In situ electrochemical synthesis of silver-doped poly(vinyl alcohol)/graphene composite hydrogels and their physico-chemical and thermal properties

This paper presents silver/poly(vinyl alcohol) (Ag/PVA) and silver/poly(vinyl alcohol)/graphene (Ag/PVA/Gr) composites prepared by the immobilization of silver nanoparticles (AgNPs) in PVA and PVA/Gr hydrogel discs previously cross linked by the freezing/thawing method. The AgNPs inside the hydrogel matrices were synthesized following an innovative in situ method of electrochemical reduction of Ag+ ions within PVA and PVA/Gr hydrogel discs. In addition, the novel materials introduced here were characterized by UV-visible spectroscopy, cyclic voltammetry, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, silver release measurements, and thermogravimetric analysis. The effective immobilization of the AgNPs inside the PVA and PVA/Gr hydrogel networks was achieved by their bonding with the exposed hydroxyl groups in PVA. Also, the incorporation of graphene into the PVA matrix and the bonding between PVA molecules and incorporated graphene sheets improves thermal stability of Ag/PVA/Gr and prevents aggregation and growth of AgNPs as observed by Fourier transform infrared spectroscopy and field emission scanning electron microscopy.