Light-Programmed Reversible Valence Reconfiguration of Polymeric Colloidal Molecules.

Polymeric colloidal molecules (CMs) with light-switchable compartmental architectures and valences are attractive building blocks for reconfigurable colloidal materials. Here, we report the stepwise and reversible light-induced valence reconfiguration of preformed AB2-type CMs. The CMs were prepared by associating an amine-functionalized trans-azobenzene (t-AZO) with the PAA corona of poly(acrylic acid)-block-poly(vinylnaphthalene) (PAA-b-PVN) micelles, producing a PVN core (A) and two t-AZO-rich PAA corona compartments (B). Upon 365 nm UV irradiation, the AB2 CMs evolved successively into AB3- and AB4-rich states, whereas 470 nm visible-light irradiation drove the reverse AB4/AB3/AB2 evolution over repeated cycles. The reversible reconfiguration is attributed primarily to photoisomerization-induced changes in AZO packing within the PAA corona, which regulate B compartment formation and number. The light-selected valence states further directed secondary assembly into linear chains, branched assemblies, and interconnected networks. Light therefore enables dynamic reprogramming of both the valence of preformed CMs and the topology of their subsequent higher-order assemblies.