Synthesis of star poly(N-isopropylacrylamide) with end-group of zinc-porphyrin via ATRP and its photocatalytic activity under visible light

A series of well-defined star-shaped poly(N-isopropylacrylamide) (ZnTHPP-PAM) with zinc-porphyrin as the core was synthesized by atom transfer radical polymerization (ATRP). Zinc(II)meso-tetra(p-bromopropionylphenyl)porphyrin (ZnTHPP-Br) was employed as the initiator, and CuBr/tris(2-dimeoeth-yl)amine(Me6TREN) was selected as the catalyst system. The structures of the target polymers were characterized by FT-IR and 1H NMR. The polydispersity index (PDI) was obtained by gel permeation chromatography (GPC), indicating that the molecular weight distribution was narrow and the polymerization was well controlled. The lower critical solution temperatures (LCST) for the aqueous solutions of ZnTHPP-PAM were generated by using turbidimetry method. The result exhibited lower value as compared to that of NIPAM homopolymer, which was arose from the incorporation of the hydrophobic porphyrin core. The photocatalytic activity of ZnTHPP-PAM was verified by the degradation of Methylene Blue in the presence of hydrogen peroxide under visible light. It was worth noting that the catalytic efficiency was higher at the LCST of the polymer, which benefited to the reuse of the photocatalyst.