Spectral and photophysical characteristics of asymmetric polymethine dyes in polyurethane matrices

Abstract

Effects of the polymer matrix polarity on the spectral and photophysical properties of asymmetric polymethine dyes were investigated. Asymmetrical cyanines of the LDS (laser dye styryl) series were used, which were introduced into elastic polyurethane matrices by an auxiliary solvent. Polymer media were synthesized by: a polyaddition reaction based on macrodiisocyanate from oligoethylene glycol adipinate, hexamethylene diisocyanate, trimethylolpropane, and a photopolymerization reaction of oligourethane acrylate with benzoin isobutyl ether. Polyurethane polarity influence on the absorption and luminescence band maxima, and the Stokes shift of the dye spectra was studied, and the obtained spectral parameters of dyes in the polymer matrices were compared with the corresponding characteristics of their ethanol solutions. The observed spectral peak positions of the absorption and luminescence bands, changes in the Stokes shift value for the LDS dyes in different environments indicated the presence of positive solvatochromism. The presented results demonstrated the possibility of the significant increase in photostability of asymmetric polymethine dyes in the polymer polyurethane matrix of high polarity, obtained by means of the polyaddition reaction.