An ultra-strong, ultra-stiff and anti-freezing hydrogel based on poly(vinyl alcohol)

Polyvinyl alcohol (PVA) hydrogels have drawn enormous attention but are severely limited on account of poor mechanical properties at subzero temperatures. Here, we propose a simple method to tackle this problem by incorporating chain entanglements of PVA chains and coordination bonds between Al3+ ions and –OH groups via air-drying and soaking in Al2(SO4)3 solution. The multiple dynamic interactions worked in tandem to achieve outstanding mechanical performance (41.0 MPa of fracture stress and 49.9 MJ/m3 of toughness). Meanwhile, the introduction of ions endowed the PVA hydrogel with excellent anti-freezing property (36.9 MPa of fracture stress and 51.4 MJ/m3 of toughness at −20 ℃), superior to most anti-freezing gels at subzero temperatures. The facile synthesis and superior properties might expand the application of PVA hydrogels.