A series of star comb polybutadiene-g-poly(methyl methacrylate) graft copolymers (SC-(PB-g-PMMA)) with various chain lengths were synthesized with the combination of living anionic polymerization and atom transfer radical polymerization (ATRP) in sequence.First

star-shaped polybutadiene with predetermined molecular weight and microstructure was synthesized by anionic polymerization of butadiene with n-butyllithium initiator in the solvent of cyclohexane at 50℃ for 3 h.Then the in-chain living functionalized star-shaped initiator containing bromine (SPB-Brn)s was obtained after expoxidated with performic acid in situ from hydrogen peroxide and formic acid

and esterification reaction with in situ 2-bromoisobutyrate.Finally

SC-(PB-g-PMMA)s were prepared from the polymerization of methyl methacrylate (MMA) and SPB-Brn with SPB-Brn as initiator and CuCl/CuCl2/N

N

N'

N

N-pentamethyldiethylenetriamine (PMDETA) as catalyst and ligand by atom transfer radical polymerization in the solvent of CHCl3 at 60℃ for 8 h.A series of star comb polybutadiene-g-poly(methyl methacrylate) graft copolymers (SC-(PB-g-PMMA)) with various chain lengths were synthesized by changing the monomer ratio.The properties of the SPB-Brn and the series of star-comb graft copolymers polybutadiene-g-poly(methyl methacrylate) were characterized by 1H-NMR

FTIR

GPC and DSC.The SC-(PB-g-PMMA)s in solution were also examined and their thermotropic behavior were discussed.All in all

the results show that well-defined target products with controlled molecular weight and low disperisity were obtained.The phase separation and branching parameters of the copolymers varied with chain lengths.