New difunctional mediators based on 4-amino-TEMPO derivatives for controlling free radical polymerization of styrene

Abstract

The free radical polymerization of styrene in the presence of a number of freshly newly synthesized bifunctional mediators differing in the number of methylene groups serving as a link between two functional 4-amino-TEMPO radicals has been investigated. It was found, that the activity of a nitroxide group in the biradicals in controlling radical polymerization of styrene differs from that of the TEMPO radical. Mediators with a lower number of connecting methylene groups between the two TEMPO rings give a higher conversion in the same reaction time. However, no simple correlation between the number of methylene groups in spacer chain and polymerization rate was observed, namely unexpectedly, high rate of polymerization was found for •C 4•. The formation of single-arm (P) and double-arm (P-P) macromolecules containing binitroxide at the core was observed.