A New Phototropic Substance and Its ESR

Hayashi, Tarō; Maeda, Kōko; Shida, Shôji; Nakada, Kazuo

doi:10.1063/1.1730961

Cited by 66 publications

(19 citation statements)

References 2 publications

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“…2c , red curve ). The g -tensor was measured to be 2.003, which exactly corresponded to the reported values for TPIR 31 , 32 . Comparison of the ESR spectra before and after UV irradiation also showed a 10-fold increase in the amount of TPIR after UV irradiation (Fig.…”

Section: Resultssupporting

confidence: 81%

Photo-triggered solvent-free metamorphosis of polymeric materials

Honda

Toyota

2017

Nat Commun

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Liquefaction and solidification of materials are the most fundamental changes observed during thermal phase transitions, yet the design of organic and polymeric soft materials showing isothermal reversible liquid–nonliquid conversion remains challenging. Here, we demonstrate that solvent-free repeatable molecular architectural transformation between liquid-star and nonliquid-network polymers that relies on cleavage and reformation of a covalent bond in hexaarylbiimidazole. Liquid four-armed star-shaped poly(n-butyl acrylate) and poly(dimethyl siloxane) with 2,4,5-triphenylimidazole end groups were first synthesized. Subsequent oxidation of the 2,4,5-triphenylimidazoles into 2,4,5-triphenylimidazoryl radicals and their coupling with these liquid star polymers to form hexaarylbiimidazoles afforded the corresponding nonliquid network polymers. The resulting nonliquid network polymers liquefied upon UV irradiation and produced liquid star-shaped polymers with 2,4,5-triphenylimidazoryl radical end groups that reverted to nonliquid network polymers again by recoupling of the generated 2,4,5-triphenylimidazoryl radicals immediately after terminating UV irradiation.

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Section: Resultssupporting

confidence: 81%

Photo-triggered solvent-free metamorphosis of polymeric materials

Honda

Toyota

2017

Nat Commun

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“…Amongst the motifs for stress-report, functional moieties changing their optical properties upon the application of stress are highly desirable as they allow the visualization of areas under heavy loading. [22][23][24][25] Moreover, HABI derivatives are already employed as radical photoinitiators in photoimaging systems 26 as well as for the realization of de-crosslinkable polymer networks. [11][12][13][14] Consequently, the implementation of both the ability to visualize as well as repair broken bonds in a polymeric material can be seen as a significant advance in the field of materials science, as recently demonstrated by Weng, Boulatov and co-workers.…”

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confidence: 99%

Stress-induced colouration and crosslinking of polymeric materials by mechanochemical formation of triphenylimidazolyl radicals

2016

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“…Molecular photoswitches are extremely sensitive to light and the two isomers of each molecular photoswitch can be reversibly converted into each other, which possess a natural advantage for the preparation of fast photoswitchable hydrogels. Typical molecular photoswitches include Azo's, 49 spiropyrans (SP's), 50 diarylethenes, 51 hexaarylbiimidazoles (HABI's), 52 and so on. (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Photomechanical polymer hydrogels based on molecular photoswitches

Luo

Xiang

et al. 2021

Journal of Polymer Science

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As intelligent materials responsive to light, photomechanical hydrogels not only possess high‐water content, excellent softness and biocompatibility, but also can accomplish various mechanical motions upon spatiotemporal stimulation of external light, which exhibit great potential in biomedical and underwater bionic fields. Molecular photoswitches have been used broadly in preparation of photomechanical hydrogels owing to their high photosensitivity and reversible molecular structure transformations induced by light. Herein, the current progress of photomechanical hydrogels based on typical molecular photoswitches such as spiropyran, azobenzene, and hexaarylbiimidazole (HABI) are introduced. Especially, as a promising building unit for photomechanical hydrogels, HABI has been highlighted due to the unique molecular structures and reversible photoswitching capability. HABI‐derived polymer hydrogels demonstrate flexible mechanical behaviors upon localized light irradiation. The characteristics and challenges of photomechanical hydrogels based on molecular photoswitches are also prospected.

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A New Phototropic Substance and Its ESR

Cited by 66 publications

References 2 publications

Photo-triggered solvent-free metamorphosis of polymeric materials

Photo-triggered solvent-free metamorphosis of polymeric materials

Stress-induced colouration and crosslinking of polymeric materials by mechanochemical formation of triphenylimidazolyl radicals

Photomechanical polymer hydrogels based on molecular photoswitches

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