Differences in emulsion polymerization fouling between acrylates and vinyl acetate studied in-situ with a quartz crystal microbalance (QCM)

Abstract Fouling is a severe problem in emulsion polymerization, which – among other consequences – currently prevents polymerization in continuous flow reactors. Measuring the early stages of fouling (< 10 μm) can be challenging due to the low sensitivity of traditional fouling detection methods (i.e., thermal resistance and pressure drop). In comparison, measurements conducted with a highly sensitive quartz crystal microbalance enable the in-situ monitoring of fouling and the detection of the initial layers fouling. In this study, a QCM-D (quartz crystal microbalance with dissipation monitoring) was configured to function as a heat transfer surface to compare the fouling of acrylates and vinyl acetate. For the acrylates, fouling is self-limiting such that the layer thickness is finite and within the range of the diameter of acrylate particles. Thus, for acrylates fouling can be described as the adsorption of a single layer of particles. For vinyl acetate, the fouling layers grow continuously and result in a thick coagulum. The mechanistic details associated with the difference between acrylates and vinyl acetate is the subject of ongoing investigations. Furthermore, this work also explores how QCM-D technology can contribute to the study of fouling in general.