Preferential solvation in polymer cosolvent systems: Polystyrene + cyclohexane + ethanol and poly(vinyl‐2‐pyridine) + nitromethane + carbon tetrachloride

Two cosolvent systems are studied by light scattering and viscosity measurements. The cosolvency mechanism is discussed in relation to the preferential adsorption, solubility parameter, and excess free energy of mixing of the two liquid components. The cosolvency effects are attributed to a “true” and an “apparent” cosolvency. Copyright © 1988 John Wiley & Sons, Inc

Polymer cosolvent system: Poly(vinyl-2-pyridine)/toluene/ethyl acetate

A study of the cosolvent ternary system, poly(vinyl-2-pyridine)/toluene/ethyl acetate, was carried out by viscometry and light scattering. An anomalous behaviour of the intrinsic viscosity in a certain composition region was observed and attributed to a conformational transition of the chain. The transition is interpreted in terms of the interactions between the constituents of the system. © 1988

Solution properties of polystyrene in mixtures of toluene with ethyl acetate

The ternary system polystyrene/toluene/ethyl acetate has been studied by viscometry and light scattering. The intrinsic viscosity of the ternary system has been found to undergo a discontinuity over a narrow solvent mixture composition range. This phenomenon is accounted for by assuming conformational changes of the chain. © 1991

Low-frequency Raman spectra of even α,ω-disubstituted n-alkanes

Low-frequency Raman spectra of even α,ω-disubstituted n-alkanes have been recorded. The major features in the spectra arise from whole-chain longitudinal and bending vibrations. The effects of end group, chain length, and temperature on the frequencies of these vibrations are described, and the frequencies of the longitudinal vibrations are interpreted in terms of the chain model of Minoni and Zerbi. © 1989 American Chemical Society

Low‐frequency Raman spectra of odd α,ω‐disubstituted n‐alkanes

Low‐Frequency Raman spectra of odd α,ω‐dibromo‐ and α,ω‐dihydroxy‐n‐alkanes were recorded. The longitudinal acoustic mode (LAM‐1) frequencies were assigned by references to the published results for n‐alkanes and even α,ω‐disubstituted n‐alkanes and also by taking account of the effects of end intermolecular forces and end‐group masses by use of the chain model of Minoni and Zerbi. Copyright © 1991 John Wiley & Sons, Inc

Transition conformationnelle du chlorure de polyvinyle en solution dans des melanges binaires de solvants polaires et non-polaires

We have observed a conformational transition of PVC in solution taking place in a composition region for each mixture, of a polar solvent (THF) and a non-polar solvent (toluene, dioxane 1,4 or n-hexane). This transition is related to the existence of two ordered structures of the polymer chain, one stable before and the other after the transition region. The transition is indicated by a discontinuity of experimental values of the intrinsic viscosity and the intensity of scattered light measured for polymer solutions as a function of solvent composition. We have attributed this transition to the polarity of PVC, as indicated by the change of the polarity of solvent mixtures, used as an intensive parameter, during the addition of the non-polar solvent to the polar. © 1980

Transition conformationnelle du chlorure de polyvinyle en solution dans des melanges binaires de solvants polaires et non-polaires

We have observed a conformational transition of PVC in solution taking place in a composition region for each mixture, of a polar solvent (THF) and a non-polar solvent (toluene, dioxane 1,4 or n-hexane). This transition is related to the existence of two ordered structures of the polymer chain, one stable before and the other after the transition region. The transition is indicated by a discontinuity of experimental values of the intrinsic viscosity and the intensity of scattered light measured for polymer solutions as a function of solvent composition. We have attributed this transition to the polarity of PVC, as indicated by the change of the polarity of solvent mixtures, used as an intensive parameter, during the addition of the non-polar solvent to the polar. © 1980

Mutagenicity and polycyclic aromatic hydrocarbons analysis of ambient airborne particles collected in Athens, Greece

Samples of airborne particulates from the Athens atmosphere were examined for mutagenicity and various polycyclic aromatic hydrocarbons (PAH). Extracts induced linear, dose-related increases in TA98 His+ revertants in the Ames/Salmonella assay and contained average benzo[a]pyrene (BaP) levels of 3.9 ng/m3 of air. The levels of revertants/m3 of the samples showed a linear relation to their BaP and benzo[b]-(BbF) + benzo[k]-fluoranthene (BkF) concentrations and were higher in areas with dense traffic than in industrial areas. It is suggested that the atmosphere of Athens favours the formation of secondary direct-acting mutagens due to the oxidation and nitration of PAH by ozone and nitrogen oxides, which are more abundant in the late spring months. © 1986

Influence de la solvatation preferentielle sur les dimensions des polymeres en solution dans des melanges de solvants

We have studied the dependence of the intrinsic viscosity number of polymers on the composition of binary solvents. The systems studied are: polystyrene in CCl4/CH3OH, C6H6/CH3OH and C6H6/heptane and poly-2-vinylpyridine in CHCl3/CH3CH2OH. We have also studied, for the same systems, preferential solvation of the polymers, using light scattering. We have observed that, near the θ point, short polystyrene chains exhibit a higher expansion than long chains. This was explained in terms of the dependence of preferential solvation on molecular weight. For the system poly-2-vinylpyridine/CH3CH2OH/CHCl3, we have established the viscosity increment dependence on solvent composition. The curve describing this increment differs markedly from the theoretical curve based on GE values (excess free energy) of the solvent mixture. However, taking into consideration the process of preferential solvation, the experimental curve can be corrected and becomes very similar in shape to the theoretical curve but there still remains a quantitative difference between the two curves. © 1973