Solid-state photoswitching in arylazopyrazole-embedded polydimethylsiloxane composite thin films

Ghebreyessus, Kesete; Uba, Ikemefuna; Geddis, Demetris; Hömmerich, U.

doi:10.1016/j.jssc.2021.122519

Cited by 7 publications

(10 citation statements)

References 66 publications

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“…An irradiation with green light of the PDMS–AAP composite resulted in the original absorbance spectrum of the trans state being retrieved with almost 100% of the original intensity. This distinct behavior is due to the efficient reversible isomerization the AAP unit embedded in the PDMS matrix [ 21 , 22 ]. Comparison of the index of refraction in the trans and cis states as well as that of pure PDMS of the same thickness were described in our recently reported studies [ 21 ].…”

Section: Resultsmentioning

confidence: 99%

“…The full impact manifests in higher modes where, for example, 340 nm isomerization to cis state constrains all modes to a fundamental mode, leading to even parity attractive force of Figure 9 c. Optical forces induce deformation in paired structures [ 16 ], which on account of the present contribution, may be regulated by photoisomerization for structure consisting of PDMS–AAP materials and similar hybrids. Furthermore, mechanical actuation was recorded in free-standing PDMS–AAP materials [ 22 ] and can enhance optical force-induced deformations. Thus, integrating the material on nanophotonic chips will provide a different level of controlled displacement.…”

Section: Resultsmentioning

confidence: 99%

“…The arylazopyrazole (AAP) molecular switch was synthesized following procedures developed in our previous studies using commercially available aniline [ 21 , 22 ].…”

Section: Methodsmentioning

confidence: 99%

“…If successfully integrated into a host that promises stoichiometric freedom, not only can a photoswitch induce a new set of indices in the material, but it can also reversibly switch the value through photoisomerization. Among several photoswitches, aryazopyrazole (AAP) was successfully embedded into polydimethylsiloxane (PDMS) [ 21 , 22 ]. The PDMS–AAP composite exhibited actuation, high index (≈2.0), and regulation of same via isomerization.…”

Section: Introductionmentioning

confidence: 99%

“…We note that AAPs have thermal stability and half-life of 1000 days, unlike ubiquitous azobenzene, and they attain high switching efficiency [ 23 ]. In particular, the AAP derivative reported in [ 21 , 22 ] achieved ≈ 100% efficiency in solid matrix over repeated switching. It is then logical to examine suitability of this composite for nanophotonic circuits.…”

Section: Introductionmentioning

confidence: 99%

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A Study of Wave Confinement and Optical Force in Polydimethlysiloxane–Arylazopyrazole Composite for Photonic Applications

et al. 2022

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A refractive index of dielectrics was modified by several methods and was known to have direct influence on optical forces in nanophotonic structures. The present contribution shows that isomerization of photoswitching molecules can be used to regulate refractive index of dielectrics in-situ. In particular, spectroscopic study of a polydimethylsiloxane–arylazopyrazole (PDMS–AAP) composite revealed that refractive index of the composite shifts from 2.0 to 1.65 in trans and cis states, respectively, of the embedded AAP. Based on this, a proposition is made for a waveguide structure, in which external UV/Vis source reversibly regulates the conformation of the PDMS–AAP core. Computational study is performed using Maxwell’s equations on buried waveguide structure. The simulation, implemented in PYTHON, sequentially utilizes empirical refractive indices of the composite in the isomeric states in lieu of regulation by a source. The simulation revealed highly confined wave propagations for injected signals of 340 and 450 nm wavelengths. It is observed that the cis state suppresses higher order mode when propagating UV wavelength but allows it for visible light. This modal tuning demonstrated that single mode can be selectively excited with appropriate waveguide dimensions. Further impact of the tuning is seen in the optical force between waveguide pair where the forces shift between attractive and repulsive in relation to the isomeric state of the PDMS–AAP core. These effects which stem from the adjustment of refractive index by photoisomerization suggests that in-situ regulation of index is achievable by successful integration of photoswitching molecules in host materials, and the current PDMS–AAP composites investigated in this study can potentially enhance nanophotonic and opto-mechanical platforms.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The arylazopyrazole (AAP) molecular switch was synthesized following procedures developed in our previous studies using commercially available aniline [ 21 , 22 ].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Study of Wave Confinement and Optical Force in Polydimethlysiloxane–Arylazopyrazole Composite for Photonic Applications

et al. 2022

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Photoinduced Ultrafast Shape-Changing Self-Assembled Arylazopyrazole-Based Polymeric Micelles

Manna,

Dolai,

Ghosh

et al. 2024

Macromolecules

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In recent times, photoinduced shape-changing polymers have demonstrated great potential in various applications. The solvent-dependent/free photochromism and conformationdependent shear viscosity modulation of the developed materials enhance their relevance from industry to academia. Here, two hydrophobically modified photoresponsive arylazopyrazole-based copolymers have been developed via reversible addition−fragmentation chain-transfer (RAFT) polymerization technique using hydrophilic poly(ethylene glycol) methyl ether methacrylate [PEGMA] moieties. The nonsubstituted arylazopyrazole-based copolymer has a shorter half-life that fosters the development of the difluorosubstituted copolymer with a longer half-life. Both copolymers exhibit self-assembly behavior in water to form micelles, as has been evidenced by photoluminescence spectroscopy and surface morphological analyses. Upon UV light exposure, both copolymeric micelles photoisomerize from trans-state to cis-state. The electron microscopic analyses (both FESEM and TEM) can detect that the shape-changing morphology has been perceived from spherical to deformed spherical only for the difluoro-substituted copolymer. Rheological studies reveal the impact of photoisomerization-induced changes in the hydrophobicity of two arylazopyrazoles on solution aggregation. Two distinct photoinduced glass transition temperatures and phase transition temperatures of both copolymers have been evidenced by differential scanning calorimetry (DSC). The study offers a new finding toward the impact of varying the hydrophobicity of stimuli-responsive end groups on aggregation and viscoelastic behaviors. Nevertheless, it is essential to mention that the extended thermal half-life of the developed material advances its applicability in smart devices for biomedical sciences optics, coating, energy storage, and so on.

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Toward real-world applications: promoting fast and efficient photoswitching in the solid state

Sun

Wang

2022

J. Mater. Chem. C

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Solid-state photoswitching in arylazopyrazole-embedded polydimethylsiloxane composite thin films

Cited by 7 publications

References 66 publications

A Study of Wave Confinement and Optical Force in Polydimethlysiloxane–Arylazopyrazole Composite for Photonic Applications

A Study of Wave Confinement and Optical Force in Polydimethlysiloxane–Arylazopyrazole Composite for Photonic Applications

Photoinduced Ultrafast Shape-Changing Self-Assembled Arylazopyrazole-Based Polymeric Micelles

Toward real-world applications: promoting fast and efficient photoswitching in the solid state

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