Free-surface molecular command systems for photoalignment of liquid crystalline materials

Fukuhara, Kei; Nagano, Shusaku; Hara, Mitsuo; Seki, Takahiro

doi:10.1038/ncomms4320

Cited by 145 publications

(163 citation statements)

References 37 publications

(54 reference statements)

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“…Unlike previous works that highlighted the important role exerted by a top coat layer for controlling the LC alignment by exploiting its polar-to-nonpolar chemical conversion [52], Fukuhara et al demonstrated that no additional coating procedure was necessary. The observed selective surface segregation of a surface-active polymer component could be exploited for applications requiring surface functions like adhesive and frictional properties and biocompatibility and for the fabrication of optical and mechanical devices based on LC alignment [53].…”

Section: Self-assembled Lcps Through Surface Effectsmentioning

confidence: 99%

Exploitation of Self‐Assembly Phenomena in Liquid‐Crystalline Polymer Phases for Obtaining Multifunctional Materials

Giamberini

Malucelli

2016

Advanced Materials Interfaces

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This chapter aims to provide a recent overview on the self-assembly phenomena that take place within specific liquid-crystalline polymer (LCP) phases and can be driven by different strategies (such as surface effects, amphiphilic interactions and weak intermolecular forces like hydrogen bonding, -stacking, etc.). Indeed, these phenomena are able to induce the formation of liquid-crystalline domains that may show peculiar thermal, mechanical, barrier, optical, and/or dielectric properties, which can be exploited for the build-up of multifunctional materials for a wide range of applications. Some examples of self-assembled LCP systems are thoroughly discussed, showing the correlations between their structure, the final properties, and some potential applications.

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Section: Self-assembled Lcps Through Surface Effectsmentioning

confidence: 99%

Exploitation of Self‐Assembly Phenomena in Liquid‐Crystalline Polymer Phases for Obtaining Multifunctional Materials

Giamberini

Malucelli

2016

Advanced Materials Interfaces

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“…Fukuhara et al 128 showed that the photoresponsive skin layer of PBMA-b-PAz functions as a free-surface command layer for side chain LC polymer films containing a phenyl benzoate (PPBz) or cyanobiphenyl side chain (chemical structures shown in Figure 14). The procedures were the same as described for the PS-b-PAz.…”

Section: Command Surface Effect From the Free Surfacementioning

confidence: 99%

“…128 In this process, LPL was first used to irradiate an entire film area, followed by a subsequent irradiation with LPL in the orthogonal direction, as shown in Figure 16a. This procedures provided patterned in-plane alignment of the PPBz mesogens (Figure 16b).…”

Section: New Strategies In Photoalignment T Sekimentioning

confidence: 99%

New strategies and implications for the photoalignment of liquid crystalline polymers

Seki

2014

Polym J

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135

118

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The photoalignment of liquid crystalline materials has been studied extensively over the past two and a half decades and has recently become of technological importance in the liquid crystal display panel industry. This review introduces recent attempts at the photoalignment of liquid crystalline polymers and focuses on two aspects. First, strategies to ensure effective in-plane alignment of photoresponsive mesogens are highlighted. Despite the numerous investigations reported to date, film systems have not been well optimized in terms of realizing efficient photoreactions that consider the mesogen orientations. Second, new photoalignable systems composed of block copolymers with surface-grafted polymers and block copolymer films are introduced. The photoalignment processes in these mesoscopic systems involve strong cooperative motion of the different hierarchical size features. In the course of these approaches, a new strategic platform, photoalignment of liquid crystalline polymers via commanding from the free surface, is proposed. These approaches are expected to offer new concepts and possibilities for smart light-responsive materials and systems. Polymer Journal (2014) 46, 751-768; doi:10.1038/pj.2014.68; published online 13 August 2014 INTRODUCTIONPhotoreactions in ordered media have been the subject of numerous studies. In liquid crystal (LC) systems, molecules are packed with substantial motional freedom, and photoreactions trigger changes in the packing state or the collective molecular orientation. The effects can be amplified to the mesoscopic, microscopic and even macroscopic levels due to strong motional cooperativity. Photochromic reactions have frequently been incorporated in LC media because of their repeatability for controlling material properties. This approach has provided various types of smart, light-responsive materials 1 exhibiting surface-mediated photoalignment of LC materials, 2-6 photoinduced phase transitions, 7-12 photoorientation/addressing of polymer thin films, 13-18 photoinduced mass migrations, [19][20][21][22][23][24][25][26][27][28] phototactic sliding motions, 29-31 photo-driven motions and morphology of monolayers, 32-35 and macroscopic photomechanical deformations. [36][37][38][39][40][41][42][43][44][45][46] Photoalignment research and technology started in 1988 with the discovery of the reversible alignment control of nematic LCs by the photoisomerization of azobenzene on a substrate surface (Figure 1) by Ichimura et al. 47 It was demonstrated that the E/Z (trans/cis) photoisomerization of an azobenzene monolayer on a substrate can switch the alignment of nematic LC molecules between the homeotropic and planar modes. This active functional surface was dubbed a 'command surface' or 'command layer.' Shortly after this finding, Gibbons et al., 48 Dyadyusha et al. 49 and Schadt et al. 50 showed that angular selective excitation of an azo dye-doped polyimide or a photocrosslinkable polymer film with linearly

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“…For further functionalization of the LC polymer materials, molecular orientation, defect control and domain formation should be more precisely controlled. 269 For example, new techniques 44,[270][271][272][273] are proposed to control alignment using LC polymers. New materials will be used for the preparation of liquid crystals.…”

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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Free-surface molecular command systems for photoalignment of liquid crystalline materials

Cited by 145 publications

References 37 publications

Exploitation of Self‐Assembly Phenomena in Liquid‐Crystalline Polymer Phases for Obtaining Multifunctional Materials

Exploitation of Self‐Assembly Phenomena in Liquid‐Crystalline Polymer Phases for Obtaining Multifunctional Materials

New strategies and implications for the photoalignment of liquid crystalline polymers

Functional liquid-crystalline polymers and supramolecular liquid crystals

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