Ambient Temperature Reversible Addition-Fragmentation Chain Transfer Radical Polymerization Under UV-Vis Radiation

There has been rapid progress in living free radical polymerization in the past decade. Reversible Addition Fragmentation chain Transfer (RAFT) radical polymerization has got much attention since its discovery. It has become a powerful technique for the synthesis of well-defined polymers or copolymers with both low polydispersity and functionalized end group as well as polymers with complex architectures. From both academic and industrial standpoints, it is desirable to develop a rapid and well-controlled RAFT polymerization under mild conditions. This thesis focuses on the effect of radiation wave range and addition of photoinitiator on the living behavior of ambient temperature RAFT polymerization under UV-vis radiation. Several chain transfer agents (CTA):S-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid) trithiocarbonate (DDMAT), S, S'-bis(α,α'-dimethyl-α''-acetic acid) trithiocarbonate (BDMAT), 2-cyanoprop-2-yl (4-fluoro)dithiobenzoate (CPFDB), cumyl dithiobenzoate (CDB) and cumyl phenyldithio acetate (CPDA) etc, and bisacylphosphine oxide photoinitiator had been synthesized. Their UV-vis absorption characteristics were investigated. The full wave, long wave and visible radiation source with wave ranges at 254-405 nm, 365-405 nm and 405 nm respectively were utilized as activation sources for these ambient temperature RAFT polymerization. UV-vis spectrophotometry has been used to follow the initialization period where the initial CTA was consumed, and the UV-induced decomposition of the CTA moiety in (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO)-initiated and thiocarbonylthio compounds mediated RAFT polymerization. Addition of TPO photoinitiator and optimizing functional groups of CTA remarkably suppress retardation effect in RAFT process, thus shorten initialization period and accelerate overall RAFT process. The CTA moiety decomposed much faster under full wave radiation than long wave and visible radiation; Trithiocarbonates and aliphatic dithioesters decayed much slower than aromatic dithioesters, CDB and CPFDB, under long wave radiation.Trithiocarbonates, e.g., BDMAT and DDMAT, exert well control over the ambient temperature RAFT polymerization of methyl acrylate (MA) and styrene...