Photoinduced Crystal-to-Liquid Phase Transitions of Azobenzene Derivatives and Their Application in Photolithography Processes through a Solid–Liquid Patterning

Norikane, Yasuo; Uchida, Etsuo; Tanaka, Satoko; Fujiwara, Kyoko; Koyama, Emiko; Azumi, Reiko; Akiyama, Haruhisa; Kihara, Hideyuki; Yoshida, Masaru

doi:10.1021/ol502223u

Cited by 132 publications

(172 citation statements)

References 31 publications

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“…[33][34][35][36] Introduction of pendant groups at the 2-or 3-position can reduce intermolecular π-π interactions and allow photoisomerization in the bulk state on the time scale of minutes. [28] Recent work has also suggested that lamellar or monolayer azobenzene morphologies facilitate fast photoisomerization, [26,27,37] presumably by providing increased molecular freedom. In our exfoliated monolayer system, rapid photoliquefaction is enabled by the presence of highly disordered and fluidic ODMS surrounding monolayers of crystalline azobenzene.…”

Section: Reversible Photoliquefaction and Photosolidification Of Silomentioning

confidence: 99%

“…[24,25] Furthermore, few examples have demonstrated the photocontrolled switching of liquid and solid phases in azobenzene materials. [26][27][28][29] Given the importance of molecular arrangement in photoresponsive materials, self-assembly strategies that facilitate ordering of functional motifs are prudent. Recently, we reported on the synthesis of a class of well-defined and discrete end-functionalized siloxane oligomers that form highly ordered multidomain nanomaterials with sub-5 nm periodicities.…”

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confidence: 99%

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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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Section: Reversible Photoliquefaction and Photosolidification Of Silomentioning

confidence: 99%

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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“…Previously, we have reported a molecular design criteria for the solid-liquid phase transition in rod-shaped azobenzenes and demonstrated to use an azobenzene as a photoresist [23]. Substitution of a methyl group at the 3-position to azobenzenes having para-dialkoxy groups ( Figure 1, AZ-OCn; n = 6, 10, 12) drastically altered the phase transition photoresponse compared to the azobenzenes possessing two methyl groups at the 3-and 3'-positions or no methyl groups.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Phase Transitions in Rod-shaped Azobenzene with Different Alkyl Chain Length

Norikane

Uchida

Tanaka

et al. 2016

J. Photopol. Sci. Technol.

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The direct and reversible solid-liquid phase transitions by photochromic reactions at constant temperature are of interest because of potential applications in reusable adhesives, photoresists and so on. We report photoinduced solid-liquid phase transitions in rod-shaped azobenzenes, possessing a methyl group at the 3-position and alkoxy groups with different chain length (Cn = 1-18) at the 4-and 4'-positions. Thermal property, photochemical property, and adhesive properties were investigated. We found that the azobenzenes with alkyl chain length of 6-10 showed relatively fast photoinduced solid-liquid phase transition than that with shorter (Cn = 1-5) and longer (Cn = 11-18) ones. Tensile shear strength were measured by using these azobenzenes as photoresponsive adhesives. Irradiation with UV light (365 nm) induced the phase transition to the liquid phase and the adhesion strength values decreased to almost zero. Then the irradiation with visible light (450 nm) recovered the adhesion strength.

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“…The early work has reported that LCs incorporating azobenzene moiety exhibit trans-cis photoisomerization behavior upon UV-Visible (UV-Vis) light irradiation [23,24]. Figure 6 shows the UV-induced trans-cis isomerization of compound 2c.…”

Section: Uv-visible Spectramentioning

confidence: 99%

Synthesis and Characterization of Photo-Responsive Thermotropic Liquid Crystals Based on Azobenzene

et al. 2018

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A series of new thermotropic liquid crystals (LCs) containing azobenzene units was synthesized. The structures of the compounds were characterized by means of NMR and FTIR spectroscopy. Their mesomorphic behaviors were investigated via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Based on the POM and DSC measurements, the optical properties of the Razo-ester were tested using UV-vis spectroscopy. The azobenzene side chain displayed a strong ability to influence the formation of thermotropic LCs.

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Photoinduced Crystal-to-Liquid Phase Transitions of Azobenzene Derivatives and Their Application in Photolithography Processes through a Solid–Liquid Patterning

Cited by 132 publications

References 31 publications

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Photoinduced Phase Transitions in Rod-shaped Azobenzene with Different Alkyl Chain Length

Synthesis and Characterization of Photo-Responsive Thermotropic Liquid Crystals Based on Azobenzene

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