In this study, ammonolyzed poly(styrene-alt-maleic anhydride) terminated with dithioester group can be self-assembled into an amphiphilic macro-reversible addition-fragmentation chain transfer (RAFT) agent, and RAFT group will be located in the interface of oil and water. RAFT polymerization of styrene (S) and butadiene (B) will be confined in the interface. The main work is to study the effect of degree of aminolysis, reaction temperature, and ratio of S/B on the polymerization kinetics and living characters. The experimental results revealed that aminolysis of dithioester group would lead to retardation and loss of living characters under higher degree of aminolysis. Interfacially confined RAFT miniemulsion polymerizations were of relatively good controlled/living characters under lower degree of aminolysis before gelation. Increase of reaction temperature and ratio of S/B will accelerate the formation of gelation. Finally, styrene/butadiene copolymer nanoparticles with uniform particle size were formed, and because of microphase segregation "core-shell" morphology with polybutadiene core and polystyrene shell was seen obviously. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2557-2565, 2013