Ce travail de thèse consiste à combattre le développement microbien des réservoirs de carburant aéronautiques dont le métabolisme entraine la production d’acides organiques susceptibles de corroder les parois métalliques des réservoirs. Des substances biocides sont habituellement utilisées pour éliminer les populations microbiennes. Ces substances peuvent être des composés organiques ou bien de manière plus courante du chrome (VI) sous forme de revêtement à la surface des parois afin de créer une couche passive et d’empêcher la corrosion chimique. Cependant, le chrome appartient à la catégorie des substances cancérogènes, mutagènes et reprotoxiques et se trouve maintenant soumis à restriction par la réglementation européenne Registration, Evaluation and Authorization of Chemicals (REACh). Pour remplacer les systèmes en place, le choix s’est porté sur la préparation de particules polymères pH-sensibles capables de libérer une molécule biocide en présence de microorganismes. De telles particules sont obtenues par copolymérisation par métathèse de cyclo-oléfines (ROMP) de norbornène avec un macromonomère linéaire de polyglycidol α-norbornenyl. Ce dernier permet d’une part la stabilisation des particules et d’autre part la multifonctionnalisation de l’objet par des molécules de biocide. Celles-ci sont introduites sur la chaîne de polyglycidol via un lien imine pH-sensible par substitution des fonctions hydroxyle par des entités dodécylamine. La libération du biocide à un pH inférieur à 7 a été validée ainsi que les capacités de ces particules à lutter contre des microorganismes tel que Hormoconis resinae souche identifiée comme se développant dans les réservoirs d’avions. Dans une dernière étape, les particules fonctionnalisées dodécylamine ont été incorporées dans un revêtement usuel en aéronautique et la capacité des particules à ne pas altérer la résistance du revêtement de base à des conditions de corrosion extrêmes a permis de vérifier leur applicabilité dans ce domaine. / The aim of this Thesis work was to address the issue of microbial contamination inside fuel tanks. Microorganisms induce the chemical corrosion of airplane tank walls due to their production of organic acids. Biocide compounds are typically used to inhibit these microorganisms, either in the form of organic small molecules, or most commonly as chromium-based coatings on the walls to hinder chemical corrosion. Organic biocides need to be replenished regularly, while chromium is a particularly dangerous compound targeted by the European Registration, Evaluation and Authorization of Chemicals (REACh) legislation due to its carcinogenic nature. A replacement approach selected for this project was the development of a smart system of multifunctional polymeric particles synthesized by dispersion ROMP, which can deliver a biocide following an acidic trigger due to the presence of microorganisms. The polymerization utilized a linear α-norbornenyl-polyglycidol macromonomer as a reactive surfactant. The hydroxyl-rich polyglycidol backbone of the macromonomer was beneficial for the conjugation of dodecylamine through a pH-sensitive imine bond and permitted the preparation of highly functionalized bioactive particles. A proof of concept for the pH sensitivity of the system was provided and the antifungal efficacy of the biocide-functionalized macromonomer and particles was verified. The particles were also integrated in a coating formulation to simulate their application on tank walls. The qualities of the original coating were preserved even after prolonged exposure to corrosive conditions, making this system viable for its foreseen application.

Living anionic polymerization techniques were applied to the synthesis of arborescent (dendritic) well-defined graft polymers having core-shell morphologies, with a hydrophobic core and a hydrophilic shell. Cycles of polystyrene substrate acetylation and anionic grafting yielded successive generations of arborescent polystyrenes. The anionic polymerization of styrene with sec-butyllithium provided polystyryllithium serving as side chains. These were coupled with a linear acetylated polystyrene substrate to obtain a generation zero (G0) arborescent polymer. An analogous G0 hydroxyl-functionalized polystyrene substrate with hydroxyl end groups was also obtained by a variation of the same technique, using a bifunctional organolithium initiator containing a hydroxyl functionality protected by a silyl ether group to generate the polystyrene side chains. These were coupled with the linear acetylated polystyrene substrate and subjected to a deprotection reaction to give the G0 polymer functionalized with hydroxyl groups at the chain ends. A similar procedure was used to generate a hydroxyl-functionalized arborescent G1 polymer from the corresponding G0 acetylated polystyrene substrate. The growth of polyglycidol chain segments was attempted from the hydroxyl-functionalized cores, to form a hydrophilic shell around the hydrophobic cores, but led to extensive degradation. A click reaction was also developed to synthesize the amphiphilic copolymers and was much more successful. In this case alkyne-functionalized arborescent polystyrene substrates, obtained by a modification of the hydroxyl-functionalized arborescent polystyrenes, were coupled with azide-functionalized polyglycidol side chains.

Living anionic polymerization techniques were applied to the synthesis of arborescent (dendritic) well-defined graft polymers having core-shell morphologies, with a hydrophobic core and a hydrophilic shell. Cycles of polystyrene substrate acetylation and anionic grafting yielded successive generations of arborescent polystyrenes. The anionic polymerization of styrene with sec-butyllithium provided polystyryllithium serving as side chains. These were coupled with a linear acetylated polystyrene substrate to obtain a generation zero (G0) arborescent polymer. An analogous G0 hydroxyl-functionalized polystyrene substrate with hydroxyl end groups was also obtained by a variation of the same technique, using a bifunctional organolithium initiator containing a hydroxyl functionality protected by a silyl ether group to generate the polystyrene side chains. These were coupled with the linear acetylated polystyrene substrate and subjected to a deprotection reaction to give the G0 polymer functionalized with hydroxyl groups at the chain ends. A similar procedure was used to generate a hydroxyl-functionalized arborescent G1 polymer from the corresponding G0 acetylated polystyrene substrate. The growth of polyglycidol chain segments was attempted from the hydroxyl-functionalized cores, to form a hydrophilic shell around the hydrophobic cores, but led to extensive degradation. A click reaction was also developed to synthesize the amphiphilic copolymers and was much more successful. In this case alkyne-functionalized arborescent polystyrene substrates, obtained by a modification of the hydroxyl-functionalized arborescent polystyrenes, were coupled with azide-functionalized polyglycidol side chains.