Effect of Polyhedral Silsesquioxane Functionalized Sulfonic Acid Groups Incorporated Into Highly Sulfonated Polyphenylsulfone as Proton-Conducting Membrane

Abstract

A Composite proton exchange membrane consists of octaphenyl polyhedral silsesquioxane (POSS) has been incorporated into a highly sulfonated polyphenylsulfone (SPPSU) for potential use in fuel cell applications. The effect of modified POSS by functionalization with sulfonic acid groups (SPOSS) addition on physicochemical properties, mechanical strength, and proton conductivity of the SPPSU is examined. Results revealed that the incorporation of POSS and SPOSS has significantly improved the mechanical strength and conductivity of the SPPSU composite membranes. SPPSU-POSS composite membrane shows tough and ductile features. Meanwhile, the SPPSU-SPOSS composite membrane exhibits mechanically lower strength but greater in flexibility as compared to SPPSU-POSS composite membrane. As per expectation, the proton conductivity of the SPPSU-SPOSS composite membrane is significantly improved compared to SPPSU-POSS composite membrane according to its relatively higher water uptake value. Based on the obtained results, it has been suggested that POSS has enhanced the proton conductivity and mechanical strength of the highly sulfonated PPSU based membrane desirable to be served as a proton exchange membrane in fuel cell application.