Thermodynamic Study on the Polyvinylpyrrolidone ＋ Water, ＋ Alkanol (n ＝ 1 ～4), ＋ 1-Methyl-2-Pyrrolidone at 298.15 K

Abstract

Enthalpies of solution of polyvinylpyrrolidone (PVP, molecular weight average, Mw ＝ 1 × 10⁴) in water, alkanol (n ＝ 1 ～4) and 1-methyl-2-pyrrolidone (NMP) were measured at 298.15 K using newly constructed calorimeter to investigate the solvation behavior of PVP in those solvents. Enthalpy of solution of PVP in water is exothermic. Enthalpies of solution of PVP in other solvents are smaller than uncertainty of calorimeter. Densities and sound velocities were also measured in same series of solution to calculate partial specific volumes at infinite dilution, V_w,2^∞, partial specific isentropic compressions at infinite dilution, K_s,w,2^∞, of PVP of different molecular weight. And viscosity was also measured to evaluate specific viscosity, η_SP, of these solutions. V_w,2^∞ of PVPs in water is larger than V_w,2^∞ of PVPs in alkanols, and K_s,w,2^∞ of PVPs in water is zero. For the alkanol solutions, V_w,2^∞, K_s,w,2^∞ and η_SP of PVPs increase with increasing number of carbon atoms in the alkanol molecules. V_w,2^∞ in NMP shows the largest value among all systems investigated. Positive values of K_s,w,2^∞ mean that solvent molecule surrounding PVP are easily compressible, for NMP system.