4D Chiral Photonic Actuators with Switchable Hyper‐Reflectivity

Zhang, Pei; Zhou, Guofu; Haan, Laurens T. de; Schenning, Albert P. H. J.

doi:10.1002/adfm.202007887

Cited by 56 publications

(80 citation statements)

References 41 publications

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“…6 ). A conversion from polarized to unpolarized reflection has been predicted 42 and observed 43 in CLCE, owing to asymmetry in the period distribution of refractive index associated with thickness-dependent (orientation-dependent) reorientation to the strain axis. The biaxial strain of BPLCE results in an alternating pattern of yellow and blue regions, indicating a complex rearrangement of the mesogens coupled with the photonic properties of the blue phase.…”

Section: Resultsmentioning

confidence: 96%

Retention and deformation of the blue phases in liquid crystalline elastomers

Schlafmann

White

2021

Nat Commun

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The blue phases are observed in highly chiral liquid crystalline compositions that nascently organize into a three-dimensional, crystalline nanostructure. The periodicity of the unit cell lattice spacing is on the order of the wavelength of visible light and accordingly, the blue phases exhibit a selective reflection as a photonic crystal. Here, we detail the synthesis of liquid crystalline elastomers that retain blue phase I, blue phase II, and blue phase III. The mechanical properties and optical reconfiguration via deformation of retained blue phases are contrasted to the cholesteric phase in fully solid elastomers with glass transition temperatures below room temperature. Mechanical deformation and chemical swelling of the lightly crosslinked polymer networks induces lattice asymmetry in the blue phase evident in the tuning of the selective reflection. The lattice periodicity of the blue phase elastomer is minimally affected by temperature. The oblique lattice planes of the blue phase tilt and red-shift in response to mechanical deformation. The retention of the blue phases in fully solid, elastomeric films could enable functional implementations in photonics, sensing, and energy applications.

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Section: Resultsmentioning

confidence: 96%

Retention and deformation of the blue phases in liquid crystalline elastomers

Schlafmann

White

2021

Nat Commun

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“…Coatings and free-standing films face the challenge of balancing response and robustness. Merit for a device Challenge for a device Device form Shape memory effect (reversible through modifications) [154,156] 500À670 nm [156] 22À171 C [156] Steady performance as films and objects…”

Section: Irreversible Response Coatings Microcapsulesmentioning

confidence: 99%

“…Finally, macroscale and reversible TR‐RC objects from CLCEs were also successfully fabricated, realized via the shape memory effect. [ 156 ] The starting material utilizes a tetrathiol that crosslinks the acrylic LC monomers via Michael addition when the mixture is aligned in a cell. After the thiol−acrylate crosslinking, the flat cholesteric film removed from the cell was deformed into the desired 3D shape, the helical pitch compressed under the stretching forces.…”

Section: Temperature‐responsive Clcs In Different Configurationsmentioning

confidence: 99%

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

Zhang

Froyen

Schenning

et al. 2021

Advanced Photonics Research

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Cholesteric liquid crystals (CLCs) are a major class of photonic materials that display selective reflection properties arising from their helical ordering. The temperature response of CLCs, comprising dynamic reflection color changes upon variation of temperature, is exploited using material systems consisting of small mesogenic molecules, polymer‐dispersed liquid crystals (PDLCs), polymer‐stabilized liquid crystals (PSLCs), or liquid‐crystalline polymers. Taking advantage of the easy processability and flexibility of the molecular design, these temperature‐responsive CLCs are fabricated into different forms of photonic devices, including cells, coatings, free‐standing films, and 3D objects. Temperature‐responsive devices developed from CLCs are integrated for application in temperature sensors, energy‐saving smart windows, smart labels, actuators, and adding aesthetically pleasing features to common objects. Herein, the device capabilities of the different material systems of temperature‐responsive CLCs are summarized: small mesogenic molecules, PDLCs, PSLCs, and CLC polymers. For each system, examples of different device forms are presented, with their temperature responsiveness and the underlying mechanisms discussed. In addition, the potential of each material system for future device applications and product developments is envisioned.

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“…Recently, several bio‐inspired materials with color‐changing ability have been developed in a variety of shapes and structures with sophisticated functions. [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ] Ko et al. developed an electrothermal soft actuator with active color‐changing functions through thermochromic pigment.…”

Section: Introductionmentioning

confidence: 99%

Bioinspired Multi‐Stimuli Responsive Actuators with Synergistic Color‐ and Morphing‐Change Abilities

Liu

Li³

et al. 2021

Advanced Science

114

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The combination of complex perception, defense, and camouflage mechanisms is a pivotal instinctive ability that equips organisms with survival advantages. The simulations of such fascinating multi‐stimuli responsiveness, including thigmotropism, bioluminescence, color‐changing ability, and so on, are of great significance for scientists to develop novel biomimetic smart materials. However, most biomimetic color‐changing or luminescence materials can only realize a single stimulus‐response, hence the design and fabrication of multi‐stimuli responsive materials with synergistic color‐changing are still on the way. Here, a bioinspired multi‐stimuli responsive actuator with color‐ and morphing‐change abilities is developed by taking advantage of the assembled cellulose nanocrystals‐based cholesteric liquid crystal structure and its water/temperature response behaviors. The actuator exhibits superfast, reversible bi‐directional humidity and near‐infrared (NIR) light actuating ability (humidity: 9 s; NIR light: 16 s), accompanying with synergistic iridescent appearance which provides a visual cue for the movement of actuators. This work paves the way for biomimetic multi‐stimuli responsive materials and will have a wide range of applications such as optical anti‐counterfeiting devices, information storage materials, and smart soft robots.

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4D Chiral Photonic Actuators with Switchable Hyper‐Reflectivity

Cited by 56 publications

References 41 publications

Retention and deformation of the blue phases in liquid crystalline elastomers

Retention and deformation of the blue phases in liquid crystalline elastomers

Temperature‐Responsive Photonic Devices Based on Cholesteric Liquid Crystals

Bioinspired Multi‐Stimuli Responsive Actuators with Synergistic Color‐ and Morphing‐Change Abilities

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