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

Abstract

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.