Studies on Interaction Parameters of Poly(N-isopropylacrylamide) in 1-Propanol–Water Mixtures by Small-Angle X-ray Scattering

Abstract
Small-angle X-ray scattering from semidilute solutions of poly(N-isopropylacrylamide) in 1-propanol–water mixtures has been measured in a poor-solvent regime. The binary and ternary cluster integrals of polymer segments were determined from the concentration dependence of the correlation length at several temperatures just below the lower critical-solution temperature. The contributions of the segment–segment interactions to the entropy S int and enthalpy H int have been calculated from the temperature dependence of interaction parameters (binary and ternary cluster integrals) and it has been found that both values are positive. The dependence of S int on the concentration of propanol does not show a simple linear relationship.

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