Wavelength Tuning of the Photonic Band Gap of an Achiral Nematic Liquid Crystal Filled into a Chiral Polymer Scaffold

Wood, Simon; Fells, Julian A. J.; Elston, Steve J.; Morris, Stephen M.

doi:10.1021/acs.macromol.6b01297

Cited by 23 publications

(14 citation statements)

References 31 publications

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“…Tailoring polymer architectures with innovations is regarded as a superior procedure for a wide array of applications. − In general, the tailoring of SCLCPs can be categorized into three parts including the polymeric matrix, LC moiety and flexible spacer. Recently, there have been contributions to the rational design of polymer matrixes to determine precise structure–property relationships in LC functional materials. − Polymeric matrixes are divided into many categories according to their composition, including homopolymers, copolymers and complexes and others. The use of copolymers instead of homopolymers as polymeric matrixes could facilitate major specific advantages.…”

Section: Results and Discussionmentioning

confidence: 99%

Effect of Topology and Composition on Liquid Crystal Order and Self-Assembly Performances Driven by Asynchronously Controlled Grafting Density

Han

Zhu

et al. 2017

Macromolecules

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A series of thermo-tunable liquid crystal block copolymers (LCBCs) with well-designed architectures were successfully synthesized. Linear/star poly[4-(4-vinylphenyl)-1-butene]-block-polybutadiene (PVSt-co-PB) moieties were obtained using living anionic copolymerization of 4-(4-vinylphenyl)-1-butene with butadiene, and topological [PVSt-co-PB]-LCBCs were generated through the adherence of mesogenic moiety via facile hydrosilylation. The PVSt LC block had well-defined grafting densities of approximately 100%, 70%, and 40%, whereas the PB LC block had an asynchronously tunable grafting density. This work included comprehensive studies on their self-assembly and yielded some interesting results. The influences of topologies and compositions on the phase transition behaviors and polarized optical performances of the resulting LCBCs that were driven by asynchronously controlled grafting density were carefully illustrated. The LCBCs with controlled molecular weight (MW) and narrow PDI showed wider LC phase ranges (ΔT) and a high tunability was added into the construction to aid thermos-responsive devices. The wide ΔT and high thermo-stability were demonstrated to be complementary between two LC blocks. However, the response-time and aggregation morphology in POM showed close similarity to LC blocks and showed a gradient in temperature-dependent changes with the PB LC block at a lower temperature and the PVSt LC block at a higher temperature. It is common for LC texture to change with varying temperature, whereas the gradient switching process was unique to LC blocks, which was further confirmed by temperature-dependent WAXD. In particular, the structural reorganization was determined to be driven by asynchronous grafting density by measuring the temperature-variation AFM, in that the asynchronous-tunable motion between LC blocks facilitates small phase separation.

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Section: Results and Discussionmentioning

confidence: 99%

Effect of Topology and Composition on Liquid Crystal Order and Self-Assembly Performances Driven by Asynchronously Controlled Grafting Density

Han

Zhu

et al. 2017

Macromolecules

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“…To mimic their performance in reflectivity, several stacked structures were made before Guo et al However, such stacked layers had drawbacks such as the diffusion between soft layers in fluid media, optical defects and losses at the interfaces. Wood et al [74], refilled the polymer template made from a chiral nematic liquid crystal with an achiral nematic liquid crystal. They tuned the photonic band gap in the refilled system by applying an electric field.…”

Section: Chiral Nematic and Blue Phasesmentioning

confidence: 99%

“…In this study, it was found that a negative strain introduced on the polymeric film produced an increase in the sensitivity of the sensor up to 15 times compared to their unstrained counterparts. Wood et al [74], refilled the polymer template made from a chiral nematic liquid crystal with an achiral nematic liquid crystal. They tuned the photonic band gap in the refilled system by applying an electric field.…”

Section: Chiral Nematic and Blue Phasesmentioning

confidence: 99%

Liquid Crystals Templating

Nagaraj

2020

Crystals

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Liquid crystal templating is a versatile technique to create novel organic and inorganic materials with nanoscale features. It exploits the self-assembled architectures of liquid crystal phases as scaffolds. This article focuses on some of the key developments in lyotropic and thermotropic liquid crystals templating. The procedures that were employed to create templated structures and the applications of these novel materials in various fields including mesoporous membranes, organic electronics, the synthesis of nanostructured materials and photonics, are described.

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“…Past decades are characterized by the explosive development of technologies based on optoelectronics and photonics . The modern elemental base of these technologies includes refractive, diffraction and optical fiber components.…”

Section: Introductionmentioning

confidence: 99%

Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

Ryabchun

Bobrovsky

2018

Advanced Optical Materials

185

106

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refractive, diffraction and optical fiber components. In particular, diffraction grating (DG) is one of the key elements for the design and creation of modern optoelectronic devices. One of the most prominent materials for the creation of DGs is liquid crystals. The main feature of these systems is that liquid crystals combine properties such as optical anisotropy inherent for crystals and molecular mobility. High sensitivity to an external field, in particular to an electric field, makes liquid crystals very useful for the creation of DGs with tunable properties. The combination of these properties enables easy control of optical characteristics of such systems and opens wide perspectives for the design of new materials for diffractive optics.Among the different types of liquid crystalline (LC) phases, cholesteric liquid crystal (CLC) phase possesses intrinsic periodicity in the form of the helical supramolecular structure (Figure 1). With the realization of definite alignment conditions, this periodicity has been exploited for generation of DGs. [8,9] Another remarkable feature of the cholesteric mesophase is selective light reflection with the reflection wavelength determined by the simple Equation (1) where n is the average refractive index, and P is the helix pitch. The specific value of helix pitch depends on the chemical structure of the molecules forming the cholesteric phase and concentration of chiral moieties. One of the easiest ways to obtain the cholesteric mesophase is by doping the nematic matrix with chiral components (Figure 1). Variation of structure of chiral molecules by external stimuli leading, for examples, to the photoisomerization, is effectively used for fine tuning of the helix pitch. [10][11][12][13][14][15][16][17] In addition, the application of an electric field also provides a convenient opportunity to change optical properties of the CLC phase. [18][19][20][21] These unique properties enable to design a great variety of optical elements and devices based on CLC layers, films, or cells. Among them it is necessary to mention the media for photo-optical data recording, [22][23][24][25] electrically switchable mirrors, [26,27] optically controllable linearpolarization rotators, [28] coatings with controllable friction and adhesion, [29] materials for display technology, [23,30] secure Modern optics and photonics constantly require break-through materials and designs in order to achieve miniature, lightweight, highly tunable, and effective optical devices. One of the basic optical components is the diffraction grating (DG), widely used for the dispersion of light, beam steering, etc. This review gathers research efforts on diffractive optical elements based on cholesteric liquid crystal (CLC) materials with a supramolecular helical architecture. All main types and fabrication approaches of periodic diffractive structures from CLCs are classified and described. Key optical properties of DGs, their advantages and drawbacks are considered. Special attention is paid on the tunability of DG...

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Wavelength Tuning of the Photonic Band Gap of an Achiral Nematic Liquid Crystal Filled into a Chiral Polymer Scaffold

Cited by 23 publications

References 31 publications

Effect of Topology and Composition on Liquid Crystal Order and Self-Assembly Performances Driven by Asynchronously Controlled Grafting Density

Effect of Topology and Composition on Liquid Crystal Order and Self-Assembly Performances Driven by Asynchronously Controlled Grafting Density

Liquid Crystals Templating

Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

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