Hierarchically Structured Nanotube Arrays as Heterogenous Photocatalysts for Highly Efficient Broadband Photoinduced Controlled Radical Polymerization

Highly ordered TiO₂ nanotube arrays (TNTAs) and their heterostructure nanocomposites by structural engineering design were utilized as heterogeneous photocatalysts for highly efficient broadband photoinduced controlled radical polymerization (photoCRP), including photoATRP and PET-RAFT. Highly efficient broadband UV-visible light responsive photoCRP was achieved by combining the acceleration effects of electron transfer derived from the distinctive highly ordered nanotube structure of TNTAs and the localized surface plasmon resonance (LSPR) effect combined with the formation of the Schottky barrier via modification of Au nanoparticles. This polymerization system was capable to polymerize acrylate and methacrylate monomers with high conversion, "living" chain-ends, tightly regulated molecular weights, and outstanding temporal control properties. The heterogeneous nature of the photocatalysts enabled simple separation and effective reusability in subsequent polymerizations. These results highlight the modular design of highly efficient catalysts to optimize the controlled radical polymerization process.