Engineering of Complex Order and the Macroscopic Deformation of Liquid Crystal Polymer Networks

Haan, Laurens T. de; Sánchez‐Somolinos, Carlos; Bastiaansen, Cees M. W.; Schenning, Albertus P. H. J.; Broer, Dirk J.

doi:10.1002/anie.201205964

Cited by 314 publications

(255 citation statements)

References 40 publications

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“…Even better control over the deformation, with an outlook to make complex, origamitype shape changes possible in free-standing films, can be achieved by the use of director gradients and director patterns. 42 Also one can make use of the polarizationdependent absorption of the azobenzene compound to redirect deformation by the direction of polarization as is shown by Ikeda et al 38 A relatively new effect in controlling shape transformations of potentially even more interest for future applications is the formation of surface topographies. 43 One method to realizing this is to make use of the reorientation of azobenzene attached as a side group in an LC side-chain polymer.…”

Section: ■ Polymer Propertiesmentioning

confidence: 99%

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

2014

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Monolithically ordered liquid crystal polymer networks are formed by the photoinitiated polymerization of multifunctional liquid crystal monomers. This paper describes the relevant principles and methods, the basic structure− property relationships in terms of mesogenic properties of the monomers, and the mechanical and optical properties of the polymers. Strategies are discussed to control the molecular orientation by various means and in all three dimensions. The versatility of the process is demonstrated by two examples of films with a patterned molecular order. It is shown that patterned retarders can be made by a two-step polymerization process which is successfully employed in a transflective display principle. A transflective display is a liquid crystal display that operates in both a reflective mode using ambient light and a transmissive mode with light coming from a backlight system. Furthermore, a method is discussed to create a patterned film in a single polymerization process. This film has alternating planar chiral nematic areas next to perpendicularly oriented (so-called homeotropic) areas. When applied as a coating to a substrate, the film changes its surface texture. During exposure to UV light, it switches from a flat to a corrugated state.

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Section: ■ Polymer Propertiesmentioning

confidence: 99%

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

2014

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“…Examples include swellable hydrogels sensitive to either temperature (Hu et al, 1995) or electric-field (Kwon et al, 2008), electroactive polymers (Jager et al, 2000), liquid-crystal elastomers (Warner and Terentjev, 2007;DeSimone and Teresi, 2009) actuated by temperature (deHaan et al, 2012), light (White et al, 2008;Camacho-Lopez et al, 2004), or electric field (Fukunaga et al, 2008), and biohybrid constructs consisting of muscle cells attached to elastomer sheets (Feinberg et al, 2007;Nawroth et al, 2012). Bioinspiration plays an important role in this field.…”

Section: Introductionmentioning

confidence: 99%

“…This viewpoint has been motivated by the shapes of flowers and leaves as a result of non-uniform growth (Nechaev and Voituriez, 2001;Marder and Papanicolaou, 2006;Sharon et al, 2004;Liang and Mahadevan, 2009;Amar et al, 2012), and has been implemented in disk and tubular topologies by non-uniform swelling/shrinkage of gels (Klein et al, 2007;Kim et al, 2012) or non-uniform switching of liquid crystal elastomers (deHaan et al, 2012;Sawa et al, 2010;Urayama, 2012). In these and most references, the non-uniformity in the deformation is accomplished by patterning non-uniform swelling or nematic director fields, see also e.g.…”

Section: Introductionmentioning

confidence: 99%

Shape control of active surfaces inspired by the movement of euglenids

Arroyo

DeSimone

2014

Journal of the Mechanics and Physics of Solids

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We examine a novel mechanism for active surface morphing inspired by the cell body deformations of euglenids. Actuation is accomplished through in-plane simple shear along prescribed slip lines decorating the surface. Under general non-uniform actuation, such local deformation produces Gaussian curvature, and therefore leads to shape changes. Geometrically, a deformation that realizes the prescribed local shear is an isometric embedding. We explore the possibilities and limitations of this bioinspired shape morphing mechanism, by first characterizing isometric embeddings under axisymmetry, understanding the limits of embeddability, and studying in detail the accessibility of surfaces of zero and constant curvature. Modeling mechanically the active surface as a non-Euclidean plate (NEP), we further examine the mechanism beyond the geometric singularities arising from embeddability, where mechanics and buckling play a decisive role. We also propose a non-axisymmetric actuation strategy to accomplish large amplitude bending and twisting motions of elongated cylindrical surfaces. Besides helping understand how euglenids delicately control their shape, our results may provide the background to engineer soft machines.

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“…In this regard, photopatterning has emerged as an efficient technique to prepare command surfaces for the development of exotic LC actuators. [214][215][216] Introduction of densely cross-linked structures into liquid crystals induces stability and free-standing properties of the materials. 50,67,184,217,218 When partial cross-linked structure is introduced into polymers that exhibit LC phases (Figure 1, right, bottom), elastomeric properties emerge at ambient temperature.…”

Section: Functional Lc Polymers and Networkmentioning

confidence: 99%

“…In addition, non-uniform deformations are achieved by creating hierarchical variations in the LC directors along the films surface. 214 Use of twisted nematic phases, 214 alignment layers with circular patterns 215 and alignment control within local volume elements (voxels) 216 have led to the development of films undergoing stimuli induced complex deformations.…”

Section: Functional Lc Polymers and Networkmentioning

confidence: 99%

Functional liquid-crystalline polymers and supramolecular liquid crystals

Kato

Uchida

Ichikawa

et al. 2017

Polym J

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The design and functions of liquid-crystalline (LC) polymers with classifying them into conventional-, supramolecular-, dendriticand network-type LC polymers are described. LC polymers show new functions as new devices in the field of energy and environment by incorporating mesogenic moieties exhibiting photonic, electronic and ionic functions. Supramolecular LC polymers show dynamic and unique properties because the mesogenic moieties are built with non-covalent interactions. Dendritic-type LC polymers exhibit liquid crystallinity by nanosegregation of aromatic and aliphatic moieties. Dendritic fork-like mesogens have also been prepared. A variety of nonmesogeic functional building blocks including fullerene, π-conjugated moieties, catenane, rotaxane and others can be incorporated into LC phases by attaching these dendritic moieties. LC networks are constructed in situ polymerization of polymerizable nematic or nanostructured liquid crystals. The specific characteristics of the LC networks have generated new research trends to develop well-defined polymers that exhibit optical, transport and separation properties. In these materials, through suitable design of LC monomers, the preservation of smectic, columnar and bicontinuous cubic phases has been successfully used for the development of membranes with one-dimensional, two-dimensional and three-dimensional nanostructures.

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Engineering of Complex Order and the Macroscopic Deformation of Liquid Crystal Polymer Networks

Abstract: Rise or fall: Complex-structured freestanding polymer films with molecular order in three dimensions were prepared through photoalignment of polymerizable liquid crystals. The resulting films deform into cone and saddle shapes upon heating.

Cited by 314 publications

References 40 publications

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Liquid Crystal Polymer Networks: Preparation, Properties, and Applications of Films with Patterned Molecular Alignment

Shape control of active surfaces inspired by the movement of euglenids

Functional liquid-crystalline polymers and supramolecular liquid crystals

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