Synthesis and properties of polyimides bearing acid groups on long pendant aliphatic chains

Abstract

A series of novel polyimide electrolytes having long pendant sulfo-or phosphoalkoxy groups were synthesized for fuel-cell applications. Sulfodecyloxy-, phosphodecyloxy-, and sulfophenoxydodecyloxy-substituted benzidine monomers were synthesized from dihydroxybenzidine. These monomers were copolymerized with naphthalene tetracarboxylic dianhydride and fluorenylidene dianiline to give the corresponding polyimides. A flexible, ductile, and self-standing membrane was obtained via casting from the polyimide solution. Because the acid groups were on long pendant side chains and away from the main chains, the polyimide membrane showed improved oxidative and hydrolytic stability in comparison with the polyimides with sulfonic acid groups on the main chains or on the short side chains. High thermal stability (no glass-transition temperature and a decomposition temperature > 200 8C) was also obtained. The polyimide membrane displayed high proton conductivity of 10 À1 S cm À1 at 120 8C. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: [3995][3996][3997][3998][3999][4000][4001][4002][4003][4004][4005] 2006

Synthesis and properties of a polyimide containing pendant sulfophenoxypropoxy groups

“…The CÀ ÀS bonds are more likely to be thermally decomposed than the other side-chain bonds (e.g., CÀ ÀO bonds). These thermal properties are comparable to those of other sulfonated polyimides with shorter or longer aliphatic side chains, [18][19][20][21] and so we conclude that the phenylene rings introduced into the side chains do not practically affect the thermal stability.…”

“…Similar trends were observed for the even longer side chain polyimides. 21 Therefore, the most effective side-chain length seems to be three or four methylene units from the viewpoint of the proton-conducting properties.…”

“…[18][19][20] However, because of the synthetic difficulties, the effect of the side-chain length has not been well examined. 21 In this article, we report the synthesis and properties of a novel polyimide electrolyte having longer pendant sulfophenoxypropoxy groups. Its properties are compared with those of previous sidechain-sulfonated polyimide and perfluorinated Nafion membranes.…”

Synthesis and Characterisation of Sulphonated Poly(arylene sulphone) Terpolymers with Triphenylphosphine Oxide Moieties for Proton Exchange Membrane Fuel Cells

“…To overcome these drawbacks, in recent years a number of alternative membranes have been developed [2][3][4][5][6][7][8][9][10][11]. Among the alternative materials investigated, sulphonated aromatic polymers, such as sulphonated poly(arylene sulphone)s [12][13][14][15], poly(arylene ether ketone)s [16][17][18][19][20], sulphonated poly(arylene ether sulphone)s [8,[21][22][23][24][25], polyimides [26][27][28][29], sulphonated poly(benzimidazole)s [30][31][32][33], have been proposed as alternative materials for PEMFCs. They show high proton conductivity, excellent thermal and oxidative stability, good mechanical properties, good processability, exceptional hydrolytic stability and relatively low cost.…”

Aromatic Poly(ether ketone)s with Pendant Sulfonic Acid Phenyl Groups Prepared by a Mild Sulfonation Method for Proton Exchange Membranes

“…29,30 Jannasch et al reported several side-group-acid poly-(ether sulfone)s with some attractive properties based on lithiation reaction. 24,31 Polyimides with side-group-acid substituents were also developed by Okamoto et al and Watanabe et al [32][33][34] To our knowledge, there are still no detailed reports related to the control of substitution sites through adjusting their various molecular structures. In addition, there are few reports of side-group-acid PEKs and their properties.…”