Tough and super-resilient hydrogels synthesized by using peroxidized polymer chains as polyfunctional initiating and cross-linking centers

Abstract

Developing tough hydrogels with excellent resilience is important for their practical applications. We report a facile strategy for synthesizing tough and super-resilient hydrogels by using peroxidized macromolecules as polyfunctional initiating and cross-linking centers (PFICC). Peroxy groups are first introduced onto poly(N-vinylpyrrolidone) (PVP) chains by the irradiation method, and then the peroxidized PVP is used as PFICC to initiate in situ grafting polymerization of acrylamide (AAm) molecules. The resultant hydrogels made with different monomer concentrations exhibit very high compressive strengths (up to 20 MPa at 95% strain), high tensile strengths (up to 0.38 MPa), high elongations (up to 2800%), and a very good elastic recovery property. When a very small amount of a chemical cross-linker N,N′-methylenebisacrylamide (MBA) is added, although the tensile strengths and the elongations of the gels decrease, the compressive strengths and the moduli of the gels increase; more impressively, the gels exhibit an excellent elastic recovery property, as indicated by the extremely low hysteresis ratios (<0.03) and negligible stress relaxation.