RESUMEN

We report an approach to waterborne and degradable latex polymers. Emulsion polymerization of vinyl acetate (VA) with the cyclic ketene acetal 2-methylene-1,3-dioxepane (MDO) yields polymer particles and latex-based coatings that are hydrolytically degradable due to the presence of backbone ester groups. Polymerization under mildly basic conditions (pH 8) and at low temperature (40 °C) is critical: if the in-process pH is too acidic or the temperature too high, MDO is lost to hydrolysis, but when the media is too alkaline, VA monomer rapidly hydrolyzes. When coated onto commercial paper, films of these degradable particle dispersions show excellent oil and grease resistance as compared to non-degradable, VA-only compositions. This new class of latex is therefore well-suited for the design of next-generation, biodegradable and compostable single-use food service products, as well as for other applications where the erosion or degradation of polymer-based films and coatings is required.

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RESUMEN

Ultra-high performance size-exclusion chromatography (UHP SEC) is a newly developed disruptive technology that allows the high-resolution separation of synthetic polymers in as little as 2 min. The capability of UHP SEC for the characterization of synthetic polymers in organic solvents has been demonstrated. Using the Waters ACQUITY UPLC® H-Class system and ethylene-bridged hybrid size-exclusion chromatography (SEC) columns packed with 1.7 to 2.5-µm particles with pore sizes ranging from 45 to 900 Å, size-based separations of polystyrene and poly(methyl methacrylate) standards in tetrahydrofuran and poly(ethylene oxide) standards in 20 mM ammonium acetate in methanol are achieved within 2-4 min. The speed of analysis is about ten times faster than conventional SEC separations, and greater resolution is achieved. Average molecular weights of selected commercial polymers have been determined using ultra-high performance and conventional SEC. Average M data of analyzed samples are in good agreement using the two approaches. An inherent limitation of SEC in UHP mode is the characterization of very high M polymers (above ca. 2 million Da) due to the deformation and/or mechanical shearing of large molecules at high flow rates.