Synthesis of telechelic oligomers via atom transfer radical polymerization, 1 - Study of styrene

Atom Transfer Radical Polymerization (ATRP) of styrene was carried out 110degreesC using various substituted 2-bromoisobutyrates as initiators and the homogeneous catalyst CuBr/1,1,4,7,10,10-hexamethyltrienthylenetetramine (HMTETA). Telechelic oligomers were obtained by coupling the bromo terminated polymers using Cu(0)/PMDETA catalyst at 90degreesC. The products were characterized by H-1 NMR and MALDI-TOF and some unsaturated polymer chains were observed. They could originate from either disproportionation reaction or dehydrohalogenation of halogen terminated oligomers during MALDI analysis. Using this method, polymers with hydroxy, acid, or ester end groups were synthesized in a range of molecular weights from 1 000 to 13 000 g mol(-1). Coupling efficiency was between 79 and 100%, depending on the structure of the initiator.