Proton exchange membranes with cross-linked interpenetrating network of sulfonated polyvinyl alcohol and poly(2-acrylamido-2-methyl-1-propanesulfonic acid): Excellent relative selectivity

Cross-linked interpenetrating composite membranes of sulfonated polyvinyl alcohol and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (SPVA/PAMPS) were prepared for application in direct methanol fuel cells (DMFCs). SPVA was synthesized using sulfuric acid to sulfonate the hydroxyl groups of PVA. Sulfosuccinic acid (SSA) and N , N ′-methylenebis(acrylamide) (MBA) were used as the crosslinking agents to form the Cross-linked interpenetrating network structure by thermal crosslinking reaction and free-radical polymerization, respectively. The mechanical property, oxidative stability, and proton conductivity of SPVA/PAMPS composite membranes improved significantly with increasing content of AMPS. Especially, the proton conductivity of SPVA/PAMPS-40% membrane was excellent, i.e., 0.146 S cm −1  at 100 °C. Furthermore, the Cross-linked interpenetrating network structure decreased the methanol crossover of composite membranes. The methanol permeability coefficient of SPVA/PAMPS-40% membrane was 11.3 × 10 −7  cm 2  s −1  at 60 °C. The composite membranes showed better relative selectivity than pure SPVA membrane, the relative selectivity of SPVA/PAMPS-40% membrane was 7.43 × 10 4  S scm −3  at 60 °C. This study provides a method to synthesize inexpensive and readily prepared proton exchange membranes for DMFC applications.