From batch to continuous precipitation polymerization of thermoresponsive microgels
Thermoresponsive microgels are typically fabricated by precipitation polymerization. This process is carried out in batch reactors with a volume of 50 to 300 ml. Thus, gaining high amounts of microgel requires numerous time-consuming batch reactions. Researchers in the SFB 985 have developed a continuous process, which allows the fabrication of high amounts of temperature-responsive PNIPAM and PVCL microgels in a short time. The process mimics the reaction conditions from the batch synthesis and, due to its continuous nature, saves preparation time and yields large amounts of microgels. It is shown that the microgels from the continuous reactor have a comparable internal structure and responsive behavior as the ones from the batch. On the right, an image of an in-house designed glass reactor is shown. Aside from producing microgels, this reaction enables to study the reaction progress in a time-independent matter. In the image the reaction progress can be seen by the increasing turbidity of the reaction solution from top to bottom, representing the local reaction state of the growing microgel colloids.