Eco-friendly PDLC composites based on chitosan and cholesteryl acetate

Preparation and Characterization of Bilayer Polymer-Dispersed Liquid Crystals Doped with Gd2O3 Nanoparticles and Rhodamine B Base Fluorescent Dye

Using the polymerization-induced phase separation (PIPS) method, bilayer polymer-dispersed liquid crystal (PDLC) films with a PDLC-PVA-PDLC structure were prepared in this work. It was found that all PDLC performance indexes were affected by polymer mesh size after comparing the microscopic morphology and electro-optical properties of samples with different monomer ratios. Gd2O3 nanoparticles and rhodamine B base fluorescent dyes introduced into the bilayer PDLC optimized the samples' electro-optical properties and developed new functionalities. In addition, the bilayer PDLC doped with Gd2O3 and rhodamine B base held excellent progressive driving functions as well as stable durability properties. Samples doped with Gd2O3 nanoparticles and rhodamine B base also produced excellent anti-counterfeiting effects under UV irradiation at different angles, further exploiting the application potential of PDLC.

MoS2 nanoflower decorated bio-derived chitosan nanocomposites for sustainable energy storage: Structural, optical and electrochemical studies

Bio-derived chitosan-molybdenum di sulfide (Cs-MoS2) nanocomposites are prepared by a simple and economical aqueous casting method with varying concentrations of MoS2. The structural, surface morphological, optical, and electrochemical properties of the nanocomposites were studied. FTIR analysis reveals the strong interaction between Cs and MoS2. FESEM micrograph showed an increment of the surface roughness due to the incorporation of MoS2 layers into Cs. The surface wettability of the nanocomposites was found to be decreased from 73° to 33° due to the incorporation of MoS2 into the chitosan. UV-vis spectroscopy study demonstrates a reduction of optical bandgap from 4.29 to 3.44 eV as the nanofiller, MoS2, introduces localized states within the forbidden energy bandgap. The incorporation of MoS2 was found to increase the specific capacitance of Cs from 421 mFg-1 to 1589 mFg-1 at a current density of 100 μAg-1. The EIS analysis revealed an increase in the pseudo-capacitance from 0.09 μF to 4.13 μF and a reduction of charge transfer resistance that comes from the nanofiller contribution. MoS2 nanoflower introduces more active sites and expands the electroactive zone, thus improving the charge storage property of Cs. The Cs-MoS2 may offer a new route for the synthesis of eco-friendly, biodegradable, and electrical storage devices.

Preparation of Progressive Driving Bilayer Polymer-Dispersed Liquid Crystals Possessing a PDLC-PVA-PDLC Structure

In this paper, the bilayer polymer-dispersed liquid crystals possessing a PDLC-PVA-PDLC structure were prepared by integrating two monolayer PDLCs. The effect of the polymer mesh size on the electro-optical properties of a bilayer PDLC was investigated by comparing the micro-morphology and electro-optical curves under different polymerization conditions. In addition, the impact of doping MoO2 nanoparticles with surface modification on the comprehensive performance of the bilayer PDLC was further researched. The contrast ratio of the bilayer PDLC prepared under the optimal conditions was improved by more than 90% and still maintained excellent progressive driving performance. Therefore, the development of a bilayer PDLC with optimal electro-optical properties will significantly enhance the technological prospects for the application of PDLC-based devices in smart windows, displays, and flexible devices.

A Stable PDLC Film with High Ageing Resistance from an Optimized System Containing Rigid Monomer

With the switchability between transparent and light-scattering states, polymer-dispersed liquid crystals (PDLC) are widely used as smart windows, flexible display devices, projectors, and other devices. In outdoor applications, in addition to excellent electro-optical properties, there is also a high demand for film stability. In this work, a PDLC film with high mechanical strength and structural stability is prepared that can maintain stability at 80 °C for 2000 h. By choosing liquid crystals with a wide temperature range, adopting acrylate polymer monomers containing hydroxyl groups, and adjusting the polymer content, the PDLC film can work well from -20 °C to 80 °C. On this basis, the effects of the introduction of rigid monomers on the mechanical properties and electro-optical properties of PDLC films are investigated.

Preparation of Highly Durable Reverse-Mode Polymer-Stabilized Liquid Crystal Films with Polymer Walls

Reverse-mode polymer-stabilized liquid crystal (PSLC) films have wide applications in smart windows for cars as well as buildings and dimming glasses due to their low haze, low energy consumption, and better safety in case of emergency power off. However, PSLC films usually have poor stability of electro-optical properties due to their low polymer content (ca. 5 wt %), and it still remains a challenging task to improve the stability and processability by increasing the polymer content in PSLC as the driving voltage might dramatically increase. In this work, a reverse-mode PSLC film with polymer walls was prepared, which showed excellent stability of electro-optical properties even after 150 000 cycles. The film was prepared through polymerization with a photomask, in which the monomers concentrated on specific areas to form patterned polymer walls. In this way, the polymer content could be increased dramatically and the anchoring effect would not be too strong, thus avoiding a sharp increase in the driving voltage. As a result, the desired reverse-mode film with high stability, relatively low driving voltage, and high contrast ratio was obtained. The effects of monomer compositions, curing temperature, UV light intensity, and the pattern of the photomask on the microstructures, as well as electro-optical performances of the films were carefully studied. This work provides a new idea for the preparation of reverse-mode electrically switchable light-transmittance controllable films with excellent stability and good electro-optical performance, which would broaden their application in smart cars, building windows, and dimming glasses for light management and potential energy saving.

Liquid crystal droplet design by using pseudopeptidic bottlebrush polymer additives

Liquid crystal (LC) droplets are promising candidates for sensing applications due to their high sensitivity to surface anchoring changes, resulting in readily detectable optical effects. Herein, we have designed and synthesized amino acid-based bottlebrush polymers and investigated their impact on LC director configurations in the droplets. The pseudopeptidic bottlebrush polymers with an aromatic (phenyl) and aliphatic appendages are synthesized using ring-opening metathesis polymerization (ROMP). Polymer dispersed liquid crystal (PDLC) samples are prepared by employing pseudopeptidic bottlebrush polymers and 4-cyano-4'-pentylbiphenyl (5CB) LC via solvent-induced phase separation (SIPS) technique. Due to π-π stacking, the phenyl group favours radial configuration, whereas the repulsion between 5CB and aliphatic groups induces molecular alignment leading to bipolar droplet arrangement. The impact of various pendant groups attached to the polymer on the prepared PDLC sample's surface characteristics and free energy components is illustrated. The sensing capability of 5CB dispersed in pseudopeptidic bottlebrush polymers for various pH solutions is investigated using polarizing optical microscopy (POM). The PDLC samples are moderately permeable to water and sensitive to different pH solutions. The results demonstrate a simplified and straightforward approach for preparing LC-based biosensors and chemical sensors.

Recent Advances in The Polymer Dispersed Liquid Crystal Composite and Its Applications

Polymer dispersed liquid crystals (PDLCs) have kindled a spark of interest because of their unique characteristic of electrically controlled switching. However, some issues including high operating voltage, low contrast ratio and poor mechanical properties are hindering their practical applications. To overcome these drawbacks, some measures were taken such as molecular structure optimization of the monomers and liquid crystals, modification of PDLC and doping of nanoparticles and dyes. This review aims at detailing the recent advances in the process, preparations and applications of PDLCs over the past six years.