Bio-inspired thermal-responsive inverse opal films with dual structural colors based on liquid crystal elastomer

2015 ◽  
Vol 3 (17) ◽  
pp. 4424-4430 ◽  
Author(s):  
Huihui Xing ◽  
Jun Li ◽  
Jinbao Guo ◽  
Jie Wei
Keyword(s):  
Liquid Crystal ◽  
Inverse Opal ◽  
Liquid Crystal Elastomer ◽  
Structural Colors ◽  
Thermal Switching ◽  
Liquid Crystal Elastomers

The fabrication of inverse opal micropatterns based on liquid crystal elastomers with dual structural colors and their thermal switching behaviors are described.

Effect of stretching angle on the stress plateau behavior of main-chain liquid crystal elastomers

Soft Matter ◽  
2021 ◽  
Vol 17 (11) ◽  
pp. 3128-3136
Author(s):  
Suzuka Okamoto ◽  
Shinichi Sakurai ◽  
Kenji Urayama
Keyword(s):  
Liquid Crystal ◽  
Main Chain ◽  
Stress Plateau ◽  
Liquid Crystal Elastomer ◽  
Ultimate Elongation ◽  
Liquid Crystal Elastomers

Stretching angle for a main-chain liquid crystal elastomer has pronounced effects on the width of the stress plateau as well as the ultimate elongation, while it has no effect on the plateau height.

Deuteron NMR investigation on orientational order parameter in polymer dispersed liquid crystal elastomers

2020 ◽  
Vol 22 (40) ◽  
pp. 23064-23072
Author(s):  
Andraž Rešetič ◽  
Jerneja Milavec ◽  
Valentina Domenici ◽  
Blaž Zupančič ◽  
Alexej Bubnov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Orientational Order ◽  
Orientational Order Parameter ◽  
Liquid Crystal Elastomer ◽  
H Nmr ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Liquid Crystal Elastomers ◽  
Magnetically Aligned

Orientational order parameter of magnetically aligned liquid crystal elastomer particles suspended in a cured silicone matrix is assessed using 2H-NMR spectroscopy. Obtained results correspond well with the composite's thermomechanical response.

Force Characterization of Hygroscopic Liquid Crystal Elastomers

2010 ◽  
Author(s):  
Michael R. Hays ◽  
Hongbo Wang ◽  
William S. Oates
Keyword(s):  
Liquid Crystal ◽  
Water Vapor ◽  
Water Source ◽  
Vapor Source ◽  
Measuring Device ◽  
Liquid Crystal Elastomer ◽  
Liquid Crystal Elastomers ◽  
Response To Water ◽  
Water Vapor Source

The actuation forces of a hydrophilic liquid crystal elastomer (LCE) in response to water vapor was tested and modeled. These materials exhibit asymmetric swelling as water vapor is absorbed into one side of the elastomer film. This gives rise to deflection away from the water source. Deformation due to water vapor has shown to be on the order of seconds and is reversible which provides unique sensing and actuation characteristics for elastomer films. The constitutive behavior is modeled by using nonlinear continuum mechanics to predict internal changes in density of the liquid crystal elastomer and subsequent deformation by correlating moisture exposure with changes in the elastomer’s density. In order to compare the model and obtain a set material parameters, a micro-Newton measuring device was designed and tested to quantify the forces generated in the liquid crystal elastomer under bending. Forces ranging between 1 to 8 μN were measured as a function of the location of the water vapor source. The results provide important insight into chemical force response and sensing for a number of biomedical and microfluidic applications.

scholarly journals Toward Programmed Complex Stress-Induced Mechanical Deformations of Liquid Crystal Elastomers

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 315 ◽  
Author(s):  
Devesh Mistry ◽  
Helen F. Gleeson
Keyword(s):  
Liquid Crystal ◽  
Complex Stress ◽  
Stress Distributions ◽  
Director Field ◽  
Liquid Crystal Elastomer ◽  
Mechanical Responses ◽  
Mechanical Deformations ◽  
Nonlinear Mechanical ◽  
Liquid Crystal Elastomers ◽  
Spatially Varying

We prepare a liquid crystal elastomer (LCE) with a spatially patterned liquid crystal director field from an all-acrylate LCE. Mechanical deformations of this material lead to a complex and spatially varying deformation with localised body rotations, shears and extensions. Together, these dictate the evolved shape of the deformed film. Using polarising microscopy, we map the local rotation of the liquid crystal director in Eulerian and Lagrangian frames and use these to determine rules for programming complex, stress-induced mechanical shape deformations of LCEs. Moreover, by applying a recently developed empirical model for the mechanical behaviour of our LCE, we predict the non-uniform stress distributions in our material. These results show the promise of empirical approaches to modelling the anisotropic and nonlinear mechanical responses of LCEs which will be important as the community moves toward realising real-world, LCE-based devices.

Thermoresponsive Inverse Opal Films Fabricated with Liquid-Crystal Elastomers and Nematic Liquid Crystals†

Langmuir ◽  
2011 ◽  
Vol 27 (4) ◽  
pp. 1505-1509 ◽  
Author(s):  
Guanglong Wu ◽  
Yin Jiang ◽  
Dan Xu ◽  
Hong Tang ◽  
Xiao Liang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Nematic Liquid Crystals ◽  
Inverse Opal ◽  
Liquid Crystal Elastomers

scholarly journals Synchrotron Microbeam Diffraction Studies on the Alignment within 3D-Printed Smectic-A Liquid Crystal Elastomer Filaments during Extrusion

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 523
Author(s):  
Marianne E. Prévôt ◽  
Senay Ustunel ◽  
Benjamin M. Yavitt ◽  
Guillaume Freychet ◽  
Caitlyn R. Webb ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
3D Printing ◽  
Internal Structure ◽  
Smart Materials ◽  
Time Resolved ◽  
Promote Cell Proliferation ◽  
Liquid Crystal Elastomer ◽  
Smectic A ◽  
3D Printed ◽  
Liquid Crystal Elastomers

3D printing of novel and smart materials has received considerable attention due to its applications within biological and medical fields, mostly as they can be used to print complex architectures and particular designs. However, the internal structure during 3D printing can be problematic to resolve. We present here how time-resolved synchrotron microbeam Small-Angle X-ray Diffraction (μ-SAXD) allows us to elucidate the local orientational structure of a liquid crystal elastomer-based printed scaffold. Most reported 3D-printed liquid crystal elastomers are mainly nematic; here, we present a Smectic-A 3D-printed liquid crystal elastomer that has previously been reported to promote cell proliferation and alignment. The data obtained on the 3D-printed filaments will provide insights into the internal structure of the liquid crystal elastomer for the future fabrication of liquid crystal elastomers as responsive and anisotropic 3D cell scaffolds.

scholarly journals Influence of Liquid Crystallinity and Mechanical Deformation on the Molecular Relaxations of an Auxetic Liquid Crystal Elastomer

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7313
Author(s):  
Thomas Raistrick ◽  
Matthew Reynolds ◽  
Helen F. Gleeson ◽  
Johan Mattsson
Keyword(s):  
Liquid Crystal ◽  
Mechanical Response ◽  
Relaxation Times ◽  
Dielectric Relaxation Spectroscopy ◽  
Relaxation Dynamics ◽  
Liquid Crystal Elastomer ◽  
Nematic State ◽  
Out Of Plane ◽  
Liquid Crystal Elastomers ◽  
Polymer Configurations

Liquid Crystal Elastomers (LCEs) combine the anisotropic ordering of liquid crystals with the elastic properties of elastomers, providing unique physical properties, such as stimuli responsiveness and a recently discovered molecular auxetic response. Here, we determine how the molecular relaxation dynamics in an acrylate LCE are affected by its phase using broadband dielectric relaxation spectroscopy, calorimetry and rheology. Our LCE is an excellent model system since it exhibits a molecular auxetic response in its nematic state, and chemically identical nematic or isotropic samples can be prepared by cross-linking. We find that the glass transition temperatures (Tg) and dynamic fragilities are similar in both phases, and the T-dependence of the α relaxation shows a crossover at the same T* for both phases. However, for T>T*, the behavior becomes Arrhenius for the nematic LCE, but only more Arrhenius-like for the isotropic sample. We provide evidence that the latter behavior is related to the existence of pre-transitional nematic fluctuations in the isotropic LCE, which are locked in by polymerization. The role of applied strain on the relaxation dynamics and mechanical response of the LCE is investigated; this is particularly important since the molecular auxetic response is linked to a mechanical Fréedericksz transition that is not fully understood. We demonstrate that the complex Young’s modulus and the α relaxation time remain relatively unchanged for small deformations, whereas for strains for which the auxetic response is achieved, significant increases are observed. We suggest that the observed molecular auxetic response is coupled to the strain-induced out-of-plane rotation of the mesogen units, in turn driven by the increasing constraints on polymer configurations, as reflected in increasing elastic moduli and α relaxation times; this is consistent with our recent results showing that the auxetic response coincides with the emergence of biaxial order.

scholarly journals A Self-Stabilized Inverted Pendulum Made of Optically Responsive Liquid Crystal Elastomers

2022 ◽  
Vol 8 ◽  
Author(s):  
Quanbao Cheng ◽  
Lin Zhou ◽  
Kai Li
Keyword(s):  
Liquid Crystal ◽  
Inverted Pendulum ◽  
The Self ◽  
Sustained Oscillation ◽  
Static State ◽  
Pendulum System ◽  
Liquid Crystal Elastomer ◽  
Inverted Pendulum System ◽  
Potential Applications ◽  
Liquid Crystal Elastomers

The inverted pendulum system has great potential for various engineering applications, and its stabilization is challenging because of its unstable characteristic. The well-known Kapitza’s pendulum adopts the parametrically excited oscillation to stabilize itself, which generally requires a complex controller. In this paper, self-sustained oscillation is utilized to stabilize an inverted pendulum, which is made of a V-shaped, optically responsive liquid crystal elastomer (LCE) bar under steady illumination. Based on the well-established dynamic LCE model, a theoretical model of the LCE inverted pendulum is formulated, and numerical calculations show that it always develops into the unstable static state or the self-stabilized oscillation state. The mechanism of the self-stabilized oscillation originates from the reversal of the gravity moment of the inverted pendulum accompanied with its own movement. The critical condition for triggering self-stabilized oscillation is fully investigated, and the effects of the system parameters on the stability of the inverted pendulum are explored. The self-stabilized inverted pendulum does not need an additional controller and offers new designs of self-stabilized inverted pendulum systems for potential applications in robotics, military industry, aerospace, and other fields.

scholarly journals Shape-programmable liquid crystal elastomer structures with arbitrary three-dimensional director fields and geometries

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yubing Guo ◽  
Jiachen Zhang ◽  
Wenqi Hu ◽  
Muhammad Turab Ali Khan ◽  
Metin Sitti
Keyword(s):  
Liquid Crystal ◽  
Three Dimensional ◽  
Heterogeneous Material ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Field Orientation ◽  
Liquid Crystal Elastomer ◽  
Material Sample ◽  
Liquid Crystal Elastomers ◽  
Thermally Triggered

AbstractLiquid crystal elastomers exhibit large reversible strain and programmable shape transformations, enabling various applications in soft robotics, dynamic optics, and programmable origami and kirigami. The morphing modes of these materials depend on both their geometries and director fields. In two dimensions, a pixel-by-pixel design has been accomplished to attain more flexibility over the spatial resolution of the liquid crystal response. Here we generalize this idea in two steps. First, we create independent, cubic light-responsive voxels, each with a predefined director field orientation. Second, these voxels are in turn assembled to form lines, grids, or skeletal structures that would be rather difficult to obtain from an initially connected material sample. In this way, the orientation of the director fields can be made to vary at voxel resolution to allow for programmable optically- or thermally-triggered anisotropic or heterogeneous material responses and morphology changes in three dimensions that would be impossible or hard to implement otherwise.

scholarly journals Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites

10.3791/53688 ◽  
2016 ◽  
Author(s):  
Hojin Kim ◽  
Bohan Zhu ◽  
Huiying Chen ◽  
Oluwatomiyin Adetiba ◽  
Aditya Agrawal ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystal Elastomer ◽  
Liquid Crystal Elastomers
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