SOLUTE DIFFUSION IN RELATION TO THE GLASS-TRANSITION TEMPERATURE OF SOLUTE-POLYMER BLENDS

The transport of various dye solute molecules from amorphous donor pol ymer films to an amorphous acceptor polymer film has been investigated . Dye diffusion was studied by laminating dye-donor and dye-acceptor f ilms under controlled pressure and temperature. The acceptor medium wa s kept constant, whereas a wide range of polymer structures were used as binders in the donor system. At constant dye concentration, the tra nsport of the dye molecules from the donor sheet was found to be contr olled by the glass transition temperature of the dye-polymer mixture i n the donor film. This relationship was ubiquitous for all types of ch romophore and polymer studied. The data was found to fit well with fre e volume considerations and the Williams-Landel-Ferry equation by usin g the glass transition as that of the dye-polymer blend in the donor m atrix. (C) 1997 Elsevier Science Ltd.