A polyacrylic acid film saturated with Cu2+, ions displays redox-switchable electrorefractive, electrochromic, and conductivity functions upon reduction of Cu2+ to Cu-o. Surface plasmon resonance spectroscopy, adsorption spectroscopy, and conductivity measurements are used to examine these functions, which are demonstrated to be fully reversible. New types of optical filters and modulators, optoelectronic devices, and smart windows could potentially be constructed from such hybrid polymers.