Free Radical Polymerization Initiated and Controlled by Visible Light Photocatalysis at Ambient Temperature

• DOI: 10.1021/ma201546c
• Publication Date: 2011-09-06T19:09:18Z
• Authors: Guan Zhang; In Young Song; Kyo Han Ahn; Taiho Park; Wonyong Choi
• Keywords: N-BUTYL METHACRYLATE; RAFT POLYMERIZATION; PHOTOREDOX CATALYSIS; METHYL-METHACRYLATE; HIGHLY EFFICIENT; 01 natural sciences; PHOTOINITIATED POLYMERIZATION; 0104 chemical sciences; CATIONIC-POLYMERIZATION; ARGET ATRP; ELECTRON-TRANSFER; ULTRAVIOLET-RADIATION

A new method of free radical polymerization is developed on the basis of visible light photocatalysis using Ru(bpy)3Cl2 that initiates and controls the polymerization at ambient temperature. The α-haloester and benzylic halide act as radical initiators that can be activated through the Ru(bpy)3+ photoredox cycle under visible light irradiation. Successful free radical polymerizations of various methacrylates were realized using a Xe arc lamp as well as a household fluorescent lamp as light source. The polymerization is initiated with light on and immediately terminated upon turning the light off. In addition, the molecular weight of polymer can be varied by changing the ratio of monomer and initiator. The present photocatalytic method has merits of the mild reaction conditions with weak light irradiation, ambient temperature, and lower catalyst loading, which could be an alternative to the traditional thermal or photo-based free radical initiation methods. It is also advantageous over other photopolymeriz...