Facile preparation and characterization of super tough chitosan/poly(vinyl alcohol) hydrogel with low temperature resistance and anti-swelling property.

Facile preparation of super tough hydrogels with low temperature tolerance and anti-swelling property is still a challenging task for researchers. Meanwhile, the vast majority of tough hydrogels were obtained though chemical crosslinking and complicated synthesis or processing method accompanying a large number of harmful chemical reagents. Herein, the super tough chitosan/poly(vinyl alcohol) (CS/PVA) hydrogels (the maximum compressive strength of 18.97 MPa at a strain of 80% and the maximum tensile strength of 4.02 MPa at a strain of 406.4%) were successfully prepared via a simple post-treatment method. CS/PVA hydrogels were firstly prepared by freezing-thawing process and then soaking in saturated sodium chloride aqueous solution. The resultant hydrogels possess excellent swelling resistance and low temperature tolerance. This work shows that the post-treatment of immersing in saline solution is a feasible way to prepare super tough hydrogels with low temperature tolerance and anti-swelling property. This also would enlarge the application areas of CS.