Grafting‐from Afforded Cyclic Graft Copolymers from Cyclic Anionic Macroinitiator via Lithiation of Tolyl Groups

Cyclic graft copolymers consisting of poly(p‐methylstyrene) backbone and polystyrene branches with relatively low molecular weight distribution are synthesized with grafting‐from approach by living anionic polymerization of styrene from lithiated cyclic poly(p‐methylstyrene)s as multifunctional anionic macroinitiators for vinyl polymerizations. Precursors of the macroinitiators are prepared by ring‐closing metathesis reaction of α,ω‐divinyl‐terminated telechelic polymers. Subsequently, selective lithiation of tolyl groups in the cyclic polymers is conducted by s‐BuLi in the presence of tetramethylethylenediamine in cyclohexane in order to prepare the macroinitiators. Addition of styrene monomer into the cyclic macroinitiators provides shift in SEC to higher molecular weight due to graft polymerization from the macroinitiators to form cyclic graft copolymers. The unique polymer architecture of the obtained cyclic graft copolymers is confirmed by unimolecular observation by using atomic force microscopy. Cyclic graft copolymers are synthesized with living anionic grafting‐from approach. Lithiated cyclic poly(p‐methylstyrene)s are prepared as multifunctional anionic macroinitiators for anionic vinyl polymerization. Subsequent addition of styrene monomer into the macroinitiators provides cyclic graft copolymers. The cyclic architecture of the obtained polymers is confirmed by unimolecular observation by using atomic force microscopy.