination bonds crosslinked PEG gels and their mechanical properties were tested with uniaxial tension tests. The synthetic system achieved a similar behavior to that of the natural mussel fibers, showing that a thin stiff coating on a soft polymer fiber can have a dramatic effect on its mechanical behavior. The coated fibers were much stiffer at small strains than the uncoated PDMS. The linear elastic region was followed by a distinct yield stress, which indicated the coating beginning to fracture. At high strains, when the coating had failed catastrophically, the PDMS behavior dominated. The coatings were healed though hydration in a humid environment and were then able to recover their stiffness similar to mussel byssal threads.
by Inbar Yamin.
S.B.
36
Devereaux, Caitlin Albright 1980. "Self-healing properties of water filtration membranes containing amphiphilic comb polymer." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28877.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references (p. 95-100).
(cont.) and filtration experiments, as well as other characterization techniques. Surface analysis is accomplished via x-ray photoelectron spectroscopy (XPS). Membrane samples are cleaned (in hydrogen peroxide or chromic-sulfuric acid (Chromerge)) and/or annealed (in 90⁰C deionized water), and their elemental surface composition and specific carbon binding environments are determined by XPS. Filtration experiments are done by alternating feed solutions of deionized water and a foulant (either bovine serum albumin or an oil/water emulsion). The flux of the feed solution is measured before fouling, during fouling, and after fouling, to determine the extent of fouling recovery. Also, the compositions of the permeates are analyzed via ultraviolet-visible spectroscopy to determine the rejection coefficient of the membrane. The data presented in this thesis show that PVDF blend membranes containing P(MMA-r-POEM) are capable of generating a fresh surface layer of PEO multiple times, even after extended cleaning sessions using concentrated acid. Membranes of varying thickness are shown to exhibit PEO-regenerative abilities, but it appears that thick membranes have better fouling recovery than thinner, filtration-series membranes. Also, it is found that a blend membrane stripped of all of its surface PEO (by a 24-hour-long exposure to Chromerge) is able to restore PEO to its surface with roughly 24 hours of annealing ...
Freshwater shortages are a tremendous problem for certain areas of the world, and given projected world population increases, they will pose a problem for a rising number of people in the future. A variety of technologies are currently used to extract usable water from wastewater, including water filtration membranes. Membrane technologies are promising because they require little energy and are scalable. However, many membrane materials tend to foul quickly when exposed to the organic species in wastewater feed streams. Approaches to preventing membrane fouling include surface grafting of hydrophilic polymers onto membranes and the use of hydrophilic polymers as the bulk material. The former approach works moderately well, but it requires an increased number of fabrication steps, and the surface treatments tend to lose their effectiveness over time. The use of hydrophilic bulk materials leads to loss of membrane strength and resistance to wastewater elements such as chlorine. Neither option provides membranes that can maintain fouling resistance for extended periods of time. This thesis investigates an alternative method of fouling prevention, first described by Hester et al. This approach involves the fabrication of blend membranes containing poly(vinylidene fluoride) (PVDF) and roughly 10 wt% of a comb polymer additive, poly(methyl methacrylate-r-poly(oxyethylene methacrylate)) (P(MMA-r-POEM)). The additive self-segregates to the membrane surface during fabrication and imparts long-term fouling resistance to the membrane. Even after harsh cleaning, which degrades the PEO chains present at the surface, membrane performance can be partially restored with a simple 18-hour anneal in a 90⁰C water bath. Membranes are subjected to both surface
by Caitlin Albright Devereaux.
S.M.
37
Zhang, Borui. "Novel Dynamic Materials Tailored by Macromolecular Engineering." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1564157701522666.
Full text
38
Jia, Yuanyuan Wu Yue. "Structure analysis of titanate nanotube/organic molecule hybrid and self-healing polymer." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,799.
Full textAbstract:
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Dec. 18, 2007). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Department of the Department of Physics and Astronomy." Discipline: Physics and Astronomy; Department/School: Physics and Astronomy.
39
Ballout, Wael. "Microencapsulation et autoréparation (self-healing) de polymères pour des applications aérospatiales." Aix-Marseille 3, 2010. http://www.theses.fr/2010AIX30007.
Full textAbstract:
Le thème de ce travail est l'autoréparation par microencapsulation et incorporation dans un revêtement polymère (polyimide, résine. . . ) pouvant subir une dégradation. Dans notre étude, nous nous intéresserons tout particulièrement à l'autoréparation des matériaux pour une application aérospatiale. Le choix de l'agent autoréparant dépend directement des conditions physiques de l'espace (température maximum : +300°C coté exposé aux rayons solaires, -120°C coté non exposé aux rayons solaires, radiations UV 200-400 nm et une pression de 10[-4] Pa). Notre choix s'est donc porté sur le triméthylolpropane triacrylate. Les microcapsules obtenues par différents procédés d'encapsulation tels que la polymérisation, la polycondensation interfaciale et la polymérisation sol-gel ont été étudiées. Les analyses spectroscopique (IR : infrarouge) et thermique (ATG : analyse thermogravimétrique) nous ont permis de montrer la présence de l'agent de réparation dans les microcapsules synthétisées, quelque soit le procédé employé. Cependant, l'encapsulation par polymérisation sol-gel est la plus adaptée. L'incorporation de ces particules chargées en agent autoréparant dans une matrice polyimide a permis l'autoréparation après endommagement de ce dernier. En effet, l'agent autoréparant libéré par contrainte mécanique a polymérisé après 20 minutes d'irradiations UVThe aim of this work is self-healing by microencapsulation and incorporation into a polymer coatmg (polyimide, resin. . . ) may undergo degradation. In our study, we focus particularly on the self-healing materials for aerospace applications. The choice of healing agent depends directly of physical conditions in space (maximum temperature : 300 °C solar side, -120 °C dark side, UV radiations 200-400 nm and a low pressure 10[-4] Pa). Our choice is a trimethylolpropane triacrylate monomer. The microcapsules obtained by various encapsulation processes such as polymerization, interfacial polycondensation and sol-gel polymerization have been studied. Spectroscopic (IR : infrared) and thermal (TGA : thermogravimetric analysis) analysis have showed the presence of the healing agent in the synthesized microcapsules, whatever the process used. However, encapsulation by sol-gel polymerization is most adapted. The incorporation of these particles loaded in healing agent in a polyimide coating has the self-repair after damage of the latter. Indeed, the self-healing agent released by mechanical stress was cured after 20 minutes of UV irradiations
40
Latnikova, Alexandra [Verfasser], and HELMUTH [Akademischer Betreuer] MOEHWALD. "Polymeric capsules for self-healing anticorrosion coatings / Alexandra Latnikova. Betreuer: Helmuth Möhwald." Potsdam : Universitätsbibliothek der Universität Potsdam, 2012. http://d-nb.info/1025584945/34.
Full text
41
Schäfer, Sandra [Verfasser], and Guido [Akademischer Betreuer] Kickelbick. "Self-Healing Polymer-based Nanocomposites using the Diels-Alder-reaction : Studies on the Influence of Composition on Self-Healing Properties / Sandra Schäfer ; Betreuer: Guido Kickelbick." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2018. http://d-nb.info/1201647002/34.
Full text
42
Osim, Wilton [Verfasser]. "Surface modification of nanofillers and encapsulation of healing agents for ROMP- and “click”-based self-healing polymer nanocomposites / Wilton Osim." Halle, 2018. http://d-nb.info/1177798581/34.
Full text
43
Kay, Matthew. "The development and impact performance of a self-healing carbon fibre reinforced polymer material." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566817.
Full textAbstract:
Self-healing systems provide an opportunity to improve the damage tolerance of fibre reinforced polymers. This experimental study examines a hollow glass fibre (HGF) self- healing system embedded within a host carbon fibre/epoxy laminate. The performance of the laminate under various impact velocities ranging from quasi-static indentation to hypervelocity impact was assessed. The influence of the self-healing agent properties on the healing efficiency of the laminate has been established. Extensive fractography analysis was used to understand the mechanisms responsible for HGF rupture. The HGF laminate was shown to be capable of restoring laminate flexural strength after indentation damage. However, the self-healing response was not successfully initiated during low velocity and hypervelocity impacts. By investigating the reasons for these results it has been shown that the rupture of HGF is reliant upon the formation of matrix shear cracks. The thesis concludes by proposing a set of design guidelines for future self-healing materials and presents a new hollow fibre design.
44
Bolimowski, Patryk Adam. "Microcapsule-based self-healing in carbon fibre reinforced polymer composites : towards design and application." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705473.
Full text
45
Bass, Roger Wesley. "Synthesis and Characterization of Self-Healing Poly (Carbonate Urethane) Carbon-Nanotube Composites." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/2999.
Full textAbstract:
Synthesis of high molar mass polycarbonate polyurethanes using a novel polyol is described. The resulting elastomers demonstrate excellent mechanical properties as well as the capability to re-heal after rupture without the addition of additives or imbedded healing agents. The self-healing functionality is shown to greatly improve with the addition of up to 1% single and multi-walled carbon nanotubes. The interface of the carbon nanotubes and self-healing polymer are probed using Raman techniques and provide an insight into how the self-healing actions are improved with the addition of carbon nanotubes.
Synthesis of polycarbonate polyurethanes and carbon nanotube composites using a novel casting method is described and compared to the more traditional solution casting method. The dispersion of the carbon nanotubes is evaluated as well as the effect of effective dispersion on the composites through tensile testing, rheometry and hardness testing. Although complete agglomeration avoidance could not be achieved, significant size decrease was observed. Over 200% improvement in tensile strength is shown with conventional solution casting method which is further improved by the described novel solution casting method.
Contact angle measurements on our novel self-healing poly (carbonate urethane) and CNTs composites show that surface energies are drastically changed when CNTs are used. The most revealing finding is that f×svp increases in CNT composite materials from ~30% of the surface energy on average for the samples tested, to ~80%. We have shown that surface free energies increase most likely as a result of exposing hydrogen bonding sites typically found within the bulk in polyurethanes. Our polyurethane differs from traditional polyurethanes in that it has both novel soft segments made from a novel polycarbonate polyol discussed in chapter 2 and relatively soft ¡§hard¡¦ segments resulting from the use of H12MDI, all leading to increased ability to hydrogen bond within the material. The availability of the hydrogen bonding sites is demonstrated by FTIR absorbance bands for associated and unassociated hydrogen bonding sites, which do not seem to be accessible to a large until the PCPU¡¦s surface is disrupted. Once disrupted, the exposed hydrogen bonding sites are able to bond with other bonding sites of adjacent ruptured surfaces. This would explain why our material is non-blocking, e.g. won¡¦t stick to itself, until the surface is ruptured. It would also explain why any two ruptured surfaces of our material will reheal, even if they were not attached previously.
46
Vasiliu, Simona [Verfasser], Benjamin [Akademischer Betreuer] Dietzek, and Jürgen [Akademischer Betreuer] Popp. "Raman characterization of polymer formation : first step to self-healing polymer coatings studies / Simona Vasiliu. Gutachter: Benjamin Dietzek ; Jürgen Popp." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2015. http://d-nb.info/1079840745/34.
Full text
47
Strange, Gregory Alan. "RESPONSIVE MATERIALS VIA DIELS-ALDER CHEMISTRY." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/710.
Full textAbstract:
The corrosion of infrastructure imposes a significant monetary cost, and at times human cost, upon society. Methods to improve corrosion resistance of materials are described herein which utilize the reversibility of the Diels-Alder reaction to impart thermal responsiveness upon materials. Such stimuli responsiveness can potentially play a role in self healing properties which lead to reduced cracking and thus increased corrosion protection.
Reversible Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates. Hydrophobic dieneophiles were prepared and attached to glass slides and capillaries to yield a nonwetting surface. Thermal treatment of the surfaces cleaved the Diels-Alder linkage, and resulted in the fabrication of a hydrophilic surface. Preliminary analysis utilized contact angle (CA) measurements to monitor the change in surface energy, and observed a hydrophilic state (CA - 70±3°) before attachment of the dieneophile to a hydrophobic state (CA - 101±9°) followed by regeneration of the hydrophilic state (CA - 70±6°) upon cleavage of the Diels-Alder linkage. The treatments were then applied to glass capillaries, with effective treatment confirmed by fluid column measurements. Patterned treatments were also demonstrated to provide effective fluid flow gating.
Reversible Diels-Alder linkages were incorporated into polymer thermoset binding resins in order to provide a means by which a crosslinked thermoset could undergo stimuli responsive reversible crosslinking. The binder systems which were utilized included two types of amine curing agents, polydimethylsiloxane (PDMS) and Jeffamine® polyetheramines (PEA), and two types of epoxy resins, EPON resin based on diglycidyl ether of Bisphenol-A and epoxidized soybean oil. Various dienes and dienophiles were employed to functionalize the selected binder systems and were met with various degrees of success. The synthetic technique which proved to be the most promising was the Diels-Alder modification of the epoxidized soybean oil.
48
Wiacek, Kevin John. "SYNTHESIS AND ELECTRICAL PROPERTIES OF FLUORENYL POLYESTERS INCORPORATING DIAMOND FRAGMENTS." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1183079024.
Full text
49
Tyagi, Prashant. "Elaboration de membranes polymères auto-réparables." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0015/document.
Full textAbstract:
L'objectif de cette thèse est d'élaborer et de développer un type de membranes polymères qui peuvent se réparer de manière autonome en cas de fissures. Si elles ne sont pas détectées, ces fissures peuvent poser des problèmes notamment pour des applications médicales. Dans une première partie, une membrane polymère dynamique à base de micelles de copolymère tribloc ABA a été préparée. Le bloc "A" est représenté par le poly (styrene-co-acrylonitrile), copolymère bloc mécaniquement robuste, et un bloc "B" relativement mou et souple, le poly (ethylene oxide). Lorsqu'une pression est appliquée à la membrane, sa morphologie peut être ajustée grâce à la nature compressible des micelles, ainsi que les ponts dynamiques intermicellaires. Une gamme de porosités accessible peut être régulée par la pression et de manière à contrôler la performance de filtration. La même nature dynamique a également été utilisée pour montrer une réparation autonome entrainée par la pression. L'efficacité du processus de réparation dépend de la taille des fissures, de la valeur de pression et de la durée d'application de la pression. En utilisant la propriété d'auto-réparation de la membrane ci-dessus, le processus « Direct Mode Translocation » de nanoparticules a également été étudié. Quatre classes différentes de nanoparticules ont été utilisées avec diverses propriétés intrinsèques et extrinsèques. Les conclusions de ces travaux prouvent que les caractéristiques de taille, de forme et de surface des nanoparticules ainsi que la force exercée régissent le processus de translocation. Dans une seconde partie, un revêtement 2D et 3D réversible basé sur l'auto-assemblage de micelles de copolymère dibloc constitué d'un poly (methyl methacrylate) (PMMA) et du poly (n-octadecyl methacrylate) (PODMA) blocs a été développé. L'assemblage de micelles est réalisé par l'effet "Zipper", grâce aux longues chaînes pendantes du bloc PODMA. Le même effet "Zipper" permet d'enlever facilement le revêtement par lavage dans un solvant sélectif, donnant ainsi la possibilité de modifier la surface d'un substrat plusieurs fois de manière réversible. La cristallisation à température ambiante du bloc PODMA offre la possibilité d'avoir un revêtement auto-réparable thermiquement sans affecter la morphologie globale des micelles. Enfin, une dernière partie a été conceptualisée, dans laquelle l'auto-réparation se fait par « nano-gel » encapsulés et dispersés dans une membrane. Le « nano-gel » est à base d'un copolymère hydrophile en forme d'une étoile partiellement réticulée et qui doit être synthétisée par la technique de "Reversible Addition-Fragmentation Transfer" (RAFT) polymérisation. La synthèse d'un agent RAFT avec 4 bras pour la polymérisation a été accomplie, cependant, des travaux sont encore nécessaires pour valider la voie de synthèse vers la synthèse de « nano-gel » ainsi que son application pour le processus d'auto-réparationThe objective of this thesis is to develop such kind of polymeric membranes which can repair themselves autonomously in an event of damage. Such damage in a membrane, if left undetected can pose serious health issues in some of the intended applications. In the first approach, a dynamic polymeric membrane based on ABA type triblock copolymer micelles has been prepared. The block “A” is represented by mechanically robust poly(styrene-co-acrylonitrile) copolymer while block “B” by relatively soft and flexible poly(ethylene oxide). When pressure is applied to the membrane, its morphology can be fine-tuned thanks to the compressible nature of micelles as well as intermicellar dynamic bridges. A range of porosities are accessible which can be regulated by pressure and thereby controlling the filtration performance. The same dynamic nature has also been utilized to display an effective pressure driven autonomous healing. The efficiency of healing process has been found to be dependent on the extent of damage, pressure value and time duration of application of pressure. Using the self-healing property of above membrane, “Direct Mode Translocation” of nanoparticles has also been studied. Four different classes of nanoparticles were used with varied intrinsic and extrinsic properties. The findings of the work prove that the size, shape and surface characteristics of the nanoparticles as well as the applied force govern the translocation process. In a second approach, a 2D and 3D reversible coating based on the self-assembly of micelles of diblock copolymer consisting of poly(methyl methacrylate) (PMMA) and poly(n-octadecyl methacrylate) (PODMA) blocks have been developed. The assembly of micelles is accomplished via so called “Zipper” effect, thanks to the long pendant chains of PODMA block. The same “zipper” effect plays the role of removing the coating easily by washing in a selective solvent, thus giving the ability to alter the surface of substrate for many times in reversible manner. The room temperature crystallization of PODMA block provides huge implications for a thermally assisted self-healing coating without affecting the global micelle morphology. Finally, another approach has been conceptualized in which self-healing occurs via encapsulated nano-gel dispersed within a membrane. The nano-gel is based on a partially crosslinked hydrophilic star shaped block copolymer which has to be synthesized by “Reversible Addition-Fragmentation Transfer” (RAFT) polymerization technique. The synthesis of a 4- arm RAFT agent for polymerization has been accomplished however ; a substantial amount of work is still needed to validate the synthetic route towards the nano-gel synthesis as well as its further application for the self-healing process
50
Cotting, Fernando. "Obtenção de microcápsulas poliméricas contendo um agente formador de filme em seu núcleo para o desenvolvimento de revestimentos autorreparadores." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-15012018-143331/.
Full textAbstract:
A aplicação de uma ou mais camadas de tinta sobre as superfícies metálicas é a maneira mais comum e eficaz de proteger os substratos metálicos contra o fenômeno da corrosão. No entanto, os sistemas de pintura podem vir a falhar precocemente por diferentes motivos, causando um ataque corrosivo inesperado no metal a ser protegido. Por esta razão, o processo de repintura em estruturas metálicas é realizado frequentemente para garantir a integridade da estrutura pintada e aumentar sua vida útil. Como o processo de repintura gera impactos econômicos e ambientais, sistemas de pintura capazes de sofrerem uma reparação sem a necessidade de uma intervenção humana, precisam ser desenvolvidos. O encapsulamento de agentes de reparação, com propriedades de formação de filme, em microcápsulas poliméricas é uma excelente alternativa para que os sistemas de pintura se autorreparem, aumentando os intervalos de repintura. Após o processo de encapsulamento, as microcápsulas contendo o agente de reparação são incorporadas na preparação da tinta, para que o sistema de pintura seja aplicado sobre a estrutura metálica. Este tipo de aditivação confere ao revestimento a propriedade de autorreparação, pois quando o sistema de pintura é danificado as microcápsulas são rompidas e liberam o agente de reparação no local danificado, protegendo novamente o substrato metálico. Neste trabalho foi desenvolvido um sistema autorreparador monocomponente, através do microencapsulamento de uma resina a base de éster de epóxi, pelo método de polimerização in-situ. Também foi desenvolvido um sistema autorreparador bicomponente, através do microencapsulamento de uma resina a base de epóxi, pelo método de emulsão e polimerização in-situ de ureia-formaldeído-melamina e do seu endurecedor a base de poliamida, pelo método de extração de solvente em paredes de poliestireno. Foi realizado um planejamento estatístico para estudar a emulsão precursora das microcápsulas de poli(ureia-formaldeído-melamina) contendo o sistema monocomponente, onde foram estudados: o tipo e a velocidade de agitação, a presença de cloreto de sódio na formulação, o uso de uma sonda ultrassônica após a etapa de dispersão, a concentração de tensoativo na formulação e o tensoativo utilizado. Como variáveis de resposta foram determinadas: a estabilidade visual das emulsões e o diâmetro das gotículas formadas. A melhor condição de emulsificação determinada foi utilizada para a obtenção das microcápsulas de poli(ureia-formaldeídomelamina) contendo a resina éster de epóxi e das microcápsulas de poli(ureiaformaldeído-melamina) contento a resina epóxi. Entre as condições de emulsificação estudadas, apenas a condição utilizando o tensoativo goma arábica possibilitou a obtenção das microcápsulas de poli(ureia-formaldeído-melamina) na faixa de diâmetro desejada. O método escolhido para o encapsulamento do endurecedor possibilitou a obtenção de microcápsulas de poliestireno, porém com uma baixa capacidade de armazenamento. A liberação dos agentes de reparação encapsulados foi observada pela microscopia óptica e comprovada pela técnica de espectroscopia na região do infravermelho (FTIR) e pela técnica de espectroscopia Raman. Os aditivos autorreparadores desenvolvidos (mono e bicomponente) foram adicionados separadamente em uma tinta epóxi, nas proporções mássicas em base seca de 10 e 15 %. O sistema de pintura foi aplicado em um esquema de três camadas e o aditivo de autorreparação foi incorporado na primeira e/ou segunda camada aplicada. O sistema de pintura contendo o aditivo autorreparador monocomponente apresentou um aspecto visual melhor do que o sistema de pintura contendo o aditivo autorreparador bicomponente, porém o sistema bicomponente forneceu melhores propriedades de aderência, de impermeabilidade, anticorrosivas e de autorreparação à tinta aditivada. As medidas com as técnicas eletroquímicas de espectroscopia de impedância eletroquímica (EIE) e de varredura com eletrodo vibratório (SVET) comprovaram que os dois aditivos desenvolvidos proporcionaram o efeito autorreparador aos sistemas de pintura aditivados, quando estes foram danificados mecanicamente com uma microbroca ou com um estilete. Ensaios acelerados de corrosão em câmara de névoa salina e ensaios de exposição ao intemperismo natural mostraram que os aditivos desenvolvidos promoveram uma proteção adicional ao aço carbono, quando o sistema de pintura foi danificado mecanicamente.The application of one or more coating layers on the metallic surfaces is the most common and effective way to protect metallic substrates against corrosion. Nevertheless, the coating layer may fail early for different reasons, leading to an unexpected corrosive attack on the protected metal. For this reason, the coating repair process is performed to ensure the integrity during the service life of the coated metallic structures. Due to the fact that coating repair process generates economic and environmental impacts; there is a great need for the development of systems capable to repair themselves, without human intervention. The encapsulation of repairing agents, with film forming properties, in polymeric microcapsules is an excellent alternative to the coating self-repair, decreasing the coating repair process frequency. After the encapsulation process, the microcapsules containing the repair agent are incorporated into the paint preparation and the coating system could be applied normally to the metallic surface. This kind of additivation confers to the coating the self-healing property, because when the coating system is damaged the microcapsules suffers a rupture and release the repair agent into the damaged site, protecting the metallic substrate from corrosion. In this work, a mono-component self-healing system was developed, through the microencapsulation of an epoxy ester resin, by the in-situ polymerization method. A bi-component self-healing system was also developed, by the microencapsulation of an epoxy resin, through the emulsion and in-situ polymerization method and by the microencapsulation of a polyamide hardener, by the double emulsion and solvent extraction method. A factorial design was developed to study the precursor emulsion of the poly (urea-formaldehyde-melamine) microcapsules containing the monocomponent system, where the studied factors were: the type and speed of the agitation, the presence of sodium chloride in the formulation, the use of an ultrasonic probe after the emulsification, the surfactant type and concentration. The analyzed response variables were: the visual stability of the emulsions and the mean diameter of the formed droplets. The best obtained emulsification conditions were employed to produce the poly(urea-formaldehyde-melamine) microcapsules containing the epoxy ester resin and poly(urea-formaldehyde-melamine) microcapsules containing the epoxy resin. Among the studied emulsification conditions, only using arabic gum surfactant the poly (urea-formaldehyde-melamine) microcapsules were obtained. The selected method for the hardener encapsulation was efficient to obtain polystyrene microcapsules, but with low loading capacity. The release of the encapsulated repair agents was observed by optical microscopy and confirmed by infrared spectroscopy (FTIR) technique and Raman spectroscopy technique. The developed self-healing additives (mono and bicomponent) were added separately in an epoxy commercial coating, using the dry mass ratios 10% and 15 %. The coating system was applied in a three layer coating system and the self-healing additive was incorporated into the first and/or second layer. The coated samples containing the mono-component additive had a better visual appearance than the bi-component additive system; nevertheless the bi-component system provided better adhesion, impermeability, anti-corrosion and self-healing properties to the doped coating. The electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET) measurements proved that the two developed additives provided self-healing properties to the doped coating systems, when they were mechanically damaged with a micro drill or a blade. Accelerated corrosion tests in the salt spray chamber and natural atmospheric corrosion tests showed that the developed additives provided an additional protection to the carbon steel, when the coating system has been mechanically damaged.