Selenium-containing Dynamic Covalent Polymers

The dynamic covalent bond (DCB) is a kind of special bond that can cleave, reform, and exchange under external stimulus. DCBs have been evolved in a wide range of polymers like self-healing materials, shape memory materials and so on. Selenium is an essential element in human bodies. Our research group pioneered in the research of Se-containing dynamic polymers, and discovered that many Se-containing bonds are dynamic covalent bonds with very mild responsive conditions due to selenium's unique chemical properties. This feature article is aimed to summarize the recent progress in the field of selenium-containing dynamic covalent bonds and their applications in dynamic polymeric materials. We started from the discovery of several Se-containing DCBs and the introduction of their distinct responsive features, including visible light responsive Se - Se bond and Se - Te bond, UV light responsive Se - S bond and sonication responsive Se - N bond. Then we exhibited how integrating Se-containing DCBs into polymers could produce dynamic features in materials. For instance, based on the visible light responsive diselenide dynamic exchange reaction, the diselenide bond containing polymers can achieve remote self-healing, shape memory, light plasticity and information storage. By employing the balance of swelling and strain relaxation for polymers in solvent, diselenide bond containing polyurethane could achieve 3D patterning. Apart from dynamic bulk materials, selenium-containing polymer could also serve as biomaterials. We designed a Se - N bond containing polymer assembly, which showed impressive anti-cancer effect via the transformation of Se, S based DCBs.