Highly Controlled Organotellurium-Mediated Living Radical Polymerization (TERP) in Ionic Liquids (ILs). The New Role of ILs in Radical Reactions

Ionic liquids (ILs) served perfectly as solvents for the organotellurium-mediated living radical polymerization (TERP) of methyl methacrylate (MMA), methyl acrylate (MA), and styrene. The reaction rate of polymerizing MMA and MA was significantly increased as previously reported, and the controllability of the polydispersity index (PDI) was also improved by a great margin. The TERP of MMA can now give poly(methyl methacrylates) (PMMAs) with PDIs less than 1.1 and nearly full conversion in a half hour without the presence of (TeMe)(2). The kinetic study revealed that the improved control could be ascribed to a faster degenerative chain transfer (DT) reaction which plays a key role in the control of PDI for TERP. Besides the polar effect of ILs, the existence of Lewis acid-base interaction between ILs and the Te atom was proven by UV-vis spectroscopy and Te-125 NMR results. Such positive interaction lowered the activation energy of the DT process.