Photoresponsive polymers with multi-azobenzene groups

Azobenzene is a switchable compound that exhibits reversible trans-cis photoisomerization. Photoresponsive polymers have been prepared by incorporating azobenzene groups into polymers. Most of the reported azobenzene-containing polymers (azopolymers) have only one azobenzene group in the repeat unit of the polymers (mono-azopolymers). To improve photoresponsiveness, multi-azobenzene groups have been covalently or non-covalently introduced into the repeat units of azopolymers (multi-azopolymers). In this Perspective, we introduce photoresponsive multi-azopolymers. We summarize the preparation of such polymers and highlight their potential applications in photoactuation, photo-patterning, and photoinduced birefringence. The innovative potential, open questions, and remaining challenges in this field are also discussed.