DISSIPATIVE PARTICLE DYNAMICS SIMULATION STUDY ON CONTROLLING MOLECULAR WEIGHT DISTRIBUTION IN EMULSION POLYMERIZATION

The controlling factors on molecular weight distribution in emulsion polymerization are investigated using dissipative particle dynamics simulations. The propagation and bi-radical termination kinetic steps are taken into account in the simulations by coupling a Monte Carlo type reaction model. We find that monomer concentration can be very efficient on controlling molecular weight distribution and plays a decisive role on the formation of high molecular weight polymers. Increasing initiator concentration can effectively reduce the polymer molecular weight while increasing the polydispersity index. Moreover, increasing polymerization rate can slightly narrow the molecular weight distribution. We also find that, by suitably tuning the surfactant chain length, it may be possible to obtain an optimal molecular weight distribution in emulsion polymerization.