Block Copolymer-Based Symmetric Membranes for Direct Methanol Fuel Cells

Like batteries, fuel cells provide an inherently clean source of energy with no adverse environmental impact during operation. The utilization of methanol as a fuel is advantageous: it has an energy density of about 6 kWh/kg, which is, much higher than that of other commercialized batteries. This review is focused on the core of a DMFC, i.e., the symmetric membrane, in particular on the block copolymers used for its preparation as an alternative to well-known Nafion. The synthesis of block copolymer ionomers based on different building block types, with special emphasis on the critical issue of methanol permeability and proton/methanol selectivity, as well as the effect of block length and crosslinking are described and discussed.