Dispersion of multi walled carbon nanotubes in a hydrogen bonded liquid crystal

2010 ◽  
Vol 405 (21) ◽  
pp. 4418-4423 ◽  
Author(s):  
V.N. Vijayakumar ◽  
M.L.N. Madhu Mohan
2021 ◽  
Vol 2 (4) ◽  
pp. 466-481
Author(s):  
Bhupendra Pratap Singh ◽  
Samiksha Sikarwar ◽  
Kamal Kumar Pandey ◽  
Rajiv Manohar ◽  
Michael Depriester ◽  
...  

In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices.


2015 ◽  
Vol 55 (1) ◽  
pp. 140 ◽  
Author(s):  
Li Hui ◽  
Pan Fan ◽  
Wu Yuntao ◽  
Zhang Yanduo ◽  
Xie Xiaolin

2015 ◽  
Vol 6 ◽  
pp. 396-403 ◽  
Author(s):  
Amanda García-García ◽  
Ricardo Vergaz ◽  
José Francisco Algorri ◽  
Xabier Quintana ◽  
José Manuel Otón

The inclusion of nanoparticles modifies a number of fundamental properties of many materials. Doping of nanoparticles in self-organized materials such as liquid crystals may be of interest for the reciprocal interaction between the matrix and the nanoparticles. Elongated nanoparticles and nanotubes can be aligned and reoriented by the liquid crystal, inducing noticeable changes in their optical and electrical properties. In this work, cells of liquid crystal doped with high aspect ratio multi-walled carbon nanotubes have been prepared, and their characteristic impedance has been studied at different frequencies and excitation voltages. The results demonstrate alterations in the anisotropic conductivity of the samples with the applied electric field, which can be followed by monitoring the impedance evolution with the excitation voltage. Results are consistent with a possible electric contact between the coated substrates of the LC cell caused by the reorientation of the nanotubes. The reversibility of the doped system upon removal of the electric field is quite low.


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