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Small‐angle X‐ray scattering from semi‐dilute solutions of poly( N ‐isopropylacrylamide) in aqueous acetonitrile solutions
Author(s) -
Shimizu S.,
Sekine R.,
Kurita K.
Publication year - 2000
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889899013175
Subject(s) - acetonitrile , aqueous solution , chemistry , ternary operation , scattering , small angle x ray scattering , solvent , enthalpy , small angle scattering , poly(n isopropylacrylamide) , analytical chemistry (journal) , thermodynamics , chromatography , physics , optics , organic chemistry , polymer , copolymer , computer science , programming language
Interaction parameters of poly( N ‐isopropylacrylamide) in acetonitrile–water mixed solvent were determined by using small‐angle X‐ray scattering. Small‐angle X‐ray scattering measurements were carried out in conditions of the semi‐dilute poor solvent regime and just below the lower critical solution temperature. From concentration dependence of the correlation length, the binary and ternary cluster integrals were determined. The contribution of the segment–segment interactions to the entropy S int and the enthalpy H int has been calculated from the temperature dependence of these cluster integrals. It has been found that both values are positive. On addition of a small amount of acetonitrile into aqueous solution of poly( N ‐isopropylacrylamide), S int and H int increase with increasing acetonitrile content. Upon further addition of acetonitrile, these values decreased.