Double crosslinked polyetheretherketone-based polymer electrolyte membranes prepared by radiation and thermal crosslinking techniques

摘要

Novel one-step preparation of polymer electrolyte membranes without a membrane casting process is achieved by radiation crosslinking of a polyetheretherketone(PEEK)film to prevent dissolution and deformation of the original film in sulfonating solutions.The films crosslinked with doses more than 33 MGy can be effectively sulfonated in a chlorosulfonic solution,resulting in a crosslinked sulfonated PEEK(sPEEK)electrolyte membrane with high proton conductivity comparable to Nafion.Nevertheless,its water uptake was high for application in fuel cells.The thermal treatment was effective for further crosslinking of the membrane;as a result,the water uptake and methanol permeability of the double crosslinked sPEEK membranes drastically decreased,compensating for a slight decrease of proton conductivity.In addition,unlike the traditional cast sPEEK membrane showing the irreversible swelling in hot water,the double crosslinked sPEEK membranes exhibited excellent stability toward 100 deg C hot water for more than 200 h without any decrease in proton conductivity,and had the mechanical and thermal properties superior to those of Nafion.