Professor Taihyun Chang (Department of Chemistry) and his group have developed toroidal micelles of uniform size from diblock copolymers.

Block copoloymers can spontaneously self-assemble in a selective solvent to form micelles of various morphologies such as spherical micelles, cylindrical micelles, and vesicles. Recently, the variety of micellar shapes have been expanded to unconventional forms including toroids, tubes, disks, helices, and other complex forms.

Although the toroid-shaped micelles have been reported earlier, the applicability of the toroid structure had been low due to the difficulty in achieving uniformity in size despite the simplicity in shape. All the doughnut-shaped micelles reported to date were practically ring closure products of rodshaped micelles, thus their sizes are not uniform.

Professor Chang’s team succeeded in developing pure toroidal micelles of high uniformity in shape and size using block copolymer with a block of low glass transition temperature in a selective solvent. The micelle can retain its doughnut-shaped structure and size in solution over several months, appearing to be a thermodynamically stable structure. The doughnutshaped micelle, realized utilizing the phenomenon of block copolymer self assembly, is stable enough to be used as a template to grow metal nanoparticles.

The nanosized toroidal objects have great potential for practical applications. With the stable and well-defined structure, the doughnut-shaped micelles are expected to serve as a model system to study their properties, as well as being a promising candidate for a nanotemplate in the evolving field of nanoscience and nanotechnology.

Professor Taihyun Chang
Department of Chemistry
Tel: +82-54-279-2109
Fax: +82-54-279-3399
E-mail: tc@postech.ac.kr