Phase Behavior of Binary and Polydisperse Suspensions of Compressible Microgels Controlled by Selective Particle Deswelling

Authors

A. Scotti, Paul Scherrer Institut
U. Gasser, Paul Scherrer Institut
E. S. Herman, Georgia Institute of Technology
Jun Han, Paul Scherrer Institut
A. Menzel, Paul Scherrer Institut
L. Andrew Lyon, Chapman UniversityFollow
A. Fernandez-Nieves, Georgia Institute of Technology

Document Type

Article

Publication Date

9-25-2017

Abstract

We investigate the phase behavior of suspensions of poly(N-isopropylacrylamide) (pNIPAM) microgels with either bimodal or polydisperse size distribution. We observe a shift of the fluid-crystal transition to higher concentrations depending on the polydispersity or the fraction of large particles in suspension. Crystallization is observed up to polydispersities as high as 18.5%, and up to a number fraction of large particles of 29% in bidisperse suspensions. The crystal structure is random hexagonal close-packed as in monodisperse pNIPAM microgel suspensions.We explain our experimental results by considering the effect of bound counterions. Above a critical particle concentration, these cause deswelling of the largest microgels, which are the softest, changing the size distribution of the suspension and enabling crystal formation in conditions where incompressible particles would not crystallize.

Comments

This article was originally published in Physical Review E, volume 96r, in 2017. DOI: 10.1103/PhysRevE.96.032609

Recommended Citation

A. Scotti, U. Gasser, E. S. Herman, J. Han, A. Menzel, L. A. Lyon, and A. Fernandez-Nieves, Phys. Rev. E. 96, 032609 (2017). doi:10.1103/PhysRevE.96.032609

Copyright

American Physical Society