Photo‐Tuned Solid‐Liquid Transition of Azo‐Grafted Poly(thioctic acid) with Ultrahigh Photothermal Conversion Efficiency

Abstract

Abstract Functional materials with photo‐regulated solid‐liquid transition have garnered significant attention and found extensive applications across cutting‐edge domains. However, previous photo‐liquefiable behaviors of azopolymers are usually induced through UV light, which may damage the performances of the materials and is also harmful to human health. Here, a novel azopolymer (Azo‐PTA) was fabricated via the ring‐opening copolymerization of thioctic acid (TA) and azobenzene‐modified thioctic acid (Azo‐TA). Interestingly, Azo‐PTA could undergo a reversible solid‐liquid transition under green light irradiation. The phase transition process of Azo‐PTA was investigated systematically through various experimental and measurement methods. The results demonstrated that the solid‐liquid transition of Azo‐PTA was ascribed to the photothermal effect rather than the photochemical process. The light‐to‐heat conversion efficiency of Azo‐PTA was as high as 84.9%, and the temperature could increase to above 90 °C within 30 s of green light irradiation. Consequently, azopolymers with green light‐regulated solid‐liquid transition behaviors were successfully achieved. Moreover, several cutting‐edge applications of Azo‐PTA were explored, including photo‐switchable adhesion, self‐healing coating, and smart window. Our finding thus opens up a new platform for the fabrication of azopolymers with visible light‐regulated solid‐liquid transition.