Synthesis of maleimide polyanions by co-polymerization of N-(4-carboxyphenyl)maleimide with acrylic and methacrylic acid

New maleimide polyanions were prepared by homo-polymerization and co-polymerization of N-(4-carboxyphenyl)maleimide (CPMI) in 1,4-dioxane at 65 degrees C in the presence of azoizobutironitrile (AIBN) as initiator. The monomer reactivity ratios in the co-polymerization of CPMI (M-1) with acrylic acid (AA) or methacrylic acid (MAA) and Q(1)-e(1) values were determined as follows: r(1)= 0.09, r(2) = 1.38, Q(1) = 2.46, e(1) = 1.85 in the CPMI-AA system, and r(1) = 0.14, r(2) = 1.58, Q(1) = 3.23, e(1) = 2.15 in the CPMI-MAA system. The thermal stability of the resulting maleimide copolymers was investigated by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature of poly(CPMI-co-MAA), containing 49.4 %mol CPMI, T-g = 239 degrees C and an activation energy value of 160.6 J/g was determined. The thermal stability of co-polymers increases with the increasing amount of the maleimide links in the macromolecules.