Photoinduced Bending of Self-Assembled Azobenzene–Siloxane Hybrid

Guo, Sufang; Matsukawa, Kimihiro; Miyata, Takashi; Okubo, Tatsuya; Kuroda, Kazuyuki; Shimojima, Atsushi

doi:10.1021/jacs.5b06172

Cited by 99 publications

(88 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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.…”

mentioning

confidence: 99%

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Zha

Vantomme

Berrocal

et al. 2017

Adv Funct Materials

102

View full text Add to dashboard Cite

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...

show abstract

mentioning

confidence: 99%

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Zha

Vantomme

Berrocal

et al. 2017

Adv Funct Materials

102

View full text Add to dashboard Cite

show abstract

“…The shape changes of the hydrogels can be actuated by many kinds of external stimuli, such as temperature, 22,25,27,51,55,75 light, 28,51,54,72,74,[76][77][78][79][80][81][82][83][84][85][86][87] pH, 24,31,52,76 electric signal, 43,[45][46][47] solvent, 22 and so on.…”

Section: Types Of External Stimulimentioning

confidence: 99%

Shape changing hydrogels and their applications as soft actuators

Peng

Wang

2018

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

In nature, plants or animals change their geometric shapes and hence realize different functions or movements. Inspired by the shape changes of plants and animals, several hydrogels that can change their geometric shapes upon external stimuli have been developed. This article provides a brief overview of shape changing hydrogels. First, two strategies to realize the shape changes of hydrogels, that is, preparing hydrogels with inhomogeneous structures and applying inhomogeneous stimuli onto homogeneous hydrogels, are discussed. Then, external stimuli that can actuate the shape changes of the stimuli-responsive hydrogels are presented. The applications of shape changing hydrogels such as soft machines, soft robotics, drug carriers, microfluidic valves, and sensors have been provided in third part. Finally, we offer our perspective on open challenges and future areas of interest for the shape changing hydrogel actuators.

show abstract

“…Azobenzene as a photosensitive group has been widely applied to prepare photoresponsive materials based on photoinduced cis – trans isomerization . Recently, several papers have been published on the lamellar organic materials with azobenzene moieties, including covalent organic frameworks (COFs), nanosheets, and lamellar hybrid films . It has been demonstrated that the trans – cis photoisomerization of azobenzene in these materials was inhibited because of the intense hydrogen‐bonding interactions or completely cross‐linked networks, leading to restriction of molecular mobility of the azobenzene moieties.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, several papers have been published on the lamellar organic materials with azobenzene moieties, including covalent organic frameworks (COFs), nanosheets, and lamellar hybrid films . It has been demonstrated that the trans – cis photoisomerization of azobenzene in these materials was inhibited because of the intense hydrogen‐bonding interactions or completely cross‐linked networks, leading to restriction of molecular mobility of the azobenzene moieties. However, when the close packing was inhibited, increasing the flexibility and free volume of the networks, photoresponsivity of lamellar thin films could be achieved .…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Reversible Morphological Transformation of Azobenzene‐Containing Pseudo‐2D Polymers

Tang

Jiang

et al. 2018

Macromol. Rapid Commun.

View full text Add to dashboard Cite

2D polymer sheets containing azobenzene are successfully prepared by a facile strategy of "2D self-assembly polymerization (2DSP)" via free radical polymerization in solution. A bola amphiphile containing azobenzene as a novel monomer is designed and synthesized. The results indicate that single-layer covalent pseudo-2D polymers on a micrometer scale are obtained after polymerization with vinyl monomers. Moreover, the 2D polymer sheets are highly sensitive to UV light due to incorporation of azobenzene groups into the polymer. Upon alternative irradiation with UV and visible light, the morphological transformation between sheets and rolled-up nanotubes can be achieved based on the reversible trans-to-cis photoisomerization of azobenzene units in the 2D polymer sheets.

show abstract

Photoinduced Bending of Self-Assembled Azobenzene–Siloxane Hybrid

Cited by 99 publications

References 60 publications

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers

Shape changing hydrogels and their applications as soft actuators

Photoinduced Reversible Morphological Transformation of Azobenzene‐Containing Pseudo‐2D Polymers

Contact Info

Product

Resources

About