Field Flow Fractionation for the Size, Molar Mass, and Gel Content Analysis of Emulsion Polymers for Water‐Based Coatings
In the present investigation, styrene‐acrylic and pure acrylic emulsions used in water‐based decorative coatings are characterized by size exclusion chromatography (SEC) and asymmetric flow field‐flow fractionation (AF4). Both the separation techniques are coupled online to multiangle laser light scattering (MALLS) and refractive index detection to investigate the molar mass properties during the course of the free radical polymerization reaction. For the acrylic emulsion, kinetic samples are taken from the reactor at fixed time intervals and analyzed. In SEC‐MALLS, unusual elution behavior is observed which is found previously for highly branched polymer species. In contrast, the AF4 fractograms indicate normal mode elution without any unusual behavior as compared to the SEC analyses. The molar masses obtained by AF4 are significantly higher compared to the SEC results. Further, AF4 is used to determine the gel contents of the kinetic samples of the acrylic emulsion and for both the acrylic and styrene‐acrylic emulsions, AF4 proves to be a robust and feasible tool allowing for improved correlations of the molecular and materials properties of water‐based polymer emulsions.
Molecular parameters of polymer emulsions are studied utilizing size exclusion chromatography and field‐flow fractionation. The samples are synthesized with and without methacrylic acid and subsequent recovery studies point toward the development of gel resembling species as the polymerizations progressed in the reactor.
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