Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1

10-phenanthroline (Phen)and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic surfactantsodium lauryl sulfonate (SLS) or composite surfactants

such as SLS/polyoxyethylene nonyl phenyl ether (OP-10)

SLS/hexadecanol and SLS/OP-10/hexadecanol. Among which SLS and SLS/OP-10/hexadecanol systems established betterdispersed effect during the polymerization. It was found that Phen was a more syitable ligand than N

N

N′N″

N″-pentamethyldiethylenetriamine(PMDETA) to maintain an appropriate equilibrium of the activator Cu(I) and the deactivator Cu(II) between the organic phase and the water phase.The effect of several initiators(such as EBiB

CCl4 and 1-PEBr) and the temperature on such a kind of ATRP system was also observed.The number-average molar mass(Mn) of polystyrene(PS) increased with the conversion and the molar mass distribution (mw/Mn) remained narrow.These experimental data show that the polymerization could be controlled except for the quick increase of monomer conversion and the number-average molar mass of PS in the initial stage of polymerization.Furthermore

the initiator efficiency was found to be low(～57%) in CuX/Phen catalyzed system.To overcome this problem

Cu(II) X2(20 mol%-50 mol% based on CuX) was introduced into the polymerization system.In this case

higher initiator efficiency (60%-90%)

low Mw/Mn of PS (as low as 1.08) were achieved and the molar masses of the PS fit with the theoretical ones.