A review of nanocrystalline cellulose suspensions: Rheology, liquid crystal ordering and colloidal phase behaviour

Xu, Yuan; Atrens, Aleks D.; Stokes, Jason R.

doi:10.1016/j.cis.2019.102076

Cited by 100 publications

(87 citation statements)

References 102 publications

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“…[106,166,167] A phase diagram for S-CNCs was proposed to correlate NaCl concentration to a dimensionless suspension concentration based on aspect ratio and volume fraction of CNCs. [168] The phase diagram suggests a range of potential conditions based on ionic strength, geometry and concentration of CNCs in suspension to target specific phases for a desired rheological response and application. G′ progressively increased with increases in both valence (i.e., Na + < Mg 2+ < Al 3+ ) and radius (i.e., Mg 2+ < Ca 2+ < Sn 2+ ) of the cation.…”

Section: Ionic Strengthmentioning

confidence: 99%

Rheological Aspects of Cellulose Nanomaterials: Governing Factors and Emerging Applications

et al. 2021

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of nanomaterials from green, low-cost, abundant, renewable, and biodegradable natural resources. One such attractive bioresource is cellulose, the most abundant biopolymer on earth, which is widely present in various forms of renewable biomass, such as trees, plants, tunicates, and bacteria.Structurally, cellulose is a linear, high molecular weight polysaccharide with repeating glucose units linked by 1-4 glycosidic bonds. Owing to the presence of hydroxyl groups, those linear chains of glucose units link together through van der Waals forces and intermolecular hydrogen bonding to form elementary fibrils, which are further packed into larger aggregates known as microfibrils. [3] Cellulose fibrils consist of disordered (amorphous) regions and highly ordered (crystalline) regions. In the crystalline regions, cellulose chains are closely packed together in highly ordered fashion (parallel to the direction of fibril length), dictated by the intricate intraand intermolecular hydrogen bonding; whereas in the amorphous regions, cellulose chain stacking is less ordered and not as closely packed. Therefore, the amorphous regions are more vulnerable to both physical disintegration and chemical hydrolysis in comparison with crystalline regions. When cellulose is prepared in nano-scale fibrillar or crystalline forms, it is broadly referred to as cellulose nanomaterials (CNMs).The isolation, characterization, modification, and application of CNMs are currently receiving much attention. Understanding Cellulose nanomaterials (CNMs), mainly including nanofibrillated cellulose (NFC) and cellulose nanocrystals (CNCs), have attained enormous interest due to their sustainability, biodegradability, biocompatibility, nanoscale dimensions, large surface area, facile modification of surface chemistry, as well as unique optical, mechanical, and rheological performance. One of the most fascinating properties of CNMs is their aqueous suspension rheology, i.e., CNMs helping create viscous suspensions with the formation of percolation networks and chemical interactions (e.g., van der Waals forces, hydrogen bonding, electrostatic attraction/repulsion, and hydrophobic attraction). Under continuous shearing, CNMs in an aqueous suspension can align along the flow direction, producing shear-thinning behavior. At rest, CNM suspensions regain some of their initial structure immediately, allowing rapid recovery of rheological properties. These unique flow features enable CNMs to serve as rheological modifiers in a wide range of fluid-based applications. Herein, the dependence of the rheology of CNM suspensions on test protocols, CNM inherent properties, suspension environments, and postprocessing is systematically described. A critical overview of the recent progress on fluid applications of CNMs as rheology modifiers in some emerging industrial sectors is presented as well. Future perspectives in the field are outlined to guide further research and development in using CNMs as the next generation rheological modifiers.

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Section: Ionic Strengthmentioning

confidence: 99%

Rheological Aspects of Cellulose Nanomaterials: Governing Factors and Emerging Applications

et al. 2021

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“…On the other hand, the viscosity profile of the non-sonicated CNC suspension stored for 120 days exhibits a plateau at shear rates below 1 s −1 and a shear thinning behavior at higher shear rates. These features in the viscosity profile are characteristic of a chiral nematic liquid crystal phase [ 17 , 18 ].…”

Section: Resultsmentioning

confidence: 99%

“…However, shear-thinning behavior of CNC suspensions does not ensure alignment of nanocrystals, but a breakup of CNC aggregates might appear [37]. Physicochemical properties of CNC suspensions are largely depending on many factors such as the source of cellulose and hydrolysis conditions, among others [17,18].…”

Section: Birefringent Films From Fresh Suspensionsmentioning

confidence: 99%

“…In contradistinction, the application of ultrasonic power decreases the steady-state viscosity [ 13 ]. Recent reviews of the rheology of cellulose nanomaterials account for the importance to process these materials [ 17 , 18 ]. However, to the knowledge of the authors, evidence of changes of viscosity of non-sonicated CNC suspensions over time have not been reported yet.…”

Section: Introductionmentioning

confidence: 99%

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Shear-Coated Linear Birefringent and Chiral Cellulose Nanocrystal Films Prepared from Non-Sonicated Suspensions with Different Storage Time

et al. 2021

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Nanocelluloses are very attractive materials for creating structured films with unique optical properties using different preparation techniques. Evaporation-induced self-assembly of cellulose nanocrystals (CNC) aqueous suspensions produces iridescent films with selective circular Bragg reflection. Blade coating of sonicated CNC suspensions leads to birefringent CNC films. In this work, fabrication of both birefringent and chiral films from non-sonicated CNC suspensions using a shear-coating method is studied. Polarization optical microscopy and steady-state viscosity profiles show that non-sonicated CNC suspensions (concentration of 6.5 wt%) evolve with storage time from a gel-like shear-thinning fluid to a mixture of isotropic and chiral nematic liquid crystalline phases. Shear-coated films prepared from non-sonicated fresh CNC suspensions are birefringent, whereas films prepared from suspensions stored several weeks show reflection of left-handed polarized light. Quantification of linear and circular birefringence as well circular dichroism in the films is achieved by using a Mueller matrix formalism.

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“…Although CNCs are rigid, rod-like crystalline nano-objects, they form 3D interconnected hydrogel networks [ 11 ], and beads or core–shell capsules are obtained by the external or inverse gelation of CNC, respectively [ 12 ]. The morphology, rheology, and surface properties of CNCs obtained with various procedures have been extensively studied [ 13 ]. Conversely, scarce information is available on the dynamics of the CNC suspensions and on the synthesis of CNC hydrogels under external forces.…”

Section: Introductionmentioning

confidence: 99%

Effect of Process Conditions and Colloidal Properties of Cellulose Nanocrystals Suspensions on the Production of Hydrogel Beads

et al. 2021

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The influence of the physical, rheological, and process parameters on the cellulose nanocrystal (CNC) drops before and after external gelation in a CaCl2 solution was investigated. The dominant role of the CNC’s colloidal suspension properties, such as the viscous force, inertial, and surface tension forces in the fluid dynamics was quantitatively evaluated in the formation of drops and jellified beads. The similarity and difference between the behavior of carbohydrate polymers and rod-like crystallites such as CNC were enlightened. Pump-driven and centrifugally-driven external gelation approaches were followed to obtain CNC hydrogel beads with tunable size and regular shape. A superior morphological control—that is, a more regular shape and smaller dimension of the beads—were obtained by centrifugal force-driven gelation. These results suggest that even by using a simple set-up and a low-speed centrifuge device, the extrusion of a colloidal solution through a small nozzle under a centrifugal field is an efficient approach for the production of CNC hydrogel beads with good reproducibility, control over the bead morphology and size monodispersion.

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A review of nanocrystalline cellulose suspensions: Rheology, liquid crystal ordering and colloidal phase behaviour

Cited by 100 publications

References 102 publications

Rheological Aspects of Cellulose Nanomaterials: Governing Factors and Emerging Applications

Rheological Aspects of Cellulose Nanomaterials: Governing Factors and Emerging Applications

Shear-Coated Linear Birefringent and Chiral Cellulose Nanocrystal Films Prepared from Non-Sonicated Suspensions with Different Storage Time

Effect of Process Conditions and Colloidal Properties of Cellulose Nanocrystals Suspensions on the Production of Hydrogel Beads

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