Dumbbell-Shaped Thermoresponsive Microgels

by | Apr 16, 2012

Researchers from the Helmholtz-Zentrum in Berlin present nearly monodisperse thermosensitive dumbbell-shaped core-shell microgels as a versatile model system for the dynamic study of the mildly anisotropic systems.

Spherical colloidal particles have served as a perfect model system to investigate a series of phenomena in colloid science, including dynamic arrest, nucleation, crystallization, glass transition and so forth. Recently, more and more researchers have shifted their focus to non-spherical particles due to a rich phase behavior, novel structures, and other intriguing features of these systems.

Matthias Ballauff and co-workers (Helmholtz-Zentrum Berlin, Germany) now present the fabrication of homogeneous thermosensitive dumbbell-shaped microgels by attaching a thermosensitive shell of poly (N-isopropylacrylamide) networks to the dumbbell-shaped polystyrene-core particles. These particles display a very narrow size distribution. The aspect ratio of the dumbbell-shaped microgel is tunable through temperature. For dense suspensions, the microgels can form plastic crystals with Bragg reflection, which can be supported through direct observation. Moreover, the rheological measurements give powerful evidence for the crystallization process, and phase transition.

In addition to their evident interest in basic colloid science, and in modern nanotechnology, this type of particles is of particular interest in the hydrodynamic theory and modeling field, as they provide excellent systems to test theoretical or computational results.