화학공학소재연구정보센터
Journal of Polymer Science Part A: Polymer Chemistry, Vol.38, No.S, 4693-4703, 2000
Stereocontrol in the free-radical polymerization of methacrylates with fluoroalcohols
The free-radical polymerization of methyl methacrylate (MMA), ethyl methacrylate (EMA), isopropyl methacrylate (IPMA), and tert-butyl methacrylate (t-BuMA) was carried out under various conditions to achieve stereoregulation. In the MMA polymerization, syndiotactic specificity was enhanced by the use of fluoroalcohols, including (CF3)(3)COH as a solvent or an additive. The polymerization of MMA in (CFs(3))(3)COH at -98 degreesC achieved the highest syndiotacticity (rr = 93%) for the radical polymerization of methacrylates. Similar effects of fluoroalcohols enhancing syndiotactic specificity were also observed in the polymerization of EMA, whereas the effect was negligible in the IPMA polymerization. In contrast to the polymerizations of MMA and EMA, syndiotactic specificity was decreased by the use of (CF3)(3)COH in the t-BuMA polymerization. The stereoeffects of fluoroalcohols seemed to be due to the hydrogen-bonding interaction of the alcohols with monomers and growing species. The interaction was confirmed by NMR measurements. In addition, in the bulk polymerization of MMA at -78 degreesC, syndiotactic specificity and polymer yield increased even in the presence of a small amount {[(CF3)(3)COH]/[MMA](0) < 1] of (CF3)(3)COH.