Abstract

The state of sorbed water molecules in the matrix of polyvinyl alcohol is investigated via the methods of static sorption, DSC, TGA, IR Fourier spectroscopy, 1H NMR spectroscopy, and quantum-chemical simulation. It is shown that the sorption of water by polyvinyl alcohol characterized by an S-shaped isotherm is described by the double-sorption model. It is established that the low diffusion coefficients and extremely low rates of desorption processes observed in the range of low activities are determined by a shift of the equilibrium toward the formation of hydrogen-bonded complexes of water molecules with hydroxy groups of the polymer. A mechanism for the behavior of residual water in hydrophilic polymers is suggested. It implies that differences between polymers are determined only by the quantity of residual water immobilized in “traps” and the energy of hydrogen-bond formation.

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