By using reversible additionfragmentation chain transfer (RAFT) controlled polymerization, we prepared styrenemaleic anhydride copolymers with RAFT end groups. The resulting copolymers were characterized by Fourier transform infrared and 1H-NMR spectroscopy. The molecular weights and molecular weight distributions were determined with gel permeation chromatography. The dispersing ability of the hydrolyzed macro reversible additionfragmentation chain transfer (macro-RAFT) copolymers was evaluated. An organic phthalocyanine blue pigment (P.B.15 : 3) was dispersed with the macro-RAFT copolymers by vigorous stirring and ultrasonic processing. The properties (particle size and polydispersity index) of the pigment dispersions were measured. The results show that with prolonged ultrasonication time, the particle size and polydispersity index decreased first and increased slightly later. There were no remarkable differences in the particle size and particle size distribution between the macro-RAFT copolymer and poly(styrene-co-maleic anhydride) dispersed pigment dispersions. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012