Dissertations / Theses on the topic 'Acrylic adhesives'

Pressure sensitive adhesives are a category of adhesives which can be used for both permanent and removable applications. The use of radiation to cure these materials prior to application is becoming more widespread due in part to the recent drive to reduce the release of volatile organic compounds and hazardous air pollutants produced from more traditional solvent or thermal curing methods. For the manufacturer, a greater understanding of how these adhesives cure under near to real life conditions is highly desired. This thesis presents the first use of one-dimensional magnetic resonance imaging to provide information on the molecular mobility as revealed by spin relaxation times as a function of depth in cross-linking acrylic adhesives during photoinitiated curing by ultraviolet light. Imperfect curing in these adhesives may lead to crosslink density inhomogeneities and consequently, to variations in the adhesion and cohesion properties throughout the depth of the adhesive. The GARField magnet developed at the University of Surrey, along with a new high temperature sample mounting probe developed during this work allowed thin film samples to be measured at various temperatures with a spatial resolution better than 16 mum. Two separate components were identified in the exponential decay of the NMR signal from the bulk adhesive. These were attributed to the inter-crosslinked network and to lower molecular weight dangling chain ends. Curing was seen to increase the fraction of the shorter component indicative of an increase in crosslink density. GARField profiles showed that formulations with additional multifunctional acrylates produced the highest cure owing to the increased crosslink density afforded by the multifunctional acrylates. However, the addition of these groups also led to a reduced homogeneity in the depth of cure. The inclusion of further photoinitiating species, sensitive to a wider range of wavelengths was shown to reduce this effect. Measurements at 60°C showed that UV irradiation was more efficient at producing crosslinks at this temperature. However, the contrast between cured and uncured samples on GARField was reduced due to the additional, thermally driven molecular motion. The activation energy for this thermal motion was calculated to be 0.34 +/- 0.04 eV and 0.28 +/- 0.05 eV for the uncured and cured adhesives, respectively. The irradiation regime only became important when small doses separated by more than 20 minutes were used. This regime led to sufficient build up of oxygen in the upper surface of the adhesive to inhibit the curing reaction.

Five series of acrylic water-borne pressure-sensitive adhesives (PSA's) were prepared with controlled particle morphologies, including core-shell and continually-varying composition. All latex adhesives were prepared at 50 % solids content by emulsion polymerisation of n-butyl acrylate (BA) and acrylic acid (AA) as the main monomers and 1,6-hexanediol diacrylate (HDA) as a crosslinking agent. Seed particles of poly(butyl acrylate) (PBA) were grown by an in-situ batch process to produce a particle of diameter 110 nm. Direct growth of these particles by a semi-continuous process under monomerstarved conditions was employed to give a final particle diameter of approximately 310 nm. Preliminary investigations were aimed at preparation of a latex with a narrow particle size distribution and a low level of coagulum. Initial work using 2-ethylhexyl acrylate (EHA) as the main monomer was not successful because a stable 50 % solids latex could not be produced with controlled particle growth. Hence a formulation was developed using BA and AA. Three series of latexes were prepared with a core-shell particle morphology. Series 1 involved the investigation of the level of crosslinker in the core, at fixed 45:55 core:shell weight ratio, with HDA levels ranging from 0 to 37.5 mol%. Series 2 investigated the volume fraction of crosslinked core (containing 33.3 mol% HDA) over the range 55:45 to 15:85 core:shell weight ratio. Series 3 investigated the effects of the thickness of a crosslinked shell (9.1 mol% HDA) for core-shell particles with a noncrosslinked core (at 55:45, 75:25 and 90:10 core:shell weight ratios). Series 4 latexes were prepared using power-feed processes, one linear power-feed and three based on Series 1 and 2 core-shell adhesive compositions. An additional latex was prepared with a particle profile in which the composition changed linearly with particle radius. Series 5 adhesives were blends of two latexes, such that the mixture had the same composition as Series 2 core-shell adhesives and consisted of the 'core' of the core-shell adhesive blended with a latex with the same composition as the shell of the respective core-shell adhesive. Latex preparation was controlled and monitored by measuring the particle size and the conversion of monomer to polymer at intervals during the preparation. Thermal properties of the adhesives were investigated for thick film samples by dynamic mechanical analysis {DMA}to measure the glass transition temperature {Tg}. Differential scanning calorimetry {DSC}was also used to measure Tgfor comparison. DMA showed two Tg's corresponding to the core and the shell. As the level of crosslinker was increased, the two Tg's became more discrete due to the Tg of the crosslinked phase increasing. The magnitude of the peaks in loss tangent {tan 5} for the core and shell material changed in accordance with the ratio of core:shell. Power-feed adhesives showed a broad glass transition region, which spanned the regions between the Tg's of the equivalent core-shell adhesive. The peaks in tan 5 for the blended systems were more discrete than for the equivalent core-shell adhesives. Adhesive properties were assessed using shear resistance and 1800 peel adhesion tests. Static shear tests were inadequate for testing highly-crosslinked adhesives; hence a dynamic shear resistance test was developed. In comparison to a uniform {noncrosslinked} poly(butyl acrylate-eo-acrylic acid} (PBAlAA) latex, inclusion of crosslinker led to vastly reduced peel adhesion. However, as the level of crosslinker was increased in the Series 1 adhesives, both the peel adhesion and the shear resistance increased. Series 2 and 3 latexes showed that the peel adhesion increases as the amount of non-crosslinked phase is increased. Series 2 adhesives exhibited a maximum in the shear resistance, while Series 3 adhesives showed a decreased in shear resistance as amount of non-crosslinked! ehe core was increased. Adhesive properties of Series 4 power-feed latex polymers showed no dependence on overall crosslink density, but revealed that there is a dependence on the distribution of crosslinker through the particle.

Os revestimentos cerâmicos aderidos têm grandes vantagens estéticas e funcionais e seu emprego no mercado nacional vem sendo crescente, sobretudo com o uso de placas de porcelanato. Essas vantagens somente se concretizam com uma adequada durabilidade e vida útil, o que não vem ocorrendo com esses revestimentos aplicados em bases sujeitas a deformações e ou movimentações, como o caso de fachadas. Como camada de ligação entre o substrato e a placa cerâmica, as argamassas colantes apresentam papel fundamental para o revestimento cerâmico, tais como: suportar deformações e ou movimentações diferenciais, apresentar resistência mecânica duradoura e ter capacidade de aderir com segurança em qualquer substrato e placa cerâmica. O objetivo desse trabalho foi de estudar o comportamento de argamassas colantes com a aditivação de látex acrílico. Foi realizado um estudo experimental comparativo entre argamassas colantes monocomponentes e argamassas colantes aditivadas com látex acrílico. Para verificar o comportamento que essa aditivação proporciona, foram realizados ensaios de resistência de aderência, flexibilidade, resistência à compressão, resistência à tração na flexão com determinação de módulo de deformação e tempo em aberto com placas de porcelanato. Os resultados mostraram de uma forma geral que a aditivação de argamassas colantes proporcionam aumento significativo na flexibilidade. Ocorre melhora na resistência de aderência, resistência à compressão e resistência à tração na flexão e também na capacidade de absorver deformações com o aumento do teor de polímero/argamassa. A aderência em placas de baixa porosidade como o porcelanato é melhorada e o tempo em aberto de laboratório também é estendido para as argamassas modificadas com látex.
The directed adhere ceramic tiles has aesthetic and functional advantages, and its use in the national market is increasing specially with the use along with porcelain tile. These advantages can only be seen though, if the system has adequate durability and service live, which doesn\'t happen once it is applied on irreversible or cyclic movement basis as building façades. As the clingy layer between the ceramic tile and the substrate, the tile adhesives have fundamental importance for the directed adhered ceramic tile, working on deformation and movements support capability, long-term durability mechanic resistance and safety and reliability to adhere on all type of substrates and ceramic tile. The purpose of this work was to study the behavior of dry set mortar modified with acrylic latex. An experimental study has been done, comparing dry set mortar to acrylic latex Portland cement mortar. To verify the behavior that the latex provides, the following tests were realized: tensile bond adhesion, deformability, compressive strength and tensile strength with deformation modulus and open time with porcelain tile. The results showed in general, that the latex improved the flexibility of dry set mortar and the improvement of the tensile adhesion, compressive and tensile strength and deformability capacity by increasing the polymer/mortar content. The adhesion and open time in porcelain tile has been improved with latex Portland cement mortar.

Des adhésifs sensibles à la pression (PSAs) acryliques industriels, des polyacrylates et polyméthacrylates de n-alkyles modèles, ont été étudiés principalement par RMN (résonance magnétique nucléaire) du solide. Le but à long terme est de comprendre l'influence des propriétés microscopiques sur l'adhésion. Notre contribution est l'apport d'outils analytiques pour la caractérisation du branchement, de la dynamique locale et de l'hétérogénéité dynamique. Après comparaison de plusieurs techniques de RMN 13C, une méthode de quantification du branchement dans les poly(acrylates d'alkyles) par irradiation simple de l'échantillon fondu sous rotation à l'angle magique (MAS) a été proposée. Cela a permis la première estimation fiable du branchement dans les poly(acrylates d'alkyles) et est applicable directement aux échantillons industriels réticulés et multi-composants. Cela facilitera la compréhension du procédé de polymérisation. Dans le cadre d'une meilleure compréhension du mécanisme d'adhésion, une méthode de chromatographie d'exclusion stérique (SEC) multi-détection a été proposée pour la détection des longues branches (LCB) dans les poly(acrylates d'alkyles) solubles. L'utilisation de la RMN du solide pour la quantification sélective de mouvements locaux dans des polymères fondus sans marquage isotopique a été étudiée. La technique expérimentale est la même que celle de la diffusion de spin 1H conventionnelle avec filtre dipolaire, beaucoup utilisée antérieurement pour quantifier la taille d'hétérogénéités dynamiques dans des polymères ayant un fort contraste dynamique. Dans les poly(acrylates d'alkyles) et les poly(méthacrylates de n-alkyles), qui présentent un contraste dynamique faible au sein de l'unité monomère, la dynamique entravée des chaînes latérales dans les nanodomaines alkyles a été quantifiée via une analyse de relaxation croisée
Industrial acrylic pressure sensitive adhesives (PSAs), poly(n-alkyl acrylate) and poly(n-alkyl methacrylate) model samples were investigated using predominantly solid-state NMR (nuclear magnetic resonance). The long term goal is to understand the influence of their microscopic properties on adhesion. Our contribution was to provide analytical tools to characterize branching, local dynamics and dynamic heterogeneity of poly(alkyl acrylates). Several 13C NMR techniques were compared for branching quantification in poly(alkyl acrylates) and single pulse excitation of the molten sample under magic angle spinning (MAS) was proved to be the most accurate. This provided the first reliable estimate of branching in poly(alkyl acrylates) and is directly applicable to crosslinked and multi-component industrial samples. This will help the understanding of the polymerization process for these samples. In the context of a better understanding of the adhesion mechanism, an alternative method of multiple detection size exclusion chromatography (SEC) was presented to detect long branches (LCB) in soluble poly(alkyl acrylates). Extensive experimental and theoretical work will be necessary to obtain quantitative results. The use of solid-state NMR to quantify local motion of specific chemical sites in non isotopically labeled polymeric samples in the melt was investigated. The experimental scheme is the same as conventional 1H spin diffusion with dipolar filter, previously widely used to quantify the size of dynamic heterogeneities in polymeric samples exhibiting a strong dynamic contrast. In poly(alkyl acrylates) and poly(alkyl methacrylates) with a weak dynamic contrast within the monomeric unit, the hindered dynamics of the side chains in alkyl nanodomains was quantified via cross-relaxation analysis

White spot lesions (WSL) are a common complication with fixed orthodontic treatment. Fluoride incorporation into orthodontic adhesives is an effective way to prevent WSL. New fluoride releasing adhesives are being developed for this purpose. Four experimental groups were prepared by mixing different ratios of powder (polymethylmethacrylate and sodium fluoride; 10:0, 9:1, 8:2 and 7:3 wt) with liquids (60% methylmethacrylate and 40% 2-hydroxyethylmethacrylate). Therefore, this work aimed to further develop the fluoridated acrylic resin materials for possible use as an orthodontic adhesive. Acetone was added at 0%, 10%, 20%, 30% and 40wt% to reduce the materials’ viscosity. Addition of acetone up to 20% did not have detrimental effects on setting characteristics. The materials continued to release fluoride over 160 days. Different photo-initiators were investigated and the 1% camphorquinone and 1% 2-Dimethylamino ethyl methacrylate group was chosen for further development based on achieving the highest degree of conversion (DoC) at 40s of light curing. To improve bonding characteristics 4-methacryloyloxyethyl trimellitate anhydride (4-META) was added as an adhesion promoting monomer at 0% and 5wt%. The experimental materials were compared with a resin-based orthodontic adhesive (TransbondTMXT) and a glass ionomer cement (KetacTM Cem) as commercial comparator. DoC, fluoride release and recharging, water sorption and solubility were measured. Shear bond strength (SBS) was measured for the 9:1 group at two time points after 30 minutes and 30 days of insertion in phosphate buffered saline. All experimental materials had significantly higher DoC than TransbondTMXT. All experimental materials had comparable or higher fluoride release compared to KetacTM Cem. All of the developed materials showed similar recharge behaviour to the KetacTM Cem specimens. The solubility of the materials increased with increasing NaF concentrations. SBS of the experimental materials were significantly decreased at 30 days water storage compared to 30 minutes and were lower than TransbondTMXT. Addition of 4-META and NaF did not influence the SBS of the material. In summary, the developed light-cured fluoridated material showed good fluoride release and high recharge ability, which may prevent WSL. The developed material shows good DoC, in a reasonable timeframe, which would indicate stability. However, as a result of high water sorption and as a consequence of fluoride release, the SBS of the materials decreased after being in water. In conclusion, this material shows potential as a fluoride releasing orthodontic adhesive, which could help to reduce decay during fixed appliance treatment. Further work is required to iii improve the stability and bond strength of the material, which could involve investigation of different monomer combinations or different fluoride sources.

This dissertation describes a new vinyl-acrylic copolymer that displays great potential for applications in lithium ion batteries by enabling novel, faster, safer and cost-effective processes. Understanding the chemistry of materials and processes related to battery manufacturing allows the design of techniques and methods that can ultimately improve the performance of existing batteries while reducing the cost. The first and second parts of this dissertation focuses on the free radical polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA), methyl methacrylate (MMA), and isobutyl vinyl ether (IBVE) monomers to afford a vinyl-acrylic poly(PEGMA-co-MME-co-IBVE) random copolymer and the investigation of its properties as a soluble, amorphous, and adhesive electrolyte that is able to permanently hold 800 times its own weight. Such material properties envision a printable battery manufacturing procedure, since existing electrolytes lack adhesion at a single macromolecular level. Electrolytes can also be used as an electrode binder so long as it has structural integrity and allows ion transfer to and from the active electrode material during insertion/extraction processes. In the third section, the use of this electrolyte as a water-soluble binder for the aqueous fabrication of LiCoO2 cathodes is presented. Results of this study demonstrated the first aqueous process fabrication of thick, flexible, and fully compressed lithium ion battery electrodes by using commercial nickel foam as a supporting current collector. This feat is rather impressive because these properties are far superior to other aqueous binders in terms of material loading per electrode, specific area capacity, durability, and cell resistance. Finally, the fourth section expands on this concept by using the poly(PEGMA-co-MMA-co-IBVE) copolymer for the aqueous fabrication of a low voltage Li4Ti5O12 anode type electrode. Altogether, results demonstrate as a proof of concept that switching the current toxic manufacturing of lithium-ion batteries to an aqueous process is highly feasible. Furthermore, new electrode manufacturing techniques are also deemed possible.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

The performance of connections and full-scale shear walls constructed with acrylic foam pressure sensitive adhesive (PSA) tape is the focus of this thesis. The objectives of this study were first to investigate the bonding characteristics of adhesive tape to wood substrates and then to expand this investigation to cover adhesive-based shear walls subjected to high wind and seismic loadings. A total of 287 monotonic connection tests and 23 reversed cyclic wall tests were performed to achieve these objectives. Connection tests were performed in accordance with ASTM D 1761-88 (2000), and walls were tested using the CUREE (Consortium of Universities for Earthquake Engineering) general displacement-based protocol.

Variables investigated within the main study were the following: the use of OSB versus plywood sheathing, the effect of priming and surface sanding on adhesion, and the comparison of connections involving mechanical fasteners with those that utilized only adhesive tape or a combination of the two. It was found that an application pressure of 207 kPa (30 psi) or greater was needed to form a sound bond between the acrylic foam adhesive tape and a wood substrate. Properly bonded OSB and plywood connections provided fairly ductile failure modes. Full-scale walls constructed with adhesive tape performed similarly to traditional wall configurations, while walls constructed with a combination of adhesive tape and mechanical fasteners provided significant gains in strength and toughness. The results of this study serve to provide a foundation for expanding the engineering uses of acrylic foam adhesive tape for structural applications.
Master of Science

El polidimetilsiloxano (PDMS) es un polímero amorfo en base inorgánica con grupos pendientes que le imparten hidrofobicidad que es ampliamente utilidado en aplicaciones biomédicas. Debido a la baja energía superficial del PDMS, su adhesión es pobre. En algunas aplicaciones biomédicas (catéteres, prótesis) se requiere adhesión para lo cual se modifica superficialmente. Los plasmas generados en condiciones de no-equilibrio, también llamados plasmas fríos, han sido utilizados en el tratamiento superficial de PDMS para aumentar su energía superficial, pero las modificaciones producidas son poco estables, produciéndose una rápida recuperación de la hidrofobicidad (hydrophobic recovery). La estabilidad de las modificaciones superficiales del PDMS depende de las características del plasma utilizado para su tratamiento, por lo que el objetivo de la tesis doctoral se centra en la utilización de diferentes tipos de plasmas fríos para modificar las propiedades superficiales de PDMS de manera que simultáneamente se aumente su estabilidad y se mejore su adhesión. Otro aspecto innovador en el estudio consiste en la discriminación y optimización de las condiciones de tratamiento con plasma utilizando un diseño estadístico de experimentos, lo que he permitido modelar el efecto del tratamiento con plasma de superficies de PDMS empleando los ángulos de contacto y la química superficial como variables respuesta. Se ha estudiado el efecto de los diferentes tipos de plasma en la hidrofobicidad y la energía superficial del PDMS mediante medidas de ángulo de contacto. Las modificaciones en la química superficial han sido evaluadas usando espectroscopia infrarroja en modo de reflectancia total atenuada (FTIR-ATR) y espectroscopia fotoelectrónica de rayos X (XPS), mientras que los cambios en la morfología y nanorugosidad superficial se monitorizaron usando microscopía electrónica de barrido (SEM) y microscopía de fuerza atómica (AFM). Las propiedades de adhesión del PDMS se evaluaron mediante ensayos de adhesión en pelado en T y de cizalla a solape simple, utilizando un adhesivo sensible a la presión (PSA) en base acrílica para uso médico. Estas propiedades fueron además monitorizadas en función del tiempo tras el tratamiento con plasma para determinar la estabilidad de las modificaciones producidas. En general, el tratamiento superficial de PDMS con plasma produce oxidación de las cadenas de polisiloxano por sustitución de los grupos metilo por grupos hidroxilo, lo que aumenta la polaridad y la energía superficial, incrementando las propiedades de adhesión. Se produce el entrecruzamiento de cadenas mediante condensación de los grupos hidroxilo, formando una delgada capa superficial con estructura de sílice. Cuando las características del plasma son demasiado agresivas aparecen grietas superficiales favoreciendo la recuperación hidrofóbica por difusión de especies apolares desde el seno del PDMS hacia la superficie, así como por la reorientación de los nuevos grupos polares en la superficie hacia el seno del material. Este fenómeno se minimiza optimizando las condiciones de tratamiento empelando un diseño estadístico de experimentos. En sistemas de generación de plasma a baja presión, tratamientos con baja potencia durante largos tiempos mejoran la funcionalización de la superficie del PDMS, y el uso de mezclas de argón y oxígeno como gas plasmógeno resulta más efectivo que el empleo de los gases puros; la presión de trabajo tiene un papel fundamental en la estabilidad de las modificaciones producidas. En sistemas de antorcha de plasma atmosférico el tiempo de tratamiento y la distancia de la boquilla a la superficie son los parámetros más relevantes en la oxidación superficial del PDMS, mientras que en sistemas de plasma atmosférico de doble barrera dieléctrica, el voltaje, el tiempo de tratamiento y la distancia entre electrodos son las variables críticas en la efectividad del tratamiento superficial. Finalmente, la deposición de monómeros mediante antorcha de plasma permite generar nanoestructuras superficiales en el PDMS aportándole características de superhidrofobicidad.

Proteins represent major constituent of the extracellular matrix which plays an important role in the formation, maintenance and remodeling of tissues, this project focuses on adsorption of two specific serum proteins fibronectin (FN) and vitronectin (VTN) responsible for mediating cell matrix interaction through integrin binding, tripeptide Arg-Gly-Asp (RGD) sequence found in these protein features are recognized by αβV3 integrin which ultimately helps in clot formation.

L’utilisation des adhésifs dans le domaine médical prend de plus en plus de place jusqu’à leur utilisation par le grand public pour refermer certaines plaies superficielles. Les adhésifs les plus courants pour applications médicales sont formulés à partir d’hydrogel voire de silicone, prêts à l’emploi, très peu étant associés à une préparation particulière avant application comme c’est le cas dans le domaine dentaire avec l’utilisation de la photo-polymérisation. Notre travail de recherche a consisté à formuler des adhésifs photo-polymérisables permettant un collage résistant sur les tissus biologiques internes et à comprendre les mécanismes permettant d’aboutir à un collage de bonne qualité en tenant compte des contraintes fortes liées à l’application visée : (i) milieu humide dans lequel sera disposé l’adhésif, (ii) nature viscoélastique des tissus biologiques et (iii) facilité de mise en œuvre. L’ensemble des expériences a été mené sur un substrat considéré comme « modèle », le péricarde bovin, dont il a été montré que les propriétés mécaniques sont similaires à celles du péricarde humain. Ce travail a démontré que l’adhésion sur un tissu interne est dépendante de plusieurs paramètres. Pour assurer un bon collage, il est nécessaire que l’adhésif mouille le tissu biologique et pénètre suffisamment pour assurer un bon ancrage mécanique. De ce fait, des formulations adhésives à base d’acrylates de faible viscosité ont été réalisées. Nous avons montré que l’énergie d’adhésion développée diminue linéairement avec la viscosité de l’adhésif avant photo-polymérisation. Ce résultat a mené à l’hypothèse de la pénétration de l’adhésif dans le péricarde, validée par plusieurs techniques. Nous avons ainsi démontré le lien entre une adhésion forte sur un tissu biologique, la viscosité initiale de la solution adhésive et sa capacité à pénétrer le substrat. L’ensemble de ce travail a mené à la compréhension des mécanismes induits par le dépôt d’un monomère sur un substrat vivant et à des hypothèses sur la polymérisation de la couche adhésive et son interaction avec le substrat. Des expériences in-vivo sur différents organes de souris et de lapins ont permis de montrer des résultats prometteurs qui ne demandent qu’à être confirmés par une étude systématique à plus grande échelle. Enfin, une description phénoménologique est proposée au travers d’une équation simplifiée tenant compte de différents paramètres essentiels pour décrire les mécanismes en jeu
Adhesives are more and more used by the public to seal superficial wounds. The current adhesives for medical use are formulated on the basis of hydrogels, silicon and are ready to use. Only a few of them are associated to a particular preparation before application as the dental adhesives. The main goals of this research were to formulate some photo-polymerizable adhesives which induce a permanent strong anchorage into the internal biological tissues and to understand the mechanisms leading to a good quality adhesion and respecting the high constraints of the application: (i) the wetness of the media in which the adhesive is deposited, (ii) the viscoelasticity of the biological tissues and (iii) the easiness of the set up. The whole experiments were done onto a substrate considered as a “model”, the bovine pericardium, which was demonstrated to have the same mechanical properties as the human pericardium. This study showed that the adhesion onto internal tissue depends on several parameters. To create the adhesion, the adhesive has to wet and penetrate deep enough the tissue to get a strong mechanical anchorage. Thus, some low viscous acrylate-based adhesive formulations were realized. A linear correlation was found between the viscosity of the formulation before photo-polymerization and the adhesion energy: as the viscosity increases, the adhesion energy decreases. This result led to the hypothesis of the penetration of the adhesive into the tissue, which was proven by different techniques. Finally, it was proven that a strong adhesion onto a biological tissue depends on the viscosity and its capability to penetrate the substrate. This whole work led to the understanding of the mechanisms induced by the deposit of a monomer onto a living substrate and to some hypotheses about the polymerization of the adhesive layer and its interaction with the substrate. Some in-vivo experiments onto internal organs of mice or rabbits have shown promising results which are to be confirmed by multiple other experiments. Finally, a phenomenological description is proposed through a simplified equation takin into account different essential parameters to describe the mechanisms taking part into this phenomenon

Les travaux de cette thèse répondent à une motivation fondamentale, dans la mesure où on essaie d'établir une corrélation entre le pouvoir adhésif des polymères et leurs propriétés rhéologiques, physico-chimiques, et a un besoin industriel d'autre part, puisque nous avons étudié une application originale : le pelage sur la peau humaine de bandes adhésives pharmaceutiques. Deux familles d'adhésifs, à base de copolymères à blocs styreniques, et à base d'acryliques éventuellement réticules, sont enduits sur des supports de polyester. Ces bandes adhésives sont appliquées sur des substrats rigides (verre, acier, plexiglas), préalablement traités selon un protocole adapté. Une machine de pelage spécifique conçue au laboratoire, permet de maintenir le front de pelage fixe, et d'en faciliter l'observation. Elle fonctionne dans une enceinte à température et humidité contrôlées. Les mesures de la force de pelage, de la vitesse de pelage, et la visualisation détaillée du front de décollement sont effectuées simultanément. Ainsi les différents mécanismes d'écoulement dans la zone de décollement ont été identifiés en relation avec les courbes maitresses de pelage cohésif ou adhésif dans une large gamme de vitesses et de températures. L'influence de la rugosité, du substrat, de la réticulation du polymère, de l'humidité de l'atmosphère, ont été mis en évidence. Par ailleurs, la caractérisation aréométrique des adhésifs a été faite en cisaillement dynamique et en élongation uniaxiale. La physico-chimie du problème a aussi été prise en compte, et nous avons déterminé les énergies de surface des adhésifs et substrats. A la lumière des essais de visualisation qui montrent la prédominance des effets elongationnels au niveau du front de pelage, et des observations optiques du dos du support qui ont permis de constater que l'énergie est principalement dépensée dans les cordages ou filaments, nous avons proposé une corrélation de l'énergie de pelage avec les effets elongationnels. Enfin, nous proposons une relation plus générale entre l'énergie de pelage et les différents paramètres rhéologiques et physico-chimiques sous une forme adimensionnelle. En outre, la condition de transition de la rupture cohésive a la rupture adhésive est présentée sous la forme d'une loi adimensionnelle. Enfin, une application originale du pelage de bandes adhésives sur la peau humaine est présentée

博士
逢甲大學
化學工程學所
100
The purpose of this study was to modify the polymerization of Polymethylmethacrylate (PMMA) pressure-sensitive adhesives, in order to improve the heat and weathering resistance properties of acrylic adhesives. There are two methods to modify the polymerization of Polymethylmethacrylate (PMMA) pressure-sensitive adhesives. The one method is chemical modify, and the other one is physical modify. First, for chemical modify, a sol-gel method was adopted to hydrolyze the silicon precursor tetraethoxysilan (TEOS) so as to obtain silica with an -OH functional group. This was further confirmed by a Fourier Transform Infrared Spectrophotometer (FT-IR). The polymerization of acrylic pressure-sensitive adhesives was then carried out, in which hydrolyzed silica acid-alcohol was added into the reactor in order to complete the modification of adhesives. An FT-IR was used to confirm that the adhesives contained an Si-O-Si functional group, while SEM’s observation on the coatings of pressure-sensitive adhesives showed satisfactory dispersion of silica. Coatings of acrylic pressure-sensitive adhesives containing SiO2 were used to produce label, and were tested for heat and weathering resistance, along with other physical properties. The results showed that the heat resistance properties of pressure-sensitive adhesives containing SiO2 were significantly improved. In terms of adhesion, after extended UV irradiation, it was proved that pressure-sensitive adhesives containing SiO2 could prolong the recession of physical properties under severe UV conditions. The resistance to heat could be improved to more than 260℃, which is better than regular acrylic pressure-sensitive adhesives. The other study is to add hydrolysis of the silica in the polymerization of latex acrylic pressure-sensitive adhesive, The resistance to heat could be improved to more than 120℃. Adding nano-silica for the aggregation of latex acrylic adhesives strength and temperature performance results more apparent. These results can provide assistance in the improvement of the physical properties of acrylic pressure-sensitive adhesives in the future. For the physical modify, The study of surface chemical modification of SiO2 nanoparticles by silane coupling agent and their effect on the thermal and physical properties of acrylic pressure-sensitive adhesive (PSA) was discussed in this work. Aminopropyl triethoxysilane was chosen as the coupling agent and was first hydrolyzed and then condensation with the surface －OH group of SiO2 to modify the nanoparticles.The surface chemical modification of SiO2 nanoparticles was confirmed using the FT-IR spectroscopy. The hydrophobicity of these silane-modified SiO2 and their compatibility with the PSA were further confirmed by the good particle dispersion result from the SEM analysis. After applying the SiO2-modified PSA to bike label, thermal and UV stability tests were conducted to evaluate the doping effect of nanoparticles on the performance of acrylic PSA. It was found that both thermal and UV stability of PSA were significantly improved with the addition of SiO2 nanoparticles. The effect of this improvement was highly significant especially for high molecular weight acrylic PSA. Though the adhesion strength of PSA was found to decrease slightly with the addition of SiO2 nanoparticles, the UV resistance effect was highly improved especially for low molecular weight acrylic PSA. The SiO2-modified PSA has been found in this work to be a promising way to improve the performance of acrylic PSA. Key word:SiO2, Sol-gel, Polymerization, acrylic pressure-sensitive adhesives, SiO2 nanoparticles

碩士
逢甲大學
材料與製造工程所
94
The study of surface chemical modification of SiO2 nanoparticles by silane coupling agent and their effect on the thermal and physical properties of acrylic pressure-sensitive adhesive (PSA) was discussed in this work. Aminopropyl triethoxysilane was chosen as the coupling agent and was first hydrolyzed and then condensation with the surface －OH group of SiO2 to modify the nanoparticles.The surface chemical modification of SiO2 nanoparticles was confirmed using the FT-IR spectroscopy. The hydrophobicity of these silane-modified SiO2 and their compatibility with the PSA were further confirmed by the good particle dispersion result from the SEM analysis. After applying the SiO2-modified PSA to bike label, thermal and UV stability tests were conducted to evaluate the doping effect of nanoparticles on the performance of acrylic PSA. It was found that both thermal and UV stability of PSA were significantly improved with the addition of SiO2 nanoparticles. The effect of this improvement was highly significant especially for high molecular weight acrylic PSA. Though the adhesion strength of PSA was found to decrease slightly with the addition of SiO2 nanoparticles, the UV xanthosis resistance effect was highly improved especially for low molecular weight acrylic PSA. The SiO2-modified PSA has been found in this work to be a promising way to improve the performance of acrylic PSA.

碩士
逢甲大學
材料與製造工程所
96
The purpose of this research mainly is to study the effect of SiO2 nanoparticles on the heat- and UV-resistant properties of the acryl pressure-sensitive adhesives. It is found that these properties and the adhesive performance for non-polar surface of the acryl pressure-sensitive adhesives were highly improved by the modification of SiO2 nanoparticles. In the study, SiO2 nanoparticles were firstly obtained by using sol-gel method with the precursor of TEOS. The hydroxyl surface of the prepared SiO2 nanoparticles was identified by FT-IR. Secondly, the prepared SiO2 nanoparticles were added into the reactor during the PMMA polymerization reaction to obtain the SiO2-modified acryl pressure-sensitive adhesives. The Si-O-Si bonding structure in the resulting acryl adhesives was also identified by FT-IR. SEM was adopted to examine the morphology and the dispersion of SiO2 nanoparticles in adhesive films. Good dispersion and transparency of the adhesive films was also proven by UV-Vis spectroscopy. Applying the SiO2-modified acryl pressure-sensitive adhesive to the bicycle trademark paper sticker, it shows excellent heat- and UV-resistant properties. The heat-resistant property was largely improved from 150℃ to above 200℃. Negligible color change was also confirmed by the long-term UV illumination. Both heat- and UV-resistant properties of the SiO2-modified acryl pressure-sensitive adhesive were shown better than that of the current commercial acryl pressure-sensitive adhesives. These findings will be beneficial to the improvement of future acryl pressure-sensitive adhesives.

碩士
長庚大學
化工與材料工程學系
99
This study was to investigate the influence a of various curing agents on the thermal-induced cross linking of the solvent-type of acrylate pressure sensitive adhesives (PSAs), which were prepared by the polymerization of acrylate monomers. Meanwhile, the influence of the intensity of UV light on the cross linking of the UV-type of acrylate PSA was also investigated. The adhesion, initial adhesion, cohesion, and environmental stability of the acrylate PSA on the polarizer were analyzed. The cross-linking degrees on the elastic and creep properties of acrylate PSA were measured by rheometer and thermomechanical analyzer. The influence of PSA on the light leakage of liquid crystal display (LCD) panel was also investigated by color analyzer. From the experimental results, the adhesion of Thermal Curable acrylate PSA was greatly increased by the addition of isocyanate curing agent and the less light leakage of LCD panel was obtained for the addition of Al chelate compound agent. For the UV-type acrylate PSA, the adhesion decreased with the increasing of UV light intensity. Meanwhile, the G’ value of UV-type acrylate PSA was higher than that of solvent-type PSA, resulting in the stronger stiffness and the less light leakage.

碩士
元智大學
化學工程學系
93
The use of the emulsion polymerization to prepare the water-borne acrylic Pressure-Sensitive Adhesives is studied. The effects of the monomer ratio（BA（Butyl Acrylate）/2-HEMA (2-Hydroxyethyl Methacrylate) and BA/MA-L (Methyl Acrylate), the concentration of the SPS （Sdium Persulfate）initiator, and the doping time on the molecule weight, particle diameter, thermal stability of latex, and the adhesion properties of the PSAs (such as tack, peel strength, and cohesion) are analyzed. It is obtained that the increase of 2-HEMA concentration would result in the increase of the tack and cohesion but a decrease of the peel strength of the PSAs. The use of MA-L causes a decrease of the particle size of the latex. In addition, the improvement of the thermal stability and the cohesion but accompanied by the decreases of tack and peel strength are obtained from MA-L formulated PSAs. Moreover, the larger the amount of initiator SPS are used, the lower the molecular weight, the particle size, and the tack, but the greater the peel strength and the cohesion are obtained. Regarding the doping time of the monomer, a decrease of the doping time causes the increase of the molecular weight and particle size of the latex, and the improvement of the tack and peel strength of the PSAs. Yet a deterioration of the cohesion is found by using a shorter doping time during the polymerization.

碩士
國立高雄應用科技大學
化學工程與材料工程系
99
Epoxy-acrylic based UV-light-curable electrically conductive adhesives (Ag-ECAs) were formulated from epoxy-acrylic resin, silver nanoparticle and silver nanowire in which silver nanoparticle was prepared by in-suit reduction of silver nitrate (AgNO3) with N,N’-dimethylformamide (DMF). As for 1 ~ 3M AgNO3/DMF solution, silver nanoparticles are efficiently reduced by DMF with diamteter of about 30 ~ 40 nm, the surface plasma resonance characteristic peak appeared in the UV-vis spectrum in the vicinity of 420 nm. The particle size of prepared silver nanoparticle is independent of AgNO3 concentration but depends on silver nanoparticle loading. At 30 ~ 40 wt% silver nanowire loading, silver nanoparticle and silver nanowire present significantly synergistic effect in conductivity, results in the lowest resistance of cured Ag-ECAs. As for 1M AgNO3/DMF solution and 30 wt% silver nanowire loading, the crystal size of silver nanoparticle increases with increasing temperature, the resistance of cured Ag-ECAs become depressed because of metallurgical bond formation.

碩士
國立臺北科技大學
機電整合研究所
101
To increase the more function of electrical products, the more power is required. It makes the thermal shutdown of electrical products. This research featuring the self-made thermal tape. Modified the thermal powder by the coupling agent ordispersing agent, which thermal conductivity is better than commercial products (1.0 w/mk). 　　The synthesis of this study is to use a kind of acrylic Pressure Sensitive Adhesive (PSA),which is by using 2-Ethylhexyl acrylate、Butyl Acrylate and Polyvinyl acetate as monomers, in this experiment, we compared the difference ofpolyisocyanate、melamine and dicumyl peroxide crosslinker. To compensate the lowadhesion, use of self-made thickener. The mixture is filled of AlN and Al2O3 thermal powderto fabricate thermal tape. 　　In this reaserch, the solid loading 55wt.% of AlN andAl2O3 which hadcoated by peg40. It’sthermal conductivity is 1.55w/mk. The adhesion is 1690gf, tack is 1520 gf and the cohesion can hold for 72 hours, thermal weight loss of 0.8%. It’s performance is good enough to compete with the commercial product. The thermal conductivity of commercial product is 0.8-1 w/mk. The adhesion is 1300-1800 gf.Thermal weight loss of 1%. 　　The thermal tape through 50 hot and cold shock thermal conductivity decrease of approximately 5-7 %, and surface is intact and not foundbubbles.

碩士
國立臺北科技大學
有機高分子研究所
97
This paper mainly discusses the two-liquid type acrylic structure adhesive can be part to replace the epoxy glue. Given the current market the two liquid type epoxy structure adhesives storage stability and the expiration date than acrylic plastic storage stability and the Expiration date of good, but it can’t fast-curing at room temperature ; the plan''s to study to replace the epoxy structure glue, can be at room temperature fast-curing, but also to have long-term preservation of the date of acrylic structural adhesive. However, the structure of acrylic plastic at room temperature to preserve the date of the short, to be stored at low temperatures, it is to add anti-oxidants, so that the structure of acrylic plastic at room temperature for a better shelf life for 6 months, but the physical nature and mechanical properties after storage for 6 months is similar to the original. This study found that when acrylic structural adhesive does not add anti-oxidants, the MMA：2-HEMA for different weight ratio to test the storage stability and thermal stability. Experimental study found that the volume of 2-HEMA add more equipment to DSC, remoter equipment analysis, glue after 3 months storage at room temperature environment for the conduct of the test, the endothermic maximum peak temperature and viscosity of the lower value the more high, this shows that the process of dispensing their own time response has been slow. Then several of the baking oven electronic acceleration aging test, the mobility of the liquid slowly deteriorated, or gel (gel) the shorter the time. When the MMA : 2-HEMA for the 100：0 and 90：10 weight ratio of the base when the formula did not add anti-oxidants of accelerated aging test of time than other to-weight ratio of the best, but for the MMA : 2-HEMA 100：0, the reaction of curing time slightly slower, so experiment to study MMA : 2-HEMA for the 90：10 test. Therefore, MMA : 2-HEMA for the 90：10 weight ratio of formula to add different types of anti-oxidants, the experimental study of a single antioxidant know to add, after the accelerated aging test did not add to the storage stability prior to a slight increase in However, after six months, and its poor storage stability. The last change to add two phenolic antioxidants, its storage stability and mechanical properties similar to those with no major changes in the original recession.

碩士
國立臺北科技大學
化學工程研究所
100
Replacing solvent base acrylic adhesives by a more environmental friendly water base system for not only market cost competition, but rather more importantly for benign considerations in pressure-sensitive adhesive industry has been prevailing and imperative. Generally water-based acrylic system itself can not be regarded as environmental even though there is no solvent due to the fact of certain ingredients such as Nonylphenol polyethylene glycol ether (NPEO) will decompose to Nonyl Phenol(NP) in which its structure to be similar to human hormones that will interfere with own endocrine system. Eventually the development of individual organisms; constant maintenance and reproductive role; and health of future generations will be affected. Generally, yellowing resistance and water resistance for water base system are also a disadvantageous due to the nature of the composition ingredients itself. In lieu of this, main objective of this thesis will be focused on environmentally friendly; yellowing resistance; and water repellant performance. Also, relationship among all experimental variables will be studied so as to obtain an optimum reaction formula. Adhesive formula prepared by a monomer ratio of n-butyl acrylate(BA): acrylic acid(AA): 2-Ethylhexyl acrylate(2EHA) of 96:2:2; the temperature at 76 ℃; stirring speed of 140 rpm; and under the reaction time of 5 hours can obtain an overall better performance . The basis of formulation conditions were further modified by emulsifier, initiator, reducing agent, neutralizing agent, antioxidant, defoamer, and leveling agent. Using different type of emulsifiers, reactive and non-reactive, to compare adhesive properties and water repellant ability were studied and evaluated. Adhesive force(ATS) and Cohesive force (COH) of each composition using different amount of initiators, reducing agents and oxidation agents were detailed analyzed in this thesis. Antioxidants effect to yellowing resistance was implemented.

碩士
逢甲大學
化學工程研究所
79
The main purpose of this study is to investigate the effect of silicic coupling agent on acrylic pressure-sensitive adhesive (PSA). The silicic coupling agent was synthesized as follows: At first, sodium metasilicate is acidified by hydrochloric acid, the silicic acid is then partially reacted with ethanol to obtain silicic acid ester. The silicic acid ester mixture is extracted from the aqueous solution by tetra-hydrofurane. The extractantis reacted with the product obtained from the reaction of 2,4-toluene diiso-cyanate and 2-hydroxyethyl methacrylate in order to synthesize silicic coupling agent. Acrylic pressure-sensitive adhesive (PSA) is a polyacrylate resin blended or copolymerized with coupling agent. In some samples, different kind of silica was filled for the purpose of reinforcement. The polymerization type adopted in this study is solution ploymerization. The behaviors of a pressure-sensitive adhesive may be understood by measuring the following three properties: shear strength(creep resistance), peel strength and tack(stickness). It was observed from the experiments that shear strength of the PSAs copolymeried or those blended with coupling agent was increased, but peel strength of these two cases was decreased, tack of the copolymer was also decreased, but tack of the blended PSAs depends on the content of the coupling agent. Because the dispersion of the filled silica is poor, the properties were decreased in most of the conditions.

碩士
朝陽科技大學
應用化學系碩士班
92
Abstract The synthesis of acrylic adhesion is by using methyl methacrylate (MMA), butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA) as monomer. The 2,2’-Azobisisobutyronitrile (AIBN) is used as the initiator to generate free radicals, when the temperature reach to its reaction temperature, the free radical polymerization taking place at the presence of ethyl acetate and continue agitating. The amount of initiator added in the reaction can effect the size of molecule weight, the use of different monomers type and its ratio can effect the hardness of acrylic polymer, the Tack, Adhesion and Cohesion of acrylic adhesion can be changed by controlling the molecule weight and hardness. Thus the acrylic adhesion with required properties can be obtained. To modify the acrylic adhesion is the purpose of this study. Different type of water absorbent polymer is added into acrylic adhesion by 2% weight. The Tack, Adhesion and Cohesion of acrylic adhesion decreased from 18.0 % to 50.1 %. And its water absorption capability increased from 0.93 % to18.92 %. Though the adhesive properties of acrylic adhesion were decreased dramatically, but it is still better than the water based patch and no any acrylic adhesion residue on the testing steel. The experimental result proved that the water be absorbed inside the adhesion which can be release. So that, by using respirable backing that the sweat can be absorbed inside the adhesion and release through the backing side. The modified acrylic adhesion is still has outstanding adhesion properties and improved the water absorption capability, that can improve the defect and limit of its application in medical care. Water absorbent polymer was also added into several commercialized acrylic adhesions by 2% weight. The Tack, Adhesion and Cohesion of acrylic adhesion were also significant decreased and its water absorption capability was improved a lot. But part of adhesions was found with residue on the testing steel that will cause defect for the application.

碩士
國立臺北科技大學
化學工程研究所
97
The synthesis of this study is to use a kind of acrylic Pressure Sensitive Adhesive (PSA), which is by using Butyl Acrylate (BA) and Methyl Acrylate (MA) as monomers, and the cross-link reaction of acrylic PSA is added epoxy and isocyanate hardener. It is used to investigate the effects, such as the durability, cohesion, peeling force and tack performances of the polarization film while adding different hardener ratio. Besides, we investigate the influences of the peeling force of the PSA while adding the silane coupling agent of three kinds of different organic functional groups (A-174,A-187,A-1100).The properties of the degradation and creep behaviors with the variant cross-link density are analyzed by using TGA and TMA. The experimental results show which is higher cross-link density will result in peeling of polarization film; on the other hand, the bubble is produced while the cross-link density is lower. That is, the proper hardener ratio is set, the excellent durability is obtained. For adding the hardener “N,N,N,N-tetraglycidyl-m-xylene diamine” within the PSA is good for cohesion; for adding the hardener “Trimethylol propane tritoluene diisocyanate” within the glass will raise the adhesion. While adding the A-174 (Gamma-Methcryloxypropyl trimethoxy silane) within PSA, it not only increases the peeling force but also keeps the property of PSA is invariant. It can be seen that the A-174 is the best one among these.

碩士
中國文化大學
應用化學研究所
94
The reaction of toluene diisocyanate with polyester and other additives to form the conformation of water- soluble polyurethane (PU) and acrylics hybrid resin adhesive molecule has been proven by IR spectra. Experimental results showed that both viscosity and average particle size for water- soluble PU/acrylics hybrid resin adhesive increased with increasing concentration of Allyl glycidyl ether and 2-hydroxyethyl methacrylate, respectively. This maybe due to increased free volume resulting from the intermolecular interaction between the water-soluble PU/acrylics hybrid resin molecules themselves and between this hybrid resin molecules and water molecule. Thus, both average particle size and viscosity increased. In aqueous solution, the surface tension of the water- soluble PU/acrylics hybrid resin increased with increasing concentration of the water- soluble PU/acrylics hybrid resin concentration of Allyl glycidyl ether and 2-hydroxyethyl methacrylate , respectively .The reason because the hydrophobic groups of the water- soluble PU/acrylics hybrid resin adsorbed at the surface of water became even more ordered. The hardness of the film made by the water- soluble PU/acrylics hybrid resin increased with increasing concentration of Allyl glycidyl ether and 2-hydroxyethyl methacrylate, respectively, as a result of the arrangement of the molecules becoming more ordered. The gloss of the film made by the water- soluble PU/acrylics hybrid resin decreased with increasing concentration of Allyl glycidyl ether and 2-hydroxyethyl methacrylate, respectively, as a result of the arrangement of the molecules becoming less ordered. The tensile strength of the film made by the water- soluble PU/acrylics hybrid resin increased with increasing concentration of Allyl glycidyl ether and 2-hydroxyethyl methacrylate, respectively. This maybe due to increased crosslinking capability resulting from strong intermolecular interaction between the water- soluble PU/acrylics hybrid resin molecules themselves. On the other hand, the elongation of the film made by the water- soluble PU/acrylics hybrid resin decreased with increasing concentration of Allyl glycidyl ether and 2-hydroxyethyl methacrylate, respectively, as a result of strong intermolecular interaction of the PU/acrylics hybrid resin molecule itself. Thus the elongation decreased.

Poly(acrylic acid) (PAA) was grafted onto both termini of Pluronic F87 (PEO₆₇-PPO₃₉-PEO₆₇) via atom transfer radical polymerization to produce a novel muco-adhesive block copolymer PAA₈₀-b-F₈₇-b-PAA₈₀. It was observed that PAA₈₀-F₈₇-PAA₈₀ forms stable complexes with weakly basic anti-cancer drug, Doxorubicin. Thermodynamic changes due to the drug binding to the copolymer were assessed at different pH by isothermal titration calorimetry (ITC). The formation of the polymer/drug complexes was studied by turbidimetric titration and dynamic light scattering. Doxorubicin and PAA-b-F87-b-PAA block copolymer are found to interact strongly in aqueous solution via non-covalent interactions over a wide pH range. At pH>4.35, drug binding is due to electrostatic interactions. Hydrogen-bond also plays a role in the stabilization of the PAA₈₀-F₈₇-PAA₈₀/DOX complex. At pH 7.4 (α=0.8), the size and stability of polymer/drug complex depend strongly on the doxorubicin concentration. When CDOX <0.13mM, the PAA₈₀-F₈₇-PAA₈₀ copolymer forms stable inter-chain complexes with DOX (110 ~ 150 nm). When CDOX >0.13mM, as suggested by the light scattering result, the reorganization of the polymer/drug complex is believed to occur. With further addition of DOX (CDOX >0.34mM), sharp increase in the turbidity indicates the formation of large aggregates, followed by phase separation. The onset of a sharp enthalpy increase corresponds to the formation of a stoichiometric complex.
Singapore-MIT Alliance (SMA)

The present Doctoral Thesis focuses on the investigation, characterization and influence of polyacrylic materials in different scientific and technological disciplines via a detailed computer simulation using the Molecular Dynamics (MD) technique, in conjunction with the very accurate, all-atom Dreiding force-field. The main research concepts and objectives are discussed and analyzed in three separate parts. In the first part, atomistic configurations of two model pressure-sensitive acrylic adhesives (PSAs), the atactic homopolymer poly(n-BA) [poly(n-butyl acrylate)] and the atactic copolymer poly(n-BA-co-AA) [poly(n-butyl acrylate-co-acrylic acid)] in the bulk phase or confined between two selected substrates, glassy silica (SiO2) and metallic α-ferrite (α-Fe), were built and simulated by MD in the NPT statistical ensemble. First, an equilibration cycle consisting of temperature annealings and coolings was followed, in order to generate well-equilibrated configurations of the PSA systems. Detailed results from the atomistic simulations are presented concerning their volumetric behavior, glass transition temperature, conformational, structural, viscoelastic and dynamic properties. Particular emphasis was given to the analysis and characterization of the hydrogen bonds that form in the poly(n-BA-co-AA) system. By analyzing the MD trajectories, poly(n-BA-co-AA) was found to exhibit a higher density than poly(n-BA) by about 7% at all temperatures, to be characterized by smaller-size chains for a given molecular weight (MW), to exhibit significantly slower terminal and segmental dynamics properties, and to be characterized by a glass transition temperature that was approximately 40% higher than that of poly(n-BA). We also examined the type and degree of adsorption of the two acrylic systems on the selected substrates by analyzing the MD results for the local mass density as a function of distance from the solid plane and the distribution of adsorbed chain segments in train, loop, and tail conformations, and by computing the work of adhesion at the two substrates. The results revealed a stronger adsorption for both acrylics on the SiO2 surface due to highly attractive interactions between polymer molecules and substrate atoms, and as a consequence a higher value for the work of adhesion compared to that on the α-Fe surface. Furthermore, we have developed a generalized non-equilibrium molecular dynamics (NEMD) algorithm to simulate the mechanical response of the two adhesives under a uniaxial stretching deformation. In the second part of the Thesis, results have been obtained from a hierarchical simulation methodology that led to the prediction of the thermodynamic, conformational, structural, dynamic and mechanical properties of two polymer nanocomposites based on syndiotactic poly(methyl methacrylate) or sPMMA. The first was reinforced with uniformly dispersed graphene sheets and the second with fullerene particles. How graphene functionalization affects the elastic constants of the resulting nanocomposite has also been examined. The phase behavior of the nanocomposite (in particular as we varied the relative size between the sPMMA chains and the diameter of fullerene molecules) has also been studied as a function of fullerene volume fraction. The simulation strategy entailed three steps: 1) Generation of an initial structure, which was then subjected to potential energy minimization and detailed molecular dynamics (MD) simulations at T = 500K and P = 1atm to obtain well relaxed melt configurations of the nanocomposite. 2) Gradual cooling of selected configurations down to room temperature to obtain a good number of structures representative of the glassy phase of the polymer nanocomposite. 3) Molecular mechanics (MM) calculations of its mechanical properties following the method originally proposed by Theodorou and Suter. By analyzing the results under constant temperature and pressure, all nanocomposite systems were found to exhibit slower terminal and segmental relaxation dynamics than the pure polymer matrices. The addition of a small fraction of graphene sheets led in all cases to the enhancement of the elastic constants; this was significantly more pronounced in the case of functionalized graphene sheets. We further mention that, for all polymer/fullerene nanocomposites addressed here, no phase separation or variation of polymer chain dimensions was observed as a function of fullerene size and/or fullerene volume fraction. In the third part of the Thesis, and motivated by the use of acrylic polymers for the design of membranes with aligned carbon nanotubes (CNTs) for several separation technologies (such as water desalination and wastewater treatment), we report results from a detailed computer simulation study for the nano-sorption and mobility of four different small molecules (water, tyrosol, vanillic acid, and p-coumaric acid) inside smooth single-wall CNTs (SWCNTs). Most of the results have been obtained with the molecular dynamics (MD) method, but especially for the most narrow of the CNTs considered, the results for water molecule were further confirmed through an additional Grand Canonical (μVT) Monte Carlo (GCMC) simulation using a value for the water chemical potential μ pre-computed with the particle deletion method. Issues addressed in the Thesis include molecular packing and ordering inside the nanotube for the four molecules, average number of sorbed molecules per unit length of the tube, and mean residence time and effective axial diffusivities, all as a function of tube diameter and tube length. In all cases, a strong dependence of the results on carbon nanotube diameter was observed, especially in the way the different molecules are packed and organized inside the CNT. For water for which predictions of properties such as local structure and packing were computed with both methods (MD and GCMC), the two sets of results were found to be fully self-consistent for all types of SWCNTs considered. Water diffusivity inside the CNT (although, strongly dependent on the CNT diameter) was computed with two different methods, both of which gave identical results. For large enough CNT diameters (larger than about 13 Å), this was found to be higher than the corresponding experimental value in the bulk by about 55%. Surprisingly enough, for the rest of the (phenolic) molecules simulated in this Thesis, the simulations revealed no signs of mobility inside nanotubes with a diameter smaller than the (20, 20) tube. This has been attributed to strong phenyl-phenyl attractive interactions, also to favorable interactions of these molecules with the CNT walls, which cause them to form highly ordered, very stable structures inside the nanotube, especially under strong confinement. The interaction, in particular, of the methyl group (present in tyrosol, vanillic acid, and p-coumaric acid) with the CNT walls seems to play a key role in all these compounds causing them to remain practically immobile inside nanotubes characterized by diameters smaller than about 26 Å. It was only for larger-diameter CNTs that tyrosol, vanillic acid, and p-coumaric acid were observed to demonstrate appreciable mobility.
Η παρούσα Διδακτορική Διατριβή εστιάζει στη μελέτη της σχέσης μεταξύ δομής και μακροσκοπικών φυσικών ιδιοτήτων υλικών από πολυακρυλικά μέσω μίας λεπτομερούς προσομοίωσης στον υπολογιστή με τη μέθοδο της Μοριακής Δυναμικής (ΜΔ), σε συνδυασμό με ένα πολύ επακριβές πεδίο δυνάμεων (το Dreiding) σε ατομιστική λεπτομέρεια. Οι κύριες ερευνητικές έννοιες καθώς και οι στόχοι συζητιούνται και αναλύονται σε τρία ξεχωριστά μέρη. Στο πρώτο μέρος, ατομιστικές απεικονίσεις δύο προτύπων πίεσο-ευαίσθητων συγκολλητικών υλικών (acrylic pressure sensitive adhesives ή PSAs), του ατακτικού πολυ-βουτυλικού-ακρυλικού εστέρα (poly(n-BA)) και του συμπολυμερούς του με ακρυλικό οξύ (poly(n-BA-co-AA)), τόσο μακριά όσο και κοντά σε υποστρώματα σίλικας (SiO2) και α-φερρίτη (α-Fe), μελετήθηκαν στη βάση ενός φάσματος ιδιοτήτων (θερμοδυναμικές, δομικές, ιξωδοελαστικές, δυναμικές, και συγκολλητικές), όπως και η μηχανική τους απόκριση υπό συνθήκες μονοαξονικής εκτατικής παραμόρφωσης. Στο δεύτερο μέρος παρουσιάζονται τα αποτελέσματα που εξήχθησαν από μία ιεραρχική μεθοδολογία προσομοίωσης που οδήγησε στην πρόβλεψη της φασικής συμπεριφοράς και των μηχανικών ιδιοτήτων νανοσύνθετων πολυμερικών υλικών (polymer nanocomposites ή PNCs) βασισμένων στο συνδιοτατκτικό πολυ-μεθακρυλικό μεθυλεστέρα (syndiotactic poly(methyl methacrylate) ή sPMMA), ενισχυμένο με ομοιόμορφα διεσπαρμένα φύλλα γραφενίου (graphene sheets) ή σωματίδια φουλερενίου (fullerene particles). Στο τρίτο μέρος, υποκινούμενοι από τη χρήση των ακρυλικών πολυμερών στο σχεδιασμό μεμβρανών με ενσωματωμένους ευθυγραμμισμένους νανοσωλήνες άνθρακα (ΝΑ, carbon nanotubes ή CNTs) σε διάφορες τεχνολογίες διαχωρισμού μορίων (με έμφαση στον καθαρισμό του νερού), παρουσιάζουμε αποτελέσματα από προσομοιώσεις, για τη νανο-ρόφηση και την κινητικότητα τεσσάρων διαφορετικών μικρών μορίων (water, tyrosol, vanilic acid, και p-coumaric acid) στο εσωτερικό λείων μονο-στρωματικών ΝΑ (single-wall CNTs ή SWCNTs). Τα θέματα που εξετάζονται περιλαμβάνουν τη μοριακή διευθέτηση και τη διάταξη στο εσωτερικό Ν.Α. των τεσσάρων μορίων, το μέσο χρόνο παραμονής τους, καθώς και τους αξονικούς συντελεστές διάχυσής του, συναρτήσει της διαμέτρου και του μήκους των ΝΑ.