Cu Powder-Catalyzed Single Electron Transfer-Living Radical Polymerization of Acrylonitrile

Single electron transfer-living radical polymerization (SET-LRP) has been used as a new technique for the synthesis of polyacrylonitrile (PAN) catalyzed by Cu(0) powder with carbon tetrachloride (CCl4) as the initiator and hexamethylenetetramine (HMTA) as the ligand in N,N-dimethylformamide (DMF) or mixed solvent. Well-controlled polymerization has been achieved as evidenced by a linear increase of molecular weight with respect to monomer conversion as well as narrow molecular weight distribution. Kinetics data of the polymerizations at both ambient temperature and elevated temperature demonstrate living/ controlled feature. An increase in the concentration of ligand yields a higher monomer conversion within the same time frame and almost no polymerization occurs in the absence of ligand due to the poor disproportionation reaction of Cu(I). The reaction rate exhibits an increase with the increase of the amount of catalyst Cu(0)/HMTA. Better control on the molecular weight distribution has been produced with the addition of CuCl2. In the presence of more polar solvent water, it is observed that there is a rapid increase in the polymerization rate. The effect of initiator on the polymerization is also preliminarily investigated. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2588-2593, 2011