Photochemical synthesis and characterization of hydrogel–silver nanoparticle composites

Abstract

Hydrogels were synthesized by grafting polyacrylamide onto dextran using N,N′-methylene-bis-acrylamide as a cross-linker. The hydrogels were converted into polyelectrolytes by alkaline hydrolysis, and samples having various concentrations of ionic groups were obtained. The swelling behavior of the hydrogels in distilled water at room temperature was studied. Silver nanoparticles were generated in situ into the hydrogel network by silver ion reduction with ultraviolet (UV) irradiation. A series of hydrogel–silver nanoparticle composites synthesized in cross-linked polymer matrix with various degree of hydrolysis were characterized by Fourier-transform infrared (FTIR) spectroscopy, UV–Vis spectroscopy, and scanning electron microscopy. The absorption bands indicated formation of polydisperse Ag nanoparticles of 20, 50, and 100 nm in size. The FTIR spectrum of the hydrogel confirmed a weak interaction between –NH₂ groups of polymer chains and Ag nanoparticles that stabilizes the nanosystems. It was shown that such hydrogel matrices can be used as effective nanoreactors for synthesis of silver nanoparticles. The size of the nanoparticles depends on the degree of hydrolysis of the polyacrylamide as well as the irradiation time of the silver ions incorporated into the polymer matrix.