SOLVATOCHROMISM - A NEW METHOD FOR POLYMER CHARACTERIZATION

The solvatochromic method of Kamlet, Abraham, and Taft (KAT) has been used extensively for characterizing solvents, solutes, and solvent-solute interactions. Here we extend this method to characterize solid polymers as solvent phases by preparing thin films of the polymers with dissolved dyes and measuring the UV-visible absorption spectra of the films. The resulting solvatochromic measures of dipolarity/polarizability, hydrogen-bond acidity and hydrogen-bond basicity show great potential for determining solubility and sorption properties of polymers with gaseous, liquid, and solid solutes, as well as with bulk liquid solvents. Additionally, the solvatochromic parameters can be used to predict optical properties of molecules dissolved in polymers (e.g., for nonlinear optical applications). This particular application is illustrated by predicting the absorption maximum of an important nonlinear optical dye dispersed in various polymers. The ET(30) solvatochromic scale of solvent polarity developed by Reichardt is also applied to the polymers, and the results are compared to those obtained by the KAT method. © 1990, American Chemical Society. All rights reserved.