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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.


Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in

Gasser U.; Hyatt J. S.; Lietor-Santos, J. J.; Herman E. S.; Lyon, L. A.; Fernandez-Nieves A., Form factor of pNIPAM microgels in overpacked states, J. Chem. Phys. , 2014, 141(3), 034901.

and may be found at DOI: 10.1063/1.4885444


American Institute of Physics



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