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Photoresponsive Polymers
Published in Asit Baran Samui, Smart Polymers, 2022
Photomobile polymer materials have the ability to convert light energy directly into mechanical work without using any electrical or mechanical systems. However, the deformation in amorphous polymer materials occurring in an isotropic way produces too small an effect to be practically utilized. The deformation can be increased by using cross-linked LC polymers (CLCPs).43 The initial alignment of mesogens, the cross-linking density and polarization direction of actinic light, act in controlling the deformation.44 On irradiation with UV light, photochromic and mesogenic groups containing diarylethene CLCP films exhibit bending toward the irradiation source.45 The bent films come back to the initial flat position by irradiating with visible light. The photocyclization/photocycloreversal of the diarylethene derivative occurs during exposure to UV/visible light.
Effect of azimuthal anchoring energy on rewriting speed of optical rewritable e-paper
Published in Liquid Crystals, 2021
The key of the ORW e-paper device is the azo-dye alignment material SD1, which can be inplane reoriented to the direction perpendicular to the polarisation of the activating UV light. This photoalignment mechanism is different from that of previously reported azobenzene-based materials [16–19] and the diarylethene-based materials [20,21]. The diarylethene-based materials can undergo reversible photocyclization by appropriate light irradiation. For most of azobenzene-based materials, molecules change their shape between a rod-like trans-form and a bent cis-form upon proper light illumination. While the photoalignment mechanism of azo-dye alignment materials such as SD1 is pure inplane reorientation of the azo-dye chromophore molecules. Many other experimental works using SD1 has also been demonstrated on the rewriting of some specific blue phase LCs [22]. And moreover, the rewritability upon coupling effect of light irradiation and electric-field have also been found in recent years [23,24]. The theoretical diffusion model of the dye molecule reorientation is used to analyse the rewriting process of pure SD1 without LC [12]. The model uses the diffusion equation with a specific potential, which characterises the interaction of the molecules and the activated light. Both the approximations of negligible and strong molecular interaction during the process of the reorientation under the action of a polarised light are considered. However, this work does not consider the rewriting speed with different LC cell preparation process parameters. Hence, more work needs to be done to study various preparation process parameters.
Synthesis and characterization of a new photochromic alkylene sulfide derivative
Published in Journal of Sulfur Chemistry, 2018
Asim A. Balakit, Keith Smith, Gamal A. El-Hiti
The synthesis of photochromic diarylethenes containing an aldehyde group has been reported [22]. 1-[5-(Formyl)-3-methyl-2-thienyl]-2-[5-(4-cyanophenyl)-3-methyl-2-thienyl]perfluorocyclopentene (11; Scheme 2) was chosen for the model target compound because diarylethenes with electron-withdrawing substituents (e.g. CN) have interesting photochromic behavior [23].