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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 2: Hydrogels and Microgels

CPP 2.2: Vortrag

Montag, 27. September 2021, 14:00–14:15, H1

Phase behavior of ultra-soft spheres shows stable bcc lattices — •Andrea Scotti — Institute of Physical Chemistry RWTH Aachen University

The phase behavior of super-soft spheres is explored using solutions of ultra-low crosslinked poly(N-isopropylacrylamide) based microgels as a model system. For these microgels, the effects of the electric charges on their surfaces can be neglected and, therefore, only the role of softness on the phase behavior is investigated. The samples show a liquid-to-crystal transition at higher volume fraction with respect to both hard spheres and stiffer microgels. Furthermore, stable body centered cubic (bcc) crystals are observed in addition to the expected face centered cubic (fcc) crystals. Small-angle X-ray and neutron scattering with contrast variation allow the characterization of both the microgel-to-microgel distance, and the architecture of single microgels in crowded solutions. The measurements reveal that the stable bcc crystals depend on the interplay between the collapse and the interpenetration of the external shell of the ultra-low crosslinked microgels.