title: Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels.
abstract: 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.
authors: Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: U
authors: U
authors: Gasser
authors: School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
authors: J-J
authors: JJ
authors: Lietor-Santos
authors: Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: A
authors: A
authors: Scotti
authors: Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: O
authors: O
authors: Bunk
authors: Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
authors: A
authors: A
authors: Menzel
authors: School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
authors: A
authors: A
authors: Fernandez-Nieves