Composite of DNA-Stabilized Multiwalled Carbon Nanotube and Nematic Liquid Crystal for Display Performance Optimization

Abstract

We have prepared composites of a nematic liquid crystal (NLC) mixture to improve display performance by doping multiwalled carbon nanotubes (MWCNTs) and single-stranded-DNA-wrapped MWCNTs. Polarized optical microscopy images indicated the uniformity of the composite. Infrared absorption spectra showed there existed an interaction between MWCNTs and 4-pentyl-4′-cyanobiphenyl (5CB, a practical solvent-type monomer NLC) due to π–π stacking and charge transfer, indicating the anchoring of 5CB molecules on the MWCNT surface. The electro-optical property proved the incorporation of MWCNTs and DNA-wrapped MWCNTs reduced the threshold voltage and response time, thus following the changed splay elastic constant and rotational viscosity coefficient of LC, reflecting that DNA can improve the stability of MWCNTs in 5CB. Moreover, dielectric measurement showed the enhanced value to dielectric anisotropy and shift in relaxation frequency, including the changes of dielectric permittivity and loss, revealing the electrically “inertness” MWCNTs at high frequencies and the DNA-induced broadened frequency range of low dielectric loss. Then electrical conductivity tests further proved the cooperative orientation of MWCNTs with 5CB under the applied voltage and the contribution of MWCNTs’ high conducting along the long axis. This study revealed that MWCNT doping could improve the physical properties of NLCs, and DNA wrapping could pave a promising way toward stabilized MWCNT/NLC composites for display performance optimization.