Construction of an ultrahigh strength hydrogel with excellent fatigue resistance based on strong dipole-dipole interaction

A high strength hydrogel was fabricated by one-step copolymerization of dipole-dipole interaction-containing monomer, acrylonitrile, super-hydrophilic comonomer, 2-methacryloyloxyethyl phosphorylcholine and crosslinker, polyethylene glycol diacrylate (M-n = 575, PEGDA575). This dipole-dipole reinforced (DDR) hydrogel demonstrated intriguing combinations of properties such as withstanding several MPa tensile stress, tens of MPa compressive strength, excellent fatigue resistance and no yielding during tensile tests. The equilibrium water content and transparency of DDR hydrogels could be tuned by varying monomer concentration and monomer ratio. The gels exhibited low cytotoxicity and antifouling characteristic. Biodegradable high strength hydrogel could also be constructed by merely replacing PEGDA575 with bioreducible crosslinker. The method reported here offers a general strategy to design biocompatible high-strength hydrogels for tissue engineering scaffolds by copolymerizing monomer containing dipole-dipole pairing with other hydrophilic monomer.