Microscopic spacial effect on the dispersion polymerization in scCO2

We report for the first time the microscopic spacial effect on the dispersion polymerization of methyl methacrylate (MMA) in supercritical carbon dioxide (scCO₂). A variety of different-sized high-pressure vessels including microstructured holey optical fiber were employed to conduct the polymerization reactions. The molecular weights of the polymer products indicate that the function of the stabilizer and the process of chain growth are not significantly influenced. However, the SEM images show a gradual loss of the controlled morphology for the polymer products in reactors of dimension less than 1 mm under the same reaction conditions. This study provides a better understanding of the mechanism of the dispersion polymerization progress and gives a very important caution on the performance of microreactors.