Photo-responsive azo-functionalised flexible polymer substrate for liquid crystal alignment

Sivaranjini, B.; Mohana, K. N.; Esakkimuthu, S.; Ganesh, V.; Umadevi, S.

doi:10.1080/02678292.2020.1716276

Cited by 9 publications

(4 citation statements)

References 36 publications

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“…On the other hand, δ of Si-H of 1,1,3,3,5,5-hexamethyltrisiloxane near 4.53 ppm became almost disappeared in the process of hydrosilylation, suggesting that the Si-H in 1,1,3,3,5,5-hexamethyltrisiloxane were substituted (Figure 4.39, 4.41 and 4.43). [5,9,11]…”

Section: Synthesis Of Siloxane Based Azobenzene Containing Bent-core ...mentioning

confidence: 99%

Synthesis of bent-shaped azobenzene main-chain polymers for photo-switching properties

Rahman,

Xin Ting,

Sarjadi

et al. 2023

Journal of Macromolecular Science, Part A

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ChemicalsStarting materials/ reagents were procured from various manufacturers: Ethyl-4-aminobenzoate (Fluka), Hydrochloric acid (Fluka), Sodium nitrite (Sigma), Methanol (Fischer), Phenol (Sigma), Sodium hydroxide (Fluka), Allyl bromide (Fluka), 4-bromo-1-butene (Fluka), Potassium carbonate (Sigma), Potassium iodide (Sigma), Acetone (Fischer), Ethanol (Fischer), Chloroform (Fluka), Hexane (Fischer), Ethyl acetate (Fischer), 1, 3-dicyclohexylcarbodiimide (DCC) (Fluka), 4-(N, N-dimethylamino) pyridine (DMAP) (Fluka), Resorcinol (Sigma), Dimethylformamide (Sigma), Acetic acid (Sigma), 1,1,3,3,5,5-hexamethyltrisiloxane (Sigma), Platinum (0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex solution (Sigma), Toluene (Sigma), Dichloromethane (Fischer). Acetone was dried over phosphorus pentoxide, whereas dichloromethane and toluene were dried over calcium hydride and distilled out before the use. Other solvents and chemicals were used as such. CharacterizationsIn this study, a series of siloxane-based azobenzene containing bent-core polymers were synthesized via the hydrosilylation polyaddition of divinyl terminated bent-core mesogenic monomer and 1,1,3,3,5,5-hexamethyltrisiloxane. The structures of intermediates, monomers and polymers were elucidated by spectral analysis such as nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Their thermal and mesomorphic behaviours were characterized by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). On the other hand, the photos-witching behaviours of polymers in solution were studied by the UV-Vis spectroscopy. FT-IR Spectra of ethyl 4-[(4-hydroxyphenyl)diazenyl]benzoate (1)The functional groups of ethyl 4-[(4-hydroxyphenyl)diazenyl]benzoate 1 show a trend analogous with the previous papers. [1][2][3][4] . The broad peak was observed at 3390 cm -1 , indicating the existence of the hydrogen-bonded -OH group (Figure 1). The presence of the ester functional group in compound 1 was confirmed by the C=O stretching that appeared at 1717 cm -1 . This value was shifted to a lower frequency from the position in a typical aliphatic ester (1750-1735 cm -1 ) due to the conjugation of C=O with phenyl. Generally, the C-O stretching vibration of alcohol, ether, ester and carboxylic acid appears in the range of 1300-1000 cm -1 . Based on the FT-IR spectra of compound 1, the C-O stretching bonds of phenol and ester were identified at 1224 and 1133 cm -1 , respectively. Peaks found at 1592 and 1504 cm -1 , which correspond to C-C stretches in the aromatic ring, confirmed the presence of benzene ring in the molecular structure. The IR spectra also displayed the characteristic stretching band at about 1428 cm -1 associated with the N=N bond. [5] Besides, the C-H wagging peak was identified at 839 cm -1 , suggesting that compound 1 has a para-substituted benzene ring. [6] The functional groups present in compound 1 were summarized in Table 1.

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Section: Synthesis Of Siloxane Based Azobenzene Containing Bent-core ...mentioning

confidence: 99%

Synthesis of bent-shaped azobenzene main-chain polymers for photo-switching properties

Rahman,

Xin Ting,

Sarjadi

et al. 2023

Journal of Macromolecular Science, Part A

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“…Photoalignment of nematic liquid crystals (NLC) represents an emerging technology for the production of liquid crystal devices with novel properties, e.g., lenses, reconfigurable optical networks, index-tunable antireflective coatings and optically rewritable phase gratings [1]. One of these devices is flexible optically rewritable electronic paper (ORW e-paper), which is a reflective display with a photosensitive substrate coated by an azo dye layer with a thickness of 10-15 nm [2][3][4][5][6][7][8][9][10][11]. This display technology has gained significant attention from scholars due to its light weight, low cost, small thickness and easy processing [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Flexible Optically Rewritable Electronic Paper

Chigrinov,

Kudreyko,

Sun

2023

Crystals

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In this article, we present the procedure of preparation of flexible electronic paper with a photosensitive azo dye layer as the key element for changing the orientation of the polarization plane. The main steps of the technology for the fabrication of flexible e-paper are reported. The possible production of Digital Mirror Devices and the roll-to-roll process is discussed. Images on flexible e-paper are demonstrated, including bank card options. The advantages of optically rewritable e-paper technology in comparison with the e-ink usually used for this purpose are highlighted. Potential applications of flexible optically rewritable e-paper include price tags for supermarkets, indoor and outdoor advertisements, smart card labels, etc.

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“…They can rapidly undergo a reversible cis – trans isomerization reaction under illumination and heating and change from rod-like trans configuration to V-shaped cis configuration, resulting in geometric changes. − These microscale changes of a single azobenzene molecule can produce macroscale movement under appropriate conditions . It makes them widely used in light storage, optical mechanical bending, biomedicine, and other aspects. − Generally, photoresponsive polymer materials can be prepared by grafting azobenzene groups into the molecular chain of polymer through a chemical reaction. ,, However, this method is not suitable for large-scale industrial production at present because it often has too high requirements on production and technological conditions. Another way is to prepare photoresponsive materials by introducing azobenzene or its derivatives into polymer matrix by physical doping.…”

Section: Introductionmentioning

confidence: 99%

“…24−28 materials can be prepared by grafting azobenzene groups into the molecular chain of polymer through a chemical reaction. 19,29,30 However, this method is not suitable for large-scale industrial production at present because it often has too high requirements on production and technological conditions. Another way is to prepare photoresponsive materials by introducing azobenzene or its derivatives into polymer matrix by physical doping.…”

Section: ■ Introductionmentioning

confidence: 99%

Chitosan/Polyvinyl Alcohol-Based Direction-Controlled Photo-Humidity Dual Responsive Membrane

Cheng

Zhao

Duo

et al. 2021

ACS Appl. Polym. Mater.

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Photoresponsive materials based on azobenzene (Azo) and its derivatives have attracted wide attention because the cis-trans isomerization of Azo under illumination often leads to changes in shape, color, size, polarity, and so on; it has great application potential in soft robot, actuator, sensor, and other fields. In this paper, by using evaporation-induced self-assembly method, taking advantage of the hydrogen bonding among chitosan (CS), polyvinyl alcohol (PVA) and Azo, and by polishing and grinding the surface of the adopted silicon film mold in advance to form grooves, the Azo/CS/PVA film with a certain degree of oriented aggregation convex surface was prepared. The film has good deformation characteristics of dual response of light and humidity. Also, it has excellent light response direction controllability under UV light, sunlight, and LED illumination. By studying the structure, morphology, photo-stimulus response behavior, humidity-photo response behavior, and mechanical properties of the films, it is found that when the Azo content reaches 10% wt, the response speed is the fastest and the response deformation is the largest. The result shows that under the irradiation of summer sunlight (sunny day), the film can reach 144°directional bending within 55 s. Moreover, the film has excellent humidity response performance, which can absorb sweat in the fingertips, deform quickly, and recover quickly after leaving fingers. The film with an Azo content of 10% wt has a fast humidity response speed, and the maximum bending angle is 140°.The designed simple sunlight response driver can lift a heavy object five times heavier than itself to a certain height, and realize the effective conversion from light energy to mechanical energy. This work effectively broadens the application range of bio-based environmentally friendly materials and has guiding significance for the development and design of multi-stimulus response intelligent materials. The light response directional control method is simple and practical. It is of great significance for the effective utilization of solar energy.

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Photo-responsive azo-functionalised flexible polymer substrate for liquid crystal alignment

Cited by 9 publications

References 36 publications

Synthesis of bent-shaped azobenzene main-chain polymers for photo-switching properties

Synthesis of bent-shaped azobenzene main-chain polymers for photo-switching properties

Flexible Optically Rewritable Electronic Paper

Chitosan/Polyvinyl Alcohol-Based Direction-Controlled Photo-Humidity Dual Responsive Membrane

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