Free-radical copolymerization of vinyl esters using fluoroalcohols as solvents: The solvent effect on the monomer reactivity ratio

Abstract

Free‐radical copolymerizations of vinyl acetate (VAc = M1) and other vinyl esters (= M2) including vinyl pivalate (VPi), vinyl 2,2‐bis(trifluoromethyl)propionate (VF6Pi), and vinyl benzoate (VBz) with fluoroalcohols and tetrahydrofuran (THF) as the solvents were investigated. The fluoroalcohols affected not only the stereochemistry but also the polymerization rate. The polymerization rate was higher in the fluoroalcohols than in THF. The accelerating effect of the fluoroalcohols on the polymerization was probably due to the interaction of the solvents with the ester side groups of the monomers and growing radical species. The difference in the monomer reactivity ratios (r1, r2) in THF and 2,2,2‐trifluoroethanol was relatively small for all reaction conditions and for the monomers tested in this work, whereas r1 increased in the VAc‐VF6Pi copolymerization and r2 decreased in the VAc‐VPi copolymerization when perfluoro‐tert‐butyl alcohol was used as the solvent. These results were ascribed to steric and monomer‐activating effects due to the hydrogen bonding between the monomers and solvents. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 220–228, 2000

Toward Synthetic Intrinsically Disordered Polypeptides (IDPs): Controlled Incorporation of Glycine in the Ring-Opening Polymerization of N-Carboxyanhydrides

“…48,50 Most radical copolymerizations are relatively insensitive to reaction conditions as rate constants for each comonomer vary similarly to changes in solvent polarity or temperature. Nonetheless, in some cases, it is possible to modify copolymer microstructure by varying reaction conditions like solvent polarity 51 and temperature. 52 In general, much less data exists for nonradical copolymerizations, which tend to exhibit greater monomer selectivity than their radical counterparts.…”

Hydrogen bonding promoting the controlled radical polymerization of 2-vinyl pyridine: supramonomer for better control

“…Okamoto et al proposed a monomer-activating effect originating from the hydrogen bonding between less-active monomers (such as vinyl acetate) and the fluoroalcohol. 24 The monomer-activating effect was supposed to be an electronic effect by manifesting the conversion of the monomer to an electron-poor monomer. Consequently, the reaction activity between a nucleophilic radical and the electron-poor monomer increased.…”

“…Despite this, the results afforded a concrete explanation of the monomer-activating effect in the literature. 24 In the presence of HFIP, other vinyl pyridine monomers, 3-vinyl pyridine (3VP) and 2-vinylpyrazine (2VPZ) were also explored by 1 H NMR characterization (Fig. S9 and S10, ESI †).…”

Bottom-up simulation, reconstruction, and quantification of macromolecule sequences from experimental polymerizations

“…23 Finally, statistical models have been built to predict reactivity ratios directly from the chemical structure of monomers, 24 but the apparent sensitivity of these parameters to experimental variables such as solvent polarity can challenge these strategies. 25 Thus, new strategies to extract reactivity ratios from experimental data would enable more representative reconstructions of sequence distributions.…”