Fabrication and characterization of nanocrystalline cellulose films prepared under vacuum conditions

Tang, Hao; Guo, Bin; Jiang, Haitian; Xue, Lan; Li, Bengang; Cao, Xuzhi; Zhang, Qisheng; Li, Panxin

doi:10.1007/s10570-013-0034-0

Cited by 16 publications

(16 citation statements)

References 19 publications

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“…A similar trend has been observed by Lagerwall et al [4] and Dumali et al [22]. However, for vacuum-dried CNC films, the colours were blue at edge and red at centre [20]; evidently the rate of drying influences the colour sequence.…”

Section: Resultssupporting

confidence: 80%

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Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy

Gray

2015

Materials

101

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Cellulosic liquid crystalline solutions and suspensions form chiral nematic phases that show a rich variety of optical textures in the liquid crystalline state. These ordered structures may be preserved in solid films prepared by evaporation of solvent or suspending medium. Film formation from aqueous suspensions of cellulose nanocrystals (CNC) was investigated by polarized light microscopy, optical profilometry and atomic force microscopy (AFM). An attempt is made to interpret qualitatively the observed textures in terms of the orientation of the cellulose nanocrystals in the suspensions and films, and the changes in orientation caused by the evaporative process. Mass transfer within the evaporating droplet resulted in the formation of raised rings whose magnitude depended on the degree of pinning of the receding contact line. AFM of dry films at short length scales showed a radial orientation of the CNC at the free surface of the film, along with a radial height variation with a period of approximately P/2, ascribed to the anisotropic shrinkage of the chiral nematic structure.

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Section: Resultssupporting

confidence: 80%

“…Thus, there are no reports of the reflection of circularly polarized light from fluid CNC suspensions, but iridescence is often observed for films made from such suspensions [17,18,19,20,21]. …”

Section: Resultsmentioning

confidence: 99%

Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy

Gray

2015

Materials

101

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“…The nematic order is observed when a film forms from a rapidly drying CNC suspension or under shear; in contrast, chiral nematic order requires a longer equilibration time. Control over the chiral nematic order can be achieved by adjusting the interfacial forces between CNCs or by controlling variables during drying such as rate, shear, temperature, or the surface chemistry of the substrate …”

Section: Introductionmentioning

confidence: 99%

Optical Properties of Self‐Assembled Cellulose Nanocrystals Films Suspended at Planar–Symmetrical Interfaces

Tardy

Ago

Guo

et al. 2017

Small

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Hierarchically structured materials comprising rod-like, chiral, nanoparticles are commonly encountered in nature as they can form assemblies with exceptional optical and mechanical characteristics. These include cellulose nanocrystals (CNCs), which have a large potential for the fabrication of bioinspired materials mimicking those advanced properties. Fine-tuning the optomechanical properties of assemblies obtained from CNCs hinges on the transformations from suspensions of liquid crystals to long-range order in the dry state. So far, associated transitions have been studied using trivial interfaces such as planar substrates. Such transitions are explored as they evolve onto meshed supports. The meshed substrate offers a complex topology, as is encountered in nature, for the formation of CNCs films. The CNCs self-assembly occurs under confinement and support of the framework bounding the mesh openings. This leads to coexisting suspended and supported nanoparticle layers exhibiting nematic and/or chiral nematic order. Optical microscopy combined with crossed polarizers indicate that the formation of the suspended films occurs via intermediate gelation or kinetic arrest of CNCs across the mesh's open areas. The formation of self-standing, ultrathin films of CNCs with tunable optical properties, such as selective reflections in the visible range (structural color), is demonstrated by using the presented simple and scalable approach.

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“…[ 8 , 9 ] The self-assembly process is strongly dependent on the properties of the nanoscale building blocks and on the macroscopic parameters that characterise the assembly. [ 10 ]–[ 12 ] Many factors influence the optical and mechanical properties of the obtained film, including temperature and pressure[ 13 , 15 , 16 ] the substrate,[ 14 ] and the surface chemistry of the CNCs. [ 17 , 18 ] Nevertheless the self-assembly process is robust and can be coupled with a range of chemical processes.…”

mentioning

confidence: 99%

Controlled, Bio‐inspired Self‐Assembly of Cellulose‐Based Chiral Reflectors

Dumanlı

Kamita

Landman

et al. 2014

Advanced Optical Materials

202

181

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Fabrication and characterization of nanocrystalline cellulose films prepared under vacuum conditions

Cited by 16 publications

References 19 publications

Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy

Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy

Optical Properties of Self‐Assembled Cellulose Nanocrystals Films Suspended at Planar–Symmetrical Interfaces

Controlled, Bio‐inspired Self‐Assembly of Cellulose‐Based Chiral Reflectors

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