Film Materials Based on Mixed Aqueous Solutions of Poly(Vinyl Alcohol), Simple Amino Acids, and Silver Nitrate.

Composite films containing >0.5% polymer could be produced from mixed aqueous solutions of poly(vinyl alcohol) (PVA), simple amino acids (glycine and L-cysteine), and silver nitrate by casting in Petri dishes followed by drying at 30ºC. The viscosity characteristics of the mixed solutions and the mechanical properties of films produced from these solutions were studied as a function of the PVA concentration. A supramolecular gel with thixotropic properties formed with a low PVA content (≤0.1%) in the solution while the thixotropic properties disappeared and the ability to produce films appeared for concentrations ≥0.5%. The higher the polymer content in the solution and film was, the higher their viscous and stress-strain properties were. The structures and properties of the mixed solutions and hydrogels and films prepared from aqueous solutions of glycine, PVA, and silver nitrate were studied using viscometry, UV spectroscopy, dynamic light scattering, scanning electron microscopy, and elemental analysis. The presence of glycine in the solution and gel was observed to reduce the viscosity because it weakened the H-bonding between polymer macromolecules. Films that were very light sensitive with respect to formation of silver nanoparticles could be produced at PVA solution concentrations of 5% and greater, like for films based on L-cysteine and silver nitrate. [ABSTRACT FROM AUTHOR]