Solvent dependence of magnetic-field effect in a polymer-linked exciplex system

The response of pyrene-polystyrene-dimethylaniline (Py-PS-DMA) polymer (Mn = 4770) to an externally applied magnetic field has been examined in different solvents. Although the dielectric-constant (e) effect is similar to that for the unlinked system, a closer look shows an interesting dependence on the nature of the solvent mixture. In pure acetone δφ/φ is higher than that in a mixed solvent (tetrahydrofuran/dimethylformamide) of the same ε. The results have been explained on the basis of the fact that the influences of coil extension on the magnetic-field effect and the dielectric-constant effect compete with each other, resulting in different behaviours depending on the nature of the solvent mixture