The structure of micelles formed by two poly(oxyethylene)/poly(oxybutylene) block copolymers, E 76B 38 and E 155B 76, in n-hexane at 50 ℃ was studied by synchrotron Small Angle X-ray Scattering(SAXS) and Wide Angle X...The structure of micelles formed by two poly(oxyethylene)/poly(oxybutylene) block copolymers, E 76B 38 and E 155B 76, in n-hexane at 50 ℃ was studied by synchrotron Small Angle X-ray Scattering(SAXS) and Wide Angle X-ray Scattering(WAXS). Spherical micelle with a crystalline core was observed for E 155B 76. E 76B 38 also formed spherical micelles, but the core was amorphous. The radius of the core(R), the length of the amorphous chain in the shell(L) and the number of association(N) were obtained by fitting the SAXS data with the model of a spherical core attached with Gaussian chains. The result showed that the E block exhibited multiple folds. The B block tended to be more coiled and the area occupied by per chain was larger in the micelles of E 155B 76, which are favorable to the formation of spherical micelles.展开更多
Vapor-liquid equilibrium data of supercritical carbon dioxide +n-hexane system were measured at 313.15 K, 333.15 K, 353.15 K, and 373.15 K and their molar volumes and densities were measured both in the subcritical an...Vapor-liquid equilibrium data of supercritical carbon dioxide +n-hexane system were measured at 313.15 K, 333.15 K, 353.15 K, and 373.15 K and their molar volumes and densities were measured both in the subcritical and supercritical regions ranging from 2.15 to 12.63 MPa using a variable-volume autoclave. The thermodynamic properties including mole fractions, densities, and molar volumes of the system were calculated with an equation of state by Heilig and Franck, in which a repulsion term and a square-well potential attraction term for intermolecular interaction was used. The pairwise combination rule was used to calculate the square-well molecular interaction potential and three adjustable parameters (ω,k_ε,k_σ) were obtained. The Heilig-Franck equation of state is found to have good correlation with binary vapor-liquid equilibrium data of the carbon dioxide +n-hexane system.展开更多
文摘The structure of micelles formed by two poly(oxyethylene)/poly(oxybutylene) block copolymers, E 76B 38 and E 155B 76, in n-hexane at 50 ℃ was studied by synchrotron Small Angle X-ray Scattering(SAXS) and Wide Angle X-ray Scattering(WAXS). Spherical micelle with a crystalline core was observed for E 155B 76. E 76B 38 also formed spherical micelles, but the core was amorphous. The radius of the core(R), the length of the amorphous chain in the shell(L) and the number of association(N) were obtained by fitting the SAXS data with the model of a spherical core attached with Gaussian chains. The result showed that the E block exhibited multiple folds. The B block tended to be more coiled and the area occupied by per chain was larger in the micelles of E 155B 76, which are favorable to the formation of spherical micelles.
文摘Vapor-liquid equilibrium data of supercritical carbon dioxide +n-hexane system were measured at 313.15 K, 333.15 K, 353.15 K, and 373.15 K and their molar volumes and densities were measured both in the subcritical and supercritical regions ranging from 2.15 to 12.63 MPa using a variable-volume autoclave. The thermodynamic properties including mole fractions, densities, and molar volumes of the system were calculated with an equation of state by Heilig and Franck, in which a repulsion term and a square-well potential attraction term for intermolecular interaction was used. The pairwise combination rule was used to calculate the square-well molecular interaction potential and three adjustable parameters (ω,k_ε,k_σ) were obtained. The Heilig-Franck equation of state is found to have good correlation with binary vapor-liquid equilibrium data of the carbon dioxide +n-hexane system.
