Synthesis and characterization of monodisperse thermosensitive dumbbell-shaped microgels

Monodisperse thermosensitive dumbbell-shaped core-shell microgels are fabricated, which consist of a polystyrene core with a cross-linked poly (N-isopropylacrylamide) shell. The morphology of the microgels was investigated through cryogenic transmission electron microscopy and depolarized dynamic light scattering. The effective volume fraction and aspect ratio of the system could be adjusted through the swelling of the thermosensitive shell. We observe a phase transition of the microgels to an ordered, crystal-like state, which is apparent through Bragg-reflections in the visible range. These observations are further supported by rheological measurements where the shear-melting of the crystal phase is clearly detected.