The effect of specific interactions on dye transport in polymers above theglass transition

The transport of a functionalised dye solute has been studied in various am orphous polymers above the glass transition temperature. An azo dye contain ing two hydroxyalkyl groups was transferred from a constant dye-donor polym er matrix to a variety of dye-acceptor polymer matrices using dye diffusion thermal transfer printing. Using the solution-diffusion model of permeabil ity as the starting point, equations were developed to correlate solute tra nsport with dye and polymer structural characteristics, Diffusivity is stro ngly influenced by polymer T-g whereas solubility is controlled by the bala nce of physical forces and specific interactions between dye and dye-accept or polymer. An excellent correlation was established for permeability as a function of polymer T-g, dye-polymer solubility parameter difference and dy e-polymer specific interaction as characterised by the infrared shift of so lute O-H vibration. This predicted that maximum permeability would be obtai ned via a combination of low T-g, matched dye-polymer solubility parameters and strong specific acid-base dye-polymer interactions. (C) 1999 Elsevier Science Ltd. All rights reserved.