Investigation of Free-Radical Copolymerization Propagation Kinetics of Vinyl Acetate and Methyl Methacrylate

Abstract

The free-radical copolymerization propagation kinetics of vinyl acetate (VAc) and methyl methacrylate (MMA) at 50 degrees C were investigated through an experimental study combined with a computational analysis based on quantum chemistry. Copolymer composition data, obtained using pulsed laser polymerization followed by size exclusion chromatography (PLP-SEC) and proton nuclear magnetic resonance (NMR), were well represented by the terminal model using monomer reactivity ratios obtained with the computational approach (r(VAc) = 0.001 and r(MMA) = 27.9). Concerning the composition-averaged copolymerization propagation rate coefficient k(p,cop), the differences between the terminal model and the implicit penultimate unit effect (IPUE) model (s(MMA) = 0.544 and s(VAc) = 0.173) are small for VAc/MMA, with the terminal model sufficient to describe the experimental k(p,cop) data measured by PLP-SEC. Monomer and radical charge distributions determined computationally are used to explain the reactivity exhibited by the VAc/MMA system.