New chemically-selective optical materials for waveguide sensors

Two new series of chemically-selective optical materials have been made and tested on chemical sensors. One new series of materials was based on polymer blending in a host of glutaraldehyde cross-linked poly(vinyl alcohol). Chemically-selective dopants in this host demonstrate property-selective separations of chemicals from mixtures. We have optimized the composition, optical properties and the coating procedures for several specific blends for optical sensing. These blends have clear UV and visible spectral regions for direct spectroscopic sensing and they are excellent absorbers of many inorganic and organic charged species from aqueous environments. A second new series consists of polyelectrolyte containing silica composites prepared by sol-gel processing. The thickness of spin-coated films of these materials on glass can be varied from 0.1 mu m to 4 mu m. These materials are ion exchangeable and less brittle than the parent silica substrate due to the incorporation of the organic polyelectrolyte. These new composites retain the nano-scale porosity and optical transparency into the ultraviolet of the parent silica sol-gel processed glasses making them attractive host matrices for the immobilization of a variety of chemical reagents. Results obtained with film-clad sensors from both new series of materials are presented.