Effect of Trace Electrolyte on Liquid Crystal Type of Cellulose Microcrystals

and, J. A. Griffiths; Kuga, Shigenori

doi:10.1021/la0102455

Cited by 277 publications

(263 citation statements)

References 19 publications

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“…3a). The appearance of an LC phase at this concentration is consistent with the behaviour of other charged rod-like particles of similar aspect ratio such as microcrystalline cellulose 26 and chitin. 27 When further concentrated inside flat capillaries, they separated into an isotropic (upper) phase and a highly birefringent (lower) phase (see Fig.…”

Section: 18supporting

confidence: 83%

Cholesteric colloidal liquid crystals from phytosterol rod-like particles

2011

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We report the first observation of chiral colloidal liquid crystals of rod-like particles from a low molecular weight organic compoundphytosterols. Based on the particles shape and crystal structure, we attribute this phenomenon to chiral distribution of surface charge on the surface of neighbouring rods.Shape anisotropic (disc-like or rod-like) colloidal particles have been drawing the attention of scientists for many centuries, starting with the use of natural clay particles.1 The particular interest in their phase behaviour started already with the work of Onsager who theoretically predicted the occurrence of entropically driven phase transition in suspensions of disc-like particles that leads to the formation of liquid crystal (LC) phases.2 Nowadays, available synthetic methods readily provide a vast amount of (organic and inorganic) shape anisotropic colloidal particles, 3,4 which indeed in many cases give rise to the formation of various LC phases.5-7 Interestingly, shape anisotropic colloidal particles can also form a cholesteric (or chiral nematic) LC phase,8-11 initially thought to be an exclusive property of molecular LC phases which are typically composed of molecules containing a chiral centre. The latter produces intermolecular forces that favour alignment between molecules at a slight angle to one another in different layers resulting in a long-range chiral order.12 Surprisingly, chiral colloidal LC phases have been observed only in the case of shape-anisotropic particles from self-assemblies of large biopolymers (e.g. cellulose, 13 chitin 14) and macromolecules (e.g. viruses 15) and not in low molecular weight organic compounds. Although a lot of research has been done in relation to cholesteric colloidal LCs, the connection between molecular and macroscopic chirality is still not understood. 8-11,16Here we report the first observation of a cholesteric LC phase in a colloidal suspension of rod-like particles from phytosterols (PSs): a low molecular weight organic molecule. To our knowledge, this is the first observation of cholesteric LC from colloidal particles made of chiral low molecular weight organic molecules. Phytosterols are a group of plant-derived sterols that have structures similar to that of cholesterol (Fig. 1).17 Due to their different biochemistry, phytosterols are used as an efficient cholesterol lowering agent in various food products. 17,18The procedure developed for the synthesis of phytosterol colloidal particles is based on anti-solvent precipitation.19 Transmission electron microscopy (TEM) pictures (Fig. 2) show that the colloidal particles have a rod-like shape with aspect ratios L/D varying between 3 and 20, with D the particle width and length L typically in between 2 mm and 3 mm.20 Phytosterols are known to form rod-and plate-like crystals of hemi-and monohydrates when crystallized from oil solutions 21 or organic solvents in the presence of water.22 Recent studies have shown that cholesterol, which also forms hemi-and monohydrates, forms plate-like particles.23 Our rod...

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Section: 18supporting

confidence: 83%

Cholesteric colloidal liquid crystals from phytosterol rod-like particles

2011

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“…The second of these mechanisms is most likely equivalent to a mechanism proposed specifically for the case of CNCs by Araki and Kuga, 52 who also considered the role of ions in solution. Rather than Figure 5 Polarizing microscopy textural traces of CNC helix formation in the liquid crystalline (wet) state (a) and in solid CNC samples obtained by drying (b-d).…”

Section: The Helix In Liquid Crystalline Cnc Suspensionsmentioning

confidence: 90%

“…Taking as a starting point the Onsager model 51 (see Supplementary Box 1), which predicts that the required volume fraction for liquid crystal formation is inversely proportional to the rod aspect ratio, the onset concentration of liquid crystallinity is expected to decrease if the rod-like CNC is longer and thinner. Indeed, dispersions of bacterial CNCs, with lengths on the order of 1-2 mm and an aspect ratio in the range of 50-100, 30,52 show nematic ordering well below 1 wt% CNC, cf. Figure 4.…”

Section: Extraction Of Cncs From Biological Sourcesmentioning

confidence: 99%

“…The effect is weaker for CNCs with a lower surface charge and with a smaller onset concentration for liquid crystalline ordering; hence, the nonlinearity becomes negligible for bacterial CNCs, which are approximately one order of magnitude longer, with B1/20 of the surface charge of wood-derived CNCs. 30,52 Dong et al 55 conducted an elegant experiment to demonstrate the influence of the CNC counter ions on the formation of the liquid crystal phase. By adding HCl at varying concentrations to a series of CNC suspensions within the biphasic regime, such that each suspension had a constant pH of 1.61, they effectively canceled out the effect of the counter ions introduced by the cellulose nanorods.…”

Section: Extraction Of Cncs From Biological Sourcesmentioning

confidence: 99%

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Cellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin films

et al. 2014

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Cellulose nanocrystals (CNCs), produced by the acid hydrolysis of wood, cotton or other cellulose-rich sources, constitute a renewable nanosized raw material with a broad range of envisaged uses: for example, in composites, cosmetics and medical devices. The intriguing ability of CNCs to self-organize into a chiral nematic (cholesteric) liquid crystal phase with a helical arrangement has attracted significant interest, resulting in much research effort, as this arrangement gives dried CNC films a photonic band gap. The films thus acquire attractive optical properties, creating possibilities for use in applications such as security papers and mirrorless lasing. In this critical review, we discuss the sensitive balance between glass formation and liquid crystal self-assembly that governs the formation of the desired helical structure. We show that several as yet unclarified observations-some constituting severe obstacles for applications of CNCs-may result from competition between the two phenomena. Moreover, by comparison with the corresponding self-assembly processes of other rod-like nanoparticles, for example, carbon nanotubes and fd virus particles, we outline how further liquid crystal ordering phenomena may be expected from CNCs if the suspension parameters can be better controlled. Alternative interpretations of some unexpected phenomena are provided, and topics for future research are identified, as are new potential application strategies. NPG Asia Materials (2014) 6, e80; doi:10.1038/am.2013.69; published online 10 January 2014Keywords: cholesteric; gel; glass; liquid crystal; nanocellulose; photonic crystal; self-assembly INTRODUCTION Nanomaterials based on renewable resources are attracting rapidly growing interest, both from a fundamental scientific point of view and from the perspective of developing novel structural and functional macroscopic materials. 1,2 Using nature-based nanomaterials offers ecological advantages, and the extraordinary mechanical performance and/or photonic crystal character of biological composites such as bone, nacre, wood, beetle scales and butterfly wings is also an important inspiration for the development of new multifunctional materials. [3][4][5] However, full utilization of the intrinsic properties of nanosized starting materials requires the development of robust and versatile synthetic and processing routes to control assembly over several length scales. [6][7][8] Cellulose, one of the most versatile and widely found biopolymers in nature, has been used by humans for millennia as a building material, an energy source, a component of clothing and for storing and sharing knowledge and culture. Today, cellulose materials are used in a wide range of applications, and the paper and pulp industry

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“…[7][8][9][10][11][12][13]15,16 The widths of these rod-like microcrystals, commonly referred to as nanocrystals or nanowhiskers, are similar to those of their original microfibrils, whereas their lengths are reduced to 100-200 nm for microfibrils obtained from higher plants, and 1-2 mm for those from tunicins and algaes. 6 The colloidal suspensions of nanowhiskers are typical liquid crystals, showing strong flow birefringence under polarized light 11 and spontaneous formation of chiral nematic 7,10,13 or nematic 8 ordering.…”

Section: Introductionmentioning

confidence: 99%

Chitin-chitosan nanocomposite gels: reinforcement of chitosan hydrogels with rod-like chitin nanowhiskers

Araki

Yamanaka

Ohkawa

2012

Polym J

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Nanocomposite gels containing chitosan as a network polymer and chitin nanowhiskers as reinforcing fillers were prepared by cross-linking with the blocked isocyanate hexamethylene-1,6-di-(aminocarboxysulfonate) (HDS). Young's modulus and stress at break of the nanocomposite gels increased to maximum values of 169 and 135 kPa, respectively, with increase in whisker content up to 13.3%, whereas the degree of swelling decreased from 357 to 33.0.

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Effect of Trace Electrolyte on Liquid Crystal Type of Cellulose Microcrystals

Cited by 277 publications

References 19 publications

Cholesteric colloidal liquid crystals from phytosterol rod-like particles

Cholesteric colloidal liquid crystals from phytosterol rod-like particles

Cellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin films

Chitin-chitosan nanocomposite gels: reinforcement of chitosan hydrogels with rod-like chitin nanowhiskers

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