A nucleobase-inspired super adhesive hydrogel with desirable mechanical, tough and fatigue resistant properties based on cytosine and ε-caprolactone

Abstract

Adhesive hydrogels have significantly attracted scientific interest as a promising material for next-generation adhesive applications, such as tissue engineering, wound dressing, electronic skin sensor, and drug delivery. However, the acute defects of low mechanical property, limited adhesion and poor fatigue-resistant ability hinder their further applications, especially for low-surface energy materials. In this work, inspired by the advantages of cytosine from the basic units of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the cytosine methacryloylchloride (CMA) was successfully introduced into the hydrogel and crosslink with glycerol-polycaprolactone-methacrylic anhydride (GPCL-MA) to obtain excellent mechanical, tough, adhesive and recyclable hydrogels. Surprisingly, the resultant hydrogel could repeatedly adhere to various solid materials (e.g., steel, aluminum, glass, ceramics, wood, PET and rubber) as well as skin. The maximum adhesive strength was 16.6 ± 0.38 KPa on the steel substrate, it also shows the superior capability of adhesion to the low-surface energy substrates (e.g., Polypropylene (PP) and Polytetrafluoroethylene (PTFE)). Furthermore, the hydrogel exhibited robust mechanical performance: 1065% (strain loading), 81.0 KJ/m3 (toughness), 6.3 MPa (tensile elastic modulus), and it could quickly recover its initial state after 6 cycles loading-unloading deformation. As a result, the obtained hydrogel shows promise for the future development of adhesive materials with outstanding mechanical properties and functionality simultaneously.