Thermoresponsive Properties of N-Isopropylacrylamide with Methacrylic Acid Copolymer in Media of Different Acidity

다국어 초록 (Multilingual Abstract)

Linear statistic N-isopropylacrylamide copolymer containing 16.8 mol % of methacrylic acid was studied using methods of static and dynamic light scattering and turbidimetry. The experiments were performed in aqueous solutions at the concentration c = 0.015 g cm-3 in a wide temperature region from 10 to 60 °C within pH interval from 1.7 to 11.2. The rapid increase of scattered light intensity and decrease of the transmitted light intensity at heating of the solution was observed, which implied phase separation in the solution. The phase separation was confirmed by intensive aggregation of macromolecules, which was evidenced by dramatic changes in the size of the dissolved species and their fraction in the solution.
Thermoresponsiveness of the copolymer was strongly dependent on pH. The specific behavior of the N-isopropylacrylamide with methacrylic acid copolymer as compared to that with maleic acid was shown, which is caused by the presence of hydrophobic methyl group in the chemical structure of the methacrylic acid monomer.