Cell membrane–inspired reverse dialysis approach for preparation of hydrogels with tunable mechanical properties of high strength and toughness

Hydrogels are important biomaterials that have vital applications in multiple fields. The effective preparation of tough hydrogels that meet the requirements of multifunctional application remains a great challenge. Inspired by the water absorption and loss across cell membranes in nature, a novel strategy of reverse dialysis (external hydrophilic substance regulates the structure of internal polymer) was proposed. The strategy involves regulating the difference in internal and external osmotic pressure, which, in turn, regulates the hydrogen bond formation in the polymer chain. Compared to the traditional methods of hydrogel preparation, the preparation time in this study is restricted to within 3 h. During the reverse dialysis process, nanofiber-like structures were successfully formed inside the hydrogel. Especially at low concentrations of PVA (5 % w/v), ordered fiber structures are formed. The tensile strength and toughness can be modulated within the approximate range of 0.24–41.52 MPa and 1.42–222.62 MJ/m³, respectively. The hydrogel was found to exhibit good biocompatibility, ionic conductivity (up to 7.80 S/m), and frost resistance; it can be employed in supercapacitors as a solid electrolyte. The reverse dialysis method described in this study provides a sound framework for the preparation of strong and tough hydrogels with multifunctional applications.