Preparation of poly(vinyl phosphate-b-styrene) copolymers and its blend with PPO as proton exchange membrane for DMFC applications

Abstract

Poly(vinyl phosphate-b-styrene) (poly(VPP-b-St)) block copolymers were prepared via consecutive telomerization of vinyl acetate (VAc), atom transfer radical polymerization (ATR-P) with styrene, saponification, and phosphorylation with phosphorus oxychloride. The resulting block copolymers were characterized by FT-IR and pH titration. Then, the block copolymers were blended with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) to prepare direct methanol fuel cell (DMFC) membrane. The performance of poly(VPP-b-St)/PPO blend membranes was measured in terms of proton conductivity, methanol permeability, thermal and hydrolytic stability. The proton conductivities were in the range of 10(-4) to 10(-2) S/Cru (60 degrees C, RH = 95%); the methanol pemeabilities were in the range of 4.14 x 10(-8) to 9.62 x 10(-8) cm(2)/s (25 degrees C), and quite lower than that of Nafion (R) 117. Also, the thermal stability of the blend membranes was characterized by TGA, and was stable up to 400 degrees C; the blend membranes had better hydrolytic stability.