Red-Light-Activated Dual Photocatalytic ATRP of Methacrylates and Acrylates Enabled by Copper Phthalocyanines

Copper phthalocyanines (Pc) represent a promising yet underexplored class of low-cost and photostable dyes for visible-light-mediated polymerizations. In this study, we demonstrate that copper phthalocyanine (CuPc) and its derivatives efficiently mediate dual photocatalyst/copper atom transfer radical polymerization (PC/Cu-ATRP) of acrylates and methacrylates under red-light irradiation (λ = 628 nm). Using methyl acrylate (MA) as a model monomer, CuPc and its chlorinated derivative (CuPc-Cl) enable controlled polymerization in DMSO at ambient temperature, whereas the aminated analogue (CuPc-NH2) exhibits substantially lower activity. Kinetic analysis reveals apparent first-order behavior with respect to the monomer, with higher polymerization rates observed for CuPc compared to CuPc-Cl, consistent with differences in solubility. The resulting polymers display predictable molar mass evolution, low dispersity (Đ < 1.3), and good temporal control under intermittent irradiation. High chain-end fidelity is confirmed by successful chain extension, affording PMA-b-PMMA block copolymers. Molecular weight can be readily tuned by varying the monomer-to-initiator ratio. As a practical demonstration, CuPc was applied in the suspension polymerization of methyl methacrylate (MMA), yielding polymer particles (3–20 μm) incorporating the dye, as confirmed by optical microscopy and scanning electron microscopy (SEM). These findings establish copper phthalocyanines as efficient and accessible photocatalysts for red-light-driven controlled radical polymerization.