The living free-radical copolymerizations of styrene (St) with the polar monomers (methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), methyl acrylate (M-A), ethyl acrylate (EA), butyl acrylate (BA), 2-hydroxyethyl acrylate (HEA), and vinyl acetate (VAc)) mediated by TEMPO and BPO as initiator at 1.25 degrees C had been analyzed by H-1 NMR and gel permeation chromatography (GPC). The data from GPC showed that the polydispersities of the resulted copolymers were below 1.5, and the rate of polymerization increased, while the polydispersity declined with increase in St molar fraction in the feed. Monomer reactivity ratios had been determined by expanded Kelen-Tudos method. r(St) = 1.32, r(MA) = 0.14; r(St) = 1.17, r(EA) 0.23; r(St) = 0.83, r(BMA) 0.20; r(St) = 0.74, r(MMA) = 0.25; r(St) 0.76, r(EMA) = 0.30; r(St) 1.27, r(BMA) = 0.59; r(St) = 1.67, r(VAc) = 1.05; and r(St) = 0.28, r(HEA) = 0.43. In the copolymerization of St with acrylates the monomer reactivity ratio 0 (St) decreases and in the copolymerization of St with methacrylates the monomer reactivity ratio r1 (St) increases while the length of the substituted group increases. (c) 2006 Wiley Periodicals, Inc

The polymerization of styrene was mediated by copper (I) bromide/pentramethldiethyltriamine (PMDETA) using ethyl 2‐bromopropionate (EBP) as initiator and a catalytic amount of malononitrile (MN) as a novel rate‐accelerating additive. The optimal molar ratios of MN/EBP under which the polymerization of styrene can proceed fastest was 4:1. The rate‐enhancement‐efficiency had a dependence on temperature and the apparent rate constant of polymerization improved by a factor of 2.67 at 85 °C. Polymerization resulted in a conversion as high as 87% in 4.3 h in the presence of MN, while a conversion of 79.7% was gained even in 10 h without MN at 85 °C. The polymerizations of styrene in the presence of MN proceeded in a living fashion indicated by the first‐order kinetic plots, with the increase of Mn with respect to conversion and the relatively narrow polydispersity. The possible rate enhancing mechanism is that the addition of MN weakens the coordination between the copper center and ligand and facilitates the atom transfer process. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4082–4090, 2007

The acceleration effect of various agents on the rate of styrene bulk polymerization in 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) mediated polymerization was investigated, including dimethyl malonate (DMM), diethyl methyl malonate (DEMM), diethyl tert-butylmalonate (DEBM), diethyl diethylmalonate (DEDEM), 3-methyl-2,4-pentanedione (MPD), acetyl malononitrile (Ac-MN), and dimethyl malononitrile (DM-MN). Polymerization with the additive proceeded in a living manner, as indicated by keeping a low polydispersity and increasing the molecular weight with the reaction time and conversion. The structure of the styrene polymerization did not change in the presence of these additives. The monomer conversion efficiency was approximately 99% and maintained a relatively narrow polydispersity of 1.29 with the optimal [Ac-MN]/[TEMPO] molar ratios of 4 in 1.5 h. With the accelerator, dipole/dipole interactions led to a weakening of the C-ON bond and an acceleration of the reaction. There is a trend for a higher polymerization rate with more electron-withdrawing substituents.