Biphotonic holographic recording in a liquid crystalline cyanoazobenzene side-chain polymethacrylate. Polarization, intensity, and relief gratings

Sánchez, Carlos; Cases, R.; Alcalá, R.; López, Ana M.; Quintanilla, Manuel; Oriol, Luis; Millaruelo, M.

doi:10.1063/1.1365058

Cited by 26 publications

(24 citation statements)

References 41 publications

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“…4 The simultaneous application of blue and red light leads even to the induction of a surface relief. 5,7 Holographic gratings in azobenzene-containing polymer films caused by the irradiation with red light or as a result of the "biphotonic" orientational procedure are also reported in some other papers. [10][11][12][13] In these studies the time gap between the two irradiation steps was on the order of seconds to minutes.…”

Section: Introductionmentioning

confidence: 92%

Photoorientation of a Liquid-Crystalline Polyester with Azobenzene Side Groups: Effects of Irradiation with Linearly Polarized Red Light after Photochemical Pretreatment

Zebger¹,

Rutloh²,

Hoffmann³

et al. 2003

Macromolecules

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In contrast to the conventional photoorientation process with blue light, an orientation of 4-cyano-4′-alkoxyazobenzene side groups parallel to the electric field vector of the incident light is generated upon irradiating films of a liquid-crystalline side-chain polymer with linearly polarized red light. The polyester is characterized by smectic and nematic phases g24S X26SA34N46i and a strong tendency to form J-aggregates. The process requires a photochemical pretreatment by irradiation with UV light or an exposure to visible light of high power density to produce a certain concentration of the Z-isomer, which destroys any initial orientational order and J-aggregates. The orientation process is cooperative, whereas the light-induced orientation of the photochromic moiety causes an ordering of the alkylene spacers and even of the main-chain segments into the same direction. The most probable mechanism of this two-step process is the angular-selective transformation of the bulky Z-isomers to the rodlike E-isomeric formed by the red light. The aligned E-azobenzene side groups become strongly J-aggregated. Very high values of dichroism of about 0.8 and birefringence of about 0.3 were generated as a result of this combination of the photoinduced orientation process and the thermotropic selforganization, which take place simultaneously under the irradiation conditions. The process results in a uniaxial prolate order of the film, whereas conventional photoorientation leads to a biaxial oblate order. These two different three-dimensional orders have been characterized by FTIR polarization spectroscopy and exhibit also varying intermediate thermal stabilities.

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Section: Introductionmentioning

confidence: 92%

Photoorientation of a Liquid-Crystalline Polyester with Azobenzene Side Groups: Effects of Irradiation with Linearly Polarized Red Light after Photochemical Pretreatment

Zebger¹,

Rutloh²,

Hoffmann³

et al. 2003

Macromolecules

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“…Notable examples of such materials predominantly include homopolymers and copolymers with azobenzene moieties covalently attached to the main backbone. Short response times and high and stable values of photoinduced anisotropy have been found for some of these systems 6–11…”

Section: Introductionmentioning

confidence: 96%

Diblock copolymer–azobenzene complexes through hydrogen bonding: Self‐assembly and stable photoinduced optical anisotropy

Barrio

Blasco

Oriol

et al. 2013

J. Polym. Sci. A Polym. Chem.

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We have demonstrated the preparation of a series of photoaddressable supramolecular block copolymers by mixing a carboxy‐terminated azobenzene derivative, 6‐[4‐(4′‐cyanophenylazo)phenyloxy]hexanoic acid (AZO), and two polystyrene‐b‐poly(4‐vinylpiridine) (PS‐b‐P4VP) block copolymers. AZO can be selectively attached to the P4VP block of PS‐b‐P4VP through hydrogen bonding interactions. The assembly of AZO with vinylpyridine group‐containing polymers was initially investigated on a model system composed of P4VP homopolymer and AZO. Homogeneous liquid crystalline materials were obtained for ratios of AZO to vinylpyridine repeating unit, x, lower or equal to 0.50. Mixtures with higher x resulted in heterogeneous materials showing clear macrophase separation. Accordingly, a series of hydrogen‐bonded complexes of PS‐b‐P4VP and AZO, PS‐b‐P4VP(AZO)x, with x = 0.25 and x = 0.50 were prepared. Lamellar and spherical morphologies were observed for the complexes based on PS24‐b‐P4VP9.5 (Mn,PS = 24,000, Mn,P4VP = 9500) and PS24‐b‐P4VP1.9 (Mn,PS = 24,000, Mn,P4VP = 1900), respectively. Photoinduced orientation of the azobenzene units was obtained in films of P4VP(AZO)x and PS‐b‐P4VP(AZO)x with x = 0.25 and 0.50 by using 488 nm linearly polarized light and characterized through birefringence and dichroism measurements. This investigation shows a versatile and less laborious approach to azobenzene‐containing polymer materials with low chromophore content, of interest in optical application. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

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“…Diffraction gratings have been recorded in LCs doped with azobenzenes, in single‐component mesogenic azobenzenes, and in liquid crystal polymers doped with azobenzenes or with azobenzene side‐group substituents . The gratings formed in these materials can be static or dynamic.…”

Section: Directed Self‐assembly Of Liquid Crystalline Materialsmentioning

confidence: 99%

Photoresponsive Structural Color in Liquid Crystalline Materials

McConney

Rumi

Godman

et al. 2019

Advanced Optical Materials

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and then impinging on our eyes. Our brain, rightly or wrongly, interprets these and other sensed patterns as reality. Hence, the saying, "seeing is believing."Given that much of our perceived reality is the result of light-matter interactions, it is no surprise that humans have been actively pursuing methods to understand and control the appearance of materials for thousands of years. Through mixing natural dyes of primary colors, people were able to tailor the color of everyday objects by changing their spectral absorption. The science of absorption-based colored materials evolved to the point of creating materials with light-responsive absorption (photochromics) that, when combined with a camera, were used to capture scenes, thereby allowing us to recreate and share moments of reality. Despite huge advances in the ability to control objects' absorptive color over the last 200 years through chemistry, controlling objects' structural color is still quite challenging. Structural color often refers to spectral interference effects associated with periodic spatial changes in the refractive index of materials (sometimes referred to as photonic crystals). These socalled photonic materials are a unique class of materials that have the ability to strongly affect the light-matter interactions for wavelengths on the scale of the refractive index periodicity. Photonic materials have particularly vivid colors that emerge from their angularly sensitive spectral reflections. Some of the early studies in this area were performed on natural photonic materials that caught the eye of curious scientists. [1] There are many examples of naturally occurring self-assembled photonic materials, including opals, [2] Pollia fruit, [3] jeweled beetles, [1,4] chameleons, [5] and others. [6] These natural examples of structurally derived color can be emulated, altered, or reproduced by researchers. [7][8][9] The ability of biology to self-assemble materials with complex structures and functionality is still unrivaled by engineered systems, but unique opportunities now exist for major advances in autonomously adaptive materials, as scientists are deciphering the molecular mechanisms that biology uses to self-assemble amazingly complex adaptive systems. [10] Particularly relevant to this review, some of the photonic structures found in nature are able to change periodicity in Photoresponsive liquid crystalline photonic materials are a medium in which the self-regulation of light can occur. Liquid crystals are macroscopically selfassembling, optically anisotropic materials capable of amplifying photochemical changes and thus are well suited to demonstrate complex light-driven behavior. This review presents recent progress in liquid crystalline systems exhibiting photoresponsive structural color. More specifically, it surveys progress on liquid crystalline materials and structures with coloration that is the result of the constituents' spatial arrangement (not of presence of dyes or pigments) and for which this arrangement can be externally cont...

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Biphotonic holographic recording in a liquid crystalline cyanoazobenzene side-chain polymethacrylate. Polarization, intensity, and relief gratings

Cited by 26 publications

References 41 publications

Photoorientation of a Liquid-Crystalline Polyester with Azobenzene Side Groups: Effects of Irradiation with Linearly Polarized Red Light after Photochemical Pretreatment

Photoorientation of a Liquid-Crystalline Polyester with Azobenzene Side Groups: Effects of Irradiation with Linearly Polarized Red Light after Photochemical Pretreatment

Diblock copolymer–azobenzene complexes through hydrogen bonding: Self‐assembly and stable photoinduced optical anisotropy

Photoresponsive Structural Color in Liquid Crystalline Materials

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