Synthesis of polyacrylonitrile via reverse atom transfer radical polymerization initiated by 1,1,2,2-tetraphenyl-1,2-ethanediol/FeCl3/triphenylphosphine

FeCl3 coordinated by triphenylphosphine was first used as the catalyst in the 1,1,2,2-tetraphenyl-1,2-ethanediol-initiated reverse atom transfer radical polymerization of acrylonitrile. A FeCl3/triphenylphosphine ratio of 0.5 not only gave the best control of the molecular weight and its distribution but also provided a rather rapid reaction rate. The rate of polymerization increased with increasing polymerization temperature, and the apparent activation energy was calculated to be 62.4 kJ/mol. When FeCl3 was replaced with CUCl2, the reverse atom transfer radical polymerization of acrylonitrile did not show prominent living characteristics. To demonstrate the active nature of the polymer chain end, the polymers were used as macroinitiators to advance the chain-extension polymerization in the presence of a CuCl/2,2 '-bipyridine catalyst system via a conventional atom transfer radical polymerization process. (C) 2007 Wiley Periodicals, Inc.