'Living' radical polymerization of styrene with AIBN/FeCl3/PPh3 initiating system via a reverse atom transfer radical polymerization process

Well-defined polystyrenes with an alpha -C(CH,),(CRI) and an omega -chlorine atom end-groups, and narrow polydispersity (M-n = 3000-4000g mol(-1), M-W/M-n = 1.3-1.4) have been synthesized by a radical polymerization process using 2,2'-azobisisobutyronitrile (AIBN)/FeCl3/PPh3 initiation system. When the ratio of [St](0):[AIBN](0):[FeCl3](0):[PPh3](0) is 200:1:4:12 at 110 degreesC, the radical polymerization is 'living', but the molecular weight of the polymers is not well-controlled. The polymerization mechanism belongs to a reverse atom transfer radical polymerization (ATRP). Because the polymer obtained is end-functionalized by a chlorine atom, it can then be used as a macroinitiator to perform a chain extension polymerization in the presence of CuCl/2,2'-bipyridine catalyst system via a conventional ATRP process. The presence of a chlorine atom as an end-group was determined by (HNMR)-H-1 spectroscopy. (C) 2000 Society of Chemical Industry.