Files

Download

Download Full Text (946 KB)

Description

Due to the tunability of their softness and volume as a function of temperature, poly(N-isopropylacrylamide) (pNIPAm) hydrogel particles have emerged as a model system for soft colloidal spheres. By introducing AAc as comonomer, one can also tune the particle volume via pH. We report on the phase behavior of these stimuli-responsive colloids as measured with a microdialysis cell. This device, which integrates microfluidics with Particle Tracking Video-microscopy allows for simple and quick investigation of the phase behavior of suspensions the soft colloidal hydrogel as a function of pH as well as its packing density. In particular, we demonstrate the existence of an unusually broad liquid/crystal coexistence region as a function of effective particle volume fraction. Additionally, we reveal that nonequilibrium jammed states can be created in the coexistence region upon sudden large changes of pH. The phase diagram is indicative of complex interparticle interactions with weakly attractive components.

ISBN

978-0-7354-0549-3

Publication Date

2008

Publisher

American Institute of Physics

Keywords

Colloids, Microfludics, Microscopy, Rheology, Particles, Acrylic Acid

Disciplines

Fluid Dynamics | Physics

Comments

Copyright (2008) 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 Xvth International Congress on Rheology – the Society of Rheology 80th Annual Meeting, Pts 1 and 2 and may be found at http://scitation.aip.org/content/aip/proceeding/aipcp/1027.

Peer Reviewed

1

Copyright

Society of Rheology/American Institute of Physics

Direct observation of phase transition dynamics in suspensions of soft colloidal hydrogel particles

Share

COinS