Poly(di(x-alkylphenyl)stannane)s, [Sn(C n H 2n Ph) 2 ] m with n = 2-4, and a copolymer of di(3-propylphenyl)stannane and dibutylstannane of weight-average molar masses of 2-8 Á 10 4 g/mol were synthesized by dehydropolymerization of stannanes of the composition H 2 SnR 2 using Wilkinson's catalyst [RhCl(PPh 3) 3 ]. At least two methylene groups were required as spacers between the phenyl group and the tin atom for polymerization to occur. The polystannanes were characterized by, among other techniques, 1 H, 13 C and 119 Sn NMR spectroscopy, thermal analysis and X-ray diffraction. The polymers featured properties different from those of the corresponding poly(dialkylstannane)s. Specifically, the [Sn(C n H 2n Ph) 2 ] m family displayed glass transitions at remarkably low temperatures, down to ca.-50°C, and a lower value for a copolymer (-68°C). Polymers [Sn(C n H 2n Ph) 2 ] m with n = 2 and 3 and a copolymer at room temperature were of a gel-like concistence, which enabled facile orientation with shear forces. Finally, the temperature-dependent electrical conductivity was determined for poly(di(3-propylphenyl)stannane), which followed the law of typical semiconductors, with an activation energy for conduction of 0.12 eV.

Antioxidants are covalently attached to the polymer backbone in radiation grafted fuel cell membranes. The obtained membranes displayed superior stability compared to non-stabilized membranes.

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