Organocatalyzed atom transfer radical polymerization (ATRP) using triarylsulfonium hexafluorophosphate salt (THS) as a photocatalyst

Triarylsulfonium hexafluorophosphate salt (THS), an organic and inexpensive compound, was employed as a photocatalyst for atom transfer radical polymerization (ATRP) of methacrylate monomers. The propagation of polymerization did not take place without irradiation, meaning that the system can be controlled by switching light "on" and "off". We demonstrated that the polymerization rate could be significantly increased by adding sodium hydroxide (NaOH) powder into the reaction solution. Furthermore, the obtained poly(methyl methacrylate) (PMMA) presented a targeted molecular weight (M-n), narrow polydispersity indices (PDI = 1.26-1.32) and fairly high conversions in different organic solvents. Well-defined block copolymers were obtained by chain extension polymerization. A polymer brush was successfully prepared on a silicon wafer by surface-initiated ATRP using THS as a photocatalyst. This THS catalyzed ATRP system is attractive for a wide range of monomers and no metal residue was found in polymers. The obtained polymers may be useful in the synthesis of pharmaceuticals, foodstuff, and biomedical and antibacterial materials.