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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

Abstract:The quantum yield of bimolecular photoreactions in solid polymer films can be enhanced by increasing the fraction of reactive pair sites in the system. A practical realization of this idea is demonstrated on blends of electron donor and electron acceptor substituted poly(viny1 cinnamates). In the triplet sensitized materials energy migration provides an additional method of sensitivity enhancement.The photographic performance of a solid resist film depends not only on the inherent photoreactivity of its components, but also on the immediate environment of the reactants in the solid matrix which may either favor or inhibit the photochemical transformation. This aspect is particularly important in photoprocesses which involve two, or more reactants, and where the success of the photoreaction depends on their mutual configuration.In conventional photopolymers the spatial arrangement of the reactants is a matter of chance and the fraction of reactive configurations is small [l]. In these conditions the number of reactive sites could be significantly enhanced by reactant preordering. We have chosen poly(viny1 cinnamate) as a model system on which to test this idea [2], and we have used electron donor-acceptor interactions as the ordering principle.Poly(viny1 cinnamate) is a classical resist in which crosslinks are formed by photocycloaddition [3]. In this material the reactive configurations are pairs of cinnamoyl groups in approximately parallel orientation. We thought of increasing the chance of pair formation by bringing together electron donor and electron acceptor substituted cinnamoyl groups in the solid matrix. Several batches of substituted poly(viny1 cinnamates) were prepared [4] as well as similar substituted polymers in which the cinnamoyl groups were uncoupled from the backbone by tri-methylene spacers [5]. These polymers are listed in Table I.Electron donor and electron acceptor substituted polymers were blended and it was hoped that the blends would show higher photosensitivity than the individual pure components. That was found to be the case, provided the donor-acceptor interactions between the substituted cinnamoyl groups were strong enough. For example, the 5050 blend of chloro-substituted and methoxy-substituted poly(viny1