Bonding and Molecular Environment Effects on Near-Infrared Optical Absorption Behavior in Nonlinear Optical Monoazo Chromophore−Polymer Materials

Abstract

The mono-azo dyes Disperse Red 1 and Disperse Red 19 have been studied for several years as chromophores in polymers for nonlinear optical properties. These materials are examined here for the effects of dye donor group esterification in guest−host systems and by dye−polymer covalent attachment on near-infrared absorption behavior. The dye−polymer systems DR1−acrylate, DR1−poly-4-vinylphenol, and DR19−aliphatic epoxy are characterized by UV−vis absorption spectroscopy and photothermal deflection spectroscopy as guest−host systems with and without esterification of the DR1 and DR19 ethanol −OH substituents in guest−host systems, and as covalently attached dye copolymers, as a function of dye concentration up to 1700 μmol per gram of polymer. Esterification is shown to be an effective route to reducing near-IR loss in DR1/acrylate guest−host materials at high concentrations and in DR19/epoxy guest−host materials at most concentrations. Dye−polymer covalent attachment is shown to be highly effective for minimizing near-IR loss in the two DR1−polymer materials at all concentrations and is shown to be effective for DR19−epoxy materials at higher concentrations. Charge-transfer formation and the distributions of dye−polymer and dye−dye orientation states play crucial roles in the loss behavior of these materials.