Ag nanoparticles were generated within light-sensitive films composed of poly(ether ether)ketone, SPEEK and poly(vinyl alcohol), PVA. The benzophenone (BP) groups of SPEEK act as sensitizers; excited states of these functions abstract H-atoms from PVA forming benzophenyketyl (BPK) radicals which reduce Ag(I) ions present in the films. Formation of the BPK radicals via photolysis of the films in the presence of air was confirmed by optical and ESR data. Kinetic studies on the photogeneration of Ag crystallites in the solid matrices showed that the reaction rates depend on light intensity and composition of the polymer blend, but are not significantly affected by the presence of oxygen. The photoreaction proceeds with an activation energy typical of reductions initiated by free radicals. Thermal formation of the Ag crystallites occurs only at temperatures equal or higher than the glass transition temperature of PVA. The dark reaction takes place with an activation energy four times higher than that of the photochemical process and is catalyzed by Ag particles.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2007 NSTI Nanotechnology Conference and Trade Show, Volume 2
Published: May 20, 2007
Pages: 140 - 142
Industry sectors: Advanced Materials & Manufacturing | Personal & Home Care, Food & Agriculture
Topicss: Advanced Materials for Engineering Applications, Personal & Home Care, Food & Agriculture