1045hence increases the rigidity of the polymer.(ii) In the second explanation, the assumption is made that the compressibility of PVA in the adsorbed state is the same as in solution; i.e., no structural changes occur on adsorption. However, in this model the adsorbed PVA hinders the surface chemical reaction between the surface sites (sulfate and sulfonate end groups) and counterions (H+) due to dipole-ion interactions between alcohol segments of the PVA and the end groups of the latex. Ottewill and Vincent26 made a study of adsorption and wetting behavior of 1-alkanols of polystyrene latex particles. From the adsorption isotherm of 1-butanol on the latex particles, they reached the conclusion that the interaction occurred between hydroxyl groups on the butanol molecule and the hydrophilic sites of the surface. They also concluded that adsorption of alcohol molecules on the charged hydrophilic sites leads to desorption of the counterions from the inner part of the double layer.In Figure 6, the solid line represents the compressibility of the latex (from Figure 3) while the points are the compressibility calculated from data with the PVA-coated latex assuming that the compressibility observed is of the right order of magnitude to be explained by the elimination of the relaxation compressibility arising from the surface chemical reaction.With the present experimental evidence, it is not possible to distinguish between the two possible explanations given above.Acknowledgment. We are indebted to Dr. C. A. Young, who carried out the adsorption isotherms of various PVA samples on polystyrene latex samples, to Mr. M. J. Castle and Dr. M. C. Wilkinson of the Chemical Defense Establishment, Porton Down, Salisbury, Wiltshire, England, for determination of the glass transition temperature of the latex A and sucrose density centrifuge density measurements on various latices. Latex A was prepared by one of the authors (M.E.G.) in Bristol University, U.K. A sample of this latex was used in the present work with the kind permission of Prof. D. H. Everett. This research has been supported by the Office of Naval Research.Polystyrene, 9003-53-6; sodium styrenesulfonate-styrene copolymer, 39307-76-1; poly(viny1 acetate), Registry No. 9003-20-7.A lattice model is developed and used to study retention and selectivity in reversed-phase liquid chromatography (RPLC). The composition and the structure of the stationary phase are analyzed as a function of the chain length of the chemically bonded phase (CBP), the intrinsic chain stiffness, the surface coverage, and the nature of the mobile-phase solvent, for neat solvents and binary mixtures. The solute distribution process (retention mechanism) is investigated. Distribution constants are analyzed as a function of the above variables, the nature of the solute, and the temperature. The general behavior of the model system and the behavior of the special limiting cases of completely collapsed and fully extended CBP chains are considered, the former limiting case being particularly signifi...

The aqueous solubilities and octanol/water partition coefficients at 25 °C are determined for 12 chlorobenzenes and 16 polychlorinated biphenyls (PCBs) and for biphenyl by using the modified generator column method. These values are correlated with chlorine number and with either boiling point for the chlorobenzenes or the relative retention time of a polychlorinated biphenyl eluting from a gas-chromatographic (GC) column. Using differential scanning calorimetry (DSC), we have determined the melting points and enthalpies of melting for those compounds which are solid at room temperature. A correlation between the octanol/water partition coefficient and corrected aqueous solubility Is also presented, and the universality of the derived equation Is demonstrated.

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Aqueous solubilities (C,w) and octanol/water partition coefficients (/f0/w) of 62 organic solutes, falling Into 7 general chemical classes, have been systematically determined by using the modified generator column method. From thermodynamics an equation Is derived relating #f0/w to the volume-fraction-based solute activity coefficient In water ( ,*), the latter being determinable from C,w. For each class of compound, excellent linear correlations are found between log K0/w and log ,", with slopes close to the theoretical value of unity.

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