FLUORESCENCE STUDIES OF SOLVENT POLYMER INTERACTIONS AT SURFACE FUNCTIONALIZED POLYETHYLENE FILMS
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The effects of solvent on the accessibility and reactivity of an ester-bound fluorophore at a functionalized polyethylenesolvent interface have been studied. Fluorophore-labeled polyethylene surfaces were prepared by blending together a small amount of either a phenylpyrenylmethyl-terminated ethylene oligomer or a pyrene ester-terminated ethylene-ethylene glycol block cooligomer and a 20-200-fold excess of high molecular weight additive-free high-density polyethylene. Solution casting of 1,2-dichlorobenzene solutions of these mixtures generated films containing the pyrene labels. Studies of the I1/I3 values for these films in a series of solvents, studies of the extent of excimer formation, and studies of quenching of the amine fluorescence by soluble amines that are incompatible in bulk high-density polyethylene all suggest that the fluorophores are near or in the solvent-polymer interface. In contrast to soluble pyrene-labeled polymers, the extent of excimer formation for surface-bound pyrene labels was greatest with good solvents. Short grafts where the pyrene label was attached either at the graft origin or at the graft terminus produced significantly different behavior for the pyrene fluorophore label. 1994, American Chemical Society. All rights reserved.