Radiation grafting of styrene and maleic anhydride onto PTFE membranes and sequent sulfonation for applications of vanadium redox battery

摘要

Using gamma-radiation technique,poly(tetrafluoroethylene)(PTFE)membrane was grafted with styrene(St)(PTFE-graft-PS)or binary monomers of St and maleic anhydride(MAn)(PTFE-graft-PS-co-PMAn),respectively.Then grafted membranes were further sulfonated with chlorosulfonic acid into ion-exchange membranes(denoted as PTFE-graft-PSSA and PTFE-graft-PSSA-co-PMAc,respectively)for application of vanadium redox battery(VRB).Micro-FTIR analysis indicated that PTFE was successfully grafted and sulfonated at the above two different conditions.However,a higher degree of grafting(DOG)was obtained in St/MAn binary system at the same dose due to a synergistic effect.Comparing with PTFE-graft-PSSA,PTFE-graft-PSSA-co-PMAc membrane showed higher water uptake and ion-exchange capacity(IEC)and lower area resistance(AR)at the same DOG.In addition,PTFE-graft-PSSA-co-PMAc with 6% DOG also showed a higher IEC and higher conductivity compared to Nation membrane.Radiation grafting of PTFE in St/MAn binary system and sequent sulfonation is an appropriate method for preparing ion-exchange membrane of VRB.