Azo-Containing Polymer Brushes: Photoalignment and Application as Command Surfaces

Camorani, Paolo; Cristofolini, Luigi; Fontana, Marco; Angiolini, Luigi; Giorgini, Loris; Paris, Fabio

doi:10.1080/15421400902813709

Cited by 21 publications

(13 citation statements)

References 21 publications

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“…The brush polymer of a side chain azobenzene polymer can be further applied as photo‐switchable command surfaces for nematic LCs. Camorani et al synthesized an azobenzene‐containing polymer surface by SI‐ATRP and a photo‐switchable twisted/planar nematic LC cell was fabricated using these brush surfaces (Table , 6 ). The assembled device showed excellent properties in terms of uniformity and molecular order, which was comparable with that obtained with a traditional rubbed polyimide surface.…”

Section: Surface‐tethered Lc Brush Polymersmentioning

confidence: 99%

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Meso‐ and Microscopic Motions in Photoresponsive Liquid Crystalline Polymer Films

Seki

2013

Macromol. Rapid Commun.

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Photoresponsive azobenzene-containing systems ranging from molecular to macroscopic material levels have greatly been increasing their significance in materials chemistry. This review focuses on the studies on light induced or triggered motions in azobenzene liquid crystalline (LC) polymer films at mesoscopic and microscopic levels. Due to the cooperative nature of liquid crystalline materials, highly efficient photoalignment and photo-triggered migrating motions are realized in mostly repeated manners. Here, recent advances in surface-grafted LC polymer brushes, LC block copolymer films, and LC polymer films that exhibit mass migrations are overviewed. Such newly emerged photoresponsive systems are expected to provide new possibilities and applications in polymer thin film technologies.

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Section: Surface‐tethered Lc Brush Polymersmentioning

confidence: 99%

“…Schematic illustration of nematic LC alignment by surface brush polymers. An azobenzene side chain LC polymer brush (Table , 6 ) by Camorani et al (a) and a high‐density PMMA brush (Table , 8 ) by Tokita et al (b).…”

Section: Surface‐tethered Lc Brush Polymersmentioning

confidence: 99%

Meso‐ and Microscopic Motions in Photoresponsive Liquid Crystalline Polymer Films

Seki

2013

Macromol. Rapid Commun.

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“…Ref. [11]. Other applications are based on spontaneous tilting transition in the main chain LCPB [12]; LC ordering as the result of dewetting of the LCPB [13]; the synergy between the LCPB and nanotubes allowing to fabricate smart windows with their transparency controlled by the near infrared light [14] and so on.…”

Section: Introductionmentioning

confidence: 99%

Photo-switchable liquid crystalline brush as an aligning surface for liquid crystals: modeling via mesoscopic computer simulations

Yaremchuk,

Patsahan,

Ilnytskyi

2021

Preprint

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We consider the mesoscopic model for the liquid crystalline brush that might serve as a photoswitchable aligning surface for preorientation of low molecular weight liquid crystals in a bulk. The brush is built by grafting the polymer chains of a side-chain molecular architecture, with the side chains terminated by a chromophore unit mimicking the azobenzene unit, to a substrate. When irradiated with ultraviolet light, the chromophores photoisomerize into a nonmesogenic cis state and the whole system turns into an ordinary polymer brush with no orientational order and two states: the collapsed and straightened one, depending on the grafting density. When irradiated with visible light, the chromophores photoisomerize into a mesogenic trans state, resulting in formation of a transient network between chains because of a strong attraction between chromophores. Spontaneous self-assembly of the brush in these conditions results in a orientationally isotropic polydomain structure. The desired uniaxial planar ordering of chromophores within a brush can be achieved in certain temperature and grafting density intervals, as the result of a two-stage preparation protocol. An external stimulus orients chromophores uniaxially on the first stage. The system is equilibrated at the second stage at a given temperature and with the external stimulus switched off. The preoriented chromophores either keep or loose their orientations depending on the strength of the memory effect inherent to a transient network of chains, that are formed during the first stage, similarly to the case of the liquid crystalline elastomers, where such effects are caused by the covalent crosslinks.

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“…Usually, these layers represent low‐molar‐mass molecules adsorbed on the surface or chemically connected to it . In addition, some polymers of different structures (linear, comb‐shaped, grafted on the surface) containing photosensitive groups, such as azobenzene, cinnamate, or coumarin, are also very often used for the same aims. The operating principle of these materials is based on the noncontact (as opposed to mechanical rubbing of polyimide coatings) activation of the aligning layers by irradiation with polarized UV light.…”

Section: Introductionmentioning

confidence: 99%

A novel generation of photoactive comb-shaped polyamides for the photoalignment of liquid crystals

Ryabchun

Bobrovsky

Chun³

et al. 2013

J. Polym. Sci. Part A: Polym. Chem.

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A new approach to the synthesis of photoactive comb-shaped homo-and copolyamides containing azobenzene, cinnamate, and coumarin side groups for photoalignment of liquid crystals was elaborated. Photooptical properties and photoorientational ability of these polymers with respect to liquid crystals were studied. It was shown that polarized UV irradiation of all spin-coated polyamides leads to orientation of liquid crystalline molecules deposited on the polyamide thin films. The synthesized polymers containing cinnamate and coumarin side groups as well as azobenzene-containing cyanoand nitro-substituted polymers demonstrated good orientation ability in relation to liquid crystals displaying photoinduced planar orientation with high dichroism values within the range of 0.68-0.72. Contrary to the above-mentioned polyamides, azobenzene-containing fluorosubstituted polymers induced a homeotropic orientation of liquid crystals. It was shown that the synthesized photoactive polyamides can be considered as promising photoalignment materials for application in display technology, photonics, and other "smart" optical devices.

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Azo-Containing Polymer Brushes: Photoalignment and Application as Command Surfaces

Cited by 21 publications

References 21 publications

Meso‐ and Microscopic Motions in Photoresponsive Liquid Crystalline Polymer Films

Meso‐ and Microscopic Motions in Photoresponsive Liquid Crystalline Polymer Films

Photo-switchable liquid crystalline brush as an aligning surface for liquid crystals: modeling via mesoscopic computer simulations

A novel generation of photoactive comb-shaped polyamides for the photoalignment of liquid crystals

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