Synthesis, characterization, and polymer diffusion studies of poly(vinyl acetate) copolymer latexes

In the first part of this thesis, I describe polymer diffusion in films prepared from poly(vinyl acetate-co-dibutyl maleate) [P(VAc-DBM)] latex dispersions. Two sets of polymers were investigated, one set containing 50% gel (high-M), the other set, with Mw ≈ 250,000 (M250K), free of a measurable gel content. Polymer diffusion was monitored with fluorescence resonance energy transfer (ET) technique and apparent diffusion coefficients (D app) were calculated. These values increased with temperature, and were characterized by apparent activation energy (Ea) of 37 kcal/mol for the high-M polymer and 45 kcal/mol for the M250K sample. The difference in E a values for the polymer diffusion can be ascribed to changes in the microscopic friction coefficient zeta0 and the differences in Tg of the two sets of samples. Another finding is that the polymer diffusion rate depends primarily on the molecular weight and degree of branching of the diffusing species and is much less sensitive to the cross-linked nature of the matrix present in one of the samples.;In the second part of this thesis, I describe the influence of a water-soluble polymer (PVOH) on rates of polymer diffusion. In the presence of 2 to 17 wt% PVOH, the polymer diffusion rates in P(MMA-co-BA) latex films were retarded. The magnitude of the effect increased with the amount of PVOH present, and the effect was larger at 45°C than at 63°C. I show that the PVOH has its largest influence at the very early stages of polymer diffusion. The presence of post-added PVOH also retarded the polymer diffusion in the M250k P(VAc-DBM) latex films, while the presence of grafted PVOH significantly promoted the polymer diffusion rate and this effect increased with an increase of the degree of PVOH grafting.;Finally, I describe the synthesis of dye-labeled poly(vinyl acetate- co-ethylene) (EVA) latexes for ET experiments. I show that polymer diffusion in these EVA latex films was so rapid that mixing was complete by the time when the film was dry. I attribute this to a low T g of the EVA and low monomeric friction coefficient zeta0 at temperatures close to its Tg.