Proton-conduction in poly(alkylenecarbonate)/poly(thiophenylenesulfonic acid) composites

Highly sulfonated poly(thiophenylenesulfonic acid) (PTPSA) was prepared from a soluble polysulfonium salt precursor and mixed with poly(alkylenecarbonate) (PAC, alkylene = ethylene, PEC; propylene, PPC; butylene, PBC). The PTPSA and PAC were employed as a proton source for conduction and a flexible base matrix for proton dissociation and conduction pathway, respectively. For the composites of PTPSA/PAC (3/1, 2/1, 1/1 and 1/2, by weight), the effect of alkyl chain lengths of PAC, temperature dependence of proton-conductivity, and water content on the composites was studied. The proton-conductivity of the PTPSA/PAC composites increased with the increasing PTPSA portion. The PTPSA/PBC (3/1) composite shows the highest proton-conductivity of 1.5×10^-6 Scm^-1 at 30 °C. However, the increased incorporation of PTPSA does not contribute to producing the higher proton conduction of the composites. Moreover, the PTPSA/PBC (3/1) composite including 15 wt% of water retained the proton-conductivity of 7.1×10^-2 Scm^-1 at 140 °C, which could be the conductivity comparative to the Nafion membrane and thermal stability.