Energetics of phase separation in aqueous solutions of poly( N -isopropylacrylamide)

摘要: The energetics of phase separation in dilute aqueous solutions poly(N-isopropylacrylamide) is studied by high-sensitivity differential scanning calorimetry. temperature dependences the partial heat capacity polymer are obtained. effect heating rate on their shape examined. concentration thermodynamic parameters transition determined. After system, much smaller than its state a swollen random coil. This finding indicates occurrence hydrophobic structure concentrated system probably form clusters monomer units. profile described Schroder-van Laar equation with van’t Hoff enthalpy independent concentration. size cooperative unit ordered hydrate estimated and found to be coincident Kuhn segment. High-velocity sedimentation measurements conducted at various temperatures both below above binodal curve system. It shown that sizes macromolecules before diluted after coincide. Thus, phase, retain coil conformation.