Solvent Effect\nin the Copolymerization of Ethylene\nand Vinyl Acetate

The copolymerization of ethylene vinyl acetate (VAc)\nat 4.0 MPa\nand 75 °C has been studied experimentally and computationally\nin four organic solvents, namely, methanol (MeOH), <i>tert</i>-butyl alcohol (TBA), methyl acetate (MA), and dimethyl carbonate\n(DMC), to reveal the effect of the solvents on copolymerization. The\nresults show a significant dependence of the copolymerization rate\nand reactivity ratio on the nature of the solvent. Polymerization\nrate constants decrease in the order of TBA > MeOH > DMC >\nMA. The\nresults from FTIR spectra and complexation energy calculation suggest\nthat the variance of the copolymerization rate is closely related\nto the interaction between the monomer and the solvent. A stronger\ninteraction between the monomer and the solvent might decrease the\naverage effective monomer concentration. Various reactivity ratios\nare interpreted in terms of the stabilization effect of the solvent\non electron-deficient species that changes the selectivity of macroradicals.\nDensity functional theory (DFT) calculation performs well in predicting\nthe change in the reactivity ratio in different solvents. The molecular\nweight of the ethylene vinyl acetate copolymer is remarkably affected\nby the solvents due to the chain transfer reaction, while the unit\nsequence is little affected.