REACTANT PREORDERING IN SOLID POLYMER MATRICES .2. EFFECT OF DECOUPLING THE REACTANT GROUPS FROM THE POLYMER BACKBONE

In blends of electron donor and electron acceptor substituted poly(vinyl cinnamates) a significant enhancement of photosensitivity over the mean of the sensitivities of the pure components was reported earlier.1 In this paper the effect of decoupling the cinnamoyl groups from the polyvinyl backbone is investigated. It is found that the dilution of the reactive moieties that accompanies the introduction of spacers has a stronger effect on photosensitivity than the decoupling of the side-chain reactants. This is interpreted as a lowering of the probability of pair formation between groups belonging to different polymer chains. The shape of the quantum yield vs composition curves and other observations indicate a partial persistence of the coil structure of the individual components in the blends and the imperfect intermingling of the side chains of different backbones. The stabilization energies of the polymer-bound donor-acceptor complexes that are the source of enhanced photosensitivity were found from the effect of casting temperature on the quantum yield of cross-link formation. For blends of CI- and CH3O-substituted polymers these stabilization energies are 3.2 and 7.7 kcal/mol for nonspacer and spacer polymers, respectively. © 1990, American Chemical Society. All rights reserved.