New Insights into the Flow and Microstructural Relaxation Behavior of Biphasic Cellulose Nanocrystal Dispersions from RheoSANS

Published

December 7, 2017

Author(s)

Alexander D. Haywood, Kathleen Weigandt, Partha Saha, Matthew Noor, Micha J. Green, Virginia A. Davis

Abstract

Understanding microstructure and shear response is a prerequisite for the controlled and predictable assembly of anisotropic nanomaterials into large area structures. Much of the framework for understanding the rheological behavior of lyotropic dispersions was developed for rod-like polymer mesogens; rod-like nanomaterial mesogen dispersions have been shown to exhibit many of the same characteristics. However, definitive identification of one key characteristic, the existence of three regions in the viscosity versus shear rate curve, has proven elusive for several nanomaterial mesogen systems. In this work, the combination of rheology and small angle neutron scattering (Rheo-SANS) was used to measure changes in order parameter as a function of shear rate for isotropic, biphasic, liquid crystalline, and gel dispersions of cellulose nanocrystals (CNS)in deuterium oxide (D₂O). This resulted in clear identification of three region behavior; plots of order parameter as a function of shear rate enabled quantitative identification of three region behavior. In addition, measurement of dispersion order parameter at rest and after shear cessation enabled insights into quiescent microstructure and relaxation dynamics. The results of this work are valuable for guiding the development of processing methodologies for producing ordered materials from CNC dispersions. In addition, the results of this investigation suggest that Rheo-SANS may enable new insights into other lyotropic nanomaterial mesogen dispersions.

Citation

Soft Matter

Volume

13

Issue

45

Pub Type

Journals

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Keywords

Cellulose nanocrystal, Order parameter, rheology, rheoSANS

Citation

Haywood, A. , Weigandt, K. , Saha, P. , Noor, M. , Green, M. and Davis, V. (2017), New Insights into the Flow and Microstructural Relaxation Behavior of Biphasic Cellulose Nanocrystal Dispersions from RheoSANS, Soft Matter, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=923249 (Accessed December 6, 2024)