(582d) Controlled Synthesis of Hyperbranched Polymers Via Semibatch Atom Transfer Radical Copolymerization

Hyperbranched polymers (HPs) are a class of randomly branched polymeric materials with unique physical properties that are critical to a broad spectrum of applications, ranging from microelectronics and filtration membranes to biomedicine. Though controlled/living polymerization has been developed extensively for the design and synthesis of diverse macromolecular architectures, there are few synthetic tools for the controlled growth and functionalization of HPs. This lack of synthetic techniques not only limits our thorough study and understanding of HPs but also restricts their applications. In this presentation, I will introduce a novel synthetic route for the design and synthesis of well-defined HPs that can be readily post-functionalized and integrated into higher-order hierarchical structures. This controlled synthesis was achieved through atom transfer radical copolymerization of a regular monomer with a rationally designed co-monomer that can serve as an initiator (a branching site) once it is incorporated in the mainchain. Semi-batch reactors were employed to manipulate the cross-propagation of these two monomers in order to regulate the degree of branching and maintain a relatively narrow molecular weight distribution (M_w/M_n down to 1.3). Block copolymers containing HP blocks were realized through this synthetic approach.