Preparation and Properties of Blend Proton Exchange Membranes Based on Side-chain Type Fluorine-containing Sulfonated Poly(ether sulfone) and Sulfonated Polyimide

A series of blend membranes from a side. chain type fluorine. containing sulfonated poly( ether sulfone) s( sSPFES) and sulfonated polyimide( SPI) was prepared and characterized. The two sulfonated copolymers showed good compatibility in their trimethylamine salt form, producing uniform, transparent and ductile blend membranes during solution blending and casting processes. The resulting sSPFES/ SPI blend membranes with ion exchange capacities in the range of 1.76-1. 88 mmol/ g showed some property differences in the water uptakes, size changes, proton conductivity and hydrolytic stability with the un-modified ones. Especially, their swelling behavior was considerable effected by the composition with obvious larger size changes in the membrane out. of. plane direction than the in. plane direction, exhibiting size changes no more than 10% in in. plane direction at 60 degrees C in water. The blend membranes could maintain rather good mechani. cal toughness after aging in water at 140 degrees C. for 24 h with mass loss less than 6. 1%. For the fully hydrated blend membranes, their proton conductivity all reached 0. 1 S/ cm at temperature above 50 degrees C.