Highly proton conducting fluorinated sulfonated poly(arylene ether sulfone) copolymers with side chain grafting

Abstract

A series of new copolymers HPPQSH-XX PS were synthesized from preformed sulfonated ionomers HPPQSH-XX in order to get high proton conductivity along with other excellent properties. They were prepared by direct copolymerization of bisphenol HPP with two bishalides, QBF and SDCDPS. Again the copolymers were post-sulfonated using 1,3-propanesultone in the presence of NaH and were analysed by spectroscopic techniques. The random copolymers HPPQSH-XX with different statistical distribution of –SO₃H moiety showed very small ionic clusters (5–10 nm) whereas the grafted copolymers showed larger ionic domains (60–100 nm) in their TEM images. All ionomer membranes showed good mechanical properties, high oxidative and dimensional stability with low water uptake and swelling ratios. Ion exchange capacities (weight and volume based) were also calculated to explain better the correlation with water uptake and proton conductivity (14–125 mS cm⁻¹ at 80 °C and 15–142 mS cm⁻¹ at 90 °C under fully hydrated condition) of the membranes.