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http://hdl.handle.net/11375/22239
Title: | Cooperative Ordering and Kinetics of Cellulose Nanocrystal Alignment in a Magnetic Field |
Authors: | De France, Kevin Yager, Kevin Hoare, Todd Cranston, Emily |
Department: | Chemical Engineering |
Publication Date: | 2016 |
Publisher: | American Chemical Society |
Abstract: | Cellulose nanocrystals (CNCs) are emerging nanomaterials which form chiral nematic liquid crystals above a critical concentration (C*) and additionally orient within electromagnetic fields. The control over CNC alignment is significant for material processing and end-use; to date, magnetic alignment has only been demonstrated using strong fields over extended or arbitrary timescales. This work investigates the effects of comparatively weak magnetic fields (0 – 1.2 T) and CNC concentration (1.65 – 8.25 wt%) on the kinetics and degree of CNC ordering using small angle x-ray scattering. Interparticle spacing, correlation length, and orientation order parameters (η and S) increased with time and field strength following a sigmoidal profile. In a 1.2 T magnetic field for CNC suspensions above C*, partial alignment occurred in under 2 min followed by slower cooperative ordering to achieve near-perfect alignment in under 200 min (S = –0.499 where S = –0.5 indicates perfect anti-alignment). At 0.56 T, near-perfect alignment was also achieved, yet the ordering was 36% slower. Outside of a magnetic field, the order parameter plateaued at 52% alignment (S = –0.26) after 5 hours, showcasing the drastic effects of relatively weak magnetic fields on CNC alignment. For suspensions below C*, no magnetic alignment was detected. |
URI: | http://hdl.handle.net/11375/22239 |
Identifier: | 10.1021/acs.langmuir.6b01827 |
Appears in Collections: | Chemical Engineering Publications |
Files in This Item:
File | Description | Size | Format | |
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De France et al - Langmuir 2016 - Post print.pdf | 1.4 MB | Adobe PDF | View/Open |
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