An overview of synthetic polymer-based membrane modified with chitosan for direct methanol fuel cell application

The materials used for fuel cell membrane must have a high proton conductivity, a strong enough wall to block the reactant flow rate and be chemically or mechanically stable in the environment around the fuel cell. To improve the effectiveness of fuel cell membranes and reduce production costs, several synthetic polymer membranes have been developed, including polyethersulfone, polysulfone, polyvinyl alcohol, and polystyrene. Membranes from this polymer have the advantage of being cheap, commercially available, and allowing its structure to store moisture so it can operate at higher temperatures, yet it has low hydrophilic property. Chitosan, as a biopolymer that has strong hydrophilicity property resulted from numerous hydrophilic groups (e.g. –OH, –NH 2 and –NR 3 þ), can be used for various chemical modifications including to increase mechanical and chemical stability and modification to the possibility of producing ion exchange and increasing ionic conductivity which is a requirement for fuel cell membrane. The purpose of this study is to review the use of chitosan as synthetic polymer-based membrane modification from its structure and properties. Recent achievements and prospect of its applications have also been included.