Submicrometer periodic patterns fixed by photopolymerization of dissipative structures

Hoischen, Andreas; Benning, Stephan A.; Kitzerow, Heinz‐S.

doi:10.1063/1.2990762

Cited by 10 publications

(8 citation statements)

References 15 publications

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“…Voltages with higher frequencies induce periodic structures without flow, for example, a chevron pattern ͑dielectric regime͒. [17][18][19] The aim of this work was to investigate the stability diagrams in the ͑frequency, voltage͒ plane and the influence of composition and UV intensity on the properties of a simple model system that is particularly suitable for this purpose ͑Table I͒. However, more recent studies reveal the appearance of dissipative structures also in certain liquid crystals with positive dielectric anisotropy [7][8][9] and in liquid crystals with negative anisotropy of the conductivity.…”

Section: Introductionmentioning

confidence: 99%

Electroconvection of liquid crystals: Tool for fabricating modulated polymer surfaces

Hoischen

Benning

Kitzerow

2009

Journal of Applied Physics

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Reversible optical control of transmittance in polymer/liquid crystal composite films by photoinduced phase transitionElectrically induced dissipative structures in liquid crystals can be stored by the photocuring of reactive mesogens. Thus, spontaneous pattern formation can be used to fabricate phase gratings or polymer films with a periodic surface modulation from an initially uniform sample. Different patterns, both in the conductive and in the dielectric regimes, have been stored. Photopolymerization and subsequent investigation by atomic force microscopy provide a useful tool in analyzing dissipative structures, even if the lattice constants are smaller than 1 m. This method indicates surface modulations with amplitudes of up to 12 nm and periodicities between 800 nm and several tens of micrometers. The influences of composition and curing conditions on the topography have been studied.

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Section: Introductionmentioning

confidence: 99%

Electroconvection of liquid crystals: Tool for fabricating modulated polymer surfaces

Hoischen

Benning

Kitzerow

2009

Journal of Applied Physics

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“…1(a)). [27][28][29][30][31][32][33][34] It has been repeatedly demonstrated that EHD-induced periodic DGs can also be promising for beam steering applications 28 in various optoelectronic devices, such as tunable spectral filters, polarizing sensors, etc. 29 Recently, a fascinating example of light-driven EHD instabilities was demonstrated by G. Zhou et al 30 The LC mixture with a high negative dielectric anisotropy (De = À8.3) was doped with the spiropyran photochromic substance.…”

Section: Introductionmentioning

confidence: 99%

Photo- and electro-controllable 2D diffraction gratings prepared using electrohydrodynamic instability in a nematic polymerizable mixture

et al. 2023

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“…Among all, LC-based devices are more economical and efficient owing to their reliability, cost effectiveness, and low operating voltage requirement . The mechanical and thermal properties of LCs are further enhanced by combining them with polymer materials to form liquid crystal polymer composites (LCPCs) with improved switching properties. − These materials have dynamic electro-optic (E-O) properties and are, therefore, excellent candidates for the fabrication of optoelectronic devices. LCPCs have many benefits over conventional LC-based devices, such as nondegradability over time and no requirement of a polarizer in addition to their enhanced resistance to thermal and mechanical stress. − …”

Section: Introductionmentioning

confidence: 99%

Pseudopeptidic Polymer Microsphere-Filled Liquid Crystals as High-Performance Light-Scattering Switches

Kumari

Dhawan

Singh

et al. 2021

ACS Appl. Polym. Mater.

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We, herein, report the fabrication of light-scattering switches from polymer microsphere-filled liquid crystals (PFLCs) using pseudopeptidic bottlebrush polymers. A simple method of precipitation of a polymer using the 4-cyano-4′-pentylbiphenyl (5CB) nonsolvent is employed for the preparation of PFLC devices. For this, a series of phenylalanine (Phe)-based bottlebrush polymers having different chain lengths are synthesized by ring-opening metathesis polymerization (ROMP) using the Grubbs second-generation ruthenium catalyst and used in a nematic liquid crystal (LC) matrix. The developed PFLC devices are well-characterized using various ultramicroscopic techniques such as field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM). For the first time, the effect of the molecular weight of a polymer on electro-optic (E-O) properties of PFLC is investigated. PFLCs show significant differences in microsphere size, required operating voltage, transmittance, contrast ratio (CR ratio), memory effect, and switching speed upon subtle variation of the dopant polymer units. Overall, we demonstrated that the chain length of a polymer plays a crucial role in controlling the performance of PFLC devices. The presented methodology offers promising possibilities for the fabrication of PFLC-based switchable scattering devices with improved performance for optoelectronic applications.

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Submicrometer periodic patterns fixed by photopolymerization of dissipative structures

Cited by 10 publications

References 15 publications

Electroconvection of liquid crystals: Tool for fabricating modulated polymer surfaces

Electroconvection of liquid crystals: Tool for fabricating modulated polymer surfaces

Photo- and electro-controllable 2D diffraction gratings prepared using electrohydrodynamic instability in a nematic polymerizable mixture

Pseudopeptidic Polymer Microsphere-Filled Liquid Crystals as High-Performance Light-Scattering Switches

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