Thermodynamic, spectroscopic and DFT studies of binary mixtures of poly(vinylpyrrolidone) (PVP) with ethanol, 1-propanol and 1-butanol

Abstract Ultrasonic velocity measurements along with derived parameters provide an important information regarding the nature of miscibility and molecular interactions in polymeric solutions. Experimental measurements on ultrasonic velocity (u), density (ρ), refractive index (n) and viscosity (η) have been made for poly(vinylpyrrolidone) (PVP) with ethanol, 1-propanol, and 1-butanol at varying concentrations ranging from (0.1% to 0.9%) and temperatures (283.15 K to 303.15 K). Thermo-physical parameters viz. intermolecular free length (Lf) and adiabatic compressibility (βα) have been evaluated from the experimental data. On the basis of the variation of these parameters with concentration, the nature of polymer-solvent interaction has been studied which indicates the existence of molecular interaction between the polymer and the alcohols. FT-IR spectrum of pure PVP and their solutions and optical absorption spectra at concentrations (0.3%, 0.4%, 0.5%, 0.6%) have been recorded in the wavenumber range (4000–500 cm−1) and wavelength range (200–400 nm) respectively. The optical band gap has been calculated for PVP solutions. The experimental data are in good agreement with the calculated data as obtained by the DFT/B3LYP method.