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Form factor of pNIPAM microgels in overpacked states

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2014
Author Gasser Urs, Hyatt J. S., Lietor-Santos Juan-Jose, Herman E. S., Lyon L. A., Fernandez-Nieves Alberto,
Project Phase behavior of concentrated microgel suspensions
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Original article (peer-reviewed)

Journal The Journal of Chemical Physics
Volume (Issue) 141
Page(s) 034901
Title of proceedings The Journal of Chemical Physics

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 frac- tion 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 inter- penetration. Noteworthily, the suspensions remain liquid-like for ζ larger than 1, emphasizing the importance of particle softness in determining suspension behavior.
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