Chain folding double-network hydrogels leads to ultra-strong, stretchable and tough sensors

Abstract

Strong, stretchable and tough sensors are in great demand but challenging. Here, we present a simple and generable strategy toward fabricating high-performance sensors by folding the polymer chains of the ionic double-network (DN) hydrogels via dehydration in poor solvent of ethanol. The combination of chain folding and DN network dramatically improved stress buffering and energy dissipation capacity of hydrogels during the unfolding/stretching process. The as-prepared hydrogels exhibited ultra-high strength (1.06 MPa), stretchability (15,400%) and toughness (88 MJ m−3), representing the most tough hydrogels reported as far as we know. By taking these advantages, the hydrogels were demonstrated as strain sensors with extremely broad work window (0.05–8000%). This chain folding DN concept provides an attractive strategy to improve the whole mechanical properties of hydrogels to new limits and expand the scope of applications.