Novel photopolymerized self-healing polymer films with physical cross-linking between alcohol molecules

Abstract

Self-healing materials recover their properties after damage and have been developed to increase the reliability of various materials. Because mobility is the most important feature for self-healing, thermal polymerization has been used to form the inner spaces needed in self-healing materials. Hydrogel self-healing polymers exhibit rapid self-healing with high reliability and recyclability. Although hydrogel-based self-healing polymers are one of the most successful types at present, they are limited by their lack of healing ability in the absence of water. Despite their fast and recyclable self-healing, these passive self-healing polymers are also limited by their opacity, difficult polymerization, difficult film formation, and lack of spontaneous healing, and thus have not become widely used. In the present work we report the first instance of a photopolymerized self-healing film. This is achieved by using a novel self-healing additive that replaces the chemical cross-linker and water in hydrogel and that also serves as a self-healing moiety, thereby yielding a transparent, easily fabricated, and spontaneously photopolymerized self-healing polymer (Phoshmer). This can be achieved by various alcohol molecules. The additive can be introduced to replace chemical cross-linking with physical cross-linking to increase the freedom of motion of dangling bonds and to increase the flowability of the polymer. The Phoshmer film was confirmed by means of optical microscopy to heal scratch damage within 1 min, and by means of universal testing machine measurements to recover to 85% of its initial mechanical strength. Therefore, it is expected to be applicable to various materials such as scratch recovery films, flexible adhesives, coatings, paints, and sealants.