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 (Mw/Mn = 1.08-1.32) and the linking efficiency was close to 100%.