Mechanical properties of tough hydrogels synthesized with a facile simultaneous radiation polymerization and cross-linking method

•Polyacrylamide hydrogels are prepared by radiation polymerization method.•Systematic study on the mechanical properties of the gels is provided.•The gels show high compressive and tensile strengths.•The gels show high fracture energies and excellent elastic recovery property.

Radiation-induced polymerization and cross-linking method has been applied to hydrogel preparations for decades, but less attention has been paid to the mechanical properties of the hydrogels. In this work, we provide a systematic study on the mechanical properties of hydrogels synthesized with the simultaneous radiation polymerization and cross-linking method. The prepared polyacrylamide (PAAm) had very good mechanical properties, namely high compressive strengths (several to more than 10 MPa), high tensile strengths (up to 260 kPa), high fracture strains (up to 12) and high fracture energies (10–160 J/m2). Absorbed dose and monomer concentration were the two important factors affecting the mechanical properties of the gels. The compressive strength and elastic modulus of the gels increased with increasing absorbed dose and monomer concentration, while the tensile strength, fracture strain and fracture energy of the gels decreased with increasing absorbed dose. The gels also showed excellent elastic recovery property, as indicated by the low stress–strain hysteresis ratios in cyclic tensile tests as well as the small loss factors measured with dynamic mechanical analysis (DMA).