In this study, new polyelectrolytes with highly crosslinkable and proton-conducting properties for pore filling membranes with no external solvents were introduced. It was found that the liquid monomers show more facile copolymerization as well as crosslinking than solid monomers dissolved in a solvent. Moreover, the membranes exhibited better durability due to extensive crosslinking and proton conductivity due to facile copolymerization. The resulting membrane exhibits proton conductivity of 0.09 S cm(-1) at room temperature with stable fuel cell operation for 1000 h.