Photoswitching of the melting point of a semicrystalline polymer by the azobenzene terminal group for a reversible solid-to-liquid transition

Abstract

Semi-crystalline polymers are widely used in daily life. However, due to their high melting point, their processing normally requires the application of high temperature or the addition of plasticizers. Here, we report a semi-crystalline polymer with a light controlled melting point. Under UV light irradiation, the polymer consisting of azobenzene end functionalized polycaprolactone is capable of undergoing reversible solid-to-liquid transformation, which is likely due to the decreased melting point caused by the trans-to-cis isomerization and the temperature rise due to the photothermal effect of azobenzene groups. Accompanying this process, both the transparency change and self-healing properties are observed, which facilitate the application of the azobenzene terminated polycaprolactone in information encryption and smart window fields. The current study thus opens up new opportunities to decrease the melting point of semi-crystalline polymers through the introduction of end functional groups for facile processing and diverse applications.