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Fouling in emulsion polymerization

In reaction technology, "fouling" refers to the (usually undesirable) formation of deposits on surfaces. Examples include limescale deposits in pipes or biofilms, which are also well known from everyday life. Polymer fouling is a major problem in the production of latex dispersion, i.e. colloidal particles in water. Thin polymer layers always form on the walls of the reactor.As long as these layers remain thin, they are not a problem. The problem arises when the layers become so thick that they hinder heat transport through the wall and, in the worst case, even block the pipes. The fouling problem currently prevents the production of latex dispersions in continuous flow in tubular reactors. Large vessels are used and batch operation is employed.

The working group has recently established a method to monitor the formation of fouling layers in emulsion polymerization in-situ using quartz crystal microbalance (QCM).[1 ] It turns out - not entirely unexpectedly - that the fouling layer is sometimes self-limiting in its growth, but that in other cases it is not. The conditions that lead to the catastrophic growth of the layer are currently poorly understood.The QCM allows us to follow the growth during the reaction. In particular, there is evidence of compaction during the formation of the layer.[2] Such compaction can be better understood in the context of particle fouling than in the context of reaction fouling. According to this idea, in the cases studied so far, polymer particles form first in the liquid, which later attach to the surface. Polymerization directly on the surface plays a subordinate role.

We are continuing this work as part of the DFG project JO 278/25-1 (together with AK Scholl, TU Braunschweig).


  1. Böttcher, A.; Petri, J.; Langhoff, A.; Scholl, S.; Augustin, W.; Hohlen, A.; Johannsmann, D.
    Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall.
    Macromolecular Reaction Engineering2022, 16, (2).
  2. Johannsmann, D.; Petri, J.; Leppin, C.; Langhoff, A.; Ibrahim, H.
    Particle Fouling at Hot Reactor Walls Monitored In-Situ with a QCM-D and Modeled with the Frequency-Domain Lattice Boltzmann Method.
    Results in Physics 2023, 45, 106219.