Self-sorting systems of photoresponsive polymer micelles: isomerization drives reversible and switchable self-assembly.

Herein, we report self-sorting systems of photoresponsive polymer micelles obtained from amphiphilic statistical copolymers bearing hydrophilic poly(ethylene glycol) (PEG) chains and hydrophobic/photoresponsive azobenzene (Azo) groups. The PEG/Azo copolymers self-folded or intermolecularly self-assembled via the association of the azobenzene pendants to form photoresponsive unimer or multichain micelles in water, where the core-forming Azo groups show cis/trans isomerization in response to UV/vis irradiation. The PEG/Azo copolymer micelles not only induced self-sorting in the presence of other PEG copolymer micelles with different compositions and/or pendants but also exhibited photoresponsive and reversible self-sorting/co-self-assembly with an anionic copolymer micelle via the cis/trans isomerization of the Azo units. We successfully developed self-sorting and co-self-assembly systems of binary polymer mixtures that can be dually controlled by molecular design and UV/vis light without using externally added reagents.