Abstract
Organization of nanoparticles is essential in order to control their light-matter interactions. We present cellulose nanocrystal suspension organization in flow towards a unidirectional state. Visualization of evolving polarization patterns of the cellulose nanocrystal suspensions is combined with steady and oscillatory shear rheology. Elucidation of the chiral nematic mesophase in a continuous process towards unidirectional order enables control of alignment in a suspension precursor for structural films and reveals thus far in situ unrevealed transition states that were not detectable by rheology alone. The coupled analytics enabled the suspensions of interest to be divided into rheological gels and rheological liquid crystal fluids with detailed information on the microtransition phases. Both populations experienced submicron organization and reached macro-scale homogeneity with unidirectional ordering in continued shear. We quantify the time, shear rate, and recovery time after shear to design an optimizing formation process for controlled wet structures as precursors for dry products.Graphic abstract
Highlights
Cellulose is synthetized in the wood cell wall in fibrils exhibiting periodicity in molecular ordering
Rheology is an essential tool for the characterization of suspension flow properties; birefringence patterns proved to be more sensitive to flow-induced structural changes than rheology alone
Critical shear rate conditions for linear, nonlinear, and the onset and development of a uniformly oriented flow field (Maltese-cross pattern) were determined from birefringence pattern dynamics and proved difficult to detect in the corresponding shear viscosity functions
Summary
Cellulose is synthetized in the wood cell wall in fibrils exhibiting periodicity in molecular ordering. An increase in the concentration of the CNC suspension is reported to result in a transition to a gel state in which the chiral ordering is no longer detected but instead only birefringence appears (Shafiei-Sabet et al 2012). Three distinct rheological responses over specific concentrations were observed due to varying shear responses of the isotropic and liquid crystals domains in the biphasic CNC suspension.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
