Enhancing the photochemical reversibility of coumarin-containing polymers by molecular orientation control

Inacker, Sebastian; Kahler, Philipp; Hampp, Norbert

doi:10.1039/d2py01230h

Cited by 9 publications

(11 citation statements)

References 36 publications

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“…The illumination setup is further described in detail elsewhere. 14 The reaction was monitored via UV-Vis spectroscopy using a PERKIN ELMER LAMBDA 35 spectrometer. The reaction process was followed by the absorption at wavelength 321 nm, as this is the coumarin monomer motifs absorption maximum.…”

Section: Illumination Procedures and Monitoring Of The Photo Reactionmentioning

confidence: 99%

“…In the confined geometry with defined molecular orientation, up to seven illumination cycles could be performed without significant losses in the photo-switchable amplitude. 14 When the molecular orientation is lost, e.g. by use of higher mobility polymers or heating, the reversibility also decreases significantly.…”

Section: Reversibility Of the Photoreactionmentioning

confidence: 99%

“…In typical coumarin-containing polymers, the cycloreversion reaction for cyclobutane cleavage is performed under illumination with UV-C light (λ < 300 nm), although this has several drawbacks in the view of undesired side reactions like backbone damage. 5,14 In addition, the short wavelength UV light can not be used for illumination of thicker materials, as the formed monomeric coumarin species absorb strongly in this wavelength range. Therefore, two photon absorption induced cycloreversion has to be performed for the splitting in thicker material layers.…”

Section: Two Photon Induced Reactionmentioning

confidence: 99%

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Photo-switchable optical properties polymers with enhanced reversibility

Inacker

Hampp²

2023

Organic Photonic Materials and Devices XXV

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In the field of light-responsive polymers, coumarin is one of the most commonly used structural motifs. By applying different wavelengths, materials' properties can be changed. Hereby, limited reversibility of the reaction is reported in many cases. By introducing a novel intramolecular coumarin dimer (ICD) based polymer architecture, the reversibility of the reaction is increased significantly. The photoreaction of the reversion and addition reaction is performed over several illumination cycles with alternating UV-wavelength light (λ = 265 nm for cycloreversion, λ = 345 nm for cycloaddition). A high degree of reversibility is reached by keeping the mobility low. Performing the illumination cycles at low temperatures and using a highly crosslinked material for structural confinement, the clean photochemical reaction path is maintained. Loss of the preferred molecular orientation, e.g. by heating, resembles the coumarin moieties, which results in non-defined photoreaction and decreased reversibility. By incorporating the ICD structure in different polymers, a bunch of applications are presented. Besides light-induced refractive index modulation, also fluorescence changes in polymer thin films were achieved. In addition, the cycloreversion reaction was performed under two-photon absorption (TPA) conditions using intense visible light laser pulses. For the TPA-induced reaction, a different reaction mechanism compared to the UV-light-induced reaction was found. The TPA-induced reaction offers great potential in further applications in the field of light-responsive polymers, e.g. for optical data storage or waveguide technologies.

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Section: Illumination Procedures and Monitoring Of The Photo Reactionmentioning

confidence: 99%

Section: Reversibility Of the Photoreactionmentioning

confidence: 99%

Section: Two Photon Induced Reactionmentioning

confidence: 99%

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Photo-switchable optical properties polymers with enhanced reversibility

Inacker

Hampp²

2023

Organic Photonic Materials and Devices XXV

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“…[38][39][40][41] Subtle structural changes in polymer networks such as stereo-, regio-, and topological isomerisation can critically affect material properties. [42][43][44] Specifically for covalent dynamic polymer materials, the exact nature of the molecular network connectivity before and after (re)processing can be significantly altered. 45,46 For instance, networks based on the bench-mark thermoreversible furan/maleimide system have been observed to undergo chemical aging when subjected to repeated material (re)processing, resulting from differences in network rearrangement caused by endo/exo isomerisation of the dynamic crosslinks (Fig.…”

Section: Introductionmentioning

confidence: 99%

Regioselective photocycloaddition for light-stabilised dynamic materials design

et al. 2023

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“…Coumarin groups with light mediated [2 + 2] cycloaddition reaction exhibit excellent reversible photodimerization properties. When irradiated with 365 nm UV light, the alkene of coumarin groups can form cyclobutane rings, whilst irradiated with 254 nm UV light can lead to the cleavage of cyclobutanelinked dimer to revert to initial ole n (Abdallh et al, 2019;Hughes et al, 2019;Inacker et al, 2022;You et al, 2022). In the past few years, brilliant advances have been made in the development of various photoreversible self-healing polymers based on coumarin and its derivatives to meet the requirements of different applications.…”

Section: Introductionmentioning

confidence: 99%

Cellulose nanocrystals/fluorinated polyacrylate with mechanical tunability and self-healing capability via photo actuated reversible associations

Zhou

et al. 2023

Preprint

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Traditional fluorinated polyacrylate has been extensively applied in various fields, which is favored by many researchers. However, the polymer usually can lose usefulness when it is damaged. Endowing the polymer with self-healing capability provides a potential solution to address the conflict. Herein, a series of photo actuated self-healing fluorinated polyacrylate based on coumarin groups was synthesized by Pickering emulsion polymerization using the cellulose nanocrystals (CNCs) as the stabilizer, n-butyl acrylate (BA) as the soft monomer, and methyl methacrylate (MMA) as the hard monomer. The influences of the amount of 7-(4-vinylbenzyloxy)-4- methylcoumarin) (VBMC) and the mass ratio of BA and MMA on the emulsion polymerization and latex film properties were studied. The results showed that the latex particle size and its distribution decreased and then increased as the VBMC dosage and BA/MMA increased. The latex film exhibited not only high ultimate tensile stress (6.36 MPa) and large stretchability (575.71%) but also a certain anti-fatigue characteristic. Besides, the latex film can achieve efficient self-healing capability due to the mobility of polymer chains associated with low glass transition temperature (Tg) and the reversible [2 + 2] cleavage/dimerization reaction of the coumarin groups upon ultraviolet (UV) irradiation of 254 nm and 365 nm. The work offers a substantial reference for developing different photo-actuated self-healing polymers with great prospects and promising futures.

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Enhancing the photochemical reversibility of coumarin-containing polymers by molecular orientation control

Abstract: The cycloaddition and -reversion of coumarin is one of the most prominent examples of reversible photo-driven reactions, which are used in a broad field of applications. By applying different illumination...

Cited by 9 publications

References 36 publications

Photo-switchable optical properties polymers with enhanced reversibility

Photo-switchable optical properties polymers with enhanced reversibility

Regioselective photocycloaddition for light-stabilised dynamic materials design

Cellulose nanocrystals/fluorinated polyacrylate with mechanical tunability and self-healing capability via photo actuated reversible associations

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