Light induced reversible structuring of photosensitive polymer films

Jelken, Joachim; Santer, Svetlana

doi:10.1039/c9ra02571e

Cited by 39 publications

(46 citation statements)

References 60 publications

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“…The light‐driven phenomena like molecular photoorientation, photo‐induced mass transfer, generation of mechanical forces, and so on have been used extensively to create various functional materials for optics, photonics, and soft‐robotics . Particularly, azobenzene‐based polymers are increasingly drawing attention of the scientific community as materials for the holographic data storage and the recording of a wide range of diffraction gratings (polarized gratings, surface relief gratings, reflection gratings, and so on) . In contrast to amorphous polymers, which are mostly interesting for the fabrication of surface relief gratings, liquid crystalline (LC) polymers are suitable for a polarization grating recording due to their high optical birefringence and cooperativity at the molecular level .…”

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confidence: 99%

Polarization Gratings in Azobenzene‐Based Fully Liquid Crystalline Triblock Copolymer

Bugakov

Sakhno

Boiko

et al. 2019

Macromol. Rapid Commun.

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surface relief gratings, liquid crystalline (LC) polymers are suitable for a polarization grating recording due to their high optical birefringence and cooperativity at the molecular level. [15] The majority of recent reports on this kind of materials concern LC homopolymers, random copolymers, and block copolymers that contain azobenzene and amorphous blocks. In block copolymers, the formation of an LC phase competes with the nanoscale segregation of constituent blocks. It yields synergy of various nanostructures such as spheres, cylinders and lamella, and properties of an LC phase (a cooperative molecular motion and high anisotropy of physical parameters). [16,17] In addition, due to the formation of a microphase-separated structure, the local concentration of azobenzene groups in block copolymer films is as high as in azobenzene homopolymers. It can provide considerable faster recording and higher efficiency in comparison with random copolymers. [18] To date the holographic recording in LC block copolymers containing azobenzene and amorphous blocks has been studied extensively. [17][18][19][20][21][22] Amorphous blocks of such block copolymers do not contribute to the optical response and do not participate in the holographic recording. On the other hand, introducing LC (mesogenic) groups in each block of block copolymers assures controlling optical properties of every microphase. [23] The presence of mesogenic groups in each block may bring into a play the whole polymer volume, thus increasing efficiency of these materials from the standpoint of the holographic recording. However, there is only one short mention concerning the holographic recording in films of azobenzene LC diblock copolymers comprised of only mesogenic monomer units. [24] Although fully LC block copolymers are envisioned as novel efficient materials for the holographic recording, such copolymers are far from being elucidated properly.In our previous work, we have synthesized LC photo sensitive ABA triblock copolymers comprised of azobenzene (Azo) and non-photosensitive phenyl benzoate (PhM) units. [23] We have also demonstrated that the irradiation of these materials with linearly polarized light and subsequent annealing offer an efficient tool for the selective control over the orientation of Azo and PhM groups. [25] In this communication, we aim to study holographic behavior of fully LC ABA triblock copolymer (Block) composed of Azo and PhM mesogenic units (Figure 1a) with the focus on polarization holographic gratings. As reference samples, Photosensitive liquid crystalline (LC) block copolymers are a universal platform for designing functional materials for optics and photonics. Here, azobenzene LC ABA triblock copolymer containing mesogenic groups in each block is studied as a medium for the recording of polarization holographic gratings. The fast recording of polarization gratings is successfully performed with two orthogonally circularly polarized light beams of a 532-nm laser. It is shown that annealing of the recorded polarization g...

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confidence: 99%

Polarization Gratings in Azobenzene‐Based Fully Liquid Crystalline Triblock Copolymer

Bugakov

Sakhno

Boiko

et al. 2019

Macromol. Rapid Commun.

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“…When combined with a similar, but composed of light‐absorbing gold, grating, the rising Moiré interference effect enables to achieve contrast values, significantly higher than when using material‐wise identical gratings. The observed effect can be easily tuned over the micrometer‐range distance and maintained for large interlattice separation that opens up a possibility to replace the spacer with various functional materials, such as photosensitive polymers, [ 33 ] activated at the QDs emission wavelength, or electrically conductive resins, [ 34 ] to extend the discussed concept to stimuli‐responsive metasurfaces. Moreover, such spatially controllable, yet strong contrast can be further employed for security labeling, [ 32 ] taking the advantage of the simplicity of mass production and optical durability.…”

Section: Resultsmentioning

confidence: 99%

Tunable Circular Dichroism by Photoluminescent Moiré Gratings

Aftenieva

Schnepf

Mehlhorn

et al. 2020

Advanced Optical Materials

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In nanophotonics, there is a current demand for ultrathin, flexible nanostructures that are simultaneously easily tunable, demonstrate a high contrast, and have a strong response in photoluminescent polarization. In this work, the template‐assisted self‐assembly of water‐dispersed colloidal core–shell quantum dots into 1D light‐emitting sub‐micrometer gratings on a flexible substrate is demonstrated. Combining such structures with a light‐absorbing metallic counterpart by simple stacking at various angles results in a tunable Moiré pattern with strong lateral contrast. Furthermore, a combination with an identical emitter‐based grating leads to a chiroptical effect with a remarkably high degree of polarization of 0.72. Such a structure demonstrates direct circular polarized photoluminescence, for the first time, without a need for an additional chiral template as an intermediary. The suggested approach allows for reproducible, large‐area manufacturing at reasonable costs and is of potential use for chiroptical sensors, photonic circuit applications, or preventing counterfeit.

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“…There are several ways to create dynamic photocontrollable surfaces based on amorphous azobenzene-containing polymer systems 11 , 12 and LC networks, which are mainly multistep and require lithography, masks, or exposure to interference patterns. 13 − 21 However, dynamic surfaces can be fabricated by homogeneous photopolymerization of cholesteric layers with fingerprint texture.…”

Section: Introductionmentioning

confidence: 99%

Light-Fueled Nanoscale Surface Waving in Chiral Liquid Crystal Networks

Ryabchun

Lancia

Katsonis

2021

ACS Appl. Mater. Interfaces

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Nano-and micro-actuating systems are promising for application in microfluidics, haptics, tunable optics, and soft robotics. Surfaces capable to change their topography at the nano-and microscale on demand would allow control over wettability, friction, and surface-driven particle motility. Here, we show that light-responsive cholesteric liquid crystal (LC) networks undergo a waving motion of their surface topography upon irradiation with light. These dynamic surfaces are fabricated with a maskless one-step procedure, relying on the liquid crystal alignment in periodic structures upon application of a weak electric field. The geometrical features of the surfaces are controlled by tuning the pitch of the liquid crystal. Pitch control by confinement allows engineering one-dimensional (1D) and two-dimensional (2D) structures that wave upon light exposure. This work demonstrates the potential that self-organizing systems might have for engineering dynamic materials, and harnessing the functionality of molecules to form dynamic surfaces, with nanoscale precision over their waving motion.

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Light induced reversible structuring of photosensitive polymer films

Abstract: In this paper we report on photoswitchable polymer surfaces with dynamically and reversibly fluctuating topographies.

Cited by 39 publications

References 60 publications

Polarization Gratings in Azobenzene‐Based Fully Liquid Crystalline Triblock Copolymer

Polarization Gratings in Azobenzene‐Based Fully Liquid Crystalline Triblock Copolymer

Tunable Circular Dichroism by Photoluminescent Moiré Gratings

Light-Fueled Nanoscale Surface Waving in Chiral Liquid Crystal Networks

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