Oxidation of R-(N-alkylamino) phosphonic acid esters, carrying one or two alkyl groups as substituents on their R-carbon, by m-chloroperbenzoic acid afforded the corresponding stable β-phosphonylated nitroxides. The nitroxides derived from R-mono-tert-butyl R-alkylaminophosphonic acid esters are stable compounds despite the presence of a hydrogen atom on the R-carbon bound to the nitroxyl group. The ESR study of these nitroxides in solution showed that this β-hydrogen atom lies in the nodal plane to the nitroxyl function. These β-phosphonylated nitroxides were found to efficiently control the free radical polymerization reaction of styrene, with a much faster rate of propagation than that observed in TEMPO-mediated systems.

In this study the possibilities offered by “living” ring-opening metathesis polymerization (ROMP) are exploited to engineer novel macromolecular architectures. It is indeed shown that amphiphilic branched structures of hitherto unreported topologies can be prepared by ROMP of miscellaneous macromonomers, provided the latter polymers carry an end-standing norbornene unsaturation. Janus-type architectures are, for instance, accessible by sequential ROMP of polystyrene (PS) and poly(ethylene oxide) (PEO) macromonomers; other original branched structures, whose topology makes them particularly attractive for applications such as unimolecular micelles or associative thickeners, can be obtained through homopolymerization of macromonomers based on PS-b-PEO diblock copolymers.