Electrochromic Devices Based on the Reversible Formation of Ag Nanoparticles and Clusters in PVA-Based Thin Films

摘要

This study explored the feasibility of electrogenerating nanometer- sized Ag particles and clusters inside thin polymer films in a reversible fashion. Such process, which could be the bases for new electrochromic systems, was demonstrated to occur in the presence of air utilizing swollen, crosslinked films of poly(vinyl alcohol)/poly(acrylic acid) blends. CV methods limited the reversible particle formation to only 2 reduction/oxidation cycles but galvanostatic procedures extended the reversibility to 8 cycles and produced colored small Ag nanoparticles. Complete reversibility of the Ag+ reduction in the films seems feasible using tetramethyl benzidine (TMB) as redox mediator. A novel oxidation of the Ag particles by TMB2+ was discovered, which is not only a key step for achieving reversibility in particle-based ECD's, but could have a wide range of applications. A methylated derivative of poly(Cl4DPTD) has been synthesized with similar properties to the parent compound. Dynamic EQCM has shown the limiting factors in switching and suggest new electrolyte combinations.