Khorolskyi O. Structural and non-equilibrium properties of polyvinyl alcohol solutions in dimethyl sulfoxide and water

The thesis deals with determining the features of concentration and temperature behavior of macromolecules of poly(vinyl alcohol) (PVA) in aqueous and dimethyl sulfoxide (DMSO) solutions based on experimental data, and defines the nature of temporal changes in physical properties of PVA solutions. The method of low-frequency dielectric spectroscopy, the method of capillary viscometry, the pycnometric method, and the methods of mathematical modeling have been used to study the structural and non-equilibrium properties of PVA solutions. The applicability of cell models for describing the viscosity of dilute PVA solutions has been established. The model of a macromolecule with relatively hard core and rarefied periphery describes adequately the architecture of macromolecular coils of PVA in dimethyl sulfoxide and water for dilute solutions. Those allow appropriate reproducing of the viscosity of the PVA solutions as the function of temperature and concentration close to the values of the volume concentration of the macromolecules φ≤0.5. The author for the first time has recorded the long-term variations in time of the dielectric permittivity of concentrated PVA solutions in DMSO which indicate the periodic changes in the structure of the polymer solution. A physical model is proposed in which the time oscillations of the dielectric permittivity of concentrated PVA solutions in DMSO are related to the formation of the microheterogeneous structure of solutions. The model of fading harmonic oscillations has been constructed and the characteristic life periods of the microinhomogeneities in the PVA solutions in DMSO have been determined. There is a similarity between the processes of equilibrium determination in PVA solutions and aqueous monoatomic alcohols solutions. The similarity law has been used to describe the time dependencies of equilibrium determination in PVA solutions in DMSO and aqueous glycerol solutions.