Kinetic Modeling of Precipitation Terpolymerization for Functional Microgels

Abstract Microgels based on poly( N -isopropylacrylamide)- and poly( N -vinylcaprolactam) can be synthesized by precipitation polymerization. To get a better insight into the kinetics of the microgel synthesis, a model-based approach is pursued. Herein, the approach proposed by Janssen et al. (2017) is extended to the terpolymerization system. The kinetic model for a two-phase terpolymerization is combined with parameter values from quantum mechanical calculations. The remaining unknown parameter values are estimated from experimental data using reaction calorimetry and Raman spectroscopy. Acceptable agreement of simulation and experimental measurements is obtained. The prediction of the gel phase growth is combined with the consumption of comonomers and the cross-linker N,N ’-methylenebis(acrylamide) to predict the average distribution of comonomers, thus giving insight into the microgel structure. The resulting particle structures indicate uniform N -vinylcaprolactam and N -isopropylacrylamide compositions in the core and an outer layer with a high N -vinylcaprolactam fraction, while the cross-linker distribution decreases from core to shell.