Paper Number
PO33 

Session
Poster Session

Title
Three region rheological and order parameter behavior in nanocylinder dispersions

Presentation Date and Time
October 17, 2018 (Wednesday) 6:30

Track / Room
Poster Session / Woodway II/III

Authors (Click on name to view author profile)

  1. Noor, Matthew M. (Auburn University, Chemical Engineering)
  2. Weigandt, Katie M. (NIST, Center for Neutron Research)
  3. Pospisil, Martin J. (Texas A&M University, Chemical Engineering)
  4. Green, Micah J. (Texas A&M University, Chemical Engineering)
  5. Davis, Virginia A. (Auburn University, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Matthew M. Noor1, Katie M. Weigandt2, Martin J. Pospisil3, Micah J. Green3, and Virginia A. Davis1
1Chemical Engineering, Auburn University, Auburn, AL; 2Center for Neutron Research, NIST, Gaithersburg, MD 20899; 3Chemical Engineering, Texas A&M University, College Station, TX 77843

Speaker / Presenter 
Noor, Matthew M.

Text of Abstract
There is significant interest in producing macroscale materials with anisotropic optical, mechanical, or electrical properties via the controlled fluid phase assembly of rod-like nanomaterials. However, there is still relatively limited understanding of these systems’ phase behavior, rheological properties and microstructural relaxation after shear cessation. In this study, rheology and rheo-optics were used to understand the behavior of two aqueous lyotropic systems: sulfonated cellulose nanocrystals (CNC) and double-stranded DNA stabilized single-walled carbon nanotubes (dsDNA/SWNT). In addition, a combination of rheology and small-angle neutron scattering (RheoSANS) were used to measure changes in the viscosity and flow-oriented order parameter as a function of shear rate for lyotropic dispersions of nanocylinders dispersed in deuterium oxide (D2O). In contrast to plots of viscosity versus shear rate, the order parameter trends show three distinct rheological regions over a range of concentrations. This finding is significant because the existence of three rheological regions as a function of shear rate is a long-standing signature of liquid crystalline phases composed of rod-like polymers. However, observing this trend has been elusive for high-concentration dispersions of anisotropic nanomaterials. The results of this work are valuable for guiding the development of processing methodologies for producing ordered materials from nanocylinder dispersions.