Thermosensitive four-arm star-shaped copolymers with phthalocyanine as core and porphyrin copolymer as arms was used as visible light photocatalyst

Porphyrins and phthalocyanines are considered as visible light catalysts with great development potential due to their unique π-conjugated structure, strong visible light absorption and structural tunability. However, they are easy to aggregate and difficult to dissolve, and their application in the field of photocatalysis is limited. Based on the above problems, in this study, three four-arms star-shaped thermosensitive copolymers (PcZn-(PNIPAM n -co-PUMPP m ) 4 ) photocatalysts with zinc phthalocyanine as the core and porphyrin thermosensitive copolymer as the arms was constructed by using RAFT polymerization technology and the ’core first’ route. The visible light catalytic activity of the prepared star-shaped copolymers was evaluated by using 1,5-dihydroxynaphthalene (DHN) and methylene blue (MB) as model pollutants. The three copolymers were found to be effective in oxidizing DHN to juglone and degrading MB. Among them, PcZn-(PNIPAM 33.5 -co-PUMPP 1.6 ) 4 (P3) showed the highest DHN conversion efficiency (100.0 %), reaction yield (70.0 %) and MB degradation (96.9 %). 1 O 2 and O 2 · - are the main active substances in the visible photocatalytic process. Based on UV–vis absorption spectra, Fluorescence spectra, EIS Nyquist plots and transient photocurrents, it is confirmed that P3 has a wider range of visible light absorption, and there is effective energy and electron transfer between TTPcZn and UMPP units in P3, which makes it have higher catalytic activity. More importantly, the lower critical solution temperature (32.6 ∼ 32.9 °C) of P3 makes it possible to achieve homogeneous catalysis and heterogeneous recovery through simple temperature regulation in the catalytic process, which makes P3 have good reusability. This work paves a way for the construction of high-performance and recyclable visible polymer photocatalyst.