Complex macromolecular architectures by combining TEMPO living free radical and anionic polymerization

A combination of TEMPO living free radical (LFRP) and anionic polymerization was used for the synthesis of star, graft, block-graft, block-brush, and graft-block-graft copolymers of styrene and isoprene. For graft copolymers with polystyrene (PS) backbone and polyisoprene (PI) branches, living free radical copolymerization of styrene and p-chloromethylstyrene (CMS) was performed, followed by a linking reaction at -20°C of the chloromethyl groups of the backbone with living 1,1-diphenylethylene end-capped polyisoprenylithium (PI-DPELi). Similarly the reaction of the chloromethyl groups of a diblock copolymer of styrene and p-chloromethylstyrene, obtained by LFRP, with PI-DPELi gave a block-brush copolymer with polyisoprene branches. Reaction of low molecular weight p-chloromethylstyrene homopolymers (PCMS) with PI-DPELi lead to polyisoprene stars. Finally reaction of a (PS-g-PS)-b-(PS-co-PCMS) with PI-DPELi resulted to a graft-block-graft copolymer. All products were analyzed and molecularly characterized by size exclusion chromatography, low angle laser light scattering, membrane osmometry, ¹H NMR spectrometry, and viscometry. In all cases the molecular and compositional polydispersity was low (M_w/M_n = 1.08-1.32) and the linking efficiency was close to 100%.