Poly(phenylacetylene) and polystyrene which contain galvinoxyl and trimethylsilyl units were synthesized by copolymerization of the corresponding monomers or polymer reaction of the corresponding methyl benzoate polymers with [3,5-di-tert-butyl-4-(trimethylsiloxy)-phenyl]lithium. The copolymers obtained from (4-trimethylsilyl)phenylacetylene and (4-ethynylphenyl)hydrogalvinoxyl using [Rh(norbornadiene)Cl](2) catalyst had very high molecular weights. On the contrary, the copolymers of (4-trimethylsilyl)styrene and methyl 4-vinylbenzoate nearly completely reacted with [3,5-di-tert-butyl-4-(trimethylsiloxy)phenyl]lithium to give the corresponding galvinoxyl-copolymers with high molecular weights. The hydrogalvinoxyl could be fabricated to self-supporting membranes. We succeeded in obtaining such stable polyradical membranes that the initial spin concentration was maintained for a few days. The oxygen permselectivity (alpha = P-O2/P-N2) increased and the oxygen permeability (P-O2) decreased as galvinoxyl units increased, owing to the rigid character of galvinoxyl moiety. (C) 2000 Elsevier Science Ltd. All rights reserved.