Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

Prijatelj, Matej; Ellabban, Mostafa A.; Fally, Martin; Domenici, Valentina; Čopič, Martin; Drevenšek‐Olenik, Irena

doi:10.1364/ome.6.000961

Cited by 6 publications

(4 citation statements)

References 52 publications

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“…However, new promising mechanisms based on photo-actuation, magneto-actuation, and “Joule”-heating electrically driven actuation were observed and are described in this review, taking into account very recent works [107,108,109,110,111,112]. Future developments of these polymer composite materials will probably expand to the field of biological applications and biomimetics [65,113,114,115,116], optical tunable gratings [117,118,119], three-dimensional (3D) printing and 3D morphing technologies [20,32,120,121,122], and flexible stretchable electrodes [123,124].…”

Section: General Conclusion and Perspectivesmentioning

confidence: 99%

Nanostructured Composites Based on Liquid-Crystalline Elastomers

et al. 2018

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Liquid-crystalline elastomers (LCEs) are the object of many research investigations due to their reversible and controllable shape deformations, and their high potential for use in the field of soft robots and artificial muscles. This review focuses on recent studies about polymer composites based on LCEs and nanomaterials having different chemistry and morphology, with the aim of instilling new physical properties into LCEs. The synthesis, physico-chemical characterization, actuation properties, and applications of LCE-based composites reported in the literature are reviewed. Several cases are discussed: (1) the addition of various carbon nanomaterials to LCEs, from carbon black to carbon nanotubes, to the recent attempts to include graphene layers to enhance the thermo-mechanic properties of LCEs; (2) the use of various types of nanoparticles, such as ferroelectric ceramics, gold nanoparticles, conductive molybdenum-oxide nanowires, and magnetic iron-oxide nanoparticles, to induce electro-actuation, magnetic-actuation, or photo-actuation into the LCE-based composites; (3) the deposition on LCE surfaces of thin layers of conductive materials (i.e., conductive polymers and gold nanolayers) to produce bending actuation by applying on/off voltage cycles or surface-wrinkling phenomena in view of tunable optical applications. Some future perspectives of this field of soft materials conclude the review.

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Section: General Conclusion and Perspectivesmentioning

confidence: 99%

Nanostructured Composites Based on Liquid-Crystalline Elastomers

et al. 2018

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“…In addition to the deeply investigated structural and physical properties of a thermally induced actuator based on LCEs [10][11][12][13][14][15][16][17][18][19][20], an increasing number of papers concerns the application of external stimuli, such as UV-vis light, microwaves and infrared waves, and electric and magnetic fields, to obtain controlled and reversible shape deformations in LCE-based systems. For instance, UV-visible light can be used to induce reversible local geometric deformations in LCEs containing azo-mesogens or other photosensitive molecules, as crosslinkers, comonomers, or dopants [21][22][23][24][25], which are at the basis of several applications in the field of optical tunable gratings and light-driven motors. LCE-based materials responsive to infrared radiations were prepared by inserting carbon nanotubes or graphene sheets into the LCE matrix [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

New Liquid Crystalline Elastomeric Films Containing a Smectic Crosslinker: Chemical and Physical Properties

et al. 2023

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Side-chain liquid crystal elastomers (SC-LCEs) have been designed by using a new smectic crosslinker. Two types of monodomain films were prepared based on polysiloxane chains, with a different relative concentration of both crosslinker and mesogenic comonomers. The mesomorphic behavior of the two SC-LCE systems was investigated by differential scanning calorimetry and polarized optical microscopy showing a different mesomorphic behavior: in one case, we obtained a nematic SC-LCE film, in the other case, a Smectic A SC-LCE film. In both systems, the mesophases were stable in a wide temperature range. Moreover, the SC-LCE films possess a relatively high orientation at room temperature. The physical-chemical properties, such as the local orientational ordering, structural organization, and dynamics of SC-LCEs’ constituents were studied by means of static and dynamic 2H NMR experiments, small-angle X-ray, and wide-angle X-ray diffractions. The relevant physical properties, such as the thermo-elastic and thermo-mechanic behaviors, are reported and discussed in view of the practical applications.

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“…Light-sensitive LCEs are also very efficient for recording polarization gratings generated by the superposition of orthogonally polarized writing beams. In the vicinity of the Bragg angle, those gratings exhibit an unusual splitting of the diffraction peak, which is a consequence of the strong absorption anisotropy for the actinic optical radiation [11].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Manipulation of Diffractive Properties of Optical Holographic Gratings from Liquid Crystalline Elastomers

Bošnjaković

Gregorc

et al. 2018

Applied Sciences

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An appealing property of optical diffractive structures from elastomeric materials is a possibility to regulate their optical patterns and consequently also their diffractive features with mechanical straining. We investigated the effect of strain on diffraction characteristics of holographic gratings recorded in a monodomain side-chain liquid crystalline elastomer. The strain was imposed either parallel or perpendicular to the initial alignment direction of the material. At temperatures far below the nematic-paranematic phase transition, straining along the initial alignment affects mainly the diffraction pattern, while the diffraction efficiency remains almost constant. In contrast, at temperatures close to the nematic-paranematic phase transition, the diffraction efficiency is also significantly affected. Straining in the direction perpendicular to the initial alignment strongly and diversely influences both the diffraction pattern and the diffraction efficiency. The difference between the two cases is attributed to shear-stripe domains, which form only during straining perpendicular to the initial alignment and cause optical diffraction that competes with the diffraction from the holographic grating structure.

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Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

Cited by 6 publications

References 52 publications

Nanostructured Composites Based on Liquid-Crystalline Elastomers

Nanostructured Composites Based on Liquid-Crystalline Elastomers

New Liquid Crystalline Elastomeric Films Containing a Smectic Crosslinker: Chemical and Physical Properties

Mechanical Manipulation of Diffractive Properties of Optical Holographic Gratings from Liquid Crystalline Elastomers

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