UV-curable castor-oil-based multi-crosslinking polymer networks containing dynamic disulfide bonds: High toughness, self-healing, and shape memory properties

Novel functional dynamic covalent-bonded polymer networks (DCPN) containing dynamic disulfide bonds were prepared from castor oil via a simple process. Firstly, UV-curable castor-oil-based polyurethane acrylate (COPUA) containing disulfide bonds and unsaturated double bonds was synthesized, then added with glycidyl methacrylate (GMA) to reduce viscosity (named COPUA-GMA) and mixed with different proportions of glycidyl esters containing unsaturated double bonds to form a series of UV-cured polymers named COPUA-GMA-EP. FTIR and NMR demonstrated the target pre-polymers and DCPNs were successfully synthesized. The DCPNs possessed controllable mechanical properties. Tensile tests showed the polymers had a range of tunable stiffness and flexibility. The COPUA-GMA-EP-2 copolymerized system containing 50 wt% COPUA-GMA had relatively excellent tensile strength of 11.8 MPa and elongation at break of 72.3%. Thermal analysis showed that DCPNs had excellent thermal stability, and COPUA-GMA-EP-2 had higher crosslinking density. Importantly, COPUA-GMA-EP-2 displayed excellent shape memory properties with Rf of 98.9% and Rr of 79.0%. Meanwhile, this DCPN exhibited certain self-healing properties. The DCPNs will be widely applied with good prospects owing to their excellent UV-curable, eco-friendly and shape memory properties.