Thermodynamic Properties of Poly(γ-benzyl-l-glutamate) Solutions over Entiore Concentration Range

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Abstract
The solvent activities for the poly(γ-benzyl-L-glutamate)-dirnethylformamide system were obtained from isothermal distillation and vapor pressure measurements in the concentration range 15–100 vol % of polymer at 30[ddot]C. Three samples were studied. The results were combined with osmotic pressure data obtained previously. The solvent activitiesat comparatively low concentrations were compared with the Cotter modified theory. The solvent activity behavior of the lower molecular weight sample (M = 23,800) is in rough agreement with that predicted by the theory over both isotropicand anisotropic regions, provided that the polymer with some amount of solvent acts as a kinetic unit. The results at higher concentrations are reasonably explained by the Flory-Leonard model of mixing of polymer side-chain with solvent. The solution process is discussed over a wide concentration range.