Mastering the Photothermal Effect in Liquid Crystal Networks: A General Approach for Self‐Sustained Mechanical Oscillators

Gélébart, Anne Hélène; Vantomme, Ghislaine; Meijer, E. W.; Broer, Dirk J.

doi:10.1002/adma.201606712

Cited by 218 publications

(243 citation statements)

References 44 publications

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“…Recent research also shows an influence of temperature upon irradiation. This leads to photothermal effects described as photo-softening [42,[110][111][112]. A full understanding of the driving mechanism in the creation of surface structures in azo polymers is sought to improve or fabricate new surface topography changing coatings.…”

Section: Discussionmentioning

confidence: 99%

Light-Triggered Formation of Surface Topographies in Azo Polymers

et al. 2017

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Properties such as friction, wettability and visual impact of polymer coatings are influenced by the surface topography. Therefore, control of the surface structure is of eminent importance to tuning its function. Photochromic azobenzene-containing polymers are an appealing class of coatings of which the surface topography is controllable by light. The topographies form without the use of a solvent, and can be designed to remain static or have dynamic properties, that is, be capable of reversibly switching between different states. The topographical changes can be induced by using linear azo polymers to produce surface-relief gratings. With the ability to address specific regions, interference patterns can imprint a variety of structures. These topographies can be used for nanopatterning, lithography or diffractive optics. For cross-linked polymer networks containing azobenzene moieties, the coatings can form topographies that disappear as soon as the light trigger is switched off. This allows the use of topography-forming coatings in a wide range of applications, ranging from optics to self-cleaning, robotics or haptics.

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Section: Discussionmentioning

confidence: 99%

Light-Triggered Formation of Surface Topographies in Azo Polymers

et al. 2017

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“…[ 12 ] Broer and coworkers reported UV‐light‐fueled LCN oscillators through doping photothermal molecules into the LCN matrix. [ 14,15 ] The remarkable and fast oscillation of LCN‐based oscillators makes them valuable in collecting solar energy and generating electricity. [ 16,17 ] Compared with the UV light or visible light, near‐infrared (NIR) light is more attractive and highly preferred due to its invisibility and biocompatibility for remote activation with highly spatial and time precision, exhibiting tremendous potential in practical application prospects such as the fabrication of biomedical devices and development of intelligent soft robotics.…”

Section: Figurementioning

confidence: 99%

Near‐Infrared Photodriven Self‐Sustained Oscillation of Liquid‐Crystalline Network Film with Predesignated Polydopamine Coating

et al. 2020

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Movement is one of the vital features of living systems, and remote control of bioinspired soft robotic systems in a precise, contactless and harmless way is extremely desirable but challenging. A near‐infrared (NIR) photodriven polymeric oscillator is designed and fabricated by selectively coating a mussel‐inspired polydopamine (PDA) polymer layer on the surface of splay‐aligned liquid crystalline network (LCN) film. The oscillating motions of the LCN oscillators can be facilely manipulated by tuning light intensity and film thickness. More importantly, the programmability of the PDA coating enables the oscillating behaviors of LCN film to be predesignated and finely adjusted by coating the film with PDA locally and repeatedly. The self‐oscillating movement mechanism can be attributed to the temperature oscillation at the PDA‐coated LCN film since it is alternatively exposed and sheltered to the NIR‐light irradiations. Owing to over 50% NIR irradiation in solar spectrum, PDA‐coated film is found to oscillate upon exposure of focused sunlight, presenting great potential in fabrication of solar power generation devices. This provides a versatile strategy to fabricate NIR‐light‐actuated polymeric oscillators, providing inspirations in the development of biological soft robots and advanced biomimetic devices.

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“…These can be controlled by selectively illuminating the azobenzene's absorption bands, being 365 and 455 nm, respectively. [7][8][9][10] However, it remains a challenge to obtain reversible and/or dynamic topographies at high respond speeds combined with large topographical changes. At most, the deformations achievable are up to a micrometer at best.…”

Section: Doi: 101002/admi201800810mentioning

confidence: 99%

Compliance‐Mediated Topographic Oscillation of Polarized Light Triggered Liquid Crystal Coating

Hendrikx

Sırma

Schenning

et al. 2018

Adv Materials Inter

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The ability to induce oscillating surface topographies in light‐responsive liquid crystal networks on‐demand by light is interesting for applications in soft robotics, self‐cleaning surfaces, and haptics. However, the common height of these surface features is in the range of tens of nanometer, which limits their applications. Here a photoresponsive liquid crystal network coating with a patterned director motive exhibiting surface features that oscillate dynamically when addressed by light with modulated polarization is reported. By utilizing a compliant intermediate layer, the surface topographies increase with a factor 10, from roughly 70–100 nm to 1 µm. This increase in topography height is accompanied by a superimposed dynamic oscillation with an amplitude of ≈100 nm. These values can be translated to a 16.7% average static strain with 3.3% oscillations with respect to the coating thickness. Moreover, utilizing the complying support increases the maximum rotation speeds with an in‐phase response from 2.5 up to 25° s−1. However, at this maximized rotation speed the oscillation amplitude decreases to about half of the initial value.

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Mastering the Photothermal Effect in Liquid Crystal Networks: A General Approach for Self‐Sustained Mechanical Oscillators

Cited by 218 publications

References 44 publications

Light-Triggered Formation of Surface Topographies in Azo Polymers

Light-Triggered Formation of Surface Topographies in Azo Polymers

Near‐Infrared Photodriven Self‐Sustained Oscillation of Liquid‐Crystalline Network Film with Predesignated Polydopamine Coating

Compliance‐Mediated Topographic Oscillation of Polarized Light Triggered Liquid Crystal Coating

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