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Amphiphilic block copolymers (BCPs) form self-assembled aggregates in solution with a range of morphologies including spherical micelles, cylindrical micelles, vesicles (polymersomes) and bicontinuous nanospheres. This research focuses on the formation of bicontinuous nanospheres using a number of different BCPs for use in thermo-responsive drug delivery. It has been shown previously that PEO-b-PODMA (poly(ethylene oxide)-block-poly(octadecyl methacrylate)) forms semi-crystalline bicontinuous nanospheres with a phase transition temperature (Tm) of 21.8ᵒC. This corresponds to the melting transition of the semi-crystalline PODMA block. To increase the Tm, while maintaining all other properties, the hydrophobic monomer ODMA, was replaced with docosyl methacrylate (DSMA), which has a higher melting point. Upon self-assembly the PEO-b-PDSMA (25 wt % PEO) formed bicontinuous nanospheres. Analysis using differential scanning calorimetry (DSC) revealed the Tm of PEO-b-PDSMA in bulk and aggregate solution to be 41.3°C and 41.1°C respectively. To further demonstrate the control achieved over the Tm, random copolymers of ODMA and DSMA using a PEO macroinitiator were synthesised at varying wt % ratios of PODMA:PDSMA. DSC analysis of these polymers showed that an increase in PDSMA led to an increase in the Tm for the bulk and self-assembled samples. The controlled release of Ibuprofen from these bicontinuous nanospheres was investigated to determine the rate of release and the optimum temperature for release following a previously used method. The concentration of release was then analysed using HPLC. To incorporate acid functionality into the bicontinuous nanospheres PMAA-b-PODMA (poly(methacrylic acid)-block-poly(octadecyl methacrylate)) was synthesised (via ATRP) with hydrophilic wt % of 20 %. The self-assembled solution of PMAA-b-PODMA was analysed using cryo-TEM which revealed the presence of bicontinuous nanospheres. Another approach to incorporate acid functionality into bicontinuous nanospheres was the self-assembled of PEO-b-PS and PEO-b-PODMA followed by the alkaline hydrolysis of PEO to leave an acid end group.

L’objectif de cette thèse est de mettre au point des formes adéquates d’hydrogels thermosensibles destinées à une application textile transdermique de libération contrôlée de médicament. Les travaux concernent les hydrogels thermosensibles à base de poly(N-isopropylacrylamide) (PNIPAAm). Ce polymère a été combiné sous une forme linéaire et/ou réticulée avec l’alginate, pour former des hydrogels ayant une structure de réseaux de polymères interpénétrés. On améliore ainsi les propriétés du PNIPAAm pur. Des hydrogels de PNIPAAm et d’alginate de calcium (CA) ont d’abord été synthétisés sous forme de films. La présence de CA contribue à l’amélioration des propriétés mécaniques, sans modifier la température de transition de phase du PNIPAAm. Nous avons ensuite appliqué la technique d’extrusion électrostatique pour préparer des microsphères d’hydrogel. Les paramètres du procédé ont été variés afin de comprendre et d’optimiser les conditions de fabrication de microsphères ayant un diamètre inférieur à 20 µm et une forme sphérique régulière. Nous avons utilisé la polymérisation en suspension inverse pour synthétiser des microsphères qui sont de forme plutôt régulière et sphérique, avec un diamètre variant de 20 à 80 µm. Leur structure était poreuse, en forme de nid d’abeille. La libération de l’hydrochlorure de procaïne des microsphères d’hydrogel a été étudiée avec une cellule de diffusion de Franz. L’incorporation de CA dans le réseau de PNIPAAm engendre une libération de type légèrement négatif, tandis que le PNIPAAm pur présente un type positif. La libération de procaïne dépend non seulement du phénomène de diffusion mais aussi du comportement de l’hydrogel au gonflement. / The objective of this thesis is to develop adequate forms of thermosensitive hydrogels intended for a textile-based controlled transdermal drug release application. This work deals with thermosensitive hydrogels based on poly(N-isopropylacrylamide) (PNIPAAm). This polymer was combined in both linear and crosslinked form with alginate to form hydrogels with interpenetrating polymer network structure. Thus, the properties of conventional pure PNIPAAm hydrogel have been improved. Hydrogels of crosslinked PNIPAAm and calcium alginate (CA) were initially synthesized in the form of films. The presence of CA contributes to the improvement of mechanical properties without affecting the volume phase transition temperature (VPTT) of PNIPAAm. The technique of electrostatic extrusion was applied for the preparation of hydrogel microbeads. Operating parameters were varied to understand and optimize the conditions of the production of microbeads below 20 µm in diameter and of regular spherical shape. Inverse suspension polymerization was afterwards used for the preparation of microbeads of regular spherical shape and diameter in the range from 20 to 80 µm. They had porous, honeycomb-like structure. A Franz diffusion cell was employed to investigate the release of procaine hydrochloride from selected hydrogel microbeads. The incorporation of CA in PNIPAAm network resulted in slightly temperature-negative drug release pattern in comparison with temperature-positive drug release from the pure PNIPAAm hydrogel microbeads. The mechanism of the drug release at temperatures above and below the VPTT of microbeads depended on hydrogel swelling behavior and not solely on diffusion.

This thesis explores the use of polymer nanoreactors in catalysis as well as the use of water-soluble polymers in enzyme stabilisation. Chapter 1: An introduction to the literature currently covering the research topics relevant to the techniques used within this thesis, providing further background on the fundamental enzyme theory that is to be explored Chapter 2: This looks at the techniques available for tethering the catalyst triazabicyclodec-5-ene to the hydrophobic block of an amphiphilic block copolymer, synthesised by nitroxide mediated polymerisation and the assembly of these polymers. Chapter 3: The previously synthesised nanoreactors were used to catalyse Michael additions with varied loadings within the core of the micelles. Chapter 4: Looks into the effect of using water soluble polymers of varying molecule weights on the activity of Lipases Circular dichroism spectroscopy and stain tests were used as tools to indicate changes to the native structure and activity. Chapter 5: Thermostability of lipase was investigated, and the use of the water-soluble polymers to extend the lifetime of the enzyme in solution was investigated through monitoring changes in the melting temperatures as well as stability studies.

Latex coating has gained increasing attention. It is prepared by mixing latex, a dispersion of polymer particles in water, with pigments, fillers, and additives. As water is used as solvent, emission of VOCs can be minimised. However, coalescing agent emission and excessive surfactant residual hinder its further applications. To solve these two problems, we tried to use room temperature ionic liquid (RTIL), a potential multi-functional additive with non-volatility, to replace coalescing agent, and employed silica nanoparticle as emulsifier to stabilise the latex. The preparation of latex containing 1-octyl-3-methylimidazolium hexafluorophosphate (C8mimPF6), the target RTIL in this study, could be achieved by encapsulating C8mimPF6 inside particles via miniemulsion polymerisation. Two kinds of emulsifiers, surfactant and silica nanoparticle were employed to stabilise miniemulsion/latex. To achieve this encapsulation, three steps were carried out in succession: preparation of miniemulsion, miniemulsion polymerisation, and characterisation of latex containing C8mimPF6. Factors, especially C8mimPF6, on initial droplet size and stability of miniemulsion, yield and stability of polymerisation process, and final functionality of latexes were systemically investigated. For miniemulsion stabilised by surfactant, sodium dodecyl sulfonate (SDSO), initial droplet size decreased apparently with the addition of C8mimPF6 up to 1 wt% due to the effect of C8mimPF6 on oil phase viscosity and interfacial tension. During storage, C8mimPF6 above 10 wt% led to the frequent coalescence of droplet as it decreased the absolute zeta potential. During polymerisation, when initiated by hydrophobic 2, 2-azobis (isobutyronitrile) (AIBN), C8mimPF6 had a promoting effect on the reaction rate at low concentrations, but this effect might reverse upon certain C8mimPF6 concentrations, e.g. 10 wt%; while initiated by hydrophilic hydrogen peroxide/ascorbic acid (H2O2/AAc), this promoting effect faded even at low C8mimPF6 concentrations. The different limiting factors, kinetic or transfer of radicals, might determine the reaction rate with different types of initiator. The final particle size depended on the nucleation mechanism as well as the coalescence of droplets/particles during polymerisation. For the final latex, C8mimPF6 promoted the decrease in glass transition temperature (Tg) and the deformation of particles, due to its function as an external plasticiser with low Tg and compatibility with poly (methyl methacrylate) (PMMA) inside particles; the film became more flexible and had better thermal stability in the present of C8mimPF6. To solve excessive surfactant residual, silica nanoparticles were employed as emulsifiers to stabilise miniemulsion. Adding 1 wt% C8mimPF6 resulted in a sharp decline in droplet size, due to the combined effects of C8mimPF6 on the viscosity of oil phase and interfacial tension. Because of the low absolute zeta potential, creaming or sediment occurred at different C8mimPF6 concentrations, determined by the density difference between the oil and water phases. During polymerisation, a higher yield could be achieved by AIBN, compared with H2O2/AAc. The change of C8mimPF6 concentration had a greater impact on product stability e.g. only above 10 wt% C8mimPF6, stable products could be achieved. For product yield, there was only small effects, varying from 85 wt% to 91 wt% with C8mimPF6 changing from 0 to 30 wt%. For the final latex, the Tg of the obtained polymer decreased with the increase of C8mimPF6 concentration, indicating its function as an external plasticiser, but deformation of particles was limited, probably due to obstacles of silica nanoparticles on the surface of particles. Compared with bulk PMMA, films containing C8mimPF6 had a better thermal stability at temperatures ranging from 300 oC to 450 oC.

The Barton reaction involves the photoinitiated rearrangement of nitrite esters and is used primarily in the synthesis of complex steroidal structures. The rearrangement results in the introduction of active hydrogen atoms into the molecule and a novel use of this reaction for the production of polyurethane coatings through a photopolymerisation reaction with isocyanates has been discovered. The nitrite esters were synthesised from nitrous acid produced in situ from sodium nitrite and sulfuric or nitric acid. Yields of 79.5 and 76.4% were obtained in the synthesis of the mononitrite esters butyl- and hexyl-nitrite, however lower yields of 55.1 and 53.4% were obtained in the synthesis of butane-1,4- and hexane-1,6-dinitrite respectively. It was found that the nitrite esters are very rapidly hydrolysed and loss of product through hydrolysis occurs during the synthesis because of the aqueous environment in which it is carried out therefore a position of equilibrium is reached. The kinetics of the hydrolysis reaction was studied by monitoring the change in pH over time for both butyl- and butane-I,4-di-nitrite. The sensitivity of the nitrite esters to hydrolysis not only makes the synthesis of nitrite esters problematic but it also means that storage above the critical pH of 6.8 and at a temperature of 2-8°C is crucial to maximise the storage stability of the samples. The stability of the nitrite esters mixed with isocyanates was determined, the results indicated that the two reagents did not react and therefore the compounds could be stored together prior to irradiation. An extensive study on the reactions occurring after the photolysis of a series of nitrite esters was undertaken. The optimum wavelength range of 3 10-385 nm was confirmed for the occunence of the Barton reaction and results showed that the competing reaction of disproportionation also occurred after irradiation. The structure of the starting nitrite was found to have a significant effect on the reactions occurring after photolysis. A chain length of greater than 4 carbon atoms was found necessary for the Barton reaction to dominate over disproportionation because the intramolecular hydrogen abstraction 111 step involved a secondary hydrogen atom, whereas when a nitrite ester with only a 4 carbon chain was subjected to photolysis the disproportionation reaction was the dominant reaction because a primary hydrogen atom was abstracted. However this trend was not observed during the photolysis of dinitrite esters, the Barton reaction occurred to a greater extent than the disproportionation reaction even when a primary hydrogen atom was abstracted due to the second nitrite group which facilitates its removal. A series of coatings were produced from solutions of nitrite esters and isocyanates. It was found that a catalyst was essential to drive the reaction towards the Barton reaction and prevent the occurrence of the disproportionation reaction in order to ensure the formation of highly cured coatings. An excess of nitrite was required to compensate for the loss of nitrite ester through evaporation that prevented the production of highly cured coatings. The occurrence of a post-curing reaction was observed due to the continuation of the reaction of the isocyanate with residual active hydrogen compounds. The film thickness, nitrite ester, isocyanate and catalyst used were all found to have an effect on the rate of the polymerisation reaction. The photolysis reaction was also affected by the conditions under which the photopolymerisation reaction was undertaken. In a heated system an oxime compound was formed after photolysis whereas when a cooled curing oven was used a dimer was produced. The formation of the dimer also resulted in coatings with inferior properties; this is because the absence of oxime groups and the lower temperature reduces the rate of the polymerisation reaction resulting in increased formation of by-products. The properties of the coatings produced were tested and were found to have good solvent resistance (over 100 MEK double rubs), pencil hardness (7H), resistance to deformation (3mm pass in the bend test), adhesion (cross-cut value of 0) and weathering resistance. The properties of the coatings were also comparable to standard coatings indicating that they may have commercial importance.

Ce travail, en amont du projet WIBIO portant sur le développement de films d’emballage alimentaire partiellement biosourcés, a pour but de caractériser et de comprendre les relations entre la structure et les propriétés thermomécaniques de l’amidon et du Gaïalène, mélange à base d’amidon et de polyoléfine. L’étude des amidons natifs souligne l’influence de l’eau sur leurs propriétés thermiques ainsi que la difficulté de les déstructurer sans induire de recristallisation. La caractérisation thermomécanique des amidons thermoplastiques plastifiés par l’eau ne permet pas de trancher entre les effets de masse moléculaire et de composition. Malgré un taux d’étirage élevé, aucun phénomène significatif d’orientation n’a cependant pu être mis en évidence. L’étude de tri-esters d’amidon, obtenus par substitution des groupements OH de l’amidon par des chaînes alkyles, montre que ces matériaux hydrophobes présentent une structure en feuillets dans laquelle les chaînes amylacées sont confinées dans des zones planaires séparées par les chaînes alkyles. La composition des amidons n'affecte pas les propriétés thermiques. La longueur des chaines alkyles induit par contre une réduction drastique de la ductilité, dès lors qu'elles ont la capacité de cristalliser. Le suivi par diffraction X in-situ de l’évolution structurale sous étirage des matériaux amorphes révèle une orientation progressive des chaînes amylacées selon l’axe de sollicitation durant l’étirage. / The present work, carried out in the frame of the WIBIO project which deals with the development of partly bio-based food packaging, is aimed at understanding relationships between structure and thermo-mechanical properties of starch based films.The study of native starches underlines the influence of water on the thermal properties and the difficulty to achieve destructuration without promoting recrystallization. Mechanical characterization of water plasticized thermoplastic starch does not enable to conclude on the respective influences of molar mass and composition. Also, in spite of achieving a fairly large draw ration, no significant orientation phenomenon is revealed from X-ray analysis. Structural investigations of starch triesters, obtained by full substitution of starch OH groups by alkyl chains, show that these hydrophobic materials display a sheet-like structure in which the amylaceous chains are confined in planar zones separated by extended alkyl chains. Starch composition has no influence on the thermal properties of these materials. On the contrary, alkyl chain length induces a drastic reduction in drawability, as soon as the chains are long enough to interpenetrate and crystallize. In-situ X-ray diffraction experiments reveal the gradual orientation of amylaceous chains towards the draw axis during the stretching of fully amorphous compositions.

Ces travaux de thèse sont globalement inscrits dans un contexte d’élaboration des polymères biosourcés comme alternative aux polymères d’origine fossile. Dans un premier temps, des modifications structurales des polyesters biosourcés ont été réalisé par extrusion réactive afin d’améliorer leur viscosité/élasticité à l’état fondu. Il est apparu que l’ajout de 1% en masse de Joncryl à un polyester biosourcé permet d’améliorer son élasticité et son comportement élongationnel. Dans un deuxième temps, la stratégie de modification des polymères biosourcé par mélanges (réactifs) à l’état fondu a été étudié afin de développer une morphologie nano(fibrillaire) lors du procédé d’extrusion et d’injection d’un mélange de type acide polylactique/polyamide (PLA/PA). En modifiant l’élasticité de la matrice (PLA) par extrusion réactive, il a été possible de développer une morphologie nano(fibrillaire) lors de l’extrusion et l’injection. A travers cette étude, des gradients de vitesses critiques liés à la transition nodule-fibrille ont été déterminés et les résultats sont en bon accord avec la condition de fibrillation Ca/Ca(crit)≥4. Enfin, une dernière partie a été consacrée au développement des mélanges de polymères biosourcés à morphologie nano(fibrillaire) par le procédé d’extrusion-gonflage. Les paramètres rhéologiques qui contrôlent l’évolution de la morphologie ont été étudiés dans le cas d’un écoulement élongationnel avec un mélange de type poly(butylene succinate-co-adipate)/polyamide 11 (PBSA/PA11). Il a été montré que La transition nodule-fibrille est purement liée à l’écoulement élongationnel appliqué en sortie de filière de l’extrudeuse et que, le maintien du "strain hardening" de la matrice PBSA dépend de la formation des fibrilles de PA11 sous écoulement élongationnel. / The present study is globally included in a general context of the elaboration of biobased polymers as an alternative to the traditional fossil polymers. In a first step, structural and rheological modifications of the biobased polyesters were carried out by reactive extrusion in order to improve their melt viscosity/elasticity. It has been found that the addition of 1% wt of Joncryl to a biobased polyester makes it possible to improve its elasticity and its elongational behavior. In a second step, the strategy of modifying biobased polymers by melt blend was studied to develop a nano(fibrillar) morphology during the process of extrusion and injection of a polylactic acid/polyamide blend (PLA / PA). Increasing the elasticity of the matrix (PLA) by reactive extrusion, it was possible to develop a nano(fibrillar) morphology during extrusion and injection. Through this study, the critical shear rate related to the nodule-fibril transition was determined and the results were in good agreement with the Ca/Ca(crit)≥4 fibrillation condition. Finally, a last section was devoted to the development of biobased polymer blends with a nano(fibrillar) morphology by film blowing process. The rheological parameters controlling the evolution of the morphology were studied in the case of extensional flow using poly(butylene succinate-coadipate)/polyamide 11 (PBSA/PA11) blends. It has been shown that the nodule-fibril transition is purely related to the extensional flow applied at the die exit of the extruder and, the maintenance of the strain hardening of the PBSA matrix depends on the development of the PA11 fibrils under extensional flow.

Lors de l'extrusion, en présence de plastifiants, l'amidon peut être transformé en une phase fondue homogène. Les modifications structurales de l'amidon ayant lieu pendant la transformation, sont la fragmentation des grains, la fusion des cristaux et la dégradation moléculaire. La maitrise des mécanismes de fusion et du comportement rhéologique de l’amidon est nécessaire pour optimiser les conditions de mise en œuvre et ainsi contrôler la qualité des produits. L’influence de l’état de transformation (présence de granules résiduels) sur la viscosité en cisaillement de l’amidon suggère l’analogie avec les modèles rhéologiques. Dans ce but, deux amidons de différentes origines botaniques (pois et pomme de terre) ont été transformés par extrusion bi-vis, en présence d’eau (25, 30, 35%), avec différentes intensité de traitement (SME) et de température, T 100°C. Ces différentes teneurs en eau permettent de moduler la température de fusion, Tm, préalablement déterminée par DSC. La déstructuration de l’amidon a été étudiée à différentes échelles structurales: moléculaire (chromatographie A4F), cristallin (diffraction des rayons X, DSC), granulaire (microscopie avec analyse d’images et rhéologie d’empois). Les résultats montrent que l’écart (T-Tm) gouverne ces modifications, et qu’une dépolymérisation peut avoir lieu avant la fusion complète. Enfin, la viscosité de l'amidon partiellement fondu a été déterminée sur un rhéomètre à pré-cisaillement, le Rheoplast®, simulant l'extrusion dans des conditions contrôlées. La variation de l’intensité du traitement permet d’évaluer l’influence de la fraction de grains d’amidon sur la viscosité. / During extrusion, in presence of plasticizers, starch can be converted into a homogenous molten state. Process conditions may lead to different structural changes, such as fragmentation of granules, crystals melting, molecular degradation (depolymerization) which have an influence on final material properties. Therefore, a good understanding of starch melting and its rheological behavior is necessary to determine optimal processing conditions and better control of the products quality. Viscosity dependency on starch transformation suggests an analogy with a suspension of solid particles in a fluid, where residual starch fragments act as a decreasing fraction of solid fillers embedded in a molten starch matrix. Two starches of different botanical origin (pea and potato) were processed on a twin-screw extruder under various specific mechanical energy inputs (SME), in presence of water contents (25, 30, 35%) in order to monitor the melting temperature of starch Tm (determined beforehand by DSC). Starch destructuration was investigated at different structural scales: molecular (chromatography), crystal (X-ray diffraction, DSC), granular (microscopy and paste rheology). When compared with extrusion conditions, these analytical results first show that (T-Tm) is an important variable to assess changes, and that fragmentation may be induced by shear, whereas depolymerization may occur before complete melting. Finally, the viscosity of partly molten starch was determined on a pre-shearing rheometer, Rheoplast®. By combining flow curves with experimental results of starch destructuration, it enables to ascertain melting mechanism and test the suspension model.

Le but de ces recherches est d’étudier le vieillissement de l’acide polylactique (PLA) ignifugé. Trois vieillissement différents ont été étudiés i.e. température/ultra-violet (T/UV), température/humidité relative (T/RH) et température/ultra-violet/humidité relative (T/UV/RH). Afin de comprendre le rôle des retardateurs de flamme lors du vieillissement, l’étude de la dégradation du PLA vierge à tout d’abord été mené. Des méthodologies innovantes ont été développées et les propriétés physico-chimiques du polymère ont été caractérisées en fonction de la durée et du type d’exposition. Les mécanismes de dégradation dépendants du vieillissement (T/UV, T/RH et T/UV/RH) ont été élucidés et comparés à la littérature. L’influence des retardateurs de flamme (i.e. Mélamine, Polyphosphate d’ammonium et Cloisite 30B) lors du vieillissement des formulations ignifugées a ensuite été étudiée. Il a été prouvé que ces additifs ont une influence directe sur le vieillissement, au niveau des propriétés physico-chimiques et des mécanismes de dégradation. La masse molaire s’est révélée être cruciale dans la mesure où elle gouverne l’évolution des propriétés physico-chimiques du matériau durant le vieillissement, et donc sa durabilité. Sachant que le PLA est ignifugé par incorporation d’additifs retardateurs de flamme, il était primordial de comprendre l’effet du vieillissement sur ces additifs et donc leurs effets sur les propriétés feu du PLA. Il a ainsi été montré que les performances feu de ce matériau sont améliorées au cours du vieillissement, jusqu’à sa dégradation complète. Ces performances ont été corrélées avec l’évolution des propriétés physico-chimiques survenant au cours du vieillissement, présentant un rôle prépondérant sur la cinétique d’intumescence. / This work deals with the ageing of flame retarded (FR) Polylactic acid (PLA). The impact of three accelerated ageing conditions i.e. temperature/ultra-violet (T/UV), temperature/relative humidity (T/RH) and temperature/ultra-violet/relative humidity (T/UV/RH) was studied. In order to understand the role of fire retardant additives on ageing of flame retarded PLAs, the first study was focused on neat PLA. Innovative methodologies were developed, the change in physico-chemical properties of the polymer was characterized as a function of ageing exposure and ageing duration. Moreover, the mechanisms of degradation occurring during T/UV, T/RH and T/UV/RH exposure were elucidated and compared to the literature. Then, the influence of flame retardants (i.e. Melamine, Ammonium polyphosphate and Cloisite 30B) on the ageing behavior of FR-PLAs was investigated. FR fillers were evidenced to have a direct influence on physico-chemical properties and mechanisms of degradation of the material during ageing. The molecular mass was reported to be a crucial parameter, as it is related to the physico-chemical properties and thus to the durability of the material. The main goal of flame retardants is to improve the flammability of PLA thus the effect of ageing on the fire properties of PLA was determined. It is noteworthy that the fire properties of flame retarded PLA are improved during ageing, until the complete degradation of the materials. These surprising performances were found to be correlated to the change in physico-chemical properties which play a key role on the kinetics of intumescence.