Order−Disorder Conformational Transitions of N-Isopropylacrylamide−Sodium Styrene Sulfonate Copolymers in Aqueous Solutions

Copolymers of N-isopropylacrylamide (NIPA) with sodium styrene sulfonate (SSS) synthesized in aqueous medium at 70 °C undergo reversible cooperative conformational transitions without phase separation of their aqueous solution. Data obtained by high-sensitivity differential scanning calorimetry and velocity sedimentation for the NIPA-SSS copolymers have shown that depending on the SSS content either intermolecular association (micellization) or intramolecular chain folding take place upon heating.