Light-responsive polymer micelles, nano- and microgels based on the reversible photodimerization of coumarin

This paper highlights our recent work on light-responsive polymer micelles, nano- and microgels prepared with amphiphilic or double-hydrophilic block copolymers (BCPs) bearing coumarin moieties. On the one hand, with amphiphilic BCPs, by incorporating coumarin chromophores onto either core-forming or shell-forming block, photo-controlled stabilization and de-stabilization of micelles could be achieved by reversible photo-crosslinking of polymer chains based on the reversible photodimerization of coumarin groups and photo-cleavage of cyclobutane bridges. On the other hand, various designs of double-hydrophilic BCPs bearing coumarin made possible the reversible size change of nano- and micrometer-sized hydrogel particles. We discuss the light-responsive behaviours and the underlying mechanisms of these coumarin-containing BCP micellar aggregates.