Synthesis and characterization of thermoresponsive shape-memory poly(stearyl acrylate-co-acrylamide) hydrogels

A novel series of thermoresponsive shape-memory copolymer hydrogels (poly(stearyl acrylate-co-acrylamide)) were synthesized by radical copolymerization of stearyl acrylate (SA) and acrylamide (AM). The chemical structure and crystal property of the poly(SA-co-AM) hydrogels were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimeter. The thermodynamic property of the hydrogels was studied by dynamic mechanical analysis. The swelling ratio and the shape recovery ratio of the hydrogels were also investigated. The results indicate that base on a reversible order–disorder transition, the large difference in storage modulus below and above the crystal melting temperature (T m) of the poly(SA-co-AM) hydrogels. Furthermore, the prepared hydrogels can present excellent thermoresponsive shape-memory performance by changing the operation temperature below or above T m, and the highest shape recovery ratio can reach 97%.