Precise growth of polymer brushes on silica-based nanocomposites via visible-light-regulated controlled radical polymerization

Precise control over molecular variables of grafted polymer brushes is of crucial importance for obtaining polymer nanocomposites with desirable architectures and physicochemical properties, yet it remains a significant synthetic challenge. Recent advances in photoinduced electron/energy transfer reversible addition fragmentation chain transfer (PET-RAFT) polymerization have enabled light-regulated polymer synthesis, in a well-controlled and environmentally friendly manner. However, the utilization of this modern synthetic technique for the precise control of polymer brushes is underdeveloped. Here, PET-RAFT polymerization has been proceeded in a spatiotemporally controlled manner upon light regulation, producing silica nanocomposites coated with well-defined polymer brushes of target molecular weights, narrow dispersities and high grafting densities. The versatility and robustness of this technique have been demonstrated by its extendibility to other monomers and silica-containing nanomaterials. In all examined cases, the resultant high-value polymer nanocomposites possess defined chain sequences and architectures, high uniformity, and can be further expanded to a library of complex nanostructures. This work represents the first demonstration of adopting the PET-RAFT approach for generating precisely controlled polymer brushes on silica-based nanomaterials, and opens a new avenue for developing polymer nanocomposites with sequence-controlled polymer brushes and complex architectures required for a variety of target applications.