Dissertations / Theses on the topic 'UV-polymerization'

The present work was performed at Sherwin–Williams Sweden group AB with the objective of comparing short-wavelength light emitting diodes (UVB/UVC) with the conventional mercury arc lamp as a curing method of acrylate-based, UV-paint undergoing free-radical polymerization when exposed to UV-radiation. Due to environmental and health risks, mercury-doped radiation sources will be phased out in the near future, according to the United Nations Minamata convention, hence new alternatives are needed. Light-emitting diodes differ from the mercury arc lamp as they provide semi-discrete output intensity lines within the UV spectrum instead of a broad output distribution with several main intensity lines. The power output is also considerably lower compared to the conventional method which limits the irradiance and dose that are key parameters in activating and propagating free-radical polymerization of UV-paint. Seven different light-emitting diodes between 260–320 nm was examinedand compared to the conventional mercury arc lamp. Cured coatings were evaluated by measuring the relative extent of acrylate conversion with ATR-FTIR and micro-hardness indentation test. Both methods correlate to the relative cross-linking density and qualitatively describe the curing process for each radiant source at a specific irradiance and dose. Three different paint formulations with widely different properties were used in the experiments. All three paints were able to cure with one or several light emitting diodes at comparable doses and 10 to 20 times lower irradiance to the conventional mercury arc lamp, resulting in similar acrylate conversion and hardness.

The work in this thesis is split into three experimental chapters: The first section involves the development of the directional freezing and frozen polymerization method to prepare crosslinked aligned porous polymers with improved mechanical stability. Monomer solutions were directionally frozen in liquid nitrogen to orientate the growth of solvent crystals and the frozen samples are polymerized by UV irradiation. The solvent is removed under vacuum at room temperature to produce aligned porous structure. The mechanical stability is improved by two orders of magnitude compared to the usually freeze-dried porous materials. The materials are modified with graphene and a conducting polymer to make conducting monoliths, whilst maintaining the aligned porous structure. The aligned porous monolith is also assessed by high performance liquid chromatography (HPLC), showing fast separation of hydrocarbon compounds with low back-pressure. The second section uses directional freezing and frozen UV initiated polymerization to prepare aligned porous stimuli-responsive hydrogels. Oligo-ethylene glycol methacrylates and dimethylamino ethyl methacrylate monomers were used to produce temperature and pH-responsive hydrogels respectively. Aligned porous morphologies are observed in both dry and hydrated states. The hydrogels exhibit stimuli-responsive behaviour in aqueous conditions and anisotropic compressive strength and diffusion behaviour with respect to freezing direction. Section three uses directional freezing and frozen UV polymerization method to prepare aligned porous monoliths containing silica. The surface of the materials was post-functionalized to make two different types of aligned porous composites. Hydrothermal synthesis using Teflon lined autoclaves was used to functionalize monoliths separately with silver and metal organic frameworks (MOFs). The MOF composite materials were used as a stationary phase to try and separate a mixture of organic compounds.

Production of particles with dimension in the submicron scale underwent a significant increase in the last decades. The idea to exploit these devices to actively target a wide range of applications drove many important efforts in the development of such particles. In particular, the possibility to encapsulate and release active ingredients with desired rates, as well as to specifically target certain areas of the human body, is of huge importance in therapeutic treatments. Among the broad spectrum of micro and submicron particles, polymeric particles represent an extremely versatile class of devices. Their high biocompatibility and possibility to swell or degrade to enhance release once in contact with body fluid are particularly interesting in drug administration. This work was focused on the development of new techniques to produce structured polymeric particles in the micro and nano regions. Two rather different polymerization techniques were investigated and modified in order to pursue this goal: miniemulsion and aerosol polymerization. In both cases, polymerization triggering was achieved by UV light in presence of photo-initiator compounds and two reaction mechanisms were investigated: radical and cationic. Miniemulsion polymerization was studied as a case study of a well-known technique for production of polymeric particles. One major modification was applied to the standard experimental setup: polymerization was confined at the interface between dispersed and continuous phase, thus producing capsules with a polymeric shell and a liquid core. The product was characterized and the impact of process conditions on size and morphology of capsules was evaluated. In particular, ultrasound exposure time was used to design capsules size. After optimization of process parameters, an active ingredient was encapsulated. Its controlled release was evaluated in case of different polymeric shells. Differences were observed using different degrees of crosslinking in the polymeric material, thus showing the possibility to design release rate by varying the ratio between monomer and crosslinker. Aerosol polymerization was studied as a rather new technique for production of polymeric particles. It is a continuous process that does not require a liquid medium nor, usually, surfactants. For these reasons, it does not imply a cumbersome downstream work of purification. One major drawback of this technique is the challenging particles structuring process. In our work, phase separation was induced within aerosol droplets to obtain structured particles. Mixtures of ―good‖ and ―bad‖ solvents were used to carefully design solubility of the monomer and its oligomers in the sprayed solution. Thus, it was possible to obtain different porous particles morphologies simply by varying the ratio between the two solvents. Capsules structures were obtained using different approaches in cationic and radical mechanism. Chain transfer mechanism was applied in cationic polymerization by adding an alcohol in the sprayed solution, while the addition of a soft-maker was crucial for the production of polymeric shells in radical polymerization. In both cases, the goal was to delay gelation of the polymeric structure, thus providing more time for the structuring process. Once the particles morphology was designed, an active ingredient was encapsulated within different types of particles and its release was monitored. Molecular dynamic simulations were carried out to study the mechanisms that control the structuring process in aerosol cationic polymerization. Diffusion of the oligomer in the solvent mixture, as well as its interactions with the solvents, were calculated and the results confirmed the strong impact of solvent composition on the macromolecules transport parameters and, therefore, on their morphology.

It was demonstrated for the first time that RAFT polymerizations of NIPAAm can be carried out directly in water at room temperature without photo initiator under UV radiation. Under these conditions, the controlled/living features could be proven for a large range of monomer/RAFT agent ratios. Moreover, even at a monomer conversion exceeding 80%, polymerization control (PDI<1.2) is maintained. It is also demonstrated that the RAFT polymerization of AA can be carried out without photo initiator in water at ambient temperature in the presence of TRITT at short wavelength. At these wavelengths, the controlled/ living characteristics is maintained even at a monomer to polymer conversions exceeding 80%. UV/Vis spectrometry was employed to monitor the functional group (-S(C=S)S-) changes of the employed trithiocarbonate RAFT agent S,S???-Bis(??,?????-dimethyl-acetic acid)-trithiocarbonate (TRITT) in aqueous solution when exposed to UV radiation. It is shown that the degradation pattern of TRITT alone as well as TRITT in the presence of NIPAAm deviate from each other. Surprisingly, it is found that TRITT completely decomposed at 254 nm while the addition of monomer prevented the decomposition of TRITT at the same wavelength. Nuclear magnetic resonance (NMR) techniques were applied to study the decomposition products of TRITT in solution without the addition of monomer. Methanol-d4 was selected as the solvent. In addition, high-resolution soft ionization mass spectrometry techniques were used to map the product species generated during UV radiation induced RAFT polymerizations of NIPAAm and AA in aqueous media, allowing for the tentative assignment of end groups. The NMR analysis suggests that the decomposition of TRITT in methanol-d4 under UV radiation has three cleavage patterns. These three cleavage patterns (described in the current thesis in detail) all occur at the ???S(C=S)S- group, which is the weakest structural unit in TRITT molecule. iii However, polymerization occurs prior to decomposition, if monomer is present. The mass spectrometric analysis suggests that the initial radicals result from the dissociation of TRITT, as well as monomer. Trithiocarbonate end group degradation leading to the formation of thiol terminated chains is also occurring. In the case of NIPAAm polymerization, a peak which may be associated with a cross termination product of the intermediate radical was observed under both 302 nm and 254 nm wavelength irradiation. Interestingly, this peak does not occur in AA polymerization at any wavelength (nor is it expected to form under conventional RAFT conditions and was not observed in previous mass spectrometry studies in thermal or ??-initiated polymerizations of NIPPAm with TRITT) and thus this assignment should be treated as very tentative only.

Depuis une dizaine d'années, les polymères hyperbranchés sont apparus dans la littérature. Ils possèdent un grand nombre de branchements ainsi qu'un grand nombre de groupes terminaux. La structure globulaire des polymères hyperbranchés les empêche de former des enchevêtrements. Il en résulte un avantage décisif pour leur application sous forme de revêtement de surface: les polymères hyperbranchés ont une viscosité plus faible à l'état fondu que les polymères linéaires. Cela permet aisément de les étaler sous forme de films minces sans utiliser de solvant. De plus, les polymères hyperbranchés possèdent un grand nombre de groupes terminaux qui peuvent être fonctionnalisés avec des monomères photoréticulables.

Le but du travail de thèse est d'obtenir de nouveaux revêtements de surface, à partir de polymères hyperbranchés ou de polymères fortement branchés, qui trouveront leur application dans l'industrie chimique.

La thèse s'articule autour de trois chapitres de synthèse suivis d'un chapitre traitant de la photoréactivité des oligomères linéaires, fortement branchés, et hyperbranchés.

La première approche de synthèse envisagée est la copolymérisation alternante radicalaire. Divers maléimides ont été engagés dans des copolymérisations radicalaires avec des allyléthers sans succès.

Lorsque ces derniers sont remplacés par des vinyls éthers, une copolymérisation alternante est observée. Néanmoins, une importante irreproductibilité est constatée, certains batchs donnant lieu à une gélification.

La seconde voie de synthèse étudiée est l'approche classique de polycondensation de monomères de type AB2 .Le monomère AB2 est obtenu par addition de Michael de la diéthanolamine sur l'acrylate de méthyle. La polycondensation est concomitante avec l'acrylation des fonctions alcools. La compétition entre ces deux réactions limite les masses molaires accessibles bien que les réactions de transestérification soient catalysées par des dérivés du Zr et que la stoechiométrie ait été variée.

La troisième voie de synthèse se base aussi sur la réaction de Michael. Des oligomères fortement branchés sont obtenus à partir de 1,6-hexanedioldiacrylate et d'éthylènediamine. Leurs analogues linéaires sont synthétisés en remplaçant l'éthylènediamine par la propylamine. Lors de ces synthèses, il est apparu que les oligomères fortement branchés ont une viscosité supérieure à celle des oligomères linéaires!

Les oligomères hyperbranchés et acrylés, les oligomères linéaires et leurs analogues fortement branchés ont été étudiés du point de vue de leur photoréticulation sous rayonnement UV. Contrairement à ce qui était attendu, ils se sont montrés moins réactifs que les produits les plus performants de Cytec-Surface Specialties. Lors de cette étude, l'effet bénéfique des mines tertiaires sur l'inhibition par l'oxygène est apparu plus complexe que décrit dans la littérature.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished

This Ph.D. thesis is focused on kinetic study of propene and hex-1-ene coordination polymerizations initiated by complex [(2-tBuC6H4)N=C(1,8-naphtalenediyl)C=N(2-tBuC6H4)]NiBr2 activated by simple organoaluminium compounds and on product properties. In first three parts proper activators are chosen in model polymerizations. The attention is paid to the reproducibility of polymerizations and analytical methods. The fourth part is focused on propene polymerization kinetics with the aim to define optimal reaction conditions, especially polymerization temperature and time. The four part concerns also properties of polymers. The fifth and sixth parts deal with hex-1-ene polymerization kinetics conducted at various activator/initiator molar ratios and various catalytic precursor concentrations, to find out kinetic orders with respect to catalyst and cocatalyst concentration. Last part is oriented on detail mechanistic investigation of nickel diimine complexes activation process. Results of measurements in presence or absence of monomer enabled to propose new interpretation of UV-vis spectra based on concrete structures of absorbing species.

L'objectif de cette thèse concerne le développement de nouveaux matériaux reconfigurables et recyclables pour l'acoustique. L'idée générale est de donner à un matériau des fonctions acoustiques qui peuvent être modifiées par l'application d'un stimulus externe et d'assurer ainsi sa polyvalence. Les matériaux ciblés par ce projet sont des lentilles acoustiques plates qui se présentent sous la forme de films ultraminces (également appelés « métasurfaces acoustiques »). Dans ce travail, nous cherchons à modifier localement la valeur de la vitesse du son au sein de la lentille en contrôlant la réticulation d’une matrice polymère poreuse et souple par l'application d'un stimulus UV d'intensité réglable. Pour ce faire, nous avons greffé des fonctions chimiques (les groupements cinnamoyl) sensibles aux UV sur différents squelettes de polymères (polybutadiène, polycaryophyllène, polydiméthylsiloxane) et mesuré l'évolution de leurs propriétés mécaniques en fonction du temps d'illumination UV. Nos résultats montrent que les propriétés mécaniques et acoustiques des matériaux peuvent être modifiées de manière significative aux fréquences ultrasonores d’intérêt pour l’imagerie acoustique. Nous avons ainsi pu produire des lentilles acoustiques plates, ultra-minces et ajustables pour la focalisation d'ondes ultrasonores
The purpose of this thesis is to develop new reconfigurable and recyclable materials for acoustics. The general idea is to provide a material with acoustic functionalities that can be modified by the application of an external stimulus, thus ensuring its versatility. The materials targeted in this project are flat acoustic lenses in the form of ultrathin films (also referred to as “acoustic metasurfaces”). In this study, we aim to locally modify the value of the sound speed by controlling the crosslinking of a soft and porous polymer matrix through the application of a UV stimulus of adjustable intensity. To this end, we grafted UV-sensitive chemical functions (cinnamoyl groups) onto various polymer backbones (polybutadiene, polycaryophyllene, polydimethylsiloxane) and measured the evolution of mechanical properties as a function of UV illumination time. Our results show that the mechanical and acoustical properties of materials can be significantly modified by the application of this stimulus at ultrasonic frequencies of interest for acoustic imaging. We were thus able to produce ultra-thin, flat and tunable acoustic lenses for ultrasonic focusing

Les emballages alimentaires et pharmaceutiques doivent de nos jours répondre à de nombreux critères : ils doivent non seulement préserver le produit emballé, mais également être inoffensifs, économes en énergie et jetables. Les polymères barrières ont permis de répondre à ces besoins, en offrant des alternatives à des matériaux plus demandeurs en énergie et plus lourds tels que le verre ou les métaux, tout en conservant une faible perméabilité à l’eau et/ou à l’oxygène. Parmi la grande variété de polymères barrières existants, les copolymères du poly(chlorure de vinylidène) (PVDC) offrent une protection plus complète aux contaminants extérieurs, grâce à leurs faibles perméabilités à l’eau et à l’oxygène. Cependant, les films de PVDC sont sujets à des processus de dégradation ayant lieu lors du thermoformage ou sous exposition aux rayonnements UV. Ces effets sont encore plus prononcés dans le cas de films obtenus à partir de latex, dû à des quantités plus importantes d’additifs qui accentueraient les phénomènes de dégradation du polymère. Par conséquent, la synthèse de latex à base de PVDC pour des applications en tant que films barrières aux stabilités thermique et UV améliorées revêt un grand intérêt. Des latex composites à base de PVDC ont tout d’abord été synthétisés en présence de latex semences à fonctionnalité époxy en vue d’améliorer la stabilité thermique du polymère. En effet, les groupements époxy jouent le rôle de stabilisants thermiques en piégeant le chlorure d’hydrogène, dégagé lors du thermoformage et présentant un effet catalytique indirect sur le processus de dégradation du polymère. Dans une première étape, des latex semences à fonctionnalité époxy ont été synthétisés par copolymérisation en émulsion du methacrylate de glycidyle (GMA) et du methacrylate de butyle (BMA). Lors d’une seconde étape, la copolymérisation en émulsion ensemencée du chlorure de vinylidene et de l’acrylate de méthyle a été effectuée en présence des semences de poly(GMA-co-BMA). Des analyses thermogravimétriques effectuées sur les échantillons composites ont mis en évidence le rôle de stabilisant thermique joué par les fonctions époxy. La seconde partie du projet concerne la synthèse de latex hybrides à base d’oxyde de cérium (CeO2) afin d’améliorer la résistance du PVDC aux rayonnements UV. Les nanoparticules d’oxyde de cérium sont en effet attrayantes en tant que stabilisants UV en raison de leur haute absorption des rayonnements UV et d'une faible activité photocatalytique. Cependant, étant donné l’incompatibilité intrinsèque entre les phases inorganique et organique, la synthèse de latex hybrides requiert souvent une étape préliminaire de modification de surface des particules minérales. Le greffage d’alcoxysilanes a d’abord été entrepris sur des particules d’oxyde de cérium afin d’encourager la réaction de polymérisation à leur surface. Des observations par cryo-Microscopie Electronique à Transmission (cryo-MET) effectuées sur les latex hybrides obtenus par cette stratégie ont montré que le greffage d’alcoxysilanes ne permettait pas d’améliorer efficacement la compatibilité entre les phases inorganique et polymère. Enfin, des macro-agents RAFT amphiphatiques ont été employés comme agents comptabilisant réactifs afin de promouvoir la réaction de polymérisation à la surface de l’oxyde de cérium. Des oligomères RAFT ont été obtenus par des réactions de co- ou terpolymérisation en présence d’un agent de contrôle RAFT. Après caractérisation de l’adsorption des macro-agents RAFT à la surface de l’oxyde de cérium, les particules modifiées ont été utilisées dans des réactions de polymérisation en émulsion. Les observations des latex hybrides par cryo-MET ont confirmé l’efficacité de la méthode pour l’obtention de structures hybrides. Cette stratégie semble ainsi la plus prometteuse pour la synthèse de latex hybrides CeO2/PVDC pour des applications en tant que films barrières présentant une stabilité UV améliorée
Food and pharmaceutical packages should nowadays fulfill a wide range of requirements : not only should they preserve the packed products from external polluting agents, but they must also be innocuous, more energy-efficient and disposable. Barrier polymers have enabled to meet these criteria, by offering alternatives to more energy-consuming and heavier materials like glass or metals, while maintaining a low permeability to water and/or oxygen. Among the large variety of barrier polymers, poly(vinylidene chloride) (PVDC) copolymers provide a more complete protection to external contaminants, due to their extremely low permeabilities towards water and oxygen. Nonetheless, PVDC films still suffer from limitations as far as their thermal and UV stabilities are concerned. This effect is even more pronounced in the case of films obtained from latexes, due to the presence of higher amounts of additives that could take part in the polymer degradation. Therefore, the synthesis of PVDC-based latexes for use as waterborne barrier films with improved thermal and UV stabilities are of great importance. PVDC-based composite latexes were first synthesized from epoxy-functionalized seed latexes in order to enhance the polymer thermal stability. Given that hydrogen chloride displays an indirect catalytic effect on the polymer degradation, epoxy groups were indeed expected to act as thermal stabilizers by scavenging the HCl released by the polymer under thermal stress. In a first step, epoxy-functionalized seed latexes were synthesized via the emulsion copolymerization of glycidyl methacrylate (GMA) and butyl methacrylate (BMA). In a second step, the seeded emulsion copolymerization of vinylidene chloride and methyl acrylate was carried out in the presence of poly(GMA-co-BMA) seed latexes. Thermogravimetric analyses carried out on the resulting composite samples evidenced the thermal stabilization provided by epoxy groups. The second part of the project focused on the synthesis of cerium oxide-based hybrid latexes so as to improve the stability of PVDC to UV radiation. Cerium oxide (CeO2) nanoparticles are indeed very attractive as UV-stabilizers due to their high absorption of radiation in the UV range and a low photocatalytic activity. However, due to the intrinsic incompatibility between inorganic and polymer phases, the synthesis of inorganic-organic hybrid latexes often requires a preliminary step of modification of the mineral particles surface. The grafting of alkoxysilanes onto nanoceria was first attempted in order to promote the polymerization reaction at the surface of the inorganic particles. Cryo-Transmission Electron Microscopy (cryo-TEM) observations of hybrid latexes obtained via this route showed that this strategy was unsuccessful at improving the compatibility between the inorganic and polymer phases. Amphiphatic macro-RAFT agents were finally considered as reactive compatibilizing agents to direct the polymerization towards the cerium oxide surface. RAFT oligomers were first obtained by co- or terpolymerization reactions in the presence of a RAFT controlling agent. After characterizing the adsorption of amphiphatic macro-RAFT agents at the surface of nanoceria, surface-modified cerium oxide particles were then engaged in reactions of emulsion polymerization reactions. In most cases, cryo-TEM observations carried out on the resulting latexes confirmed the efficiency of the amphiphatic macro-RAFT agent route for the synthesis of hybrid structures. Therefore this route appeared so far to be the most promising for the synthesis of CeO2/PVDC hybrid latexes for use as waterborne barrier films with improved UV-stability

Les revêtements poudres UV suscitent un développement croissant en raison, entre autres, de leurs qualités et de leur respect de la législation sur la minimisation des émissions polluantes. Un nouveau revêtement poudre UV à base de (co)polyamide de faible masse molaire et porteur de fonctions réactives sous UV a été élaboré en vue d'une application sur des supports sensibles aux hautes températures. Nous avons donc synthétisé un copolyamide 6/11/12 alpha, oméga-insaturé présentant une température de fusion de 107°C et une masse molaire moyenne en nombre de 7250 g/mol. L'irradiation sous UV de ce copolyamide, en présence de 4 % en masse de benzophénone, a permis, par polymérisation des doubles liaisons allyliques et formation des liaisons covalentes au niveau des ponts amide, de compenser la perte de cristallinité en le réticulant. Le revêtement obtenu, bien que restant à optimiser, a montré globalement de meilleures propriétés que celles des matériaux références fournis par Arkema.

La phosphorylation de protéines est un régulateur clé de voies de signalisation cellulaire. Elle est impliquée dans la plupart des événements cellulaires et contrôle les processus biologiques tels que la prolifération, la différenciation et l'expression des gènes. Une phosphorylation anormale de protéines peut être observée dans diverses maladies comme certains cancers ou maladies neurodégénératives. Ces protéines constituent donc des biomarqueurs potentiels pour le développement d’outils de diagnostic. Cependant les phosphoprotéines peuvent être présentes à faibles concentrations dans les liquides biologiques et des techniques d’enrichissement sélectif des protéines phosphorylées doivent être développées en amont des analyses. L'une des approches les plus courantes est basée sur la chromatographie d'affinité de type IMAC. Le but de ce travail de thèse était de développer un microsystème contenant un monolithe en tant que support solide d'extraction pour réaliser une préconcentration sélective de phosphopeptides par IMAC. La polymérisation par UV et la caractérisation (perméabilité, porosité et surface spécifique) d'un monolithe à base de phosphate de méthacrylate d'éthylène glycol dans des capillaires de silice ont été d'abord réalisées. Puis, nous avons tenté d'optimiser les différentes étapes de l’IMAC (immobilisation du métal, chargement de l’échantillon, lavage et élution). Une immobilisation efficace de zirconium sur le monolithe phosphaté a été démontrée par des mesures de FEO dans un capillaire et a été par la suite confirmée par la rétention d'un phosphopeptide modèle. Nous avons démontré que le monolithe phosphaté était également un support d’échange de cations vis-à-vis de peptides fortement basiques. Les protocoles de chargement et d'élution ont également été étudiés, mais nécessitent encore d’être améliorés. La transposition de l'enrichissement de phosphopeptides par IMAC sur un système miniaturisé a ensuite été envisagée. Nous avons choisi deux matériaux pour la puce : le PDMS, qui est un polymère attractif pour son faible coût, sa facilité de microfabrication, ses excellentes propriétés en termes de biocompatibilité ainsi que ses nombreuses possibilités d'intégration (enrichissement, séparation, détection) et le verre plus communément employé pour développer des microsystèmes analytiques et possédant une bonne transparence aux UV. Toutefois, le PDMS présente deux inconvénients majeurs: son absorption élevée et sa perméabilité importante à l'oxygène qui inhibe la polymérisation radicalaire. A l’exception de quelques tentatives, ce matériau n'a jamais été employé avec succès comme support pour la polymérisation d’un monolithe. Afin de pouvoir surmonter ces problèmes, nous avons étudié plusieurs stratégies de traitement de surface du PDMS tels que le traitement par plasma d’oxygène ou encore le revêtement au borosilicate. Enfin, nous avons démontré que notre module d’IMAC fonctionnait correctement dans un microsystème en verre. Ce module miniaturisé devrait à l’avenir s’intégrer dans un microsystème d’analyse dédié au diagnostic de la maladie d'Alzheimer
Protein phosphorylation is a key regulator of cellular signaling pathways. It is involved in most cellular events and strictly controls biological processes such as proliferation, differentiation and gene expression. An abnormal phosphorylation can be observed in various diseases such as some cancers or neurodegenerative diseases. Therefore, these proteins are potential biomarkers for the development of diagnostic tools. However, phosphoproteins can be present at low abundance in biological samples and selective enrichment techniques have to be developed prior to the analysis process. One of the most common approaches is based on Immobilized metal affinity chromatography (IMAC). The goal of this work was to develop a microsystem which contains a porous polymer monolith (PPM) as a solid phase extraction for a selective preconcentration of phosphopeptides by IMAC. UV-polymerization and characterization (permeability, porosity and specific area) of a monolith based on ethylene glycol methacrylate phosphate in silica capillaries was first performed. Then, we tried to optimize the different IMAC steps (metal immobilization, sample loading, washing and elution). An efficient immobilization of zirconium on the phosphated PPM was demonstrated by EOF measurements in capillary and confirmed by retention of a model phosphopetide. We demonstrated that the phosphated monolith was also a strong cation exchanger of highly basic peptides. Protocols of loading and elution were also studied but need to be further optimized. Transposition of phosphopeptides enrichment by IMAC on a miniaturized system was then considered. We selected two microchip materials: PDMS is an attractive polymer for its low cost, its ease of microfabrication, its excellent working properties (biocompatibility, UV transparent with low autofluorescence) and many integration possibilities (enrichment, separation and detection) and glass microchip more common and having a good UV transparency. However, PDMS presents two major disadvantages: high absorption property, and oxygen permeability which quench free radical polymerization. Except a few attempts, this material has not been employed successfully as mould for monolith polymerization. To overcome these problems, we investigated several strategies for PDMS surface treatments such as plasma treatment and borosilicate coating. Finally, we demonstrated that our IMAC module performed well on glass microchip. This miniaturized module should be integrated in the future into a microsystem dedicated to the diagnosis of Alzheimer disease

Quantum chemical methods have been used to provide a better understanding of the photochemistry of astaxanthin and phytochromobilin; the photoenzymic repair of UV-light induced DNA damages; and the formation of lignin.

The carotenoid astaxanthin (AXT) is responsible for the colouration of lobster shell. In solution, the electronic absorption spectra of AXT peak in the 470-490 nm region, corresponding to an orange-red colouration. Upon binding to the lobster-shell protein-complex α-crustacyanin, the absorption maximum is shifted to 632 nm, yielding a slate-blue colouration. Herein, the structural origin of this bathochromic shift is investigated on the basis of recent experimental work.

The tetrapyrrole phytochromobilin (PΦB) underlies the photoactivation of the plant photoreceptor phytochrome. Upon absorption of 660-nm light, PΦB isomerizes from a C15-Z,syn configuration (in the inactive form of the protein) to C15-E,anti (in the active form). In this work, a reaction mechanism for this isomerization is proposed.

DNA photolyases are enzymes that repair DNA damages resulting from far-UV-light induced [2+2] cycloaddition reactions involving pyrimidine nucleobases. The catalytic activity of these enzymes is initiated by near-UV and visible light, and is governed by electron transfer processes between a catalytic cofactor of the enzyme and the DNA lesions. Herein, an explanation for the experimental observation that the repair of cyclobutane pyrimidine dimers (CPD) – the major type of lesion – proceeds by electron transfer from the enzyme to the dimer is presented. Furthermore, the formation of CPD is studied.

Lignin is formed by dehydrogenative polymerization of hydroxycinnamyl alcohols. A detailed understanding of the polymerization mechanism and the factors controlling the outcome of the polymerization is, however, largely missing. Quantum chemical calculations on the initial dimerization step have been performed in order to gain some insight into these issues.

This master‘s thesis concerns gel polymer electrolytes formed on a methyl methacrylate base with selected types of nanoparticles. In the thesis are also analyzed the methods for measuring electrochemical properties. The practical portion deals with sample preparations of gel polymer electrolytes with different contents of alkaline salt in a solvent, creating gels with different nanoparticle content and comparing gel polymer electrolytes polymerized with heat and UV radiation. The thesis deals with the evaluation of these samples from the viewpoint of electrical conductivity and potential windows as well as thermal analysis of selected samples.

Les caractéristiques et les propriétés de libération de microparticules chargées de médicament dépendent de la nature des matériaux employés, des propriétés physicochimiques des microparticules, du choix de la méthode de production, et enfin des propriétés des molécules encapsulées. A l'inverse de la plupart des méthodes conventionnelles, les méthodes microfluidiques présentent l’avantage de bien mieux contrôler la génération de gouttelettes, leur taille et leur distribution de tailles. Ainsi des dispositifs microfluidiques à base de capillaires ont été développés pour obtenir des microbilles de polymère mais également des microparticules de type janus, coeur-écorce ou troyenne, toutes monodisperses en taille et chargées de médicament(s). Ces particules ont été produites à partir de solutions de monomère qui furent polymérisées par irradiations UV de telle sorte à garder intacte l'activité des molécules chargées. Ces dispositifs peuvent être assemblés dans un court laps de temps et un simple changement dans leur conception permet d’obtenir des morphologies de particules très différentes. Ces particules ont été développées dans le but de résoudre les problèmes rencontrés dans l’administration orale de médicaments. Par exemple les microbilles peuvent être utilisées pour délivrer des anti-inflammatoires non stéroïdiens de manière continue tandis que les particules Janus peuvent libérer, simultanément et sur le même site, deux principes actifs possédant des propriétés complètement différentes (solubilité, compatibilité) également de manière prolongée. Quant aux particules coeur-écorce, elles ont été conçues pour cibler la région du côlon de l'intestin humain, et y libérer simultanément deux médicaments. Les particules troyennes furent synthétisées à l’aide d’un procédé microfluidique semi-continu qui a permis une manipulation plus sécurisée des nanoparticules vectrices ainsi que la libération continue d’un médicament dans un liquide gastrique simulé. Chaque système a été entièrement caractérisé pour assurer l’invariance entre lots et la reproductibilité. En général, la libération des ingrédients actifs a pu être facilement contrôlée/ajustée par le réglage des paramètres opératoires et de matériaux tels que les débits des différentes phases, la nature et la concentration du médicament, des (co)monomères, des agents tensioactif et de réticulation, le pH du milieu de libération. Ces différents paramètres influencent les propriétés des microparticules telles que leur morphologie, forme, taille et densité de réticulation du réseau polymère
Characteristics and release properties of drug loaded microparticles depend upon material used and choice of production method. Conversely to most of the conventional ones, microfluidic methods give an edge by improving the control over droplet generation, size and size distribution. Capillary-based microfluidic devices were successfully used to obtain monodisperse drug(s) loaded microbeads, janus, core-shell and trojan particles using UV initiated free radical polymerization while keeping activity of active loaded molecules. These devices can be assembled in a short period of time and a slight change in design gives completely different microparticles morphologies. These particles were developed with the aim to address different issues experienced in oral drug delivery. For instance microbeads can be used to deliver NASIDs in a sustained release manner while janus particles can release two APIs with completely different properties (solubility, compatibility) also in a sustained release manner. Core-shell particles were designed to target colonic region of human intestine for dual drug delivery. Trojan particles were synthesized in a new semi-continuous microfluidic process, thus improving nanoparticles safety handling and release in simulated gastric fluid. Each system was fully characterized to insure batch to batch consistency and reproducibility. In general, the release of active ingredients was controlled by tuning the operating and material parameters like phases flow rates, nature and concentration of drug, (co)monomers, surfactant and crosslinker, pH of release media with the result of different particle morphologies, sizes and shapes or matrix crosslinking density

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Die fortschreitende Entwicklung auf dem Gebiet der kontrollierten Polymerisationstechniken ermöglicht heutzutage die Synthese definierter Makromoleküle. Durch das Design der Primärstruktur dieser Makromoleküle kann ein starker Einfluss auf die sich bildende Sekundärstruktur ausgeübt werden. Um den Grad der Kontrolle über den Polymerisationsprozess zu erhöhen sollten in dieser Arbeit photoschaltbare Azobenzolfunktionalitäten in Guanidin- und Thioharnstoffmotive integriert werden, so dass durch die reversibel photoschaltbare Ausbildung von Wasserstoffbrücken die vorliegenden Polymerisationsprozesse beeinflusst werden können. In einem Ansatz wurden dazu neuartige azobenzolverknüpfte Guanidin- und Thioharnstoffkatalysatoren für die Ringöffnungspolymerisation (ROP) von Lactid (LA) synthetisiert. Im Fall der photoschaltbaren Guanidinkatalysatoren wurde eine Synthesemethode entwickelt, welche die zu Beginn langwierige Aufreinigung der Katalysatoren bedeutend vereinfacht und somit die Darstellung mehrerer Katalysatorgenerationen ermöglichte. Die erste Guanidinkatalysatorgeneration zeigte keine katalytische Aktivität. Durch die Synthese von verschiedenen Referenzguanidinen und deren Einsatz in der ROP von LA konnten die aromatischen Substituenten der Guanidinfunktionalität als Ursache der katalytischen Inaktivität identifiziert werden. Daraufhin wurde eine mit zwei Alkylsubstituenten versehene zweite Generation synthetisiert und erfolgreich in der ROP von Lactid eingesetzt. In einem anderen Ansatz wurde versucht ein azobenzolverknüpftes Guanidinium-Carboxylat-Zwitterion so zu gestalten, dass es als photoschaltbares Monomer zur Bildung supramolekularer Polymere verwendet werden kann. Hierzu wurden zwei Generationen photoschaltbarer Zwitterionen synthetisiert. Die Eigenschaften der zweiten Generation wurden mit verschiedenen spektroskopischen Methoden untersucht. Dabei wurden Hinweise auf die Bildung eines supramolekualren Polymers gefunden.
Following the progressive development in the field of controlled polymerizations, it is now possible to synthesize well defined macromolecular structures. Controlling the primary structure in these macromolecules significantly influences the secondary structure, allowing the preparation of smart materials. In order to improve the achievable degree of control, this work aims to incorporate azobenzene functionalities into guanidine and thiourea moieties and, through the photo triggered reversible formation of hydrogen bridges, influence polymerization processes. Novel azobenzene substituted guanidine and thiourea catalysts for the ring opening polymerization (ROP) of lactide were synthesized. In the case of the photoswitchable guanidine catalysts, a new synthetic protocol was developed to overcome the difficult purification of the catalysts, allowing the facile preparation of multiple catalyst generations. The first generation of photoswitchable guanidines showed catalytic activity. Synthesis of reference guanidine catalysts demonstrated a negative effect between aromatic guanidine substituents and the catalytic performance. Following this observation, a second generation of alkyl substituted guanidine catalysts was synthesized and applied successfully in the ROP of lactide. In a concurrent approach, a guanidinium carboxylate zwitterion was rendered photoswitchable by the incorporation of an azobenzene functionality and used as a monomer in supramolecular polymerization processes. The first generation of photoswitchable zwitterions showed promising photochemical properties, but its poor solubility in apolar, aprotic solvents prevented a final proof of the concept. To achieve this, a second generation of photoswitchable zwitterions was synthesized, incorporating solubilizing functionalities into the molecular design. The properties of the second generation zwitterion were examined by various spectroscopical methods, indicating the formation of supramolecular polymers.

This thesis deals with the engineering of novel nanomaterials, particularly nanocomposites and nanostructured surfaces with enhanced functionalities. The study includes two parts; in the first part, an in situ sol-gel polymerization approach is used for the synthesis of polymer-inorganic hybrid material and its exceptional transparent UV-shielding effect has been investigated. In the second part, electrodeposition process has been adapted to engineer surfaces and the boiling performance of the fabricated nanostructured surfaces is evaluated.

In the first part of the work, polymer-inorganic hybrid materials composed of poly(methylmethacrylate) (PMMA) and zinc compounds were prepared by in situ sol-gel transition polymerization of zinc complex in PMMA matrix. The immiscibility of heterophase of solid organic and inorganic constituents was significantly resolved by an in situ sol-gel transition polymerization of ZnO nanofillers within PMMA in the presence of dual functional agent, monoethanolamine, which provided strong secondary interfacial interactions for both complexing and crosslinking of constituents.

In the second part of the work, nanoengineering on the surface of copper plates has been performed in order to enhance the boiling heat transfer coefficient. Micro-porous surfaces with dendritic network of copper nanoparticles have been obtained by electrodeposition with dynamic templates. To further alter the grain size of the dendritic branches, the nanostructured surfaces underwent a high temperature annealing treatment.

Comprehensive characterization methods of the polymer-inorganic hybrid materials and nanoengineered surfaces have been undertaken. XRD, 1H NMR, FT-IR, TGA, DSC, UV-Vis, ED, SEM, TEM and HRTEM have been used for basic physical properties. Pool boiling tests were performed to evaluate the boiling performance of the electrodeposited nanostructured micro-porous structures.

The homogeneous PZHM exhibited enhanced UV-shielding effects in the entire UV range even at very low ZnO content of 0.02 wt%. Moreover, the relationship between band gap and particle size of incorporated ZnO by sol-gel process was in good agreement with the results calculated from the effective mass model between bandgap and particle size. The fabricated enhanced surface has shown an excellent performance in nucleate boiling. At heat flux of 1 W/cm2, the heat transfer coefficient is enhanced over 15 times compared to a plain reference surface. A model has been presented to explain the enhancement based on the structure characteristics.

This thesis describes the synthesis and characterization ofbranched semi-crystalline polymers. Included in this work isthe SEC characterization of a series of dendrimers. Thebranched semi-crystalline polymers were synthesized in order toinvestigate the concept of their use as powder coatings resins.This concept being that the use of branched semi-crystallinepolymers in a UV-cured powder coating system may offer a lowertemperature alternative thus allowing the use of heat sensitivesubstrates and the added benefit of a reduced viscositycompared to linear polymers.

A series of branched poly(ε-caprolactone)’s (PCL)(degree of polymerization: 5-200) initiated from hydroxylfunctional initiators were synthesized. The final architectureswere controlled by the choice of initiator structure;specifically the dendritic initiators yielded starbranchedPCL’s while the linear initiator yielded comb-branchedPCL’s. The dendritic initiators utilized were: (1) a3rd-generation Boltorn H-30, commercially availablehyperbranched polyester with approximately 32 hydroxyl groups,(2) a 3rd-generation dendrimer with 24 hydroxyl groups, and (3)a 3rd-generation dendron with 8 hydroxyl groups. Linear PCL wassynthesized for comparison. All dendritic initiators are basedon 2,2- bis(methylol) propionic acid. The comb-branchedpolymers were initiated from a modified peroxide functionalpolyacrylate. The resins were end-capped withmethylmethacrylate in order to produce a cross-linkable system.The polymers and films were characterized using 1H NMR, 13CNMR, SEC, DMTA, DSC, FT-IR, FT-Raman, rheometry and a rheometercoupled to a UV-lamp to measure cure behavior.

The star-branched PCL’s exhibited considerably lowerviscosities than their linear counterparts with the samemolecular weight for the molecular region investigated (2-550kg mol-1). It was also found that the zero shear viscosityincreased roughly exponentially with M.

The PCL star-branched resins are semi-crystalline and theirmelting points (Tm) range from 34-50°C; films can beformed and cured below 80°C. The viscoelastic behaviourduring the cure showed that the time to reach the gel point, afew seconds, increased linearly with molecular weight. Thecrossover of G’and G’’was used as the gelpoint. Measurement of mechanical properties of films showedthat the low molecular weight polymers were amorphous whilethose with high molecular weight were crystalline after cure.The polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) fromoligo- and multifunctional initiators was evaluated utilizingcoordination and cationic polymerization. Two tin basedcatalysts, stannous(II) 2-ethylhexanoate and stannous(II)trifluoromethane sulfonate, were compared with fumaric acid.Fumaric acid under bulk conditions resulted in lowerpolydispersity and less chance of gelling. The synthesis ofstar-branched polymers was confirmed by SEC data. The starpolymers exhibited a Tg at 20-30°C and a Tm at about100°C.

All semi-crystalline resins exhibited a fast decrease inviscosity at Tm. Blends of combbranched semi-crystalline resinsand amorphous resins exhibited a transition behavior inbetweenthat of pure semi-crystalline resins and that of amorphousresins.

The SEC characterization of a series of dendrimers withdifferent cores and terminal groups showed that the core had animpact on the viscosimetric radius of the core while theterminal groups appeared to have no effect.

Keywords:star-branched, semi-crystalline,comb-branched, ring-opening polymerization,poly(ε-caprolactone), dendritic, thermoset, lowtemperature curing, powder coating, UVcuring,poly(5,5-dimethyl-1,3-dioxane-2-one), size exclusionchromatography, rheology, dendritic aliphatic polyester

Le sujet de cette thèse concerne le développement et la caractérisation de résines photosensibles pour le prototypage rapide. L'étude a tout d'abord consisté à optimiser des systèmes photoréticulables commerciaux : systèmes hybrides acrylates/époxydes. La réactivité des différentes formulations préparées ainsi que leurs propriétés thermomécaniques ont pu être évaluées grâce à la spectroscopie infrarouge à transformée de Fourier résolue dans le temps (RT-FTIR) et par analyse mécanique dynamique (DMA). En parallèle, une étude plus fondamentale visant à mieux comprendre et à contrôler la formation de réseaux polymères interpénétrés simultanés méthacrylate/époxyde a été menée. L'influence de paramètres physico-chimiques tels que l'intensité lumineuse, la concentration en photoamorceur sur les propriétés finales du matériau a notamment été abordée. Ensuite, des résines dont la chimie est moins conventionnelle ont été considérées. Comme très peu de ces monomères sont disponibles commercialement, certains d'entre eux ont dû être synthétisés. Certaines formulations ont démontré non seulement une bonne réactivité mais aussi d'intéressantes propriétés thermomécaniques et une limitation du retrait de polymérisation. Finalement, une méthode de mesure du retrait linéaire simple et facile à mettre en œuvre a été mise en place afin de comparer les différents systèmes chimiques proposés au cours de la thèse. L'utilisation de cet outil est très appréciable car il pourrait permettre de choisir le type de formulations induisant le moins de retrait possible lors de la réalisation d'un objet couche par couche
The aim of this thesis is to develop and characterize UV curable resins for rapid prototyping application. The study started with the optimization of commercially available hybrid acrylate/epoxide systems (IPNs) commonly used in this industrial field. The reactivity of the different tested formulations in conjunction with their thermomechanical properties have been assessed by means of Real time Fourier transform infrared spectroscopy (RT FTIR) and Dynamic mechanical analysis (DMA). In the meantime, a more academic study has been performed on an epoxide/methacrylate mixture in order to get a better understanding and a control of the IPN formation. The influence of the light intensity and the photoinitiator concentration on the final properties has been examined. Then, UV curable resins whose chemistry is less conventional have been considered. Owing to the lack of commercial availability of some monomers, time has been spent to synthesize them. Some formulations display promising features especially in terms of reactivity, thermomechanical properties and linear shrinkage. Finally, a simple method to measure linear shrinkage has been set up to compare the different systems proposed during the thesis and thus evidences the less shrinkable UV curable system

The optimisation of existing chemistries by the introduction of environmentally friendly materials and the simplification of the device production process are intriguing challenges to promote the future widespread diffusion of LIBs. Moreover, the recent development of the next-generation electronic devices promoted a new research field for the modification of the current systems into light, flexible and/or micro-sized device. The enhancement of mechanical properties through the introduction of flexible electrodes will enable LIBs to be embedded into various functional systems in a wide range of innovative products such as smart cards, displays and implantable medical devices. Moreover, the optimisation of the electrolyte by moving towards an all-solid-state configuration will offer adaptability to various designs and stressful mechanical handling, as well as enhance cell safety and reliability. During the three years of the Ph.D. course, the attention was focused on the optimisation of innovative materials for Li-ion batteries as well as the development of easily up-scalable procedures for the production of electrodes and polymer electrolytes. The basic idea was to start from eco-friendly materials to develop simple, low-cost and easily adaptable processes in order to propose innovative solutions for LIBs with a wide range of possible applications. Moreover, during my experimental activities, I considered the performances and the cycling stability of Li-ion batteries, by studying the mechanisms related to the capacity fade of lab-scale batteries and also by analysing commercial Li-ion batteries for automotive application. The results of the research work are presented in this thesis (Chapters 4-7) following an introductory section that provides the general information needed to follow the discussions (Chapters 1-3). The experimental research work presented in Chapter IV was carried out in collaboration with the Laboratory of Pulp and Paper Science and Graphic Arts (LGP2) in Grenoble (France). A well-known natural material such as cellulose was exploited for the production of innovative low-cost and easily recyclable electrodes for Li-ion batteries. A simple aqueous filtration process, based on a well-known industrialised paper-making technology, was developed and the electrodes (graphite-based anodes and LiFePO4-based cathodes) produced and partly characterized in Grenoble by Dr. Lara Jabbour were electrochemically studied in our Labs in Politecnico di Torino. In particular, cellulose fibres (FBs) were used as natural binder for the production of paper-like electrodes obtained without addition of any synthetic binder and/or solvent and showing electrochemical performance comparable to those produced with the same active materials by a standard process. In Chapter V, results are reported regarding a newly developed procedure where a methacrylic-based polymer electrolyte is directly formed in situ at the interface with the electrodes. Exploiting the versatile nature of UV-induced free-radical photo-polymerisation, novel ready-to-use multiphase electrode/electrolyte composites (MEEC) were developed in which the electrode is conformally coated by the polymer electrolyte. This “one-shot” process was successfully applied to enhance the cycling performances of two nanostructured materials conceived for microbattery application, such as Cu2O (in collaboration with CSHR@Polito IIT research institute in Torino) and V2O5 (in collaboration with Prof. Mustarelli’s group in University of Pavia), prepared in the form of thin films and proposed respectively as anode and cathode. The proposed one-shot process, thanks to the intimate interfacial contact between electrodes surface and electrolyte obtained by in situ process, induced a huge effect of stabilization thus improving the cycling stability of both the nanostructures. All along Chapter VI, the problems related to the assembling of complete Li-ion cells, starting from two well performing electrodes, are progressively discussed and valuable solutions are proposed. A strong capacity fade was initially found, thus the possible causes were studied also considering the failure mechanisms proposed in the literature. Several measures were adopted to improve the cycling stability, considering the effect of all the different cell components as well as the effects of both charging protocol and cell apparatus. Moreover, due the knowhow progressively achieved on the intimate characteristics of complete Li-ion cells and their assembly, even thanks to a three months stage at ENEA Casaccia Research Centre of Rome, the installation of a 10 m2 dry room was personally followed at our Electrochemistry Research Group Labs in Politecnico di Torino and the results obtained are presented in the same Chapter VI. These results include the realisation of an all-paper Li-ion battery with the cellulose-based electrodes and paper hand-sheets as separator. Finally, the cycling stability and the failure prediction issue was studied for a 53 Ah commercial battery. The results obtained, by means of different standard reference tests, are reported in Chapter VII. The commercial battery was also disassembled in the controlled atmosphere of an Ar-filled dry box in order to study the system structure and characterise the various components. A testing protocol was personally developed and the results obtained allowed to evaluate the commercial battery based on the performances requested for HEV and EV application. In particular, an easy measure of the internal resistance was developed, by opportunely modulating the measured parameters, and the obtained results were found to be very useful in directly predicting the cell failure which is fundamental in practical application.

Capillary electrophoresis (CE) is a modern analytical technique, which is electrokinetic separation generated by high voltage and taken place inside the small capillaries. In this dissertation, several advanced capillary electrophoresis methods are presented using different approaches of CE and UV and mass spectrometry are utilized as the detection methods. Capillary electrochromatography (CEC), as one of the CE modes, is a recent developed technique which is a hybrid of capillary electrophoresis and high performance liquid chromatography (HPLC). Capillary electrochromatography exhibits advantages of both techniques. In Chapter 2, monolithic capillary column are fabricated using in situ photoinitiation polymerization method. The column was then applied for the separation of six antidepressant compounds. Meanwhile, a simple chiral separation method is developed and presented in Chapter 3. Beta cycodextrin was utilized to achieve the goal of chiral separation. Not only twelve cathinone analytes were separated, but also isomers of several analytes were enantiomerically separated. To better understand the molecular information on the analytes, the TOF-MS system was coupled with the CE. A sheath liquid and a partial filling technique (PFT) were employed to reduce the contamination of MS ionization source. Accurate molecular information was obtained. It is necessary to propose, develop, and optimize new techniques that are suitable for trace-level analysis of samples in forensic, pharmaceutical, and environmental applications. Capillary electrophoresis (CE) was selected for this task, as it requires lower amounts of samples, it simplifies sample preparation, and it has the flexibility to perform separations of neutral and charged molecules as well as enantiomers. Overall, the study demonstrates the versatility of capillary electrophoresis methods in forensic, pharmaceutical, and environmental applications.

Etude de monomeres liquides ou solides sous l'action des plasmas froids. Influence des parametres du plasma sur la vitesse de polymerisation et la structure chimique de la surface du polymere. Aux interfaces entre le plasma et le polymere, se produisent des reactions qui ont pour origine deux transferts d'energie du plasma. Le transfert indirect, attribue aux rayonnements uv-visible, provoque la polymerisation des acrylates. Le transfert direct, du au bombarbement par des especes metastables, radicaux, ions. . . Sur la surface du polymere, amorce des reactions de modification d'addition ou de terminaison

Nous avons etudie la cinetique des radicaux cf et cf#2 dans un plasma pulse de cf#4 utilise pour la gravure de couches minces de si ou sio#2 dans l'industrie micro-electronique. Les profils de concentration spatiaux resolus dans le temps de ces especes ont ete determines par la technique de fluorescence induite par laser. Ils permettent d'etudier les mecanismes de perte et de production de ces radicaux en phase gazeuse et sur les surfaces du reacteur. Un nouveau mecanisme de production en surface de cf et de cf#2 a ainsi ete mis en evidence, en particulier sur un substrat de silicium. Nous avons alors developpe des techniques pour comparer les flux absolus des neutres cf#x produit au flux d'ions incident. La concentration de cf#2 a ete determinee par la technique d'absorption uv, alors que pour celle de cf, nous avons developpe une nouvelle theorie permettant de rendre la f. I. L. Quantitative en prenant en compte les effets de saturation partielle de l'absorption. Enfin, pour mesurer le flux ionique en milieu polymerisant, nous avons mis au point un nouveau type de sonde electrostatique capable de fonctionner dans les chimies fluorocarbonees qui deposent rapidement un film isolant sur la surface de la sonde. Les resultats quantitatifs obtenus nous ont permis de montrer que le mecanisme de production de cf est la neutralisation et fragmentation des ions incidents. Dans le cas de cf#2, un deuxieme mecanisme lie a la decomposition d'un couche de polymere domine lorsque la concentration de fluor est faible. Cette couche (responsable de la selectivite de la gravure) est formee a partir de neutres lourds c#xf#y eux meme formes par un mecanisme de polymerisation en phase gazeuse (par des reactions c#xf#y+cf#2).

Etude de la cinétique de la polymérisation électrolytique de dérivés du chiophène et amélioration de son efficacité et de sa sélectivité en vue d'obtenir la meilleure conductivité électrique possible; relation entre la conductivité et les propriétés spectroscopiques et électrochimiques des polymères. Modification des polythiophènes par voie électrochimique et greffage covalent de groupes fonctionnels sur le monomère; étude des facteurs stériques et électroniques associés aux differents substituants en vue de conserver les propriétés conductrices du polymère. Préparation électrochimique de polymères fonctionnels conducteurs aux propriétés de reconnaissance moléculaire

碩士
國立交通大學
理學院應用科技學程
102
In this study, UV-curable epoxy resins were used to encapsulate the organic devices. The epoxy resin shows a high glass transition tem-perature (Tg ≧110℃）, good adhesion to the glass substrate (≧2.0 kgf/mm2） after UV curing. The encapsulant reveals a very low volume shrinkage （≦4%）, high water vapor transmission resistance ability （WVTR ≦10 g/m2-day）. In this study, the epoxy resins were used to encapsulate the organic device such as organic light-emitting diode（OLED） and organic photovoltaics（OPV） devices. The results demonstrate that the lifetime of the encapsulated devices is enhanced. For the OPV devices, their PCE values are around 60% of original values af-ter keeping the encapsulated device in atmosphere for 1,000 hrs.

碩士
國立臺灣科技大學
應用科技研究所
107
Abstract In this study, zwitterionic polymers and hydrogels were synthesized under low energy, eco-friendly, and high efficiency photo-polymerization. Two zwitterionic polymers, 2-Methacryloyloxyethyl phosphorylcholine (poly-MPC) and [2-(Methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (poly-DMAPS) exhibited different electrostatic charge interaction. The inter and intrapolymer interaction in poly-DMAPS resulted upper critical solution temperature (UCST) property. In addition, the UCST of poly-DMAPS can be tuned with concentration of polymer solution and molecular weight. For low molecular weight of poly-DMAPS (21kDa), the UCST presented at 37°C, 42°C and 49°C for the concentration range from 1wt%, 5wt% to 10wt%, respectively. For high molecular weight of poly-DMAPS (46kDa), the UCST presenting 51°C, 57°C and 69°C for the polymer concentration range from 1wt%, 5wt% to 10wt%, respectively. To further preparation of tough hydrogel, we consider to prepare zwitterionic hydrogel with interpenetrating double network. The designed system was that, one of the zwitterionic polymer was homogenously dispersed inside another zwitterionic polymeric hydrogel. In the first gel, the synthesized poly-MPC was blended in poly-DMAPS hydrogel, called MD gel. In the MD gel, this gel involved chemical crosslinking and physical crosslinking (electrostatic interaction chain) at the same chain. In the second gel, the synthesized poly-DMAPS was blende in poly-MPC hydrogel, called DM gel. In the DM gel, the physical crosslinking moiety was at poly-DMAPS and chemical crosslinking moiety was at poly-MPC, separately. The highest viscosity was founded in MD hydrogel when compare with DM and random gels. This result suggests that the tough zwitterionic hydrogel can be obtained by designing the rigid and soft crosslink moiety at same network. In addition, the MD hydrogel also exhibited a higher compressive strength of 1.4 MPa•s and a denser packed structure (pore size = 4μm) than that of DM and random gels. We have further tested the design hydrogel on cell adhesion experiment and anti-adhesion of surgical animal model. Those result indicated the further potential application of tough hydrogel in bio-implanted application.

碩士
南台科技大學
化學工程與材枓工程系
96
In this study, UV polymerization was used to prepare the hydrogels composed of Chitosan, acrylic acid (AAc) and 2-Hydroxyethyl methacrylate (2-HEMA). The epidermal growth factor (EGF) was incorporated inside the hydrogels to stimulate the wound healing. The results indicate that hydrogels after UV polymerization had a swelling ratio of 4.32 (w/w), a water content of 80.6%, a water vapor transmission rate of 1732 (g/m2/day), and a compressive strength of 0.34 MPa with 53.4% compressive strain, and 15% acceleration thrombus formed rate was obtained. Chitosan-PAA-pHEMA hydrogel also had good ability of antibacterial in Staphylococcus aureus, Escherichia coli, and Pseudomonas aerus. The release of EGF reached 50% in the first day and the effect would continue for 7 days. The result of cell culture indicates all the prepared hydrogels were non-toxic material which may help cell adhesion and proliferation. The animal test indicates Chitosan-PAA-pHEMA hydrogel incorporated EGF could accelerate wound close up rate. The Chitosan-PAA-pHEMA hydrogel prepared in this study may be a potential candidate used as a wound dressing material.

碩士
大同大學
材料工程學系(所)
98
External environment can induce the smart hydrogels to have inflation, shrinkage and bending. For example, the temperature, pH, electric field, magnetic field, light, bio-activity, and the change of ionic strength. Hence, it could be used in drug delivery system for artificial muscle, artificial organ, bio-sensor…etc. Now widely investigate smart hydrogel is temperature sensitive hydrogel, using LCST (lower critical solution temperature) to shift chemical and physic properties of hydrogels. In this study , using high power UV-light to irradiate AAm and AAc mixing solution, to form temperature sensitive hydrogels. This kind of hydrogels would change there structure at UCST (upper critical solution temperature), the color would be change at the same time immediately. This study discuss the effect that degree of polymerization by ratio of AAm to AAc concentration. Assay the characteristic of swelling and the effect of temperature…etc. The FT-IR shows that the peak of functional groups –COOH and -CONH2 of AAc and AAm, ,respectively ; then the DSC shows that the Tg is 6℃；the swelling is about one hundred ratio；then SEM micrographs to observation structure of hydrogels.

博士
大同大學
材料工程學系(所)
94
In this study, we used plasma treatment and photo-induced grafting polymerization technologies to surface modify the character of materials for applications to biosensor and biomaterial fields. For biomaterial application, we fabricate an easy-strip gelatin scaffold on surface of PNIPAAm gel /polypropylene (PP) nonwoven to application in wound dressing. Nonwoven have wide industrial application due to its cheapness, low density, excellent mechanical properties and high porosity. However, due to lack of chemical functionalities, the hydrophobic natures of these surfaces have restricted the use of polypropylene. Hence, in this study, we used thermal-sensitive culture scaffolds to develop a novel easily-stripped cell membrane manipulation to cure different cells. The cell membrane was fabricated by Ar plasma treatment and photo-induced graft-polymerization thermo-sensitive monomer N-isopropylacrylamide (NIPAAm) to modify the surface character of PP nonwoven. Then, after immobilization of the porous gelatin as cell membrane, it can be easily removed from PNIPAAm gel when it is immersed in cold water. The stability of the carrier materials under in-vitro conditions and proliferation of the cells was investigated by SEM and MTT test. Microscopic investigation showed that corneal epithelium cell morphology is stretched out along the length of the gelatin and even penetrated into the inner gelatin organization. Furthermore, the results of SEM and HE staining also showed that corneal epithelium and fibroblasts cells could attach to the scaffold. The porous structure of the gelatin scaffold provided an excellent space that was suitable for cell growth in this circumstance. Thus membrane-transferred corneal epithelium stem cells can be used to regenerate corneal epithelium in the eye or fibroblasts cell in the skin. Secondly, biosensor technology offers the possibility of monitoring hybridization in real time and with high selectivity. In this study, we developed a sensing system for detection of Vibrio parahaemolyticus using its oligonucleotide probe immobilization on the gold electrode surfaces of QCM. However, since the QCM surface was an inorganic substance, it is difficult to immobilize the oligonucleotide probe. In this study, the plasma surface modification of QCM for deposition of hexamethyldisilazane (HMDSZ) films as an interlayer was investigated. This provided good adhesion to the substrate and had a uniform structure. Then, we use chemical bonding to immobilize the DNA probe on the amino surface via a glutaraldehyde (GA) linker. The effect of post-treatment of the immobilized process, such as surface graft AAm and PEI treatment, is compared and the determinate limit for this way is discussed. The surface properties after each modification process were verified by water contact angle and ESCA spectra. The results demonstrate that the shift of resonance frequency of QCM was improved via subsequent graft polymerization of AAm and PEI treatment onto the electrodes. The QCM sensor after plasma deposition and surface modification could provide detection sensitivity up to 86 ng/ml and retained 90% detection sensitivity after 11 days of storage at 0oC. After washing with 0.1 M NaOH solution and 7 of repeated uses for detection, the regeneration rate of QCM could be as high as 60%.

碩士
國立成功大學
化學工程學系碩博士班
100
Helical arranged cholesteric liquid crystal (ChLC) reveals both Bragg reflection and circular dichroism. In general, cholesteric liquid crystals are prepared by adding chiral components into nematic liquid crystals. In this study, both achiral 4,4’-Bis(6-(acryloyloxy)hexyloxy)biphenyl (BAHB) monomer and (4-Cyanophenyl)-4'-(6-acryloyloxyhexyloxy)benzoate (CAHB) were used to imprint cholesteric helical structure via multiple UV polymerization. Dependence of reflection properties on imprinted polymer matrices was investigated. Tuning properties of the reflection band of the imprinted polymer matrices were investigated using uniaxial thermo stretching equipment. In order to shorten the fabrication period, both conditions of high energy short time irradiation and high surrounding temperature were applied. Optimal irradiation time, diffusion temperature, and UV exposure times of the imprinting processes were studied. Dependence of mask pattern size on imprinting efficiency was studied. It was found that masks with smaller spot pattern are available for the improving of imprinting efficiency at ambient temperature via this multiple UV polymerization.

碩士
大同大學
材料工程學系(所)
98
Polystyrene (PS) is one of important and has usually been used. However,there are troublesome problems for PS because it`s hydrophobicity, low surface energy and surface inert-bio, that induces poor adhesion and coating properties. Chemical Vapor Deposition (PECVD) using Hexamethyldisilazane(HMDSZ) and oxygen(O2) is performed to plasma deposit and activate the substrate surface, and produce alkyl-amino, alkyl-oxygen or functional group on substrate surface. After plasma surface treatment, photo-induced grafting polymerization of N-isopropylacrylamide (NIPAAm), and cross linking of biomaterial like chitosan on PNIPAAm surface. Quartz Crystal Microbalance (QCM) were used to measure the weight change of substrate for different plasma treatment. Poly(N-isopropylacrylamide) (PNIPAAm) has been extensively investigated for temperature-modulated drug delivery systems due to its thermosensitive properties, such as the lower critical solution temperature (LCST of 32 ℃), above the LSCT, Below LCST, the hydrophilic PNIPAAm chains interact with water. From FTIR, Raman analysis, there are some special function group like amine group、C=O and C-H function group on PS surface after UV light grafted PNIPAAm. From ESCA analysis, the ratio of C、N and O elements were changed before and after PD-HMDSZ and grafted PNIPAAm.

博士
國立臺灣科技大學
化學工程系
106
Rigid gas permeable (RGP) contact lenses are composed mainly of fluorosilicone acrylates (FSA) / with polymethyl methacrylate (PMMA). The surface of RGP contact lens is generally hydrophobic; therefore, after blinking, the tear cannot be spread evenly over the surface of the lens surface and this will result in discomfort for the eye. Low-temperature plasma is one of the most commonly applied methods to increase the surface hydrophilicity of the RGP contact lens. However, plasma treated lenses often were reported to have problems of aging and hydrophobicity recovery within a certain period of time after treatement. Protein ans lipids deposited on RGP contact lenses are due to the equilibrium state of surface hydrophobicity and hydrophilicity of materials. Therefore, this study aims to apply argon plasma and N-vinyl-2- pyrrolidone (NVP) / poly (ethylene glycol methyl ether methacrylate) (PEGMA) coatings on contact lens to investigate the changes on lens surface properties. In this study, the wettability of the contact lens treated by argon plasma was investigated by water contact angle measurements to find the optimum storage conditions (temperature and environment) and plasma treatment parameters (applied power, flow rate, pressure, and treatment time). Additionally, the effects of the storage time on surface wettability of lens were evaluated after 30 days of storage. The correlations between hydrophobicity recovery and plasma parameters showed that optimized plasma treatment conditions were with 80 W argon plasm, 120 seconds treatment, by using 10 sccm flow rate under 100 mTorr. However, even through RGP was plasma treated with this optimized parameter, the water contact angle on the surface of RGP increased from 37° at day one to 59° at day 7 because of hydrophobic recovery. The FTIR analyses confirmed that there was no significant difference between the surface of RGP before and after argon plasma treatment. Based on ISO 18369-4, the results of polarographically for oxygen transport showed that there was no significant difference for DK, light transmittance, cytotoxicity, and cell viability. Moreover, protein adsorption and antibacterial potency tests show significant reduction of adsorbed protein, and no inhibition efficacy toward Staphylococcus Aureus. In addition to plasma treatment, this study also applied UV induced grafting polymerization (UV-IGP) and plasma enhanced chemical vapor deposition (PECVD) of NVP/PEGMA to promote hydrophilicity and resistance to protein and bacteria on RGP. FTIR analysis confirmed the success of graft polymerization of NVP and PEGMA on the surface of RGP contact lens. Moreover, the cytotoxicity and cell viability of the NVP/PEGMA grafted RGP contact lenses were evaluated by cultivation of L-929 fibroblasts and through lactic dehydrogenase (LDH) assays. The preliminary results showed that on the grafted RGP contact lens there was a significant reduction of adsorbed protein. In addition, PEGMA grafted RGP showed better efficacy for the reduction of protein adsorption than the NVP grafted ones. In addition, the antibacterial tests performed on the treated RGP contact lens exhibited inhibition efficacy toward the growth of Staphylococcus Aureus. This study shows great potential for the plasma grafting technology in the modification of contact lenses. Comparing to UV-IGP, PECVD can produce a thinner and more uniform coating on the RGP contact lens surface and has lower environmental impact.

碩士
大同大學
材料工程學系(所)
98
The stainless steel is one kinds of an inorganic material, it`s difficult to immobile the polymer due to its metallic properties. In this study, using plasma treatment to deposit an interface layer, then using UV-induced polymerization to form poly(acrylic acid) hydrogel. It could be used in drug delivery system which is one kinds of pH sensitive hydrogel, and it could be deposited a layer of HMDSZ film to stem drug released. Then immerse into EDC/NHS solution to immobile chitosan and alginate on the surface which suitable for cell adhesion. The surface wettability will become hydrophile after UV-induced polymerization.It is contributive of chitosan immobilization. Then the amount of chitosan by using acrylic acid immobilization is about 2.08mg/cm2, it is much higher than which is only by surface activation production about 0.24mg/cm2. Besides, the effect of amount of chitosan/alginate mixed solution was followed by alginate ratio increase. As the result of increasing the alginate ratio will favorable for surface immobilization. The results indicate that plasma deposited HMDSZ film can suspend swelling ratio of poly(acrylic acid) from 43~47 to 25~30 ratio, but in the drug release system is not significantly.

New complex silicon-containing molecules were made by B(C6F5)3-catalyzed hydrosilation, dehydrocoupling, and dealkylative coupling reactions starting from Si-H reagents. The scope of reactions starting from disilane was expanded to include the formation of silicon-sulfur1, silicon-oxygen and silicon-alkyl side-chains. Reaction inhibition was found with some heteroatom substrates, such as phenols and imines, that strongly bound to B(C6F5)3, and was consistent with the proposed mechanism (Chapter 2). B(C6F5)3 was found to be selective for Si-H activation in reactions of disilane and no competing Si-Si bond cleavage side-reactions were observed. This result will guide future studies and application of B(C6F5)3-catalyzed reactions with polysilanes. A different type of selectivity, the competing B(C6F5)3-catalyzed over-reduction, is evaluated and discussed in Chapter 3. This over-reduction reaction was classified into two distinct cases: alkyl groups for which over-reduction reaction was dependent on the steric bulk of the alkyl group and benzylic groups for which over-reduction was dependent on having an alpha-aryl group. These reactions are consistent with the proposed Piers-Oestreich mechanism (see Chapter 3) and suggest the rate-determining step for over-reduction is the nucleophilic attack of the alkoxysilane (R -O-SiR3) to the R3Si•••H•••B(C6F5)3 complex. Benzylic side-chains were over-reduced regardless of the steric bulk of the aryl groups. Literature precedents suggest that benzyl over-reductions must undergo an alternative mechanism to the Piers-Oestreich mechanism. A number of mechanisms have been proposed in the literature and in Chapter 3, suggesting conventional heteroatom substrate borane or silane-borane complexation. Furthermore, over-reduction of benzylic sulfur containing side-chains was found and this reaction was exploited in the B(C6F5)3-catalyzed synthesis of unique silicon-sulfur silicon-containing products. These over-reduction reactions highlighted the role of the silane for over-reduction and the challenges associated with the post-polymerization modification of poly(phenylsilane). The advances in B(C6F5)3-catalyzed synthesis of small silane molecules suggested reaction conditions and gave spectroscopic benchmarks that were applied to the post polymerization modification of poly(phenylsilane) (Chapter 4). New X-modified poly(phenylsilane) derivatives with thiolato (sulfur), alkoxy/aryloxy (oxygen), amido (nitrogen) and alkyl(carbon) side-chains were prepared with 10-40% incorporation of the ‘X’ group into poly(phenylsilane). These new polysilanes were characterized by the following methods: 1H/13C/29Si NMR, IR, MALS-GPC, EA, and UV-vis absorption spectroscopy. Together, these characterization methods showed that the polysilane had not undergone Si-Si cleavage and thus demonstrated the utility of B(C6F5)3 for the selective activation of Si-H bonds. Thermal decomposition of X-modified poly(phenylsilane) derivatives and parent poly(phenylsilane) showed interesting redistribution pathways (Chapter 5). The thermal decomposition products of poly(phenylsilane) were identified: volatile monosilanes, a structurally complex not-yet-identified phenylsilicon-containing material generated at 500 °C, and a mixture of silicon carbide (SiC) and elemental carbon generated at 800 °C. The B(C6F5)3-catalyzed post-polymerization method (Chapter 4) was evaluated based on the substitution percentage for X-functionalized poly(phenylsilane) derivatives. Reactions of highly electron-donating substrates gave a low amount of X incorporation (10%, e.g. aryloxy side-chains derived from phenol). Aryloxy groups were alternatively introduced via demethanative coupling, which gave a polymer with a greater substitution percentage (25%). The overall impact of the H-to-X substitution reactions was gauged by UV-vis absorption spectra and desirable UV absorption properties would require the modified poly(phenylsilane) to have a high degree of substitution.
Graduate
2017-09-02