One-step formation of two new unimolecular initiators on the basis of styrene and HO-TEMPO

Two kinds of modified unimolecular initiators for nitroxide-mediated radical polymerization were formed in a one-step and one-pot BPO initiated reaction of styrene with 4-hydroxy-2,2,6,6-tetramethylpiperidine- 1-oxyl (HO-TEMPO) involving an additional oxidation reaction. Their ability to initiate and to control the radical polymerization of styrene was verified and the newly produced initiators did not show any differences compared to the well-known TEMPO-based initiator. (HNMR)-H-1 spectra of the resultant polymers showed the presence of the end-group in the functionalized polymers. HO-TEMPO used in a binnolecular initiator system gave similar results as the significantly more expensive TEMPO, but in general the use of unimolecular initiators gives a better control over the molecular weight of the polymers synthesized.