Property of POSS-(PMMA₂₆-b-SPS₁₅₆)₈ block copolymer/PVDF blend proton exchange membrane

Blend proton exchange membranes were prepared from blending polyhedral oligomeric silsesquioxane (POSS) containing star-shaped block copolymer POSS-(PMMA₂₆-b-SPS₁₅₆)₈ with polyvinylidene fluoride (PVDF). The effect of PVDF content on the properties of blend membrane was investigated, ion exchange capacity(IEC), proton conductivity and water uptake, swelling rate and spin-spin relaxation time(T₂)of the blend PEM were studied. The results shows that IEC, water uptake and swelling rate decrease with adding PVDF amount in blend membranes. Blend proton exchange membrane shows higher dimensional stability. The proton conductivity of blend PEM shows a continuous increasing with adding different ratio of PVDF. The dependence of proton conductivity on relative humidity is reduced owing to adding PVDF. It is found that proton conductivity of 50%PVDF blend membrane is higher about one order of magnitude than that of pure copolymer membrane in 30% RH at 80℃. The reason of proton conductivity which is enhanced at low RH was investigated by comparing relaxation time T₂ of different binding water via low field NMR.