Discotic liquid crystalline crosslinkers and anisotropic networks

Braun, Christian; Lub, Johan

doi:10.1080/026782999203832

Cited by 17 publications

(12 citation statements)

References 25 publications

(31 reference statements)

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“…Chemicals. 11-Bromoundecyl methacrylate 30 and 11-(4hydroxyphenoxy)undecyl acrylate 31 were kindly provided by Philips Research. 4,4′-Biphenol, sodium iodide, anhydrous N,N-dimethylformamide, anhydrous chloroform, thionyl chloride, anhydrous tetrahydrofuran (THF), t-butyl-hydroquinone, 4-carboxybenzo-15-crown-5, terephthaloyl chloride, magnesium sulfate, hydrochloric acid (37%), and silica were purchased from Merck Life Science.…”

Section: Methodsmentioning

confidence: 99%

“…Subsequent cross-linking fixates the nanostructures. LC polymer membranes have already been investigated for water filtration. − However, these materials are rarely used for gas separations. Bara et al showed the importance of molecular order for gas separation, by testing the performance of light gasses, of cross-linked LC polymer membranes with an ordered but not aligned columnar morphology.…”

Section: Introductionmentioning

confidence: 99%

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On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation

et al. 2021

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To prevent greenhouse emissions into the atmosphere, separations like CO2/CH4 and CO2/N2 from natural gas, biogas, and flue gasses are crucial. Polymer membranes gained a key role in gas separations over the past decades, but these polymers are often not organized at a molecular level, which results in a trade-off between permeability and selectivity. In this work, the effect of molecular order and orientation in liquid crystals (LCs) polymer membranes for gas permeation is demonstrated. Using the self-assembly of polymerizable LCs to prepare membranes ensures control over the supramolecular organization and alignment of the building blocks at a molecular level. Robust freestanding LC membranes were fabricated that have various, distinct morphologies (isotropic, nematic cybotactic, and smectic C) and alignment (planar and homeotropic), while using the same chemical composition. Single gas permeation data show that the permeability decreases with increasing molecular order while the ideal gas selectivity of He and CO2 over N2 increases tremendously (36-fold for He/N2 and 21-fold for CO2/N2) when going from randomly ordered to the highly ordered smectic C morphology. The calculated diffusion coefficients showed a 10-fold decrease when going from randomly ordered membranes to ordered smectic C membranes. It is proposed that with increasing molecular order, the free volume elements in the membrane become smaller, which hinders gasses with larger kinetic diameters (Ar, N2) more than gasses with smaller kinetic diameters (He, CO2), inducing selectivity. Comparison of gas sorption and permeation performances of planar and homeotropic aligned smectic C membranes shows the effect of molecular orientation by a 3-fold decrease of the diffusion coefficient of homeotropic aligned smectic C membranes resulting in a diminished gas permeation and increased ideal gas selectivities. These results strongly highlight the importance of molecular order and orientation in LC polymer membranes for gas separation.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation

et al. 2021

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“…Accordingly, the eigen‐birefringence value is almost the same as the value before polymerization. And because the magnetic field orientation condition for THOcB (triphenylene hexa–octyloxybenzoate) by Ikeda et al is considered the state of ideal orientation order before polymerization, that the values are almost 0.08 suggests that the disorder of the liquid crystal orientation condition by polymerization of acrylate group virtually does not exist 26–30…”

Section: Hybrid Orientation Of Discotic Liquid Crystal12mentioning

confidence: 99%

Orientation Control and Fixation of Discotic Liquid Crystal

Kawata

2002

The Chemical Record

165

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We established hybrid, horizontal, vertical, and vertical-twisted alignment of discotic liquid crystals on web-coating thin film. Newly developed materials are the photopolymerizable discotic liquid crystals, in order to fix desired novel alignment, the alignment promoters that deposit toward air surface during web coating, followed by drying of solvent, and then accomplish desired alignment of liquid crystals, the alignment layers that promote desired alignment of liquid crystals from the substrate side and the chiral agents, which have strong chiral powers in small amounts. Hybrid aligned discotic liquid crystal thin film has proven quite effective in expanding the viewing angle of thin film transistor liquid crystal displays.

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“…14−16 However, the reactive building blocks have been limited solely to the calamitic RMs up to now and the construction mechanisms of hierarchical superstructures in the anisotropic LC solvents have not been fully understood. 17,18 Even though the developments of LCD technology have been mainly based on the calamitic molecules, the disk-shaped molecules recently start to open new doors in electrical and optical applications, 19−22 partially due to the extraordinary properties of disk-shaped molecules such as 1D electrical, thermal and photoconductivity including ferroelectric and photoelectric properties. 23−29 In this circumstance, here is a question: what is the self-assembly process for the construction of hierarchical superstructures when the building block is the disk-shaped LC with reactive functions?…”

Section: ■ Introductionmentioning

confidence: 99%

Hierarchical Striped Walls Constructed by the Photopolymerization of Discotic Reactive Building Blocks in the Anisotropic Liquid Crystal Solvents

et al. 2015

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A triphenylene-based reactive mesogenic molecule (abbreviated as HABET) was newly designed and synthesized as a programmed building block to construct the striped walls by the photopolymerization in the anisotropic liquid crystal (LC) solvents. On the basis of thermal, scattering and microscopic analyses, it was found that HABET formed three ordered structures: a columnar hexagonal LC phase (Φ H ), a tilted columnar hexagonal LC phase (Φ T ) and a highly ordered columnar oblique crystal phase (Φ OK ). The microscopic molecular orientations in the hierarchical superstructures were controlled in the anisotropic LC solvents with the help of surface anchoring forces, while the dimensions of the striped wall morphologies were determined by the patterned photomasks. The long axis of self-assembled columns in the striped walls was perpendicular to the surface alignment direction regardless of the photomask direction. Additionally, it was realized that the shapes of water drops as well as the surface water contact angles can be tuned by the hierarchical superstructures and morphologies of the polymerized HABET networks. The anisotropic hierarchical superstructures and morphologies concurrently fabricated during the polymerization in the anisotropic LC medium can offer a potential pathway for liquid transportation in the microfluidic devices.

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Discotic liquid crystalline crosslinkers and anisotropic networks

Cited by 17 publications

References 25 publications

On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation

On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation

Orientation Control and Fixation of Discotic Liquid Crystal

Hierarchical Striped Walls Constructed by the Photopolymerization of Discotic Reactive Building Blocks in the Anisotropic Liquid Crystal Solvents

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