Synthesis of hyperbranched polystyrene and its fullerene end-capped derivates with multifunctional atom-transfer radical polymerization initiator

A novel multifunctional A TRP initiator was synthesized by esterfication of a hyperbranched polyester Z5 [from pentaerythritol and 2, 2-bis Chydroxymethyl) propionic acid]. The macroinitiator contained approximately 19 initiating sites per molecule. It was used for the A TRP of styrene mediated by CuCI and N,N' ,N' ,N" ,N"- pentamethyldiethylenetriamineCPMDETA) in cyc1ohexanone at 100 ·C. The molar ratio of monomer to initiator was 100/1, 200/1, 300/1, respectively. Through hydrolysis of hyperbranched polymer, the arm chain length of the hyperbranched polystyrene was detected by GPC, the results showed that A TRP process under these conditions was well controlled. The hyperbranched PS was further reacted with sodium azide in dimethyl formamide at room temperature to yield an azide end-functional hyperbranched polymer. Then a covalently bonded C6o-hyperbranched polymeric derivative was achieved by reacting C60 with the sodium azide end-capped hyperbranched polymer in 1, 2-dichlobenzene solution at 130 ·C. In the hyperbranched polymeric derivatives, the mass fraction of the fullerene was about 1%-2.5%.