Proton exchange membranes from sulfonated poly(ether ether ketone) reinforced with silica nanoparticles

Abstract

The feasibility of sulfonated poly(ether ether ketone) (SPEEK) membranes reinforced with unmodified silica (SiO2) and modified silica (SiO2–SO3H) nanoparticles as proton exchange membranes (PEMs) was investigated here. The sulfonated membranes were characterized for degree of sulfonation, thermal stability, as well as water/methanol uptake properties. The incorporation of SiO2 increased the hydrophilic behavior thus allowing more water retention, which facilitated an easy pathway for proton transfer. However, a reduction in proton conductivity was observed. The strong –SO3H/–SO3H interaction between SPEEK chains and SiO2–SO3H led to ionic cross-linking in the membrane structure, which compensated for this decrement in proton conductivity. The fuel cell performance study revealed the potential of SPEEK/SiO2–SO3H nanocomposite membrane to act as an efficient PEM for fuel cell application.