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

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2239
Author(s):  
Olga Rubi Juárez-Rivera ◽  
Reina Araceli Mauricio-Sánchez ◽  
Kenneth Järrendahl ◽  
Hans Arwin ◽  
Arturo Mendoza-Galván
Keyword(s):  
Self Assembly ◽  
Liquid Crystalline ◽  
Storage Time ◽  
Bragg Reflection ◽  
Polarized Light ◽  
Matrix Formalism ◽  
Polarization Optical Microscopy ◽  
Chiral Nematic ◽  
Coating Method ◽  
Evaporation Induced Self Assembly

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.

Ordered mesoporous carbon in solid-phase microextraction for analysis of volatile organic compounds in water samples

2019 ◽  
Vol 11 (29) ◽  
pp. 3741-3749
Author(s):  
Bo Liu ◽  
Yaqiong Hao ◽  
Lixiao Wang ◽  
Mengyun Li ◽  
Hui Jiang
Keyword(s):  
Self Assembly ◽  
Mesoporous Carbon ◽  
Solid Phase ◽  
Dip Coating ◽  
Ordered Mesoporous Carbon ◽  
Ordered Mesoporous ◽  
Volatile Organic ◽  
Coating Method ◽  
Evaporation Induced Self Assembly ◽  
Dip Coating Method

An ordered mesoporous carbon (OMC) film supported on graphite fiber was prepared by a dip-coating method combined with a solvent evaporation induced self-assembly (EISA) strategy.

scholarly journals Circularly Polarized Light Detection by Chiral Photonic Cellulose Nanocrystal with ZnO Photoconductive Layer in Ultraviolet Region

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3098
Author(s):  
Boyu Zhang ◽  
Sixiang Zhao ◽  
Yingying Yu ◽  
Ming Li ◽  
Liancheng Zhao ◽  
...  
Keyword(s):  
Self Assembly ◽  
Polarization State ◽  
Polarized Light ◽  
Cellulose Nanocrystal ◽  
Ultraviolet Region ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Left Handed ◽  
Chiral Nematic ◽  
Wide Range

Circularly polarized light (CPL) detection and polarization state recognition are required for a wide range of applications. Conventional polarization detection with optical components causes difficulties for miniaturization and integration. An effective design strategy is proposed for direct CPL detection with chiral material. Here, we realized direct CPL detection based on the combination of chiral photonic cellulose nanocrystal (CNC) and ultraviolet-sensitive ZnO photoconductive material. The CNC layer deposited by evaporation-induced self-assembly established the left-handed chiral nematic structure with a photonic bandgap (PBG) to recognize left-handed CPL (LCPL) and right-handed CPL (RCPL) at specific wavelengths. The PBG of CNC layer has been modulated by the adjustment of chiral nematic pitch to match the semiconductor bandgap of ZnO film in ultraviolet region. The photocurrents under RCPL and LCPL are 2.23 × 10−6 A and 1.77 × 10−6 A respectively and the anisotropy factor Δgpc of 0.23 is acquired for the CPL detection based on the chiral photonic CNC. This design provides a new approach to the detection of CPL polarization state with competitive performance.

Effect of Pore Size on the Hydrophilicity in Dark of TiO2 Films

2011 ◽  
Vol 130-134 ◽  
pp. 1049-1053
Author(s):  
Qi Wang ◽  
Cheng Pu Lin ◽  
Peng Cui
Keyword(s):  
Contact Angle ◽  
Organic Matter ◽  
Pore Size ◽  
Self Assembly ◽  
Dip Coating ◽  
Molar Ratio ◽  
Water Contact ◽  
Coating Method ◽  
Evaporation Induced Self Assembly ◽  
Dip Coating Method

Mesoporous TiO2 films was prepared by evaporation-induced self-assembly and dip-coating method. And the pore size of the TiO2 films is adjusted by controlling the molar ratio of H2O/TiO2 (H value). Water contact angle was chosen to represent the hydrophilic property, and XRD and AFM were carried out to characterize the films. With the increase of H value, the pore size increased firstly then decreased. And when H is 15, the pore size is the biggest, which hydrophilicity in dark is the best too. With the extention of the non-irridation time, the hydrophilicity is worse. And the reason may be ascribed to the adsorption of organic matter in air.

scholarly journals Chiral Nematic Cellulose Nanocrystal Films Cooperated with Amino Acids for Tunable Optical Properties

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4389
Author(s):  
Xiao Xiao ◽  
Jie Chen ◽  
Zhe Ling ◽  
Jiaqi Guo ◽  
Jianbin Huang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Self Assembly ◽  
Uv Light ◽  
Composite Films ◽  
Functional Materials ◽  
Cellulose Nanocrystal ◽  
Optical Functions ◽  
Chiral Nematic ◽  
Evaporation Induced Self Assembly ◽  
Nanocrystal Films

The exploration of functional materials relies greatly on the understanding of material structures and nanotechnologies. In the present work, chiral nematic cellulose nanocrystal (CNC) films were prepared by incorporation with four types of amino acids (AAs, glycine, histidine, phenylalanine, and serine) via evaporation-induced self-assembly. The films present ideal iridescence and birefringence that can be tuned by the amount of AAs added. The intercalation of AAs enlarged the pitch values, contributing to the red-shift trend of the reflective wavelength. Among the AAs, serine presented the most compatible intercalation into cellulose crystals. Interestingly, histidine and phenylalanine composite films showed high shielding capabilities of UV light in diverse wavelength regions, exhibiting multi-optical functions. The sustainable preparation of chiral nematic CNC films may provide new strategies for materials production from biocompatible lignocellulose.

Theory of Circularly Polarized Light Emission from Chiral Nematic Liquid Crystalline Films

1996 ◽  
Vol 425 ◽  
Author(s):  
H. Shi ◽  
S. H. Chen
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Liquid Crystalline ◽  
Light Emission ◽  
Polarized Light ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Chiral Nematic ◽  
Polarized Emission ◽  
Crystalline Films

AbstractChiral nematic liquid crystalline films with fluorescent chromophores are capable of circularly polarized emission. A theory is presented in which the effects of anisotropic absorption and film thickness are accounted for. The predicted dissymmetry factor is compared with experimental data reported by Stegemeyer et al. and with the theory for the two limiting cases treated by Pollmann et al.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

Self-Assembly Optical Components

2003 ◽  
Vol 771 ◽  
Author(s):  
Pavel I. Lazarev ◽  
Michael V. Paukshto ◽  
Elena N. Sidorenko
Keyword(s):  
Optical Properties ◽  
Self Assembly ◽  
Crystalline State ◽  
Liquid Crystalline ◽  
Film Deposition ◽  
X Ray Diffraction ◽  
Optical Components ◽  
Crystal Film ◽  
Solid Film ◽  
Thin Crystal

AbstractWe report a new method of Thin Crystal Film deposition. In the present paper we describe the method of crystallization, structure, and optical properties of Bisbenzimidazo[2,1-a:1',2',b']anthra[2,1,9-def:6,5,10-d'e'f']-diisoquinoline-6,9-dion (mixture with cis-isomer) (abbreviated DBI PTCA) sulfonation product. The Thin Crystal Film has a thickness of 200-1000 nm, with anisotropic optical properties such as refraction and absorption indices. X-ray diffraction data evidences a lyotropic liquid crystalline state in liquid phase and crystalline state in solid film. Anisotropic optical properties of the film make it useful in optical devices, e.g. liquid crystal displays.

scholarly journals Concentric chiral nematic polymeric fibers from cellulose nanocrystals

2021 ◽  
Author(s):  
Arash Momeni ◽  
Christopher M. Walters ◽  
Yi-Tao Xu ◽  
Wadood Y. Hamad ◽  
Mark J. MacLachlan
Keyword(s):  
Cellulose Nanocrystals ◽  
Liquid Crystalline ◽  
Capillary Tube ◽  
Single Domain ◽  
Cellulose Nanocrystal ◽  
Polymeric Fibers ◽  
Chiral Nematic ◽  
Chiral Nematic Structure ◽  
Crystalline Suspension

A cellulose nanocrystal liquid crystalline suspension was mixed with monomers and confined to a capillary tube. After photopolymerization, a fiber with a single-domain concentric chiral nematic structure throughout the length of the fiber was obtained.

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