Sulphonation of polystyrene‐butadiene rubber with chlorosulphonic acid for proton exchange membrane: Kinetic study

Proton exchange membrane for fuel cell application was synthesized from a hydrophobic polystyrene‐butadiene rubber (PSBR) via sulphonation at different temperatures (22, 35, 55, 65, and 75°C) and varying time with chlorosulphonic acid. Infra‐red spectroscopy (IR) and proton nuclear magnetic resonance ( 1 H‐NMR) were used to confirm the occurrence of sulphonation. Sulphonation occurred only on the phenyl ring with a maximum degree of sulphonation of 70.96 mole percent. Consequently, 10 −3 –10 −2 S/cm proton conductivity was achieved. Two models for the reaction kinetics were investigated: first‐order reversible and first‐order irreversible, respectively. However, the reaction kinetic was found to obey the first‐order reversible model. The activation energy ( E a ) of the reaction was calculated to be 41.56 kJ/mol of PSBR repeat unit, which is an indication that the reaction is nonspontaneous. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010