title: Form factor of pNIPAM microgels in overpacked states.
abstract: We study the form factor of thermoresponsive microgels based on poly(N-isopropylacrylamide) at high generalized volume fractions, ζ, where the particles must shrink or interpenetrate to fit into the available space. Small-angle neutron scattering with contrast matching techniques is used to determine the particle form factor. We find that the particle size is constant up to a volume fraction roughly between random close packing and space filling. Beyond this point, the particle size decreases with increasing particle concentration; this decrease is found to occur with little interpenetration. Noteworthily, the suspensions remain liquid-like for ζ larger than 1, emphasizing the importance of particle softness in determining suspension behavior.
authors: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland.
authors: U
authors: U
authors: Gasser
authors: School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
authors: J S
authors: JS
authors: Hyatt
authors: School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
authors: J-J
authors: JJ
authors: Lietor-Santos
authors: School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
authors: E S
authors: ES
authors: Herman
authors: School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
authors: L A
authors: LA
authors: Lyon
authors: School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA.
authors: A
authors: A
authors: Fernandez-Nieves