The influence of molecular interaction on polymerization, 6. GPC study of polymethacrylates obtained in different solvents

Abstract

AbstractPoly(2‐naphthyl methacrylate)s (P‐2‐NM), poly(benzyl methacrylate)s (PBzMA) and poly‐(methyl methacrylate)s (PMMA) obtained by radical polymerization initiated with 2,2′‐azo‐isobutyronitrile (AIBN) in benzene, acetone and acetonitrile were investigated by means of gel permeation chromatography (GPC). The GPC curves of the polymethacrylates containing aromatic rings show lower molecular weights and higher polydispersities than those of PMMA. The polymerization in benzene leads to polymers with higher molecular weights and higher polydispersities than that in acetonitrile. Acetonitrile causes a formation of polymethacrylates with lowest molecular weight distribution. In comparison with the other solvents acetone gives PMMA with lowest molecular weight. Inversely, P‐2‐NM and PBzMA prepared in acetone are of highest molecular weights. The molecular weight and molecular weight distribution of PMMA is less sensitive to the change of the solvent than those of aromatic methacrylates.The GPC curves indicate similar dependence on the change of the polymerization medium for the copolymers of 2‐naphthyl methacrylate (2‐NM) with methyl methacrylate (MMA), and of benzyl methacrylate (BzMA) with maleic anhydride (MA) prepared in benzene, carbon tetrachloride, chloroform and acetonitrile.The results are explained assuming various termination and transfer reactions in different solvents. Some correlations established between the GPC curves and the association and dissociation of the monomer molecules in dependence of the dielectric constant of the solvent, previously observed by 1H NMR, are also discussed.