Selective De-Cross-Linking of Transformable, Double-Network Hydrogels: Preparation, Structural Conversion, and Controlled Release

ACS Appl Mater Interfaces. 2018 Dec 12;10(49):42985-42991. doi: 10.1021/acsami.8b14528. Epub 2018 Nov 29.

Abstract

This study has demonstrated the design of stimuli-responsive double-network hydrogels that are formed by sequential polymerization and show chemical transformation by selective de-cross-linking without structural failure owing to chemical orthogonality. Each self-immolative and thermoresponsive network established together the double-network structure through a thiol-ene click reaction and radical polymerization. The hydrogel exhibited enhanced mechanical strength but chemically transformed through the selective de-cross-linking of specific network triggered by a molecular stimulus, which significantly alters physical properties of the material such as tunable toughness and lower critical solution temperature behavior. In addition, the material displayed a thermoresponsive, controlled release. Only after treatment with the stimulus did the hydrogel release cargo molecules on demand via de-cross-linking while maintaining the entire structure.

Keywords: LCST; controlled release; double-network hydrogel; poly(N-isopropylacrylamide); selective de-cross-linking; thiol−ene polymerization.