Directional mass transfer of azo molecular glass microsphere induced by polarized light in aqueous immersion media

Huang, Hao; Wang, Zenan; Li, Xu; Yang, Fan; Su, Yechao; Xu, Jianhong; Wang, Xiaogong

doi:10.1039/d1ra01904j

Cited by 2 publications

(4 citation statements)

References 57 publications

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“…[59,60] Microstructured azobenzene materials, such as microparticles and pillars, are able to deform in response to polarized light, elongating in the polarization direction. [61,62] Therefore, we hypothesized that the blister formation could also be photo-controlled.…”

Section: Photo-control Over Blister Shape and Formationmentioning

confidence: 99%

“…The deformation of bulk microspheres, for instance, has been studied both in air and water, and differences in the deformation were observed. [61,88] In particular, the higher the refractive index of the immersion medium, the more prominent the mass transport parallel to the substrate. Furthermore, in bulk microspheres and pillars the deformation took place only at the top surface due to the high absorbance of the material and the consequent rapid light attenuation inside the particle, leading to mushroom-shaped structures.…”

Section: Photo-controlled Blister Shape and Formationmentioning

confidence: 99%

See 1 more Smart Citation

Surface Stability of Azobenzene‐Based Thin Films in Aqueous Environment: Light‐Controllable Underwater Blistering

Audia

Fedele

Tone

et al. 2022

Adv Materials Inter

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potential in applications such as additive manufacturing, civil engineering, and biomedicine. [1][2][3][4][5][6] Among them, azobenzene-based materials, due to their unique photo-responsive features, have attracted great attention for the remote and flexible control of materials properties via light stimulation. [7,8] The light response is triggered by photoisomerization of the azobenzene units using UV or visible irradiation, [9] providing the basis for a variety of photonic applications such as energy storage, [10,11] holographic recording, [12][13][14] soft robotics, [15,16] dynamic control of surface topology in liquid crystalline elastomers [17] and nonlinear optics [18,19] where, in particular, photoinduced reorientation allows for all-optical poling. [20] As one striking example, by controlling the impinging light configuration, the photoinduced processes in azobenzene-containing thin films invoke material mass migration that leads to the formation of topographic surface patterns, a prominent example being surface-relief grating (SRG) formation upon irradiation with a light interference pattern. [21][22][23][24] SRGs show great promise as diffractive photonic elements, [25,26] biosensing substrates, [27] or as nano-/microfabrication templates. [28][29][30] The micron-scale periodicity of SRGs renders them an excellent fit for biological systems, many of which are composed of cells that are extremely sensitive to mechanical and topographic features of the surrounding microenvironment. [31,32] Hence, there is a growing interest in the use of azobenzene-based materials as smart bio-interfaces for cell culture. [33][34][35] The native extracellular matrix (ECM) of soft tissue is composed of entangled fibrous proteins, [36,37] as reproduced also in many synthetic ECM products. [38] Furthermore, ECM is continuously remodeled by the cells in physiological and pathological conditions. [39] Sinusoidal SRGs and embossed pillars in azobenzene thin films have been used for mimicking the ECM texture and controlling cellular directional migration in single and multiple cells, [40][41][42] directing axonal extension, [43,44] and determining stem cell fate. [45] The most exciting characteristic provided by azobenzenebased systems lies in the reversibility of the photoinduced processes. It is well known that SRGs recorded in thin films can be erased by heating the sample above the glass transition temperature (T g ). [46,47] SRGs can be also efficiently erased and re-inscribed optically by using single-beam irradiation [24,48,49] or Azobenzene-based light-responsive thin films are emerging as appealing candidates for smart cell-culture substrates. Their attraction lies in the fact that they can be reversibly photo-patterned, providing a route for dynamically mimicking the remodeling of the extracellular matrix. However, since the cells need to be cultured in aqueous environment, a key parameter in the layout of any biological application is the stability of the surface underwater. In this work, the authors perform a detail...

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Section: Photo-control Over Blister Shape and Formationmentioning

confidence: 99%

Section: Photo-controlled Blister Shape and Formationmentioning

confidence: 99%

Surface Stability of Azobenzene‐Based Thin Films in Aqueous Environment: Light‐Controllable Underwater Blistering

Audia

Fedele

Tone

et al. 2022

Adv Materials Inter

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show abstract

“…Depending on irradiation duration and the concentration of the AZOPD fraction, the relative stretching quantity ranges between 10–70%, which is comparable with results from literature. Comparable experiments show relative stretching ranges between 30–140% [ 38 , 39 , 48 , 49 , 50 ]. However, a small degree of degradation was obtained after the second reversion, which is observable in a decrease in the

-ratio.…”

Section: Discussionmentioning

confidence: 99%

“…The major research on directional stretching of micro- and nanostructures containing azo materials has been done with azo polymers because of their diverse properties ranging from amorphous to liquid crystalline features [ 15 , 18 , 28 , 32 , 33 , 35 , 36 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. However, it was shown that low molecular azo glasses are good candidates for directional photo-induced deformation, too [ 37 , 47 , 48 , 49 , 50 , 51 ]. In comparison to polymers, the synthesis of azo glasses allows an advantageous control for uniform molecular weight.…”

Section: Introductionmentioning

confidence: 99%

Reversible Photo-Induced Reshaping of Imprinted Microstructures Using a Low Molecular Azo Dye

et al. 2022

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A blend of low molecular azo glass (AZOPD) and polystyrene (PS) were used for the systematic investigation of photo-induced stretching and recovery of nanoimprinted structures. For this purpose, light and heat was used as recovery stimuli. The AZOPD/PS microstructures, fabricated with thermal nanoimprint lithography (tNIL), comprises three different shapes (circles, crosses and squares) and various concentrations of AZOPD fractions. The results show a concentration-dependent reshaping. Particularly the sample with 43 w-% of the AZOPD fraction have shown the best controllable recovery for the used parameters. A possible explanation for shape recovery might be the stabilizing effect of the PS-matrix.

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Directional mass transfer of azo molecular glass microsphere induced by polarized light in aqueous immersion media

Abstract: Directional mass transfer of azo molecular glass microspheres is comprehensively investigated upon polarized light irradiation in various aqueous immersion media, and the key factors to influence mass transfer and shape deformation are elucidated.

Cited by 2 publications

References 57 publications

Surface Stability of Azobenzene‐Based Thin Films in Aqueous Environment: Light‐Controllable Underwater Blistering

Surface Stability of Azobenzene‐Based Thin Films in Aqueous Environment: Light‐Controllable Underwater Blistering

Reversible Photo-Induced Reshaping of Imprinted Microstructures Using a Low Molecular Azo Dye

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