Accurate structural control and block formation in the living polymerization of 1,3-dienes by nitroxide-mediated procedures

The living free radical polymerization of 1,3-dienes, such as isoprene and 1,3-butadiene, has been shown to be a facile process in the presence of alk oxyamine initiators based on a 2,2,5-trimethyl, 4-phenyl-3-azathexane-3-oxy , 2, skeleton. These alpha-hydride nitroxide derivatives were able to contr ol the homopolymerization to high conversion and molecular weights from 100 0 to 100 000 amu with polydispersities of 1.06-1.15 readily obtained. Block and random copolymers based on combinations of 1,3-dienes with a variety o f functionalized vinyl monomers, such as styrene, acrylate, or methacrylate derivatives, could also be prepared with similar control. In comparison wi th 2,2,6,6-tetramethylpiperidinoxy (TEMPO), these new systems represent a d ramatic improvement in the ability to control the polymerization of 1,3-die nes and further demonstrate the versatility of nitroxide-mediated living fr ee radical procedures.