Improving physical properties of poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels via the Hofmeister effect

Hydrogel is a kind of three-dimensional crosslinked polymer material with high moisture content. However, due to the network defects of polymer gels, traditional hydrogels are usually brittle and fragile, which limits their practical applications. Herein, we present a Hofmeister effect-aided facile strategy to prepare high-performance poly(vinyl alcohol)/montmorillonite nanocomposite hydrogels. Layered montmorillonite nanosheets can not only serve as crosslinking agents to enhance the mechanical properties of the hydrogel but also promote the ion conduction. More importantly, based on the Hofmeister effect, the presence of (NH4)(2)SO4 can endow nanocomposite hydrogels with excellent mechanical properties by affecting PVA chains' aggregation state and crystallinity. As a result, the as-prepared nanocomposite hydrogels possess unique physical properties, including robust mechanical and electrical properties. The as-prepared hydrogels can be further assembled into a high-performance flexible sensor, which can sensitively detect large-scale and small-scale human activities. The simple design concept of this work is believed to provide a new prospect for developing robust nanocomposite hydrogels and flexible devices in the future.