Paintable temperature-responsive cholesteric liquid crystal reflectors encapsulated on a single flexible polymer substrate

Khandelwal, Hitesh; Heeswijk, Ellen P. A. van; Schenning, Albert P. H. J.; Debije, Michael G.

doi:10.1039/c9tc02011j

Cited by 36 publications

(35 citation statements)

References 31 publications

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“…[ 16–21 ] Such paints are useful to adjust surface wettability and adhesion and/or the reflective and aesthetic properties of a coating. Photonic paints usually require delicate processing to promote the formation of the photonic nanostructure, [ 21–23 ] and brush or spray‐painting is not possible. Recently, structurally blue colored silica spheres have been reported as photonic pigments that can be mixed with a binder to form static photonic paints that can be brush‐painted.…”

Section: Introductionmentioning

confidence: 99%

Brush‐Paintable, Temperature and Light Responsive Triple Shape‐Memory Photonic Coatings Based on Micrometer‐Sized Cholesteric Liquid Crystal Polymer Particles

Belmonte

Cunha

Nickmans

et al. 2020

Advanced Optical Materials

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In this work, light and temperature responsive, brush‐painted photonic coatings exhibiting three different colored and surface topographical states are reported. The different states arise from the use of cholesteric liquid‐crystalline micrometer‐sized polymer particles as shape‐memory photonic pigments that are dispersed in a shape‐memory binder. The first temporal state is induced by compressing the photonic particles at high temperature, resulting in blueshift of the structural color. The second temporal state is obtained by embossing a diffractive grating on the surface at an intermediate temperature leading to a relief topography and a rainbow optical effect. Both optical and surface topographical changes coexist and are stable at room temperature until they are reverted independently either by heating or locally by light illumination. Multicolored paints that reflect selectively left‐handed or right‐handed polarized light are developed to create arbitrary polarization‐dependent multicolor and topographical brush‐painted patterns. These temperature and light responsive triple shape‐memory photonic paints have potential applications as battery‐free optical sensors, responsive decoration, and smart adhesives.

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Section: Introductionmentioning

confidence: 99%

Brush‐Paintable, Temperature and Light Responsive Triple Shape‐Memory Photonic Coatings Based on Micrometer‐Sized Cholesteric Liquid Crystal Polymer Particles

Belmonte

Cunha

Nickmans

et al. 2020

Advanced Optical Materials

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“…Polymeric materials are required for stable-performance photonic coatings. Photonic coatings of temperature-responsive non-polymerized Ch-LC mixtures encapsulated in polymer protective layers were recently reported, showing a good stability and bandshift range by the Sm-Ch pre-transitional effect, but a subtle stratification process is required for their fabrication [17][18][19]. Alternative ways to make temperature-responsive photonic polymer coatings use either the humidity [20] or heat expansion of the materials [21,22], which are not able to induce a large reflection band shift without the presence of water.…”

Section: Introductionmentioning

confidence: 99%

Polymer Stabilized Cholesteric Liquid Crystal Siloxane for Temperature-Responsive Photonic Coatings

Zhang

Lub

Schenning

et al. 2020

IJMS

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Temperature-responsive photonic coatings are appealing for a variety of applications, including smart windows. However, the fabrication of such reflective polymer coatings remains a challenge. In this work, we report the development of a temperature-responsive, infrared-reflective coating consisting of a polymer-stabilized cholesteric liquid crystal siloxane, applied by a simple bar coating method. First, a side-chain liquid crystal oligosiloxane containing acrylate, chiral and mesogenic moieties was successfully synthesized via multiple steps, including preparing precursors, hydrosilylation, deprotection, and esterification reactions. Products of all the steps were fully characterized revealing a chain extension during the deprotection step. Subsequently, the photonic coating was fabricated by bar-coating the cholesteric liquid crystal oligomer on glass, using a mediator liquid crystalline molecule. After the UV-curing and removal of the mediator, a transparent IR reflective polymer-stabilized cholesteric liquid crystal coating was obtained. Notably, this fully cured, partially crosslinked transparent polymer coating retained temperature responsiveness due to the presence of non-reactive liquid-crystal oligosiloxanes. Upon increasing the temperature from room temperature, the polymer-stabilized cholesteric liquid crystal coating showed a continuous blue-shift of the reflection band from 1400 nm to 800 nm, and the shift was fully reversible.

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“…These chirality-inducedp hases find various applicationsi ni maging devices, information displays, reflectors/polarizers, tunable bandpass filters, and temperature or pressures ensors. [3][4][5] Compared with chiral liquids, LC materials, due to their ordered nature, along with liquidity,c an amplify the molecular chirality by manyfold. [6,7] BP is af rustrated phase, consisting of doubletwist cylinders, that occurs just belowt he isotropic liquid over an arrow temperaturer ange.…”

Section: Introductionmentioning

confidence: 99%

“…On one side of the core, there is ac holesterol moiety attached through an ester linkage, whereas, on the other side, there is a4 -n-alkoxy-2-hydroxybenzaldehyde moiety attached through an imine linkage.The homologous series with even chains, from n = 4t o 18, was synthesized. An increase in the alkyl chain length leads to the thermodynamic stabilization of the liquid-crystallinem aterial enantiotropically,a st he series makes at ransition from nonliquid crystalline (1-4, 1-6) to monotropic LC (1-8, 1-10, 1-12, and 1-14) and enantiotropic LC (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Compound 1-10 exhibited as table BP over aw ide range of 16.4 8C.…”

Section: Introductionmentioning

confidence: 99%

Chiral Bent‐Shaped Molecules Exhibiting Unusually Wide Range of Blue Liquid‐Crystalline Phases and Multistimuli‐Responsive Behavior

Punjani

Mohiuddin

Kaur

et al. 2020

Chemistry A European J

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Recently,a nu nprecedented observation of polar order,t hermochromic behavior,a nd exotic mesophases in new chiral, bent-shapeds ystemsw ith a ÀCH 3 moiety placed at the transverse position of the central core was reported. Herein,ah omologous series of compounds with even-numbered carbonc hains from n = 4t o1 8w ere synthesized, in which ÀCl was substituted for ÀCH 3 at the kink position and ad rastic modification in the phase structure of the bentshaped moleculew as observed. An unusuals tabilization of the cubic blue phase (BP) over aw ide range of 16.4 8Ch as been witnessed. Twoh omologues in this series (1-12 and 1-14) exhibit an interesting phase sequence consisting of BPI/ II, chiraln ematic, twist grain boundary,s mectic A, and smectic X( SmX) phases.T he higher homologues( 1-16 and 1-18) stabilizet he SmX phase enantiotropically over the entire temperature range. Crystal structure analysis confirmed the bent molecular architecture, with ab ent angle of 1488,a nd revealed the presenceo ft wo different molecular conformations in an asymmetric unit of compound 1-4. AD FT study corroborated that the ÀCl moiety at the central core of the molecule led to an increasei nt he dipole momenta long the transverse direction, which, in turn, facilitated the unusual stabilization of frustrated structures.C rystal polymorphism has been evidenced in three homologues( 1-10, 1-12, and 1-14) of the series. On the application of mechanical pressure through grinding, compound 1-10 transformedf rom a brighty ellow crystalline solid to ad ark orange-green amorphouss olid, which reversed upon dropwise additiono fd ichloromethane, indicating reversible mechanochromism in this class of compounds. In addition,e xcellent thermochromic behavior has been observed for compound 1-10w ith a controlled temperature-colorcombination.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.[a] Cr = crystal;I so = isotropic;N cyb * = chiral nematic phase composed of Sm clusters;T GBA = twist grain boundary phase;S mectic A = SmA; Smectic X = SmX. [b] Phaset ransitionso bserved by meanso fP OM in an ITO-coated planar cell (antiparallelrubbing). [c] Phase transitionso bserved by means of SAXS/WAXS.( 1-14: Cr 1a = amorphous,C r 2b = transition crystalline state, Cr 3c = crystal polymorph.)Chem.E ur.

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Paintable temperature-responsive cholesteric liquid crystal reflectors encapsulated on a single flexible polymer substrate

Abstract: Temperature-responsive photonic cholesteric liquid crystal reflectors deposited on flexible single substrates, encapsulated by protective polymer layers generated by photo-enforced stratification.

Cited by 36 publications

References 31 publications

Brush‐Paintable, Temperature and Light Responsive Triple Shape‐Memory Photonic Coatings Based on Micrometer‐Sized Cholesteric Liquid Crystal Polymer Particles

Brush‐Paintable, Temperature and Light Responsive Triple Shape‐Memory Photonic Coatings Based on Micrometer‐Sized Cholesteric Liquid Crystal Polymer Particles

Polymer Stabilized Cholesteric Liquid Crystal Siloxane for Temperature-Responsive Photonic Coatings

Chiral Bent‐Shaped Molecules Exhibiting Unusually Wide Range of Blue Liquid‐Crystalline Phases and Multistimuli‐Responsive Behavior

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