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Molecular thermodynamics of solute‐polymer‐supercritical fluid systems
Author(s) -
Shim JaeJin,
Johnston Keith P.
Publication year - 1991
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690370414
Subject(s) - polymer , dilution , supercritical fluid , chemistry , thermodynamics , partition coefficient , activity coefficient , supercritical fluid chromatography , molar mass , chromatography , naphthalene , diffusion , gas chromatography , aqueous solution , organic chemistry , physics
Abstract The distribution coefficients of the solutes (toluene, naphthalene, and phenanthrene) are reported at infinite dilution between silicone rubber and supercriticalfluid carbon dioxide. A new technique is described in which a thin film of polymer is coated and cross‐linked onto silica, and the distribution coefficient is measured rapidly by elution supercritical‐fluid chromatography. Because CO 2 significantly enhances the solute's volatility and its diffusion coefficient in the polymer, it is possible to study solute‐polymer interactions at room temperature for nonvolatile compounds which would be difficult to study by conventional techniques such as gas chromatography. These infinite dilution data are used to determine solutepolymer interaction parameters to calculate phase diagrams over a wide concentration range. The residual, combinatorial, and cross‐link contributions to the solute activity coefficient in the polymer are discussed as a function of concentration. In addition, pronounced pressure and temperature effects are described in terms of experimentally measured solute partial molar volumes (to – 14 L/mol) and partial molar enthalpies (to – 850 kJ/mol) in the fluid phase.