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, 1 H 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%.