Stochastic Simulation of Controlled Radical Polymerization Forming Dendritic Hyperbranched Polymers

Stochastic simulation of the formation process of hyperbranched polymers (HBPs) based on the reversible deactivation radical polymerization (RDRP) using a branch-inducing monomer, evolmer, has been carried out. The simulation program successfully reproduced the change of dispersities (Đs) during the polymerization process. Furthermore, the simulation suggested that the observed Đs (=1.5–2) are due to the distribution of the number of branches instead of undesired side reactions, and that the branch structures are well controlled. In addition, the analysis of the polymer structure reveals that the majority of HBPs have structures close to the ideal one. The simulation also suggested the slight dependence of branch density on molecular weight, which was experimentally confirmed by synthesizing HBPs with an evolmer having phenyl group

Practical Synthesis of Dendritic Hyperbranched Polyacrylates and Their Topological Block Polymers by Organotellurium-Mediated Emulsion Polymerization in Water

The practical synthesis of structurally controlled hyperbranched polymers (HBPs) by organotellurium-mediated radical polymerization (TERP) in emulsions is reported. Copolymerization of vinyltelluride, which induces controlled branch structure and is named evolmer, and acrylates in the presence of TERP chain transfer agent (CTA) in water afforded HBPs having den-dron structure. The structure of the HBPs, i.e., molecular weight, dispersity, branch number, and branch length (the number of monomer units between branch points), were controlled by changing the amount of CTA, evolmer, and acrylate monomers, and HB-poly(butyl acrylate)s (HBPBAs) with up to the 8th generation having an average of 255 branches were successfully synthe-sized. As the monomer conversion reached nearly quantitative and the obtained polymer particles were well dispersed in water, the method is highly suitable for the synthesis of topological block polymers, block polymers consisting of different topologies. Thus, linear-block-HB, HB-block-linear, and HB-block-HB-PBAs with the controlled structure were successfully synthesized just by adding the second monomer(s) to the macro-CTA. The intrinsic viscosity of the resulting homo- and topological block PBAs was systematically controlled by the degree of the branch, the branch length, and the topology. Therefore, the method opens the possibility of obtaining various HBPs with diverse branch structures and tuning the polymer properties by the pol-ymer topology

Stochastic Simulation of Controlled Radical Polymerization of Den-dritic Hyperbranched Polymers

We have recently developed a novel one-step method for the synthesis of hyperbranched polymers (HBPs) with a controlled molecular weight and branch structure and narrow dispersities (Đ = 1.5~2) based on the reversible deactivation radical polymerization (RDRP) using a branch-inducing monomer, evolmer. While the observed Đs of the resulting HBPs were sig-nificantly smaller than those of HBPs synthesized by radical polymerization (Đ > 4), they were still higher than those usually observed for linear polymers (Đ < 1.5) synthesized by RDRP. The origin of the higher dispersity of this method was exam-ined by stochastic simulation of the formation process of the HBPs consisting of the elementary steps involving RDRP. The simulation program successfully reproduced the Đs during the polymerization process. Furthermore, the simulation sug-gested that the higher Đs are due to the distribution of the number of branches instead of undesired side reactions, such as the termination reaction. In addition, the majority of HBPs have structures close to the ideal one, and the HBPs have a well-controlled branch structure. In addition, the simulation also suggested the slight dependence of branch density on molecular weight, which was experimentally confirmed by synthesizing HBPs with an evolmer having phenyl group