Synthesis of branched polymers by means of anionic polymerization. 11. anionic synthesis of densely branched polystyrenes carrying double branches in each repeating unit

We have demonstrated the first successful synthesis of well-defined densely branched polystyrenes carrying double branches in each of all repeating unit of backbone polymer by the coupling reaction of 1,1-diphenylethylene-end-capped polystyryllithiums with novel polystyrene derivatives having two benzyl bromide moieties in each monomer unit. The coupling reaction efficiently and quantitatively proceeded without any steric limitations to introduce two polystyrene branches in each repeating unit under certain conditions in THF at ?40°C. Thus, a series of 36.4- and 181-arm densely branched polystyrenes were synthesized (M_w = 365 ～ 2 000 kg/mol, M_w/M_n = 1.01 ～ 1.03). In the 36.4-arm branched polystyrenes thus synthesized, the maximum M_w value of the introduced polystyrene as a branch segment was 55.1 kg/mol. The experimental g‘ values of the 36.4-arm branched polystyrenes deterimined in the range of 0.14 ～ 0.15 were very close to the value of 0.13 calculated from the empirical equation previously reported by Roovers.