Novel triblock copolymers having self-complementary hydrogen-bonding units were synthesized by using reversible additionfragmentation transfer polymerization. As characterized by dynamic light scattering and atomic force microscopy, these polymers formed noncovalently crosslinked polymer particles and showed an aggregation behavior by intermolecular and intramolecular interactions. At low concentration, polymers formed nanoparticles, and the particle diameter increased with increasing polymer concentration. Well-ordered hexagonal microstructures were prepared by Breath Figure technique with the triblock copolymers.(c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012