Synergy Effect on Morphology Switching: Real‐Time Observation of Photo‐Orientation of Microphase Separation in a Block Copolymer

Nagano, Shusaku; Koizuka, Yusuke; Murase, Tomoya; Sano, Masami; Shinohara, Yuya; Amemiya, Yoshiyuki; Seki, Takahiro

doi:10.1002/anie.201201346

Cited by 66 publications

(91 citation statements)

References 25 publications

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“…To gain insight into such dynamic events, Nagano et al [23] conducted synchrotron X-ray measurements to achieve in-situ simultaneous structural evaluations in the course of photoinduced alignment changes of both the Az layer and MPS cylinder morphology. For these experiments, the PBMA-b-PAz, (Figure 1) possessing the amorphous polymer block with lower T g was employed.…”

Section: Photoalignment Of Block Copolymer Filmsmentioning

confidence: 99%

Photoalignment of Liquid Crystalline Polymer Films Containing Mesostructures and a Free Surface Command Layer

Seki

Fukuhara

Sano

et al. 2015

Molecular Crystals and Liquid Crystals

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Investigations on the photoaglinment processes of liquid crystalline materials started around 25 years ago, and currently great developments have been made in both academic and industrial areas. However, there remain many issues to be explored in this field. This short review introduces our recent advances regarding the photoalignment and realignment process using azobenzene-containing liquid crystalline polymer materials. Two topics are involved here: the photoalignment of microphase separation structures of block copolymer films, and photoalignment controls from the free surface of a liquid crystalline polymer film.

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Section: Photoalignment Of Block Copolymer Filmsmentioning

confidence: 99%

Photoalignment of Liquid Crystalline Polymer Films Containing Mesostructures and a Free Surface Command Layer

Seki

Fukuhara

Sano

et al. 2015

Molecular Crystals and Liquid Crystals

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“…To gain detailed insight into the process, Nagano et al 126 conducted synchrotron X-ray measurements to simultaneously achieve real-time observations during orientational changes of the mesogens and MPS cylinder morphology at a constant temperature in New strategies in photoalignment T Seki the SmA LC range. A schematic drawing of the photoswitching process is presented in Figure 12a.…”

Section: Time Course Observations Of Mps Photoalignment In Block Copomentioning

confidence: 99%

New strategies and implications for the photoalignment of liquid crystalline polymers

Seki

2014

Polym J

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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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“…18,21 The tri-block copolymers, PAz n -b-PBMA m -b-PAz n , were synthesized in the same manner starting from a dual halogenterminated ATRP initiator of ethylene bis(2-bromoisobutyrate). 18,21 The tri-block copolymers, PAz n -b-PBMA m -b-PAz n , were synthesized in the same manner starting from a dual halogenterminated ATRP initiator of ethylene bis(2-bromoisobutyrate).…”

Section: Synthesis and Characterization Of Di-and Tri-block Copolymersmentioning

confidence: 99%

“…[7][8][9][10] In the photoprocess, the pre-aligned state by initial linearly polarized light (LPL) can be ''realigned'' by successive LPL with the electric vector E in a different direction. 18,19 This approach revealed a strongly cooperative interplay between the different hierarchical structures of the MPS cylinder pattern and the smectic LC layer. [14][15][16][17] Regarding the mechanism of photoinduced alternations of MPS structure, we have attempted to make in situ observations of the dynamic alignment changes in thin films of a diblock copolymer consisting of poly(butyl methachrylate)-block-azobenzene (Az)-containing LC polymer (PBMA-b-PAz).…”

Section: Introductionmentioning

confidence: 95%

“…[1][2][3][4][11][12][13] The ability of realignment is expected to provide new possibilities in block copolymer nanotechnologies. 18 By capturing the intermediate state of the realignment process by transmission electron microscopy (TEM) and polarized optical microscopy (POM), and in situ synchrotron grazing angle X-ray scattering (GI-SAXS) measurements, the realignment was found to take place via the sub-domain rotation mechanism retaining the hierarchical structure. 18,19 This approach revealed a strongly cooperative interplay between the different hierarchical structures of the MPS cylinder pattern and the smectic LC layer.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic photoinduced realignment processes in photoresponsive block copolymer films: effects of the chain length and block copolymer architecture

et al. 2015

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A series of block copolymers composed of an amorphous poly(butyl methacrylate) (PBMA) block connected with an azobenzene (Az)-containing liquid crystalline (PAz) block were synthesized by changing the chain length and polymer architecture. With these block copolymer films, the dynamic realignment process of microphase separated (MPS) cylinder arrays of PBMA in the PAz matrix induced by irradiation with linearly polarized light was studied by UV-visible absorption spectroscopy, and time-resolved grazing incidence small angle X-ray scattering (GI-SAXS) measurements using a synchrotron beam. Unexpectedly, the change in the chain length hardly affected the realignment rate. In contrast, the architecture of the AB-type diblock or the ABA-type triblock essentially altered the realignment feature. The strongly cooperative motion with an induction period before realignment was characteristic only for the diblock copolymer series, and the LPL-induced alignment change immediately started for triblock copolymers and the PAz homopolymer. Additionally, a marked acceleration in the photoinduced dynamic motions was unveiled in comparison with a thermal randomization process.

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Synergy Effect on Morphology Switching: Real‐Time Observation of Photo‐Orientation of Microphase Separation in a Block Copolymer

Cited by 66 publications

References 25 publications

Photoalignment of Liquid Crystalline Polymer Films Containing Mesostructures and a Free Surface Command Layer

Photoalignment of Liquid Crystalline Polymer Films Containing Mesostructures and a Free Surface Command Layer

New strategies and implications for the photoalignment of liquid crystalline polymers

Dynamic photoinduced realignment processes in photoresponsive block copolymer films: effects of the chain length and block copolymer architecture

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