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Abstract:
Various latex dispersions based on poly(vinyl acetate) stabilised by different surfactants and polyelectrolytes were investigated by NMR methods to elucidate the macroscopic and molecular film-formation process of these latex dispersions. Macroscopically, the inhomogeneous drying in the film-formation process was investigated by NMR-imaging techniques. Here the influence of different amounts of surfactant on the homogeneity of the drying process was monitored. The molecular film-formation process was investigated by 1H, 2H, and 13C solid state NMR spectroscopy. For these bulk measurements, films of latex dispersions were homogeneously dried to different defined solid contents. Spectroscopic analysis allows the investigation of the drying process of the water at different solid contents with a pronounced influence on the polymer/water interface and the latex particle core. The film-formation process is correlated to the drying mechanism of different types of water within the film. External water, water at ionic and non-ionic groups at surfactants in the polymer/water interface, and water in the swollen and mobilised polymer, could be distinguished during the drying process.
