ABSTRACT
A new metallocene-based polymerization mechanism is elucidated in which a zirconium hydride center inserts α-methylstyrene at the start of a polymer chain. The hydride is then regenerated by hydrogenation to release a polyolefin containing a single terminal α-methylstyrenyl group. Through the use of the difunctional monomer 1,3-diisopropenylbenzene, this catalytic hydride insertion polymerization is applied to the production of linear polyethylene and ethylene-hexene copolymers containing an isopropenylbenzene end group. Conducting simple radical polymerizations in the presence of this new type of macromonomer leads to diblock copolymers containing a polyolefin attached to an acrylate, methacrylate, vinyl ester, or styrenic segments. The new materials are readily available and exhibit interfacial phenomena, including the mediation of the mixing of immiscible polymer blends.
ABSTRACT
The metal catalyzed polymerization of methyl methacrylate using Cu(0) as the catalyst source has been investigated in toluene. This work looks at polymerizations in a non-polar medium allowing control over the molecular weight and polydispersity with a 4-fold reduction in catalyst concentration versus conventional ATRP, while the use of an active ligand allows the reaction to proceed at room temperature. The use of an excess of PMDETA ligand allows for high conversions, and the addition of a small amount of CuBr(2) enhances living characteristics, enabling efficient chain extension.
