References of "Kizhakidathazhath, Rijeesh 50031385"
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See detailRobust cholesteric liquid crystal elastomer fibres for mechanochromic textiles
Geng, Yong UL; Kizhakidathazhath, Rijeesh UL; Lagerwall, Jan UL

in Nature Materials (2022)

Mechanically responsive textiles have transformative potential in many areas from fashion to healthcare. Cholesteric liquid crystal elastomers have strong mechanochromic responses that offer attractive ... [more ▼]

Mechanically responsive textiles have transformative potential in many areas from fashion to healthcare. Cholesteric liquid crystal elastomers have strong mechanochromic responses that offer attractive opportunities for such applications. Nonetheless, making liquid crystalline elastomer fibres suitable for textiles is challenging since the Plateau–Rayleigh instability tends to break up precursor solutions into droplets. Here, we report a simple approach that balances the viscoelastic properties of the precursor solution to avoid this outcome and achieve long and mechanically robust cholesteric liquid crystal elastomer filaments. These filaments have fast, progressive and reversible mechanochromic responses, from red to blue (wavelength shift of 155 nm), when stretched up to 200%. Moreover, the fibres can be sewed into garments and withstand repeated stretching and regular machine washing. This approach and resulting fibres may be useful for applications in wearable technology and other areas benefiting from autonomous strain sensing or detection of critically strong deformations. [less ▲]

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See detailEncoding Hidden Information onto Surfaces Using Polymerized Cholesteric Spherical Reflectors
Geng, Yong UL; Kizhakidathazhath, Rijeesh UL; Lagerwall, Jan UL

in Advanced Functional Materials (2021)

The omnidirectional Bragg reflection of cholesteric liquid crystals molded into spheres turns them into narrow-band retroreflectors with distinct circular polarization. It is shown that these cholesteric ... [more ▼]

The omnidirectional Bragg reflection of cholesteric liquid crystals molded into spheres turns them into narrow-band retroreflectors with distinct circular polarization. It is shown that these cholesteric spherical reflectors (CSRs) can encode information onto surfaces for far-field optical read-out without false positives, as the selective retroreflectivity allows the background to be easily subtracted. In order to hide the encoding from detection by the human eye, the retroreflection band is tuned to the near-UV or IR spectra, allowing ubiquitous deployment of CSRs in human-populated environments. This opens diverse application opportunities, for instance, in supporting safe robotic navigation and in augmented reality. A key breakthrough is our ability to permanently embed CSRs in a binder such that undesired scattering and reflections are minimized. This is achieved by realizing CSRs as shells that are polymerized from the liquid crystalline state. The resulting shrinkage around an incompressible fluid deforms the thinnest region of each shell such that it ruptures at a well-defined point. This leaves a single small hole in every CSR that gives access to the interior, allowing complete embedding in the binder with optimized refractive index, minimizing visibility. [less ▲]

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See detailResponsive Photonic Liquid Marbles
Anyfantakis, Manos; Jampani, Venkata S. R.; Kizhakidathazhath, Rijeesh UL et al

in Angewandte Chemie International Edition (2020), 59(43), 19260--19267

Liquid marbles have potential to serve as mini- reactors for fabricating new materials, but this has been exploited little and mostly for conventional chemical reactions. Here, we uncover the unparalleled ... [more ▼]

Liquid marbles have potential to serve as mini- reactors for fabricating new materials, but this has been exploited little and mostly for conventional chemical reactions. Here, we uncover the unparalleled capability of liquid marbles to act as platforms for controlling the self-assembly of a bio- derived polymer, hydroxypropyl cellulose, into a cholesteric liquid crystalline phase showing structural coloration by Bragg reflection. By adjusting the cholesteric pitch via quantitative water extraction, we achieve liquid marbles that we can tailor for structural color anywhere in the visible range. Liquid marbles respond with color change that can be detected by eye, to changes in temperature, exposure to toxic chemicals and mechanical deformation. Our concept demonstrates the ad- vantages of using liquid marbles as a miniature platform for controlling the liquid crystal self-assembly of bio-derived polymers, and their exploitation to fabricate sustainable, responsive soft photonic objects. [less ▲]

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See detailFacile Anisotropic Deswelling Method for Realizing Large‐Area Cholesteric Liquid Crystal Elastomers with Uniform Structural Color and Broad‐Range Mechanochromic Response
Kizhakidathazhath, Rijeesh UL; Geng, Yong UL; Jampani, Venkata UL et al

in Advanced Functional Materials (2019)

Cholesteric liquid crystal elastomers (CLCEs) are soft and dynamic photonic elements that couple the circularly polarized structural color from the cho- lesteric helix to the viscoelasticity of rubbers ... [more ▼]

Cholesteric liquid crystal elastomers (CLCEs) are soft and dynamic photonic elements that couple the circularly polarized structural color from the cho- lesteric helix to the viscoelasticity of rubbers: the reflection color is mechani- cally tunable (mechanochromic response) over a broad range. This requires uniform helix orientation, previously realized by long-term centrifugation to ensure anisotropic deswelling, or using sacrificial substrates or external fields. The present paper presents a simple, reproducible, and scalable method to fab- ricate highly elastic, large-area, millimeters thick CLCE sheets with intense uni- form reflection color that is repeatably, rapidly, and continuously tunable across the full visible spectrum by stretching or compressing. A precursor solution is poured onto a substrate and allowed to polymerize into a 3D network during solvent evaporation. Pinning to the substrate prevents in-plane shrinkage, thereby realizing anisotropic deswelling in an unprecedentedly simple manner. Quantitative stress–strain–reflection wavelength characterization reveals behavior in line with theoretical predictions: two linear regimes are identified for strains below and above the helix unwinding threshold, respectively. Up to a doubling of the sample length, the continuous color variation across the full visible spectrum repeatedly follows a volume conserving function of the strain, allowing the CLCE to be used as optical high-resolution strain sensor. [less ▲]

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