| Abstract: | The relative reactivity of acrylic acid is known to be influenced by the polymerization medium. Nonetheless, the more commonly used reactivity ratios do not show this dependence because they were calculated from low-conversion polymerizations. We have studied the copolymerization of acrylic acid and methyl methacrylate in a number of non-hydrogen-bonding and hydrogen-bonding solvents. We found that the acrylic acid fraction in the copolymer was larger when copolymerized in a non-hydrogen-bonding medium and that the methyl methacrylate fraction was larger when copolymerized in a hydrogen-bonding medium. The precise reactivity ratios were reported when toluene, benzene, isopentyl, acetate, ethyl acetate, methyl formate, and tert-butyl alcohol were used as the polymerization medium. The values were obtained by chromatographic analysis of residual monomer, followed by computation based on the nonlinear, least-squares technique of Tidwell and Mortimer. |
