Self-Organization Processes in Aqueous Solution of Polyvinyl Alcohol, L-Cysteine, and Silver Nitrate

Abstract

The self-organization processes in aqueous solution of polyvinyl alcohol (PVA), L-cysteine, and silver nitrate treated with sodium sulfate were studied by a complex of methods (viscometry, UV and IR spectroscopy, pH measurements, and dynamic light scattering). It was shown that PVA macromolecules interact with [—Ag−S(R)—Ag−S(R)—]n supramolecular chains based on cysteine and silver (where R is the cysteine residue) by the formation of hydrogen bonds. The increase in PVA concentration leads to the increase in viscosity of the obtained hydrogels; the thixotropic properties become more pronounced; the intensity of the main absorption bands of the UV spectrum corresponding to the formation of supramolecular structures becomes higher; the pH increases; the average hydrodynamic sizes of particles increase; the electrical conductivity of the system decreases. Scanning electron microscopy showed the formation of a regular macroporous structure of dried hydrogels. It was established that both the density of the spatial network and the porosity of dried hydrogel can be controlled by changing the PVA concentration in solution. A superporous structure of dried hydrogel was observed at high PVA concentration (2%) in solution.