Design of Robust Self-Healing Silicone Elastomers Based on Multiple H-Bonding and Dynamic Covalent Bond

A room-temperature self-healing silicone elastomer was prepared based on the synergistic effect of multiple H-bonding and dynamic covalent bond. The multiple bonds constructed by inserting thiourea into the polyurea network can inhibit the crystallization of hard urea H-bonds segments and activate the diffusion movement of polymer chains. Dynamic imine endows materials with a strong connection for the fracture interface by imine metathesis. The effect of thiourea on urea H-bonds was confirmed by the Fourier transform infrared spectrum, which showed obvious changes of H-bond density according to peak revolution of C═O and N-H. Differential scanning calorimetry demonstrated the transition from the crystalline to amorphous state after the introduction of thiourea. Tensile tests and scratch-healing tests showed that this design method can improve the self-healing property without sacrificing the mechanical strength. Finally, the optimized self-healing process was analyzed from the perspectives of the contact process, the interpenetration diffusion of the polymer chain, and rebuilding of crosslinking points between the two interfaces, which would build an avenue for constructing a fast, self-healing, and tough material.