Les matériaux polymères sont de plus en plus utilisés pour remplacer d’autres types de matériaux tels que la céramique ou le métal. Cependant, la majorité des polymères ont un désavantage : ils doivent être ignifugés. Néanmoins, grâce à la recherche dans le domaine des matériaux, des polymères haute performance qui résistent à la chaleur et aux scénarios feu ont été conçus. Malgré l’avantage technique qu’apportent ces matériaux, ils sont extrêmement chers. Le but de ce travail est de comprendre la réaction au feu des matériaux hautes performances afin de concevoir des retardateurs de flamme qui réagiraient comme ces polymères hautes performances quand ils sont soumis à des températures élevées ou dans un scénario feu. Dans cette optique, le comportement à haute température et la réaction au feu de trois matériaux hautes performances ont été étudiés : polyetheretherketone (PEEK), polyimide (PI), et polybenzoxazole (PBO). Les mécanismes de décomposition de ces matériaux ont été évalués à travers différentes méthodes analytique telles que le pyrolyseur GCMS et l’ATG-FTIR. La cinétique de décomposition de ces matériaux a aussi été évaluée en utilisant l’ATG dynamique sous différentes atmosphères (azote, 2% oxygène, et air). Cela nous a permis d’acquérir du recul par rapport aux comportements thermiques de ces matériaux hautes performances, que nous avons pu exploiter pour définir des nouveaux retardateurs de feu. Ainsi, une série de retardateurs de flamme ont été synthétisés. Ces retardateurs de flamme font partie de la famille de bases de Schiff et comprennent le salen et ses dérivées, ainsi que certains de leurs complexes métalliques. Le comportement thermique et réaction au feu de ses retardateurs de flamme ont été évalués dans deux polymères : le polyuréthane thermoplastique, et le polyamide 6. Bien qu’une partie de ces retardateurs de feu aient montré peu d’effet au feu, certains ont montré une amélioration importante en termes de chaleur dégagée. Cette nouvelle approche vers la conception de charges ignifugeantes est prometteuse et peut être utilisée comme une méthode complémentaire pour la conception de matériaux haute performance à bas cout. / Polymeric materials have been increasingly used as replacement for other types of materials such as ceramics or metals. However, most polymers have a serious drawback: they need to be fire retarded. Nevertheless, thanks to advanced research in the field, high performance materials that resist high temperatures and fire scenarios have been developed. While these materials have extremely enviable properties, they are also very expensive. The aim of this PhD is to understand the fire behavior of high-performance polymers and design fire retardants that would mimic these high-performance materials under extreme heat or fire. To do so, the thermal and fire behavior of three high performance materials were studied: polyetheretherketone (PEEK), polyimide (PI), and polybenzoxazole (PBO). Their thermal decomposition pathways were evaluated thanks to high temperature analytical techniques like pyrolysis-GC/MS and TGA-FTIR. Model based kinetics of the thermal decomposition of these polymeric materials were also elucidated by using dynamic TGA under three different atmospheres (nitrogen, 2% oxygen, and air). These provided insight regarding the thermal behavior high performance polymers, which were used to conceptualize novel potential fire retardants. Therefore, a series of fire retardants that have demonstrated similar behaviors as high performance polymers in fire scenarios were synthesized. These fire retardants include a Schiff base: salen and its derivatives, as well as some of their metal complexes. The thermal behavior and fire performances of these fire retardants were evaluated in two polymeric materials using a relatively low loading (< 10 wt%): thermoplastic polyurethane, and polyamide 6. While some of the fire retardants had little effect, in terms of fire retardancy, some candidates showed a significant improvement in terms of peak of heat release rate. This reverse approach towards designing fire retardants has shown some promise and can be used as a complementary method for the design of high-performance materials at lower cost.

This research aimed to develop new polymeric materials for use in membrane or adsorption processes for carbon dioxide capture. In particular, it explored the synthesis, characterization and properties of polymers incorporating a spiro-center. A dianhydride containing a spiro-center (An-1), suitable for use in the preparation of polyimides, was synthesized using a previously reported procedure. The spiro-center makes the structure of the resulting polymers (PIM-PIs) similar to polymers of intrinsic microporosity (PIMs), which are known for their high internal surface area and outstanding membrane permeation properties. PIM-polyimides PIM-PI-1 and PIM-PI-5 were successfully synthesized and characterized, and membranes prepared for permeation studies. For PIM-PI-5, gas permeation data were obtained for the first time and were shown to be in reasonable agreement with values predicted by a group contribution method. To produce membranes with even better gas permeation properties, hydroxyl-containing PIM-polyimides were introduced. The presence of a hydroxyl group in the ortho position of the imide linkage made it possible to thermally rearrange the PIM-polyimide to a PIM-polybenzoxazole (PIM-PBO) at 450 oC in an inert atmosphere. PIM-PI-OH-1 with high enough molecular weight to form a freestanding membrane was successfully synthesized using two different synthetic methods: thermal imidization and one-step polycondensation. The PIM-PI-OH-1 polymers prepared by both synthetic methods were compared in terms of gas permeation properties and CO2 uptake capacity, before and after thermal rearrangement. As expected, for polymers prepared by both methods, a significant enhancement was observed in the membranes gas permeation properties upon thermal rearrangement. Ethanol treatment was also performed on the thermally rearranged polymers, which resulted in a large increase in their permeability. The effect of aging was investigated on the ethanol treated PIM-PBO-1 membranes. It was observed that the membranes gradually lose the extra permeability created upon ethanol treatment and return to close to their original permeability value. To increase the concentration of thermally rearrangeable sites in the polymers, a dianhydride (An-2) with a smaller structure and lower molecular weight comparing to the An-1 was synthesized. A copolymer (copolymer-OH(1-2)), was synthesized using An-1 and An-2 (1:1). Gas permeation measurements were performed on the thermally rearranged polymer before and after ethanol treatment. A slight enhancement in the polymer’s selectivity toward CO2/N2 and CO2/CH4 gas pairs was observed, while maintaining the permeability. Having the same aim, PIM-PI-OH-3 was prepared using a smaller and a more rigid diamine, compared to the diamine used in the preparation of PIM-PI-OH-1. Gas permeation studies of the thermally rearranged membrane before and after ethanol treatment showed a significant increase in O2/N2 selectivity, which passed the Robeson 2008 upper bound. In adsorption experiments, CO2 uptake was higher than for PIM-PI-OH-1 and its thermally rearranged product.

Novel proton exchange membranes (PEMs) were investigated that show potential for operating at higher temperatures in both direct methanol (DMFC) and H2/air PEM fuel cells. The need for thermally stable polymers immediately suggests the possibility of heterocyclic polymers bearing appropriate ion conducting sites. Accordingly, monomers and random disulfonated poly(arylene ether) copolymers containing either naphthalimide, benzoxazole or benzimidazole moieties were synthesized via direct copolymerization. The ion exchange capacity (IEC) was varied by simply changing the ratio of disulfonated monomer to nonsulfonated monomer in the copolymerization step. Water uptake and proton conductivity of cast membranes increased with IEC. The water uptake of these heterocyclic copolymers was lower than that of comparable disulfonated poly(arylene ether) systems, which is a desirable improvement for PEMs. Membrane electrode assemblies were prepared and the initial fuel cell performance of the disulfonated polyimide and polybenzoxazole (PBO) copolymers was very promising at 80 C compared to the state-of-the-art PEM (Nafion®); nevertheless these membranes became brittle under operating conditions. Several series of poly(arylene ether)s based on disodium-3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (S-DCDPS) and a benzimidazole-containing bisphenol were synthesized and afforded copolymers with enhanced stability. Selected properties of these membranes were compared to separately prepared miscible blends of disulfonated poly(arylene ether sulfone) copolymers and polybenzimidazole (PBI). Complexation of the sulfonic acid groups with the PBI structure reduced water swelling and proton conductivity. The enhanced proton conductivity of Nafion® membranes has been proposed to be due to the aggregation of the highly acidic side-chain sulfonic acid sites to form ion channels. A series of side-chain sulfonated poly(arylene ether sulfone) copolymers based on methoxyhydroquinone was synthesized in order to investigate this possible advantage and to couple this with the excellent hydrolytic stability of poly(arylene ether)s. The methoxy groups were deprotected to afford reactive phenolic sites and nucleophilic substitution reactions with functional aryl sulfonates were used to prepare simple aryl or highly acidic fluorinated sulfonated copolymers. The proton conductivity and water sorption of the resulting copolymers increased with the ion exchange capacity, but changing the acidity of the sulfonic acid had no apparent effect. / Ph. D.