Photoinduced 3D Ordering and Patterning of Microphase-Separated Nanostructure in Polystyrene-Based Block Copolymer

Morikawa, Yuichi; Kondo, Takeshi; Nagano, Shusaku; Seki, Takahiro

doi:10.1021/cm0630845

Cited by 134 publications

(143 citation statements)

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“…Photoinduced surface relief grating (SRG) formation observed for azobenzenebased polymer films upon interference irradiation with coherent laser beams is also one of the photomechanical effects, that are believed to be due to mass transport induced at the surface area of the films upon irradiation [5][6][7][8]. Photo-triggered alignment changes of microphase-separated nanostructures and changes in phase-separated patterns of thin films using azobenzene-containing block copolymers are also the subjects of interest [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Change in Phase-Separated Structure of a Binary Film Composed of 4-[Bis(9,9-dimethylfluoren-2-yl)amino]-4'-nitroazobenzene and Poly(vinyl acetate)

Ichikawa

Nakano

2017

J. Photopol. Sci. Technol.

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In due course of our studies on photomechanical effects observed for azobenzene-based photochromic amorphous molecular materials, photoinduced change in phase-separated structure of an amorphous binary film composed of title materials has been investigated in the present study. When the phase-separated film was irradiated with a linearly polarized laser beam, the circular domains in the film extended in the direction parallel to the polarization direction of the incident laser beam. The rate of such photoinduced extension was found to increase with increasing temperature. The result seemed to be contrary to the results of the temperature dependences of other photomechanical effects observed for photochromic amorphous molecular materials we have previously reported.Azomolecules were suggested to exist both in the domains and in their surroundings and it is of importance to consider the both effects of azo-molecules existed in the domains and in their surroundings for phase-separated binary systems.

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Section: Introductionmentioning

confidence: 99%

Photoinduced Change in Phase-Separated Structure of a Binary Film Composed of 4-[Bis(9,9-dimethylfluoren-2-yl)amino]-4'-nitroazobenzene and Poly(vinyl acetate)

Ichikawa

Nakano

2017

J. Photopol. Sci. Technol.

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“…Particularly, in the case of side chain LC block polymers, the interfaces between blocks are usually formed parallel to the oriented side-chain mesogens. 110 Therefore, the orientation of MPS structures in LC block copolymers strongly 118,119 independently demonstrated the in-plane photoalignment of MPS cylinder morphologies in azobenzenecontaining block copolymer films by irradiation with LPL. In the years since, considerable data have been accumulated, and several reviews on this topic are now available.…”

Section: Photoalignment Of Block Copolymer Thin Filmsmentioning

confidence: 98%

“…119 The photoalignment process provides oriented MPS morphologies over a large area in non-contact and addressable manners, without using particular devices. In the first stage, the photoalignment of PS cylinder domains has been attempted at room temperature.…”

Section: Photoalignment Of Block Copolymer Thin Filmsmentioning

confidence: 99%

New strategies and implications for the photoalignment of liquid crystalline polymers

Seki

2014

Polym J

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141

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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“…Considerable work has been reported on the photoalignment and photopatterning of block copolymer films containing azobenzene moiety (Kadota et al, 2006). Seki et al (1999) and Morikawa et al (2007) studied controlling phase separated morphology by light in the block copolymers. They synthesized the block copolymer of azobenzene-containing acrylate monomer and vinyl alcohol or styrene.…”

Section: Introductionmentioning

confidence: 99%

Surface pattern based on an azobenzene-containing copolymer thin film and its light-driven morphology modulation

Zhang

Wang

2013

J. Zhejiang Univ. Sci. A

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Abstract:A type of azobenzene-containing block copolymer polymethyl methacrylate-b-poly (n-butylmethacrylate-co-6-(4-(phenylazo) benzoate) hexyl methacrylate) (PMMA-b-(PnBMA-co-PAzoMA)) was synthesized by the atom transfer radical polymerization (ATRP). Macroinitiator polymethyl methacrylate (PMMA) was prepared by ATRP and used to initiate the copolymerization of monomer n-butyl methacrylate (nBMA) and azobenzene-based methacrylate monomer (AzoMA). Herein, three block copolymers with different molecular weights and block volume fractions were obtained and spin-coated on a silicon substrate or quartz plate before annealing at 180 °C for 14 h. The surface morphologies in these annealed copolymer films were observed by atomic force microscopy (AFM). Bicontinuous stripe or island patterns with different sizes were formed dependent on the film thickness. These ordered patterns are considered to be formed arising from the dewetting process of the surface layer in the copolymer film. Photoisomerization of azobenzene units in the copolymer films changed the dewetting behaviors of the surface layer of the thin film. Therefore, some copolymer annealed films showed a reversible morphology conversion between bicontinuous stripe and island structure when exposed to UV light and upon being stored in the dark. It was found that the composition of the block copolymer had obvious influences on the photoinduced morphology conversion behaviors in these copolymer thin films. When the volumes of PnBMA and PAzoMA phases in the block copolymer were large enough, the surface morphology could be modulated by UV light irradiation and storage in the dark. This work proposes a new possibility for photoinduced control and design of the dewetting processes of thin films using a linear block copolymer.

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Photoinduced 3D Ordering and Patterning of Microphase-Separated Nanostructure in Polystyrene-Based Block Copolymer

Cited by 134 publications

References 18 publications

Photoinduced Change in Phase-Separated Structure of a Binary Film Composed of 4-[Bis(9,9-dimethylfluoren-2-yl)amino]-4'-nitroazobenzene and Poly(vinyl acetate)

Photoinduced Change in Phase-Separated Structure of a Binary Film Composed of 4-[Bis(9,9-dimethylfluoren-2-yl)amino]-4'-nitroazobenzene and Poly(vinyl acetate)

New strategies and implications for the photoalignment of liquid crystalline polymers

Surface pattern based on an azobenzene-containing copolymer thin film and its light-driven morphology modulation

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