Holographic gratings and holographic image storage via photochemical phase transitions of polymer azobenzene liquid-crystal films

Yamamoto, Takahiro; Hasegawa, Makoto; Kanazawa, Akihiko; Shiono, Takeshi; Ikeda, Tomiki

doi:10.1039/a905501k

Cited by 83 publications

(53 citation statements)

References 29 publications

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“…[1±4] Generally, the chromophore used is either doped in a polymer matrix [3,4] or covalently bounded to the polymer. [1,2] Azobenzene-containing polymers are among the most studied photoactive polymers. [1,2,5±10] The reversible photoisomerization between the stretched trans and the bent cis isomers of the chromophore is the property exploited in all studies.…”

Section: Introductionmentioning

confidence: 99%

Holographic Recording in a Photoactive Elastomer

Zhao¹,

Bai

Asatryan

et al. 2003

Adv Funct Materials

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This work explores the use of photoactive elastomers as elastic holographic materials. Holographic gratings were recorded on stretched films of an azobenzene elastomer, which is composed of a side‐chain liquid‐crystalline polymer with azobenzene mesogens, grafted to the rubbery polybutadiene block of a styrene–butadiene–styrene (SBS) triblock copolymer. The grating‐formation dynamics measurements revealed the formation of two gratings of different natures resulting from the coupled mechanical and optical effects. A first grating, formed quickly upon exposure, is due to the photoisomerization of oriented azobenzene groups. A second grating, developed at longer exposure times, may originate from changes in the anisotropic structure of the SBS matrix, which is induced by the photochemical phase transition of azobenzene mesogens. The first grating is unstable, but the second grating remains in relaxed films. Both mechanisms can be enhanced by deformation of the film.

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Section: Introductionmentioning

confidence: 99%

Holographic Recording in a Photoactive Elastomer

Zhao¹,

Bai

Asatryan

et al. 2003

Adv Funct Materials

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“…Such photocontrol of order/disorder has been used to induce rapid nematic-to-isotropic phase transitions in LC films for applications in optical image storage [22] and holography. [23] The reversibility of azobenzene photoisomerization is beneficial for such applications, and the ability of azobenzene materials to undergo many trans-cis photoisomerization cycles without noticeable degradation in performance has been demonstrated. [24,25] Furthermore, few examples have demonstrated the photocontrolled switching of liquid and solid phases in azobenzene materials.…”

mentioning

confidence: 99%

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Zha

Vantomme

Berrocal

et al. 2017

Adv Funct Materials

102

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Materials with highly ordered molecular arrangements have the capacity to display unique properties derived from their nanoscale structure. Here, the synthesis and characterization of azobenzene (AZO)-functionalized siloxane oligomers of discrete length that form photoswitchable supramolecular materials are described. Specifically, synergy between phase segregation and azobenzene crystallization leads to the self-assembly of an exfoliated 2D crystal that becomes isotropic upon photoisomerization with UV light. Consequently, the material undergoes a rapid athermal solid-to-liquid transition which can be reversed using blue light due to the unexpectedly fast 2D crystallization that is facilitated by phase segregation. In contrast, enabling telechelic supramolecular polymerization through hydrogen bonding inhibits azobenzene crystallization, and nanostructured pastes with well-ordered morphologies are obtained based on phase segregation alone, thus demonstrating block copolymer-like behavior. Therefore, by tailoring the balance of self-assembly forces in the azobenzene-functionalized siloxane oligomers, fast and reversible phase-changing materials can be engineered with various mechanical properties for applications in photolithography or switchable adhesion to lubricant properties. In these materials, contraction along the LC director occurs with isomerization of the planar trans-azobenzenes to the bent cis-azobenzenes. By limiting the depth of photoactivity, generally through utilizing the inherently high absorption coefficient of the azobenzenes, this contraction can give rise to anisotropic bending in poly mer films, [7,8] gels, [9] fibers, [10][11][12] and even crystals. [13] Different modes of motion arise with more complex molecular arrangements. For example, expansion of chiral nematic LCs along the helical axis has been utilized to create polymer coatings with photoswitchable topologies [14][15][16][17] and polymer films with macroscopic helical motion. [18] Additionally, polymer films with splay-bend configuration, in which LC-mesogens gradually change orientation throughout the film cross-section, have shown to exhibit inherently anisotropic bending as well as achieve significantly faster and larger bending when compared to uniaxially aligned films. [19][20][21] The ability of azobenzene photoisomerization to generate anisotropic dimension change and motion in LC networks typically results from increased molecular disorder caused by bent cis-azobenzene relative to networks with rod-like transazobenzene. Such photocontrol of order/disorder has been used to induce rapid nematic-to-isotropic phase transitions in LC films for applications in optical image storage [22] and holography. [23] The reversibility of azobenzene photoisomerization is beneficial for such applications, and the ability of azobenzene materials to undergo many trans-cis photoisomerization cycles without noticeable degradation in performance has been demonstrated. [24,25] Furthermore, few examples have demonstrated the photocontrolled swit...

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“…4,50 If the alignment change in a periodic structure is induced in accordance with the interference patterns produced by overlapping two coherence beams, a large refractive-index modulation in LC materials can be obtained. [51][52][53] The diffraction efficiency is strongly related to the refractive-index modulation produced in the materials. In photochromic polymer films, surface-relief structures are formed on the surfaces of the polymers and refractive-index modulation occurs upon irradiation with two coherent laser beams ( Figure 2).…”

Section: Photoinduced Change In the Molecular Alignment Of Liquid-crymentioning

confidence: 99%

Photomechanical energy conversion based on cross-linked liquid-crystalline polymers

Mamiya

2012

Polym J

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An actuator is an energy transducer that can convert input energies into work. Cross-linked liquid-crystalline polymers show photoinduced deformation with changes in the molecular shape and alignment of the polymers. Polymer materials can transduce converted light energy into mechanical stress by the macroscopic deformation of the polymers (photomechanical effect). The effect of the molecular structures of the photochromic liquid-crystalline polymers on the photoinduced deformation is studied. The mechanism of the photoinduced deformation of the polymers is investigated. Three-dimensional movements of the liquid-crystalline polymers are achieved by laminating the polymers into a flexible polymer sheet. In this review, the design of the polymer materials with a photochromic moiety and an evaluation of their photomechanical effects are described. The photomodulation of the alignment of liquid-crystalline polymers and their applications for light-driven polymer actuators are summarized.

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Holographic gratings and holographic image storage via photochemical phase transitions of polymer azobenzene liquid-crystal films

Cited by 83 publications

References 29 publications

Holographic Recording in a Photoactive Elastomer

Holographic Recording in a Photoactive Elastomer

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Photomechanical energy conversion based on cross-linked liquid-crystalline polymers

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