Mesogen-co-polymerized transparent polyimide as a liquid-crystal alignment layer with enhanced anchoring energy

Tong, Faqin; Chen, Shuangshuang; Lü, Xuemin; Lu, Qinghua

doi:10.1039/c8ra00479j

Cited by 9 publications

(3 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As illustrated in Figure a, the orientational control can be either single-axis, where only the long axis of the AWCs is aligned, or dual-axis, where not only the long axis but also the in-plane orientations of the AWCs are aligned. Mechanical shearing and applying alignment films have been proven effective in producing the single-axis homogeneous alignment of LC materials, ,− whereas dual-axis orientational control has been more difficult to achieve. Dual-axis orientational control was only achieved recently in studies that apply strong magnetic or electric fields to obtain the dual-axis homogeneous and homeotropic alignment of films. − Most amphiphiles, however, are more sensitive to specific solvents than to the electromagnetic fields.…”

Section: Resultsmentioning

confidence: 99%

Dual-Axis Alignment of Bulk Artificial Water Channels by Directional Water-Induced Self-Assembly

et al. 2022

View full text Add to dashboard Cite

Approaching single-crystal-like morphology has always been important in driving materials toward their optimal properties. With only orientational order, liquid crystal (LC) materials require dual-axis orientational control to optimize their structural order in the bulk phase. However, current external guiding fields such as electrical, magnetic, and mechanical guiding fields are less effective in aligning amphiphilic LCs. In this study, water is developed as an excellent structural stabilizer and orientation-directing agent of an amphiphilic discotic molecule (AD) in the water-induced self-assembly (WISA) process. Thermal analysis and structural characterization results show that water increases the stability and domain sizes of the hexagonal columnar (Colh) phase of the AD by co-assembling with the ADs to form bulk artificial water channels (AWCs). Moreover, through control over the nucleation conditions (degree of supercooling and location of nucleation), dual-axis alignment in both the planar and vertical growth of the AWCs is achieved by applying water as the guiding field in the directional WISA. With precise control over the hierarchical structures, the bulk AWC array of the AD delivers excellent salt rejection properties and water permeability. Considering that all the amphiphilic LCs have hydrophilic segments, these new roles of water in the WISA process could launch the further development of functional amphiphilic LCs by providing a dynamic interaction and a readily available guiding field.

show abstract

Section: Resultsmentioning

confidence: 99%

Dual-Axis Alignment of Bulk Artificial Water Channels by Directional Water-Induced Self-Assembly

et al. 2022

View full text Add to dashboard Cite

show abstract

“…(1) The ion-free AL material must be quite pure. (2) It must have the ability to form a robust film with excellent dimensional stability, excellent chemical/thermal stability, good compatibility with LC molecules, excellent optical transparency, and a high surface hardness to withstand the mechanical rubbing process [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer

et al. 2021

View full text Add to dashboard Cite

This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA−ODA-based polyimide (PI) prepared by the thermal cyclic dehydration of the polyamic acid (PAA) was soluble in various polar solvents. After forming a thin film by mixing trifunctional epoxide [4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline] with the 6FDA−ODA-based PAA, it was confirmed that thermal curing at −110 °C caused an epoxy ring opening reaction, which could result in the formation of a networked polyimide not soluble in tetrahydrofuran. The crosslinked PI film showed a higher rigidity than the neat PI films, as measured by the elastic modulus. Furthermore, based on a dynamic mechanical analysis of the neat PI and crosslinked PI films, the glass transition temperatures (Tgs) were 217 and 339 °C, respectively, which provided further evidence of the formation of crosslinking by the addition of the epoxy reagent. After mechanical rubbing using these two PI films, an LC cell was fabricated using an anisotropic PI film as an LC alignment film. LC cells with crosslinked PI layers showed a high voltage holding ratio and low residual direct current voltage. This suggests that the crosslinked PI has good potential for use as an LC alignment layer material in advanced LCD technologies that require high performance and reliability.

show abstract

“…Polyimide (PI), one of the best comprehensive organic polymer materials, usually applied in aerospace, microelectronics, liquid crystal, separation membrane, laser fields in virtue of its excellent dielectric properties, chemical resistance, thermostability, and mechanical performance, as well as the tribological properties under specific environments, like under high load, high temperature, and in seawater environment. However, the excellent performance of PI has been unable to meet the demand of increasing development of industries.…”

Section: Introductionmentioning

confidence: 99%

High mechanical and tribological performance of polyimide nanocomposite reinforced by fluorinated graphene oxide

Min

Liang

et al. 2019

Polymer Composites

View full text Add to dashboard Cite

Novel polyimide/fluorinated graphene oxide (PI/FGO) nanocomposites with outstanding mechanical, thermal, and tribological properties were obtained using FGO nanosheets which were successfully fabricated by simple hydrothermal reaction. FGO exhibited distinguished interface adhesion with PI matrix due to covalent bonds, resulting improved mechanical and wear resistance of PI/FGO nanocomposites. Wherein, PI/FGO‐0.5 nanocomposite demonstrated conspicuous tribological performance accompanied with 33.1% decrease of friction coefficient and 80.8% reduction of wear rate compared with pure PI under dry friction. Notably, PI/FGO nanocomposites manifested better wear resistance under seawater than that under dry friction, illustrating its great potentiality as high wear‐resistant material suitable for ocean environment.

show abstract

Mesogen-co-polymerized transparent polyimide as a liquid-crystal alignment layer with enhanced anchoring energy

Abstract: This work shows the key role played by the mesogens side groups of polyimides in enhancing the azimuthal anchoring energy.

Cited by 9 publications

References 34 publications

Dual-Axis Alignment of Bulk Artificial Water Channels by Directional Water-Induced Self-Assembly

Dual-Axis Alignment of Bulk Artificial Water Channels by Directional Water-Induced Self-Assembly

Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer

High mechanical and tribological performance of polyimide nanocomposite reinforced by fluorinated graphene oxide

Contact Info

Product

Resources

About