Photo-polymerized self-healing polymers depending on the amount of two diurethane acrylate monomers

Abstract

Self-healing polymers are smart materials which have an ability to repair themselves after being damaged. Among the secondary interactions, hydrogen bonding, although it had weak interaction energy, indicated remarkable self-healing ability owing to its reversibility, and directionality. However, in the case of hydrogen bonding for self-healing, spontaneity is not possible without mediators such as water. Recently our group made a thin film using the photo-polymerization method and confirmed that it indicated self-healing ability without a mediator. This was achieved by using a self-healing additive replacing a chemical crosslinker and water in hydrogel with a physical crosslinker and also serving as a self-healing moiety, thereby yielding transparent, and spontaneously photo-polymerized self-healing polymers, which could be achieved by alcohol molecules. In this research, we have fabricated two self-healing monomers, diurethane acrylate (DUA) and diurethane cyclic acrylate (DUCA) before, and in this work we observed the tendency of mechanical and self-healing properties by mixing the two healing monomers with a specific ratio. As results, when the two monomers were mixed, the properties were better as the amount of DUCA got higher. This was because the DUCA monomer created an inner space by steric hindrance and then could improve the mechanical strength and healing properties. The polymers indicated at least 97% of transmittance and the copolymer with higher amount of DUCA had nearly 90% of healing efficiency. Self-healing polymers are expected to be used for surface protection against scratch.