Impact of Neutral Linear Polymers on the Polyelectrolyte Properties of Semi-interpenetrating Polymer Networks

This study investigates the influence of a neutral linear polymer on the key properties of a polyelectrolyte network within a semi-interpenetrating polymer network (semi-IPN) architecture. To this end, poly(epichlorohydrin) (PECH), cross-linked with 1,4-diazabicyclo-[2,2,2]-octane (DABCO) (PECHD), was combined with either a hydrophilic polymer, poly(vinyl alcohol) (PVA), or a hydrophobic, hydroxyl-terminated perfluoropolymer, Fluorolink E10H (E10H), in varying weight ratios. The PVA-rich phase was found to be cocontinuous with the PECHD-rich phase, whereas E10H was homogeneously distributed, appearing grafted onto the PECHD network. The semi-IPNs were characterized in terms of mechanical properties, water uptake, ion exchange capacity, ionic conductivity, and selectivity, both before and after immersion in 8 M KOH at 50 °C for 28 days, to evaluate the impact of neutral polymer incorporation on both initial properties and their evolution under harsh chemical conditions. Interestingly, while some properties improved with the introduction of the hydrophilic polymer, others were significantly reduced, and vice versa, both initially and upon aging.