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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


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.