scholarly journals Flexible and Structural Coloured Composite Films from Cellulose Nanocrystals/Hydroxypropyl Cellulose Lyotropic Suspensions

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 122 ◽  
Author(s):  
Diogo V. Saraiva ◽  
Ricardo Chagas ◽  
Beatriz M. de Abreu ◽  
Cláudia N. Gouveia ◽  
Pedro E. S. Silva ◽  
...  

Lyotropic colloidal aqueous suspensions of cellulose nanocrystals (CNCs) can, after solvent evaporation, retain their chiral nematic arrangement. As water is removed the pitch value of the suspension decreases and structural colour-generating films, which are mechanically brittle in nature, can be obtained. Increasing their flexibility while keeping the chiral nematic structure and biocompatible nature is a challenging task. However, if achievable, this will promote their use in new and interesting applications. In this study, we report on the addition of different amounts of hydroxypropyl cellulose (HPC) to CNCs suspension within the coexistence of the isotropic-anisotropic phases and infer the influence of this cellulosic derivative on the properties of the obtained solid films. It was possible to add 50 wt.% of HPC to a CNCs aqueous suspension (to obtain a 50/50 solids ratio) without disrupting the LC phase of CNCs and maintaining a left-handed helical structure in the obtained films. When 30 wt.% of HPC was added to the suspension of CNCs, a strong colouration in the film was still observed. This colour shifts to the near-infrared region as the HPC content in the colloidal suspension increases to 40 wt.% or 50 wt.% The all-cellulosic composite films present an increase in the maximum strain as the concentration of HPC increases, as shown by the bending experiments and an improvement in their thermal properties.

2021 ◽  
Author(s):  
Arash Momeni ◽  
Christopher M. Walters ◽  
Yi-Tao Xu ◽  
Wadood Y. Hamad ◽  
Mark J. MacLachlan

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.


2021 ◽  
pp. 089270572110649
Author(s):  
Muhammad Zahid ◽  
HM Fayzan Shakir ◽  
Zulfiqar Ahmad Rehan

The chemical oxidative polymerization and co-precipitation methods were employed for the preparations of polyaniline (PANI) and silver-doped zinc sulfide (ZnS) nanoparticles to be used for electromagnetic interference (EMI) shielding. PVC-based composite films were fabricated by the incorporation of Ag/ZnS and PANI-Ag/ZnS nanoparticles. These nanoparticles were first analyzed by X-ray diffraction and zetasizer for their crystal structure and particle size. Prepared nanocomposite films were then analyzed for various properties like electrical conductivity, transmission in the near-infrared region (700 nm to 2500 nm), and EMI shielding efficiency in the microwave region (0.1 GHz to 20 GHz). These parameters were characterized by DC Conductivity, NIR spectroscopy, and vector network analyzer. It was found that with the addition of the concentration of nanoparticles, both values of conductivity and shielding efficiency improved. The highest attenuation value in 0.1 to 20 GHz reached 52.5 dB in 0.1 to 20 GHz frequency for 20 wt% PANI-Ag/ZnS and < 0.5% transmission was evaluated in the NIR region.


2020 ◽  
Author(s):  
cong wand ◽  
jian li ◽  
Erwan Paineau ◽  
Abdelghani Laachachi ◽  
Christophe Colbeau-Justin ◽  
...  

<br> <div> <p>Light harvesting capability and charge carriers lifetime play critical roles in determining the photoefficency of photocatalyst. Herein, a one-pot method is proposed to design mesostructured TiO<sub>2</sub> materials by taking advantage of the ability of cellulose nanocrystals (CNC) to self-assemble into chiral nematic structures during solvent evaporation. After the xerogel formation, the as-obtained CNC/TiO<sub>2</sub> hybrid films exhibit a chiral nematic structure and tunable Bragg peak reflection, generating lamellar TiO<sub>2</sub> mesostructure after the biotemplate removal by calcination. More prominently, this straightforward method can be extended to couple TiO<sub>2</sub> with other metal oxides, improving the light-harvesting and charge carriers separation of these photocatalysts, in particular for boosting hydrogen generation. This foolproof approach opens new doors for the development of nanostructured materials for solar energy conversion and catalysis.<br></p></div>


2021 ◽  
Vol 122 ◽  
pp. 111724
Author(s):  
Lu Huang ◽  
Wenting Wang ◽  
Xiyi Yuan ◽  
Qi Zhang ◽  
Mukhtiar Ali ◽  
...  

2020 ◽  
Author(s):  
cong wand ◽  
jian li ◽  
Erwan Paineau ◽  
Abdelghani Laachachi ◽  
Christophe Colbeau-Justin ◽  
...  

<br> <div> <p>Light harvesting capability and charge carriers lifetime play critical roles in determining the photoefficency of photocatalyst. Herein, a one-pot method is proposed to design mesostructured TiO<sub>2</sub> materials by taking advantage of the ability of cellulose nanocrystals (CNC) to self-assemble into chiral nematic structures during solvent evaporation. After the xerogel formation, the as-obtained CNC/TiO<sub>2</sub> hybrid films exhibit a chiral nematic structure and tunable Bragg peak reflection, generating lamellar TiO<sub>2</sub> mesostructure after the biotemplate removal by calcination. More prominently, this straightforward method can be extended to couple TiO<sub>2</sub> with other metal oxides, improving the light-harvesting and charge carriers separation of these photocatalysts, in particular for boosting hydrogen generation. This foolproof approach opens new doors for the development of nanostructured materials for solar energy conversion and catalysis.<br></p></div>


Nanoscale ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 3805-3812 ◽  
Author(s):  
Yi-Tao Xu ◽  
Yiling Dai ◽  
Thanh-Dinh Nguyen ◽  
Wadood Y. Hamad ◽  
Mark J. MacLachlan

Periodic aerogels with a chiral nematic structure were obtained through the solidification of phase-separated cellulose nanocrystal suspensions.


2021 ◽  
Author(s):  
Abhineet Verma ◽  
Sk Saddam Hossain ◽  
Sailaja S Sunkari ◽  
Joseph Reibenspies ◽  
Satyen Saha

Lanthanides (LnIII) are well known for their characteristic emission in the Near-Infrared Region (NIR). However, direct excitation of lanthanides is not feasible as described by Laporte’s parity selection rule. Here,...


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