Vertical Alignment of Liquid Crystals Over a Functionalized Flexible Substrate

Abstract

A simple and effective approach for vertical alignment of liquid crystals (LCs) over a functionalized transparent flexible substrate is described. Surface characterization of this commercially available plastic substrate through X-ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared spectroscopy (ATR-IR) indicated that cellulose acetate is main component of the transparent substrate. This substrate was chemically functionalized with a suitable LC compound. A trimethoxysilane terminated new rod-shaped mesogen is synthesized and covalently attached to the pre-treated film through silane condensation reaction. LC functionalization of the polymer film is confirmed through contact angle (CA), atomic force microscopy (AFM), XPS and ATR-IR spectroscopy studies. Versatility of the LC modified flexible substrates for the alignment of bulk LC sample at substrate-LC interface was assessed for nematic (N) and smectic A (SmA) phases. Remarkably, LC functionalized cellulose acetate films were found to be highly efficient in assisting a perfect homeotropic alignment of LCs (for both, a room temperature N and a high temperature SmA phase) over the entire area of the LC sample under observation indicating their superior aligning ability in comparison to their unmodified and octadecyltrimethoxysilane (OTS) modified counterparts. The demonstrated method of surface modification of flexible polymer film is easy, surface modified substrates are stable for several months, retained their aligning ability intact and more importantly they are reusable with maximum delivery.

Atomic‐Layer‐Deposited Amorphous MoS2 for Durable and Flexible Li–O2 Batteries

“…The peak at ≈286.2 eV in C 1s spectrum is consistent with absorbed electrolyte (O–CH 3 ) (Figure A) . The weak peaks at ≈288.6 eV (Figure A), ≈534.4 eV and ≈532.1 eV (Figure D) correspond to the OCO bonds which may be associated with the degradation of electrolyte or dimethyl carbonate residues (used for rinsing electrodes to remove tetraethylene glycol dimethyl ether (TEGDME) before XPS characterization) . Moreover, O 2 crossover that cannot be effectively blocked in organic liquid electrolytes and volume change of Li metal during cycling may also give rise to the degradation of Li anode.…”

Manipulating the Coordination Chemistry of RuN(O)C Moieties for Fast Alkaline Hydrogen Evolution Kinetics

“…Each C 1s spectrum involves four peaks at the binding energies (BEs) of 284.8, 286, 287.5, and 289 eV, corresponding to graphitized sp 2 carbon (CC), CN(O), CN(O), and COOH, respectively. [ 15 ] The fitted Ru 3d 5/2 spectra reveal two contributions. One with BE between 281 and 280 eV can be attributed to metallic Ru(0), and the other one between 282 and 281 eV can be assigned to the oxidized Ru species.…”

Reverse Mode Polymer Dispersed Liquid Crystal-based Smart Windows: A Progress Report

“…In recent years, flexible optoelectronic devices have received significant attention as they are lightweight, cost-effective, thin, and easy to use [33]. The market trends demand that flexible PSLC films should be developed.…”