Tough Anisotropic Bio-based Hydrogels With Directional Enhancement Via the Synergy of Alignment/Drying and Salting...

Hydrogels have great potential for application in tissue engineering and intelligent sensing fields due to their flexible, tough, and biocompatible characteristics. However, the limited mechanical properties of traditional hydrogels have severely hindered their practical applications. Inspired by the hierarchical anisotropic structure of natural biomaterials, this study proposes an effective structure-molecule engineering strategy based on alignment/drying and salting out (ADSO) for constructing an anisotropic high-amylose/polyvinyl alcohol (HSPI-ADSO) hydrogel. This hydrogel exhibits a highly ordered hierarchical structure at the millimeter-micrometer-nanometer scale and a network structure at the nanometer-molecular scale. The HSPI-ADSO hydrogel demonstrates highly adjustable mechanical properties with the tensile strength of 4.18-17.40 MPa, the elongation at break of 258%-1086%, the Young's modulus of 3.33-37.43 MPa, and the toughness of 7.60-71.63 MJ·m^{- 3}. Microscopic structure characterizations and finite element simulation confirm that this mechanism stems from the regulation of crystallinity, hydrogen bonds and the arrangement of the polymer chains by the ADSO strategy. Moreover, the ADSO strategy is also proven to have versatility to adjust the mechanical properties of other natural polymer-based composite materials (alginate, konjac glucomannan and cellulose). Therefore, this method provides a highly promising idea for the application of these materials in tissue engineering, flexible electronics and biomedical materials fields.