Design of effective systems for controlled radical polymerization of styrene: Application of 4,4′-dimethyl and 5,5′-dimethyl 2,2′-bipyridine copper(II) complexes

[Cu(II)(4,4′-dimethyl-2,2′-bipyridine)3](PF6)2 (2) and [Cu(II) (5,5′-dimethyl-2,2′-bipyridine)3](PF6)2 (4) were used together with aluminium isopropoxide and (1-bromoethyl)benzene in the controlled radical polymerization of styrene resulting in polystyrenes with predetermined molecular weight and narrow molecular weight distribution. The received polymers are colorless with a content of copper lower than 210 ppm. The substitution pattern at the bipyridine ligands has a distinct influence on the polymerization. The rate of polymerization of styrene using 2/[(CH3)2CHO]3Al/C6H5CH(CH3)Br is two times larger than utilizing 4/[(CH3)2CHO]3Al/C6H5CH(CH3)Br.