CONICET | Buscador de Institutos y Recursos Humanos

We describe the synthesis of dye-labeled poly(vinyl acetate-co-ethylene)(EVA) latexes with the purpose of understanding the polymer diffusion behavior intheir latex ﬁlms. Polymer diffusion was followed with experiments based upon ﬂuorescenceresonance energy transfer (ET). Both the batch and semibatch emulsion polymerizationsof vinyl acetateethylene (VAcE) were examined. The ethylene contentof these EVA samples was designed at 20 wt % (50 mol %). Under batch emulsionpolymerization conditions, the reaction is characterized by a rapid monomerconversion and an increment of E content with reaction time. VAcE batch emulsionpolymerization in the presence of the donor dye 9-phenanthryl methyl methacrylateproduced EVA with non-random dye distribution, which makes these samples unsuitablefor ET experiments. The semibatch emulsion polymerization of VAcE was carriedout under VAcstarved feeding conditions. The resulting EVA was characterizedby constant chemical composition throughout the feed. In addition, our data suggestthe presence of two components, distinct in molar mass and degree of branching, inthese EVA samples. More importantly, these VAcE polymerizations in the presenceof dyes [9-phenanthryl methyl acrylate as the donor and 20-acryloxy-40-methyl-4-(N,N-dimethylamino)-benzophenone as the acceptor] produced EVA with random dyeincorporation, making these samples effective for ET experiments. Unlike the typicalpolymer diffusion behavior in latex ﬁlms, characterized by small extents of polymerdiffusion in newly dried latex followed by an increase of the extent of diffusion uponannealing, our ET experiments showed that polymer diffusion in these EVA latex ﬁlmswas complete by the time the ﬁlms were dry. We attribute this striking difference tothe low glass transition temperature (Tg) of the EVA and to its low effective monomericfriction coefﬁcient at the drying temperature.

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