Preparation and characterization of directional conducting and lower methanol permeable ultrathin membrane based on poly (vinyl alcohol) and imidazolium compounds

• Cross-linked membrane was prepared successfully for ionic directional conduction.
• The conductivity of the membrane enhances obviously by ionic directional conduction.
• Alcohol resistance performance of the directional conducting membrane is better.
• The proton directional conducting membrane exhibits high oxidative stability.

To produce directional conducting and lower methanol permeable ultrathin membrane for fuel cell, the imidazolium salt as both cross-linking agent and proton donor has been designed to build a directional proton conducting channel in a poly (vinyl alcohol)-based membrane. The methanol permeability of directional conducting membrane is very low, which is about twice smaller than that of Nafion117. In addition, the membranes show a relatively high oxidative durability in H2O2 solutions, with only about 10% weight loss after the membrane being immersed in 3% H2O2 solution for 120 h. All the properties of prepared directional conducting membrane indicate their promising prospects in proton conducting membrane applications.