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Phase equilibria and solution thermodynamics in the ternary system, poly(acrylic acid)‐dioxane‐water
Author(s) -
Cowie John M. G.,
Swinyard Brian
Publication year - 1991
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990250208
Subject(s) - lower critical solution temperature , exothermic reaction , upper critical solution temperature , acrylic acid , aqueous solution , thermodynamics , polymer chemistry , endothermic process , ternary operation , 1,4 dioxane , solvent , polymer , materials science , phase boundary , phase (matter) , chemistry , organic chemistry , adsorption , copolymer , physics , computer science , programming language
The stability of solutions of poly(acrylic acid) in dioxane‐water mixtures has been examined as a function of temperature and three phase boundaries have been located when water contents are less than 10 (wt/vol)%. These collapse into one boundary at higher water contents up to 25 (wt/vol)%. The cloud points have the characteristics of a quasi‐LCST, a UCST, and an LCST, in order of increasing temperature, and this behaviour is comparable to the behaviour of poly(acrylic acid)‐dioxane solutions. Measurements of the heat of dilution showed that this changes from being endothermic in dioxane solutions to exothermic in aqueous systems at temperatures below the quasi‐LCST. Laser Raman spectra indicate the presence of hydrogen bonding between water and the polymer in the mixed solvent, which may explain the improved solvating power when water is added to dioxane.