Solvent effects on free-radical polymerization, 2. IR and NMR spectroscopic analysis of monomer mixtures of methyl methacrylate and N-vinyl-2-pyrrolidone in bulk and in model solvents

Binary systems of methyl methacrylate (MMA)/N-vinyl-2-pyrrolidone (NVP) and MMA/N-methyl-2-pyrrolidone (NMP) with NMP as saturated model of NVP and of NVP/methyl isobutyrate (MiB) with MiB as saturated model of MMA were investigated by means of IR and NMR spectroscopy. Investigations were carried out at room temperature or at 60°C in CHCl₃ (IR) or CDCl₃ and C₆H₁₂/C₆D₁₂ (NMR). It can be concluded from IR and NMR spectra that the polarity of MMA increases in the presence of NVP and the polarity of NVP decreases in the presence of MMA. Equilibrium constants K of complex formation were determined to: K = 0,169 ± 0,037 L · mol^?1 for MMA/NVP at 30°C, 0,112 ± 0,024 L · mol^?1 for NVP/MiB at 60°C and 0,125 ± 0,030 L · mol^?1 for MMA/NMP at 60°C.