The nonionic amphiphilic brush polymers such as poly[poly(ethylene oxide) methyl ether vinylphenyl-co-styrene] trithiocarbonate [P(mPEGV-co-St)-TTC] and poly[poly(ethylene oxide) methyl ether vinylphenyl-b-styrene-b-poly(ethylene oxide) methyl ether vinylphenyl] trithiocarbonate [P(mPEGV-b-St-b-mPEGV)-TTC] with different monomer sequence and chemical composition are synthesized and their application as macro-RAFT agent in the emulsion RAFT polymerization of styrene is explored. It is found that the monomer sequence in the brush polymers exerts great influence on the emulsion RAFT polymerization kinetics, and the fast polymerization with short induction period in the presence of P(mPEGV-co-St)-TTC is demonstrated. Besides, the chemical composition in the brush polymer macro-RAFT agent effect on the emulsion RAFT polymerization is investigated, and the macro-RAFT agent with high percent of the hydrophobic PS segment leads to fast and well controlled polymerization. The growth of triblock copolymer colloids in the emulsion polymerization is checked, and it reveals that the colloidal morphology is ascribed to the hydrophobic PS block extension, and the P(mPEGV-co-St) block almost have no influence just on the size of the colloids. This may be the first example to study the monomer sequence and the chemical composition in the macro-RAFT agent on emulsion RAFT polymerization, and will be useful to reveal the block copolymer particle growth. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013