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Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2013
Author Gasser Urs, Lietor-Santos Juan-Jose, Scotti Andrea, Bunk Oliver, Menzel Andreas, Fernandez-Nieves Alberto,
Project Phase behavior of concentrated microgel suspensions
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Original article (peer-reviewed)

Journal Physical Review E
Volume (Issue) 88(12)
Page(s) 052308
Title of proceedings Physical Review E


We present a small-angle x-ray scattering study of crystals formed by temperature-sensitive, swollen microgel particles consisting of poly(N-isopropylacrylamide) copolymerized with acrylic acid and 5 mol % of a cross- linker. As for hard spheres, the random hexagonal close-packed structure is predominant during crystal growth and slowly transforms toward the face-centered-cubic structure. However, a transient phase of body-centered-cubic crystal is observed in an intermediate range of effective volume fractions. We estimate that the studied suspensions are close to a transition from face-centered-cubic to body-centered-cubic structure that can be understood by the tendency of the system to maximize the excluded volume and minimize the contact area between the particles.