Photocontrol of Smectic Spacing

Folks, William R.; Keast, S. S.; Krentzel, T. A.; Zalar, Boštjan; Zeng, Huairen; Reznikov, Yuriy; Neubert, Mary E.; Kumar, Satyendra; Finotello, Daniele; Lavrentovich, Oleg D.

doi:10.1080/10587259808024385

Cited by 22 publications

(16 citation statements)

References 13 publications

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“…By photo-addressing the sample and changing the trans-to-cis ratio, one can drive the azobenzene molecules into and out of the smectic layers 116,117 . Relocation of the molecules changes the smectic layer spacing 118 which in its turn causes mechanical instabilities such as Helfrich-Hurault undulations of layers 119 .…”

Section: Static Distortionsmentioning

confidence: 99%

“…116,117 Relocation of the molecules changes the smectic layer spacing 118 which in its turn causes mechanical instabilities such as Helfrich-Hurault undulations of layers. 119 Recent studies of molecular transport in smectic LCs revealed a number of interesting features. Experimental and numerical studies of lyotropic smectics formed by long rigid rods (such as lamentous fd virus) demonstrated a hopping transport: 120,121 the rods jump from one layer to another without signicant reorientation.…”

Section: Static Distortionsmentioning

confidence: 99%

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Transport of particles in liquid crystals

2014

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Section: Static Distortionsmentioning

confidence: 99%

Section: Static Distortionsmentioning

confidence: 99%

Transport of particles in liquid crystals

2014

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“…One might notice in Figure 4b that the iteration process of filling the gaps between the large circles with the smaller one interrupts at a certain macroscopic scale, and domains smaller than about 2–3 μm in size do not form. The explanation of this cut‐off in the iterative filling is given by Folks et al:39…”

Section: Periodic Array Of Fcdsmentioning

confidence: 99%

Smectic Liquid Crystal Defects for Self‐Assembling of Building Blocks and Their Lithographic Applications

Kim

Yoon

Jeong

et al. 2011

Adv Funct Materials

111

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crystal (LC) fi lm containing an ordered, periodic array of smectic LC defects. [ 9,10 ] Unlike previously reported self-assembling materials, which have been geared toward defect-free systems of the ordered structures, these approaches rely on the order of artifi cially made defects as building blocks to create templates. The proposed approaches based on LC defects have signifi cant advantages over existing methods to micro/nanopatterning applications, including easy fabrication, the creation of long-range surface ordering, very rapid formation of periodic arrays, and the ability to generate various featured sizes ranging from the micrometer to the sub-micrometer scale. Furthermore, the ordered array of LC defects occurs rapidly due to reversible and non-covalent interactions between the LC molecules and can easily be generated by controlling surface anchoring, which is a very simple and costeffective mechanism that is well suited to mass production. In addition, this process should not be limited to specifi c rodlike LC materials and it should be applicable to other smectic LC systems forming similar defect structures. Accordingly, such defect orders of LC materials can be very strong candidates for the periodic templates, compared to other soft-building blocks such as block copolymers, colloids, and surfactants.To introduce this new type of building block based on LC defect order, fi rstly we will describe various types of LC phases and their versatile defect structures. In particular, focal conic domains (FCDs), which are typical defect structures of the smectic phase, will be demonstrated in Section 2, since FCDs were fi rstly used to create defect orders. Next, we deal with defect arrays from three different FCDs including toric FCD (TFCD), parabolic FCD (PFCD), and cylindrical oily streak (OS). The TFCDs, which are generated in an antagonistic surface anchoring condition, will be described in detail. Then, the mechanism of TFCD formation is described in terms of surface anchoring, direct internal structure observation, and energetics in Section 3. In Section 4, the template-assisted self-assembling approaches, including some manipulating methods for the domain size, arrangement, and selective patterning of TFCDs, are demonstrated. Finally, we discuss their applications in soft lithographic templates, superhydrophobic surfaces, microlens arrays, organic photomasks, and trapping templates for colloidal particles based on large-area TFCD-array patterning in Section 5.As the fi eld of information displays is maturing, LC materials research is undergoing a modern-day renaissance. Devices Smectic Liquid Crystal Defects for Self-Assembling of Building Blocks and Their Lithographic ApplicationsRecently, it has been reported that liquid crystal (LC) defects can be used to create highly periodic templates by controlling the surface anchoring and the elastic properties of LC molecules. The self-assembled defect ordering of the LC materials takes advantage of the ability to achieve fast stabilization of molecular orde...

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“…An important interplay between light and the structure of liquid crystals was first observed by Folks et al (18) and has been excellently explained by simulation studies (19) invoking the concept of photo-driven nanophase segregation in smectic liquid crystals. This concept was extended by us to explain the experimental observation of a photo-induced disorder-to-order transition (20), and induction of a layered mesophase in the presence of photo-irradiation (21,22); these observations are outlined below.…”

Section: Dynamic Self-assembly Of the Smectic Phasementioning

confidence: 97%

Photoinduced phase transitions

Prasad¹,

Nair²,

Rao³

2009

Liquid Crystals

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Employing actinic light to alter/stabilise a particular thermodynamic phase via the photo-isomerisation of the constituent molecules is an interesting tool to investigate soft matter from a new dimension. This article focuses on our recent results on several aspects of these non-equilibrium phase transitions, which are isothermal in nature. We specifically discuss (i) the influence of different parameters, such as confinement, applied electric field, pressure etc., on the dynamics associated with both the photochemical transition driving the equilibrium nematic to the nonequilibrium isotropic phase and the thermal back relaxation recovering the nematic phase, (ii) unique light-driven disorder-order transition in a reentrant system, (iii) dynamic self-assembly of the smectic A phase, which is stabilised only in the presence of actinic light, (iv) novel temperature-intensity phase diagrams and an example of primary and secondary photo-ferroelectric effects in an antiferroelectric smectic C system. These results highlight the fact that the actinic light can be used as a new tool to study phase transitions and the associated critical phenomena that could also bring about effects that are not seen in equilibrium situations.

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Photocontrol of Smectic Spacing

Cited by 22 publications

References 13 publications

Transport of particles in liquid crystals

Transport of particles in liquid crystals

Smectic Liquid Crystal Defects for Self‐Assembling of Building Blocks and Their Lithographic Applications

Photoinduced phase transitions

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