Polymer cosolvent systems Preferential solvation of a variety of polymers in a mixture of two solvents and the anomalous behaviour of its viscosity are studied by light scattering and viscometry. Conformational transitions of the polymer chain are observed as the mixture composition changes. (1974) Etude des Dimensions Moleculaires des Polymers Dissous dans des Melanges Binaires de Solvants Polaires et non Polaires I. Polyvinyl-2-Pyridine F.Vira, K.Viras, F.Aroni et A.Dondos. Europ. Polym.J., 10, 891-896. Material Science