Cooperative proton conduction in sulfonated and phosphonated hybrid random copolymers

Abstract

Hybrid random polymers with sulfonated and phosphonated (SulPhos) segments are prepared in a single step. The hybrid polymer demonstrates conductivity both at low and high temperatures simultaneously. The sulfonated segment interconnects with the phosphonic domain at a high temperature and participates in a ‘cooperative proton conduction’ requiring no water or moisture for protons to hop. The conductivity of the SulPhos polymer is mainly dominated by the Grotthuss mechanism. The state of the art polymer presented here combines the weakness of two different ionic groups in such a way that the inefficiency of one ionic group (sulfonic acid) can be used as a support for the other (phosphonic acid) under certain conditions where both the groups can perform i.e. conduct protons. These hybrid polymers after certain improvement will be used as membranes in fuel cell devices operating at low and high temperatures simultaneously.