Controlled Click Polymerization of AB Monomers toward Well-Defined Star Polymers for Artificial Light Harvesting

The synthesis of polymers with predetermined molecular weights and low dispersity through step-growth polymerization (SGP) of AB monomers is challenging because of the lack of selectivity in the coupling reaction between monomers and propagation centers. Herein, we present a reactivity-confinement synergism strategy to switch the SGP of alkynyl–azide AB-type monomers, based on the Cu(I)-catalyzed azide–alkyne cycloaddition reaction to chain-growth polymerization (CGP), through the addition of a triazole dendritic scaffold bearing multiple 1,3-triazido terminal groups. The CGP of AB monomers relies on the fact that the reaction selectivity between the 1,3-triazido groups on the dendritic scaffold and the alkynyl groups on AB monomers is significantly enhanced by the high reactivity of the monoreacted 1,3-triazido intermediates and the confinement effect of the Cu(I) catalyst provided by the triazole groups in dendritic scaffolds and their derivatives. As a result, star polymers with varied architectures and very low dispersity (Mw/Mn < 1.1) were produced. Additionally, core- and periphery-dye-labeled star polymers were prepared to showcase their potential for constructing artificial light-harvesting systems without fluorescence quenching of terminal dyes due to the flexible conformation of the arms. Overall, we provide insights into designing controlled CGP of AB monomers for structurally defined topological polymers.