High water content hydrogels with instant mechanical recovery, anti-high temperature and anti-high ionic strength properties

In this work, we show how simple mixing of mineral clay materials and a biopolymer chitosan to afford hydrogel composites with significantly enhanced performances in instant mechanical recovery and self-healing, anti-high temperature and anti-high ionic strength activities. Benefited by the electrostatic attraction between anionic clay and cationic chitosan, molecular level coassembly was achieved, which gave rise to a robust and rapidly selfhealable hydrogel. Synergistic effect between components enhanced the mechanical strength more than 10 folds and shortened the self-healable time more than 40 folds (from 220 s to less than 5 s). In addition, the binary hydrogel show extremely enhanced anti-temperature and ionic strength properties. This study offers a feasible and dramatically facile protocol to build functional hydrogel materials using commercially available mineral and biopolymer, which have promising applications in special areas such as underground oil and gas engineering.