Angular deficits in flat space: remotely controllable apertures in nematic solid sheets

Modes, Carl D.; Warner, Mark; Sánchez‐Somolinos, Carlos; Haan, Laurens T. de; Broer, Dirk J.

doi:10.1098/rspa.2012.0631

Cited by 19 publications

(20 citation statements)

References 9 publications

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“…Crosslinked liquid crystalline polymers (LCPs) have received much attention as candidates for this purpose since they can exhibit large macroscopic scale mechanical response to different external stimuli such as heat, light, pH, or moisture . Thin‐films of these materials with controlled molecular orientation, defined by the director ( n ), have predominantly been investigated as building blocks to implement a variety of responsive elements or devices . However the thin‐film character of these elements markedly limits the energy available for actuation.…”

Section: Introductionmentioning

confidence: 99%

4D Printed Actuators with Soft‐Robotic Functions

López-Valdeolivas

Liu

Broer

et al. 2017

Macromol. Rapid Commun.

298

307

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troactive polymers, [7] as well as patterned hydrogels that shape-shift on swelling. [8,9] Further development of soft elements capable to perform complex motions or functions requires adequate materials and processing technologies that enable accurate control of the mechanical response. Moreover, on the route toward practical applications, there is often a necessity to have the possibility to miniaturize these elements, produce them in large dimensions or over large areas, or integrate them with other materials, elements, or devices.Crosslinked liquid crystalline polymers (LCPs) have received much attention as candidates for this purpose since they can exhibit large macroscopic scale mechanical response to different external stimuli such as heat, light, pH, or moisture. [10][11][12] Thinfilms of these materials with controlled molecular orientation, defined by the director (n), have predominantly been investigated as building blocks to implement a variety of responsive elements or devices. [13][14][15][16][17][18][19][20][21][22] However the thinfilm character of these elements markedly limits the energy available for actuation. Even more, the reported systems, including their processing toolbox, are limited to one single material and therefore multifunctional and multiresponsive systems are difficult to create. For the true development and incorporation of these LCP structures in real life applications, the capability to generate elements of different sizes, from very small to very large, is fundamental. This needs to be done with a precise control of the material morphology and properties as well as director orientation in well-defined complex geometries, all together leading to an accurate control of the mechanical response.Additive manufacturing techniques enable digital generation of material patterns in surfaces or fabrication of 3D objects. While 3D printing of conventional materials leads to inanimate 3D objects with static shape, 4D printing of responsive materials adds a 4th dimension as it leads to architectures that, with an appropriate stimulus, change their shape over time. [9,23] Here, we report the 4D printing of liquid crystalline elastomer (LCE) macro-and microstructures. Digital control of the local anisotropy of the applied LC material is advantageously achieved through the printing process. This allows to precisely program the magnitude and directionality of the forces in response to the external stimulus, temperature in our case, and therefore well-defined reversible shape-morphing of the structures in space and time. Although 4D printing has been recently described with hydrogels charged with anisotropic cellulose fibrils that get oriented during printing, [9] the mechanical response of these materials is based on water swelling, which limits the applicability due to the specific and stringent environment required for actuation as well as the slow response 3D Printing Soft matter elements undergoing programed, reversible shape change can contribute to fundamental advance in areas such as ...

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Section: Introductionmentioning

confidence: 99%

4D Printed Actuators with Soft‐Robotic Functions

López-Valdeolivas

Liu

Broer

et al. 2017

Macromol. Rapid Commun.

298

307

View full text Add to dashboard Cite

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“…For example, these particular columnar LCLC films could serve as templates for self-folding materials, since their director "tiling" resembles the patterning studied in models of such films. 43,44 Additionally, the patterns and order induced in theses LCLC films could be transferred to suspended colloids, suspended nanotubes and bacterial systems to create novel metamaterial films. [21][22][23][24][25] …”

Section: -9 |mentioning

confidence: 99%

Elasticity-dependent self-assembly of micro-templated chromonic liquid crystal films

et al. 2014

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We explore micropatterned director structures of aqueous lyotropic chromonic liquid crystal (LCLC) films created on squarelattice cylindrical-micropost substrates. The structures are manipulated by modulating the LCLC mesophases and their elastic properties via concentration through drying. Nematic LCLC films exhibit preferred bistable alignment along the diagonals of the micropost lattice. Columnar LCLC films, dried from nematics, form two distinct director and defect configurations: a diagonally aligned director pattern with local squares of defects, and an off-diagonal configuration with zig-zag defects. The formation of these states appears to be tied to the relative splay and bend free energy costs of the initial nematic films. The observed nematic and columnar configurations are understood numerically using a Landau-de Gennes free energy model. Among other attributes, the work provide first examples of quasi-2D micropatterning of LC films in the columnar phase and lyotropic LC films in general, and it demonstrates alignment and configuration switching of typically difficult-to-align LCLC films via bulk elastic properties.

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“…This film was prepared in practice, and it was shown that the slits reversibly open when the film is floating on a hot water bath (Fig. 13d) [35]. Fig.…”

Section: Discrete Patternsmentioning

confidence: 99%