Monte Carlo Simulation On The Cyclization In Typical Hyperbranched Polymerization Systems

The effect of cyclization on the average properties of polymers formed in two types of hyperbranched polymerization systems are investigated by the method of Monte Carlo simulation,where one of the two types is AB_g type, and another is the self-condensing vinyl polymerization system. To simulate the cyclization effect, a set of differential kinetic equations based on the growth generation of polymers are given. The simulation is then performed by using the intermolecular and intramolecular reaction rates obtained by the principle of statistical mechanics. Specifically, the number of tree-like and cyclic polymers, the number of loops and its size distribution as well as the number- and weight-average molecular weights are presented. Furthermore, the effect of cyclization on the average properties of polymers is discussed. It is shown that, for the two types of polymerization systems under study, the volume fraction of monomers, solvent quality and functionality play an important role in cyclization. As a result, the cyclization effect depends in essence on the cooperation of the above three factors.There are three chapters in the dissertation as following:Chapter 1: The development of hyperbranched polymers and the intramolecular reaction are summarized. In detail, the properties of hyperbranched polymer and AB_g type and selfcondensing vinyl polymerization systems are outlined. Meanwhile, a history of intramolecular reaction in polymerization is mainly introduced.Chapter 2: Cyclization in AB_g type hyperbranched polymerization system. The size distribution and the number of loops,the number- and weight-average molecular weights are presented by Monte Carlo simulation in terms of the differential kinetic equations of AB_g type hyperbranched polymerization system with intramolecular reaction. Furthermore, the effect of the volume fraction of monomers, solvent quality and functionality on the average properties of polymers is mainly discussed.Chapter 3: Cyclization in self-condensing vinyl polymerization(SCVP) system. The number of loops and the size distribution the number- and weight-average molecular weights are presented by Monte Carlo simulation in terms of the differential kinetic equations of SCVP system with intramolecular reaction. As a result, the effect of volume fraction of monomers, and solvent quality on the average properties of polymers are illustrated. Finally, the limits in the present method is pointed out, which also provides a direction in future.