Multiphase systems provide an opportunity to develop both novel processing methods and create advanced materials through combining the properties of dissimilar phases in a synergistic manner. In this work, we detail the halogenation of poly(ether ether ketone) (PEEK) through both solution-state and gel-state functionalization methods. The multiphase gel-state chemistry restricts functionalization to the amorphous regions of the semi-crystalline parent homopolymer and generates a copolymer with a blocky microstructure. Solution-state functionalization yields random copolymers which provide matched sets to the blocky analogs for fundamental investigations into the effects of polymer microstructure on material properties. Halogenating PEEK using N-halosuccinimides allows for direct installation of pendant halogens along the polymer backbone with facile control of halogen identity. For both bromination and iodination, blocky halogenation of PEEK provides faster crystallization kinetics, higher glass transition (Tg) and melting temperatures as well as superior crystallizability than random halogenation. When comparing halogen identity, increasing halogen size results in increased Tgs, decreased backbone planarity, and for copolymers with blocky microstructures, an earlier onset of phase separation. Increasing halogen size also results in decreased crystallizability and crystallization kinetics, however, these deleterious effects are mitigated in blocky microstructures due to colocalization of the pristine repeat units. Iodination also results in greater flame resistance than bromination for PEEK-based copolymers, and preserved crystallizability allows for the generation of flame retardant aerogels. Direct halogenation of PEEK in the gel-state also provided a reactive microstructural template for subsequent functionalization. Through the use of copper mediated cross-coupling chemistries, the aryl halide functionalities were leveraged to decorate the polymer backbone with pendant perfluoroalkyl chains. The blocky perfluoro alkyl PEEK demonstrated preserved crystallizability and serves as a candidate for compatibilization of poly(tetrafluoroethylene)-PEEK polymer blends. Superacid-modified PEEK was synthesized through a similar methodology and demonstrated over 50,000% increased hygroscopicity relative to the parent homopolymer, and exhibited preserved crystallizability. Multiphase systems were also designed to additively manufacture reinforced elastomers through vat photopolymerization using a degradable scaffold approach that challenged the current paradigm that the scaffold only serves as a geometrical template in vat photopolymerization. The scaffold crosslinks were cleaved through a reactive extraction process that liberated the glassy photopolymer backbone and resulted in over 200% increased ultimate strain and 50% increased ultimate stress relative to a control that was subjected to a neutral extraction. Lastly, thermoresponsive micellar ligands were synthesized as a multiphase approach to environmental remediation of metal-contaminated aqueous systems. / Doctor of Philosophy / Multiphase systems, such as a mixture of oil and water, are of great interest due to their ability to exhibit a multitude of properties from one material. Minimizing the size of the phases, through a technique called compatibilization, often improves the properties of the material. A common example is salad dressing, where the oil phase is compartmentalized into microscopic particles using surface-active molecules known as surfactants. Surfactants, also known as amphiphiles, partition to the interface between different phases due to the surfactants being comprised of dissimilar molecular constituents. One way to generate polymeric amphiphiles, where a polymer is a large molecule comprised of a molecular chain of repeating units, is through synthesizing block copolymers. Block copolymers have blocks of different constituents that are colocalized through covalent bonds in the polymer backbone and often exhibit phase separated structures, allowing for enhanced transport properties such as is seen in membranes. Using semi-crystalline polymers in membranes allows for enhanced mechanical integrity, as the crystallites act as physical crosslinks, or tie points, similar to the knots in a 3D rope ladder. These molecular knots limit the distance that the linear segments of the rope ladder can stretch, which in membranes leads to reduced swelling and increased mechanical performance. In this work we use semi-crystalline polymers to generate blocky copolymers through the use of halogenation. Halogenation installs halogen moieties as pendant groups on the polymer backbone, which can then by used as a chemical handle for subsequent reactions to further incorporate functionality into the copolymer and achieve desired properties such as proton (hydrogen nuclei) transport in fuel cell membranes. Halogenation also allows for the generation of blocky semi-crystalline copolymers for compatibilizing polymer blends of materials like poly(tetrafluoroethylene) and poly(ether ether ketone). Also in this work, we discuss the additive manufacturing of mechanically reinforced elastomers. An elastomer is another type of crosslinked network, and a mechanically reinforced elastomer can be through of as a 3D rope ladder where some of the linear segments of rope are replaced with steel bars, thus increasing the amount of work required to deform the network. The last multiphase systems discussed are similar to salad dressing, where there is a continuous water phase and a microscopic particle phase. The microscopic particles in this work are amphiphilic block copolymers that change their solubility in water with temperature and also have functionalities that should allow for the binding of metals from water-based systems.

Polysiloxanes represent a unique class of synthetic polymers, employing a completely inorganic backbone structure comprised of repeating –(Si–O)n– 'siloxane' main chain linkages. This results in an assortment of diverse properties exclusive to the siloxane bond that clearly distinguish them from the –(C–C)n– backbone of purely organic polymers. Previous work has elucidated a methodology for fabricating flexible and elastic crosslinked poly(dimethyl siloxane) (PDMS) constructs with high Mc through a simultaneous crosslinking and chain-extension methodology. However, these constructs suffer the poor mechanical properties typical of lower molecular weight crosslinked siloxanes (e.g. modulus, tear strength, and strain at break). Filled PDMS networks represent another important class of elastomers in which fillers, namely silica and siloxane-based fillers, impart improved mechanical properties to otherwise weak PDMS networks. This work demonstrates that proper silicon-based reinforcing agent selection (e.g. siloxane-based MQ copolymer nanoparticles) and incorporation provides a synergistic enhancement to mechanical properties, whilst maintaining a low viscosity liquid composition, at high loading content, without the use of co-solvents or heating. Rheological analysis evaluates the viscosity while photorheology and photocalorimetry measurements evaluate rate and extent of curing of the various MQ-loaded formulations, demonstrating theoretical printability up to 40 wt% MQ copolymer nanoparticle incorporation. Dynamic mechanical analysis (DMA) and tensile testing evaluated thermomechanical and mechanical properties of the cured nanocomposites as a function of MQ loading content, demonstrating a 3-fold increase in ultimate stress at 50 wt% MQ copolymer nanoparticle incorporation. VP AM of the 40 wt% MQ-loaded, photo-active PDMS formulation demonstrates facile amenability of photo-active PDMS formulations with high MQ-loading content to 3D printing processes with promising results. PDMS polyureas represent an important class of elastomers with unique properties derived from the synergy between the nonpolar nature, unusual flexibility, and low glass transition temperature (Tg) afforded by the backbone siloxane linkages (-Si-O)n- of PDMS and the exceptional hydrogen bond ordering and strength evoked by the bidentate hydrogen bonding of urea. The work herein presents an improved melt polycondensation synthetic methodology, which strategically harnesses the spontaneous pyrolytic degradation of urea to afford a series of PDMS polyureas via reactions at high temperatures in the presence of telechelic amine-terminated oligomeric poly(dimethyl siloxane) (PDMS1.6k-NH2) and optional 1,3-bis(3-aminopropyl)tetramethyldisiloxane (BATS) chain extender. This melt polycondensation approach uniquely circumvents the accustomed prerequisite of isocyanate monomer, solvent, and metal catalysts to afford isocyanate-free PDMS polyureas using bio-derived urea with the only reaction byproduct being ammonia, a fundamental raw ingredient for agricultural and industrial products. As professed above, reinforcement of polysiloxane materials is ascertained via the incorporation of reinforcing fillers or nanoparticles (typically fumed silica) or blocky or segmented development of polymer chains eliciting microphase separation, in order to cajole the elongation potential of polysiloxanes. Herein, a facile approach is detailed towards the synergistic fortification of PDMS-based materials through a collaborative effort between both primary methods of polysiloxane reinforcement. A novel one-pot methodology towards the facile, in situ incorporation of siloxane-based MQ copolymer nanoparticles into segmented PDMS polyureas to afford MQ-loaded thermoplastic and thermoplastic elastomer PDMS polyureas is detailed. The isocyanate-free melt polycondensation achieves visible melt dispersibility of MQ copolymer nanoparticles (good optical clarity) and affords segmented PDMS polyureas while in the presence of MQ nanoparticles, up to 40 wt% MQ, avoiding post-polymerization solvent based mixing, the only other reported alternative. Incorporation of MQ copolymer nanoparticles into segmented PDMS polyureas provides significant enhancements to modulus and ultimate stress properties: results resemble traditional filler effects and are contrary to previous studies and works discussed in Chapter 2 implementing MQ copolymer nanoparticles into chemically-crosslinked PDMS networks. In situ MQ-loaded, isocyanate-free, segmented PDMS polyureas remain compression moldable, affording transparent, free-standing films. / Master of Science / Polysiloxanes, also referred to as 'silicones' encompass a unique and important class of polymers harboring an inorganic backbone. Polysiloxanes, especially poly(dimethyl siloxane) (PDMS) the flagship polymer of the family, observe widespread utilization throughout industry and academia thanks to a plethora of desirable properties such as their incredible elongation potential, stability to irradiation, and facile chemical tunability. A major complication with the utilization of polysiloxanes for mechanical purposes is their poor resistance to defect propagation and material failure. As a result polysiloxane materials ubiquitously observe reinforcement in some fashion: reinforcement is achieved either through the physical or chemical incorporation of a reinforcing agent, such as fumed silica, or through the implementation of a chemical functionality that facilitates reinforcement via phase separation and strong associative properties, such as hydrogen bonding. This research tackles polysiloxane reinforcement via both of these strategies. Facile chemical modification permits the construction PDMS polymer chains that incorporate hydrogen bonding motifs, which phase separate to afford hydrogen bond-reinforced phases that instill vast improvements to elastic behavior, mechanical and elongation properties, and upper-use temperature. Novel nanocomposite formulation through the incorporation of MQ nanoparticles (which observe widespread usage in cosmetics) facilitate further routes toward improved mechanical and elongation properties. Furthermore, with growing interest in additive manufacturing strategies, which permit the construction of complex geometries via an additive approach (as opposed to conventional manufacturing processes, which require subtractive approaches and are limited in geometric complexity), great interest lies in the capability to additively manufacture polysiloxane-based materials. This work also illustrates the development of an MQ-reinforced polysiloxane system that is amenable to conventional vat photopolymerization additive manufacturing: chemical modification of PDMS polymer chains permits the installation of UV-activatable crosslinking motifs, allowing solid geometries to be constructed from a liquid precursor formulation.

Yes / Vat photopolymerization has garnered interest from pharmaceutical researchers for the fabrication of personalised medicines, especially for drugs that require high precision dosing or are heat labile. However, the 3D printed structures created thus far have been insoluble, limiting printable dosage forms to sustained-release systems or drug-eluting medical devices which do not require dissolution of the printed matrix. Resins that produce water-soluble structures will enable more versatile drug release profiles and expand potential applications. To achieve this, instead of employing cross-linking chemistry to fabricate matrices, supramolecular chemistry may be used to impart dynamic interaction between polymer chains. In this study, water-soluble drug-loaded printlets (3D printed tablets) are fabricated via digital light processing (DLP) 3DP for the first time. Six formulations with varying ratios of an electrolyte acrylate …

<p>  </p> <p>3D printing techniques have been applied in many fields to provide a potential for complex fabrication, and photopolymerization methods are the current possible path to fabricate nanoscale 3D structures. Multi-photon lithography is the most common tool to reach below 100-nm resolution. These methods require femtosecond lasers to reliably create sophisticated 3D polymeric nanostructures using nonlinear photopolymerization of a light-sensitive resin. Though these methods provide high accuracy and flexibility in advanced fabrication, they are essentially limited by their cost and throughput. Therefore, in this work, multiple approaches were examined to develop new methods for one-photon nonlinear 3D printing. </p> <p>By controlling multiple competing processes in the radical polymerization scheme, a nonlinear photopolymerization effect is achieved using a one-photon absorption process with the assistance of inhibition radicals and controlled diffusion. This work makes use of this nonlinear response to fabricate 2D/3D structures using a continuous-wave diode laser, demonstrating a significantly more cost-efficient source for 3D nanolithography. In addition, a numerical model was constructed with the highly nonlinear response by actively controlling the consumption of the initiators with the assistance of these inhibitors, and it shows the same trend of nonlinearity from experiments. We use this model to study this dosage-based nonlinear response driven by the laser intensity in several 1D and 2D scenarios with different inputs and predicted the polymerization results in a confined voxel in the resin to support the observations from the experiments. Besides the demonstration of current one-photon nonlinear 3D printing, this work also involves some results of nonlinear response by operating local oxygen concentration and a two-step absorption nonlinear photoinitiator. These results help us to further study the potential of increasing the throughput of the one-photon nonlinear 3D printing process. </p> <p>In conclusion, a new one-photon-based dose nonlinear process is introduced in this dissertation to achieve nanoscale 3D printing with a low-cost-405-nm diode laser operating at milliwatt level. By controlling the activation and transport of initiating and inhibiting radicals, we achieve patterning of the nanoscale features at a high scanning speed.</p>

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / Hydrogels prepared from photopolymerization have been used for a variety of tissue engineering and controlled release applications. Polymeric biomaterials with high cytocompatibility, versatile degradation behaviors, and diverse material properties are particularly useful in studying cell fate processes. In recent years, step-growth thiol-ene photochemistry has been utilized to form cytocompatible hydrogels for tissue engineering applications. This radical-mediated gelation scheme utilizes norbornene functionalized multi-arm poly(ethylene glycol) (PEGNB) as the macromer and di-thiol containing molecules as the crosslinkers to form chemically crosslinked hydrogels. While the gelation mechanism was well-described in the literature, the network properties and degradation behaviors of these hydrogels have not been fully characterized. In addition, existing thiol-ene photopolymerizations often used type I photoinitiators in conjunction with an ultraviolet (UV) light source to initiate gelation. The use of cleavage type initiators and UV light often raises biosafety concerns. The first objective of this thesis was to understand the gelation and degradation properties of thiol-ene hydrogels. In this regard, two types of step-growth hydrogels were compared, namely thiol-ene hydrogels and Michael-type addition hydrogels. Between these two step-growth gel systems, it was found that thiol-ene click reactions formed hydrogels with higher crosslinking efficiency. However, thiol-ene hydrogels still contained significant network non-ideality, demonstrated by a high dependency of hydrogel swelling on macromer contents. In addition, the presence of ester bonds within the PEGNB macromer rendered thiol-ene hydrogels hydrolytically degradable. Through validating model predictions with experimental results, it was found that the hydrolytic degradation of thiol-ene hydrogels was not only governed by ester bond hydrolysis, but also affected by the degree of network crosslinking. In an attempt to manipulate network crosslinking and degradation rate of thiol-ene hydrogels, different macromer contents and peptide crosslinkers with different amino acid sequences were used. A chymotrypsin-sensitive peptide was also used as part of the hydrogel crosslinkers to render thiol-ene hydrogels enzymatically degradable. The second objective of this thesis was to develop a visible light-mediated thiol-ene hydrogelation scheme using a type II photoinitiator, eosin-Y, as the only photoinitiator. This approach eliminates the incorporation of potentially cytotoxic co-initiator and co-monomer that are typically used with a type II initiator. In addition to investigating the gelation kinetics and properties of thiol-ene hydrogels formed by this new gelation scheme, it was found that the visible light-mediated thiol-ene hydrogels were highly cytocompatible for human mesenchymal stem cells (hMSCs) and pancreatic MIN6 beta-cells. It was also found that eosin-Y could be repeatedly excited for preparing step-growth hydrogels with multilayer structures. This new gelation chemistry may have great utilities in controlled release of multiple sensitive growth factors and encapsulation of multiple cell types for tissue regeneration.

L’intérêt grandissant porté au cours de ces dix dernières années aux monolithes organiques pour des applications électroséparatives se justifie en partie par leur préparation aisée au sein de systèmes miniaturisés, le large choix des monomères précurseurs disponibles, ainsi que la possibilité d’ajuster les paramètres structuraux du matériau final par un contrôle judicieux des conditions opératoires. Au cours de ce travail, la synthèse de nouvelles phases monolithiques a été mise au point selon une stratégie en deux étapes. Dans une première étape, la copolymérisation radicalaire photo-initiée du Nacryloxysuccinimide avec le diméthacrylate d’éthylène glycol réalisée en présence de toluène, a permis l’élaboration de monolithes macroporeux réactifs et hautement perméables. La présence d’esters de succinimide dans la structure chimique du monolithe polymère a été mise à profit pour fonctionnaliser la surface du monolithe par des greffons de nature variée par réaction de substitution nucléophile faisant intervenir des dérivés aminés. Le choix judicieux des greffons a permis la mise au point rapide de phases stationnaires présentant des propriétés électrochromatographiques ciblées. Ainsi, le contrôle du caractère hydrophobe des supports obtenus par greffage d’alkylamines de taille variable a été mis en évidence par la séparation de dérivés benzéniques selon un mécanisme à polarité de phase inversée avec de très bonnes efficacités (200000 plateaux par mètre). L’utilisation de phases stationnaires monolithiques greffées par des sélecteurs aromatiques a été proposée comme alternative aux monolithes aliphatiques hydrophobes. La synthèse de monolithes organiques hydrophiles a été possible par la fonctionnalisation du support réactif par des alkyldiamines. La préparation d’une phase stationnaire chirale a été réalisée selon une approche originale de chimie click consistant à immobiliser un dérivé de cyclodextrine. Dans le but d’étendre l’application des monolithes à base de NAS au greffage de biomacromolécules, une nouvelle matrice monolithique incorporant dans sa structure chimique un co-monomère hydrophile a été élaborée. Les résultats préliminaires ont montré que l’augmentation du caractère hydrophile du squelette monolithique permet d’accroître sensiblement la réactivité des esters de Nhydroxysuccinimide en milieu aqueux / The continuously growing interest observed over the past ten years in the field of organic monoliths dedicated to electroseparation applications is mainly due to their easy preparation methods which are also well-suited to the development of miniaturized systems, the wide range of available monomers and the possibility of tuning the structural parameters of the final material by a judicious control of the synthesis conditions. In the present work, the synthesis of new monolithic stationary phases has been developed using a two-stage strategy. In a first step, the photo-initiated free radical copolymerization of Nacryloxysuccinimide with ethylene glycol dimethacrylate was performed in the presence of toluene allowing the preparation of reactive and macroporous monoliths with high permeability properties. The presence of succinimide esters in the chemical structure of the polymer monolith was used to functionalize the surface of the monolith by various grafts through nucleophilic substitution reaction involving amino derivatives. The judicious choice of the grafts permits the fast development of stationary phases with target electrochromatographic properties. Indeed, the tuning of the hydrophobic nature of the monolithic materials was obtained by the grafting of varied alkylamines and was demonstrated by the separation of benzene derivatives by reversed phase mechanism with very good efficiencies (200 000 plates per meter). The use of monolithic stationary phases grafted with aromatic selectors has been proposed as an alternative to the aliphatic-grafted hydrophobic monoliths. The synthesis of organic hydrophilic monoliths was possible by functionalization of the reactive support by alkyldiamines. The preparation of a chiral stationary phase was performed using an original click chemistry approach involving the immobilization of a cyclodextrin derivative. With the aim to extend the application range of NAS-based monoliths to the grafting of biomacromolecules for selective capture and enzymatic digestion applications, a new monolithic matrix incorporating in its chemical structure a hydrophilic comonomer was prepared. Preliminary results showed that the increase in the hydrophilic character of the polymeric skeleton allows increasing significantly the reactivity of N-hydroxysuccinimide esters in aqueous medium

Nesta tese, estudamos o processo de absorção multifotônica em polímeros e resinas poliméricas, abordando tanto aspectos fundamentais quanto aplicados. Com relação aos aspectos fundamentais, estudamos processos de absorção multifotônica (absorção de dois, três e quatro fótons) no polímero conjugado MEH-PPV (poly(2-methoxy-5-(2´-ethylhexyloxy)-1,4- phenylenevinylene)), utilizando a técnica de Varredura-Z com pulsos ultracurtos. Através desta técnica, determinamos o espectro da absorção de dois, três e quatro fótons do MEHPPV. As seções de choque de absorção de multi-fótons correspondentes a cada processo foram determinadas através do ajuste das curvas experimentais com um conjunto de equações desenvolvidas neste trabalho. Os resultados obtidos permitiram traçar relações entre os espectros não lineares e os níveis de energia do polímero. Na vertente mais aplicada do projeto, estudamos a fotopolimerização de resinas acrílicas através do processo de absorção de dois fótons. Devido ao confinamento espacial da polimerização, graças à absorção de dois fótons, este método permite a confecção de micro-estruturas complexas para diversas aplicações tecnológicas. Além da fabricação de microestruturas convencionais não dopadas, neste trabalho desenvolvemos uma metodologia que possibilita a fabricação de microestruturas dopadas com MEH-PPV, visando a produção de micro-elementos fluorescentes para dispositivos fotônicos, e microestruturas dopadas com quitosana, um polímero biocompatível que pode ser utilizado em aplicações médicas e biológicas. / In this thesis we have studied the multi-photon absorption process in polymers and polymeric resins, exploiting its fundamental as well as technological aspects. Regarding the fundamental aspects, we have studied the multi-photon absorption (two-, three- and four-photon absorption) in the conjugated polymer MEH-PPV (poly(2-methoxy-5-(2´-ethylhexyloxy)-1,4-phenylenevinylene)), by using the Z-scan technique with ultrashort laser pulses. Through this technique, we determined the two-, three- and four-photon absorption spectra of MEH-PPV. The multi-photon absorption cross-sections, corresponding to each specific process, have been determined by fitting the experimental data with a set of equations developed in this work. The results allowed us to correlate the nonlinear absorption spectra to the energy level of the polymer. On the technological side of this thesis, we have investigated the photopolymerization of acrylic resins by two-photon absorption. Because of the spatial confinement of the polymerization, resulting from the two-photon excitation, this method allows the fabrication of complex microstructures which can be used for several technological applications. In addition to the fabrication of undoped microstructures, in this work we have developed a methodology that allows the fabrication of microstructures doped with MEHPPV, aiming the production of fluorescent micro-elements for photonics applications, and microstructures doped with chitosan, a biocompatible polymer, that can be used for medical and biological applications.

En raison des problèmes d'instabilité à moyen termes des cellules solaires à colorant (DSSC), l'électrolyte liquide à base d'iodure a été remplacé par plusieurs types de matériaux solides transport de trous (HTM) pour obtenir des DSSCs à l'état solide (s-DSSCs). Parmi ces matériaux, l’utilisation des polymères conducteurs(PC) a attiré une attention considérable en raison de leur bonne stabilité, de leur haute conductivité et de la facilité de leur dépôt sur le semi-conducteur mésoporeux TiO2. Dans ce travail de thèse, plusieurs s-DSSCs basées sur des PC utilisés comme HTM ont été développés dans le but d'améliorer leurs performances photovoltaïques en tenant compte des deux objectifs suivants: (i) l'optimisation des processus de transfert inter facial de charge dans la cellule solaire, et (ii) l'optimisation du transport de charge dans le semi-conducteur d'oxyde de type n. Pour atteindre ces objectifs, chaque composant de la s-DSSC a été modifié afin d'étudier son effet sur les performances du dispositif final. En première tentative, une étude analytique est réalisée en faisant varier le sensibilisateur afin de déterminer les fragments de la structure du colorant, qui ont un effet important sur le processus de photopolymérization électrochimique in-situ (PEP) à la fois en milieu organique et en milieu aqueux mais aussi sur les performances des s-DSSCs. Sur la base de ces résultats, un nouveau concept a été développé et consiste en la suppression totale de l'interface entre le colorant et le HTM. Ceci est obtenu par la synthèse de nouveaux colorants liés de façon covalente à un monomère électroactif qui est co-polymérisé par la PEP in-situ. Le copolymère résultant, utilisé comme HTM, est lié de manière covalente au colorant. En outre, la nature de la liaison chimique, reliant le résidu triphénylamine TPA au monomère, est également étudiée comme un facteur clé dans les performances de s-DSSC. En outre, et pour optimiser les processus de transport de charges dans ce type de s-DSSC, de nouvelles s-DSSC basées sur ZnO ont été réalisées et étudiées. / Due to instability problems of dye sensitized solar cells (DSSCs) in longtime uses, the iodine based liquidelectrolyte has been replaced by several types of solid hole transporting materials (HTM) to perform solidstate DSSCs (s-DSSCs). Among them, the substitution by conducting polymers (CP) has attractedconsiderable attention because of their good stability, high hole-conductivity and simple deposition withinthe mesoporous TiO2 semiconductor. In this thesis work, several s-DSSCs based on CPs used as HTM havebeen developed in order to improve their photovoltaic performances taking into account the following twoobjectives: (i) the optimization of the interfacial charge transfer processes within the solar cell, and (ii) theoptimization of the charge transport within the n-type oxide semiconductor. To reach these goals, eachcomponent that constitutes the device was varied in order to investigate its effect on the device’sperformances. As first attempt, an analytical study is carried out by varying the sensitizer in order todetermine the fragments of the dyes structures, that have an important effect on the in-situ photoelectrochemical polymerization process (PEP) both in organic and in aqueous media and hence on theperformances of the s-DSSCs. Based on these results, a new concept of removing completely the interfacebetween the dye and the HTM is developed. This is achieved by the synthesis of new dyes covalently linkedto an electroactive monomer which is co-polymerized by in-situ PEP. The resulting co-polymer, used asHTM, is covalently linked to the dye. In addition, the nature of the chemical bond linking the triphenylamineresidue TPA to the monomer is also investigated as a key factor in the s-DSSCs performances. Besides, andto optimize the charge transport processes within this type of s-DSSC, the elaboration of novel ZnO baseds-DSSCs has been achieved and investigated.

Ce travail de thèse aborde l’étude mécanistique de systèmes photoamorceurs complexes et la modélisation cinétique du processus de photopolymérisation. Dans un premier temps, le mécanisme photochimique d’un système combinant le [Ru(bpy)3]2+ et des agents RAFT pour l’amorçage et le contrôle d’un processus radicalaire a été étudié. Un transfert d’énergie a été clairement démontré, contredisant le mécanisme de transfert d’électron généralement proposé. Un système photoamorceur à 3 composants bicyclique dual ITX/IOD+/RSH a ensuite été considéré pour la synthèse de matériaux hybrides organiques-inorganiques. Sous excitation lumineuse, ce système produit simultanément des radicaux et des protons, permettant d’amorcer, respectivement, des processus de polymérisation radicalaire et sol-gel. Dans un second temps, l’interdépendance entre les cinétiques de photopolymérisation et l’évolution des propriétés du milieu réactionnel a été étudiée par le biais du développement d’un modèle cinétique permettant la simulation de l’intégralité du processus de photopolymérisation. Des systèmes photoamorceurs de complexité croissante ont été inclus afin d’étudier les spécificités de leurs cinétiques. Un système de type I a permis de mettre en évidence les modes de terminaison majoritaires et leur évolution au cours de la synthèse des polymères, tandis que le rôle non négligeable du transfert d’électron inverse a été mis en exergue pour des systèmes photoamorceurs de type II. La fonction d’agent de terminaison d’un photoproduit issu d’un colorant cationique, ainsi que certaines spécificités des systèmes photocycliques à 3 composants, ont été finalement étudiés grâce à la modélisation. / This thesis deals with the mechanistic study of complex photoinitiating systems and the kinetic modeling of the photopolymerization process. In a first time, the photochemical mechanism of a system combining [Ru(bpy)3]2+ and RAFT agents for the initiation and control of a radical process has been studied. An energy transfer has been clearly demonstrated, contradicting the electron transfer mechanism generally proposed. A dual bicyclic three-component photoinitiating system ITX/IOD+/RSH has been considered for the synthesis of organic-inorganic hybrid materials. Under light exposure, this system produces simultaneously radicals and protons, enabling the initiation of a radical polymerization and a sol-gel process, respectively. In a second time, interdependence between photopolymerization kinetics and evolution of the medium’s properties has been studied, through developing a kinetic model for the simulation of the whole photopolymerization process. Photoinitiating systems of growing complexity have been included in order to study specificities of their kinetics. A type-I system has shown major termination modes and their evolution during the polymer synthesis, while the non-negligible role of back electron transfer has been highlighted for type-II photoinitiating systems. Role of terminating agent of a photoproduct based on a cationic dye, as well as some specificities of photocyclic three-component systems, have been finally studied with the model.