Photo-triggered solvent-free metamorphosis of polymeric materials

Honda, Satoshi; Toyota, Taro

doi:10.1038/s41467-017-00679-1

Cited by 55 publications

(52 citation statements)

References 42 publications

(37 reference statements)

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“…This photoresponse strongly indicates the cleavage of HABI into the pair of TPIRs (Figure 2a, (ii)) occurred even in the crosslinked H H to afford crosslinked copolymer having TPIRs ( H T ). Comparison of electron spin resonance (ESR) spectra between H L (Figure 2c, black line), H H (Figure 2c, blue line), and H T (Figure 2c, red line) directly revealed the production of radical species upon photoirradiation by the appearance of the signal at 327 mT, which is identical to the previous report [5a] . In comparison with the spectrum of H L , slight amount of TPIR is recognizable in that of H H , indicating highly restricted mobility of TPIRs within the network (Figure 2c, black and blue lines).…”

Section: Figuresupporting

confidence: 87%

Recyclable Heterogeneous Radical Generators Toward In‐Flow Polymer Elaboration System

Oka

Honda

2020

Chemistry Methods

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Radical reaction is one of the most common industrial reactions for the production of materials used in a wide variety of applications. Despite its long history, a methodology enabling efficient radical reactions with safe and easy handling still remains a challenge. Here, we describe the synthesis of crosslinked copolymers containing 2,4,5‐triphenylimidazoles (lophines) and hexaarylbiimidazoles (HABIs) (CCs) and fabrication of silica‐supported CCs (s‐CCs). Both of lophines and HABIs in these materials generated 2,4,5‐triphenylimidazolyl radicals (TPIRs) upon oxidation and photoirradiation, respectively, and thus they act as heterogeneous radical generators (HRGs). Moreover, lophine and TPIR were interconvertible via oxidation and hydrogen atom transfer reaction, enabling marked recyclability of these materials. We have further packed s‐CCs in columns and realized in‐flow disulfide synthesis and radical polymerization.

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Section: Figuresupporting

confidence: 87%

Recyclable Heterogeneous Radical Generators Toward In‐Flow Polymer Elaboration System

Oka

Honda

2020

Chemistry Methods

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“…From a previous study on the examination of molecular weight dependence on the physical state of polymerized product, an increase in the total molecular weight above 5500 Da almost solidified the resulting polymer product. 35 Since the subsequent solventfree network formation and dissociation reactions require mobility of molecular chains in the matrix, we have tuned the total molecular weight of the polymerized product to 1400 Da as analyzed by GPC using RI detector [ Fig. 1(a)].…”

Section: Resultsmentioning

confidence: 99%

“…We have also elaborated a novel repeatable MAT system between network and star-shaped polymers, relying on the cleavage and reformation of a covalent bond in hexaarylbiimidazole (HABI). 35 Moreover, we have achieved solvent-free IRLNC based upon repeatable MAT between liquid four-armed starshaped and nonliquid network polymers. To push forward the current frontier of photochemical molding technology as well as our repeatable MAT-based chemistry, to expand the scope of available cleavable and reformable covalent bonds and to achieve solvent-free tuning of viscoelasticity by photostimulations still remain crucial issues to be explored.…”

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confidence: 99%

Synthesis of star‐shaped poly(n‐butyl acrylate) oligomers with coumarin end groups and their networks for a UV‐tunable viscoelastic material

Honda

Tanaka

Toyota

2017

J. Polym. Sci. Part A: Polym. Chem.

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Solvent-free isothermal tuning of viscoelasticity of polymer materials is important for an emerging photochemical molding technology and photoreversible adhesives. In this study we designed a four-armed star-shaped poly(butyl acrylate, BA) oligomer having four coumarin end groups. The irradiation of UV at the wavelength of 365 nm (UV 365 ) to the viscous poly(BA) oligomer under a solvent-free condition produced a solid network material along with the progress of dimerization reaction with coumarin end groups. The subsequent irradiation of UV at the wavelength of 254 nm (UV 254 ) caused dimer dissociation reaction to attain change in the mixing degree of star and network architectures in the material. Moreover, viscoelasticity of the network material was tunable by repetitive UV 365 and UV 254 irradiations. V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 9-15 KEYWORDS: network polymer; star-shaped polymer; photostimulation; solvent-free isothermal process; viscoelasticity INTRODUCTION Change in the physical state of materials is one of the most fundamental phenomena we experience in everyday life. The change between physical states such as liquid-solid transition is generally caused by the shift in temperature of materials and is industrially important across the broad spectrum of applications such as heat molding plastic materials and hot melt adhesives. However, materials displaying stimuli-triggered isothermal reversible liquid-nonliquid conversion (IRLNC) are quite rare. To cause molecular ordering and disordering as undergone in a thermal phase transition process, utilization of stimuli-responsive molecules holds the key. Some groups have reported isothermal melting and crystallization of azobenzene (Azo)-containing small molecules, relying on trans-cis photoisomerization. [1][2][3] This strategy is preferable for photoreversible adhesive applications, which enables ON-OFF attachment and detachment of surfaces coated by them without using solvent fractions. 4 Although the IRLNC strategy should, in principle, be applicable for tuning viscoelasticity of materials, only two physical states, i.e., solid and liquid ones are allowed for such small molecules. Therefore, the development of materials exhibiting solvent-free IRLNC with tunable viscoelasticity remains a challenge. Recently, Zhou et al. designed acrylate and methacrylate polymers with tunable glass transition temperature

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“…The fundamental concept of reversibility has been widely utilized to drive the development of new polymeric materials, which can display distinct but reversible change in properties upon receiving a stimulus [ 1 , 2 ]. In light of this, a library of reversible materials based on polymers have recently been achieved, including self-healing materials bearing reversible-covalent linkages [ 3 , 4 , 5 , 6 , 7 , 8 ], recyclable materials such as vitrimers [ 9 , 10 , 11 ], polymer networks enabling reversible sol-gel transitions [ 12 , 13 , 14 ], architecture-transformable polymers [ 15 ], and covalent or metal organic frameworks harnessing reversible bonds [ 16 , 17 , 18 , 19 , 20 , 21 ]. Despite the tremendous success in the aforementioned polymer systems, little attention has been paid to achieving reversible polymerizations.…”

Section: Introductionmentioning

confidence: 99%

A Perspective on Reversibility in Controlled Polymerization Systems: Recent Progress and New Opportunities

Tang

Luan

et al. 2018

Molecules

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The field of controlled polymerization is growing and evolving at unprecedented rates, facilitating polymer scientists to engineer the structure and property of polymer materials for a variety of applications. However, the lack of degradability, particularly in vinyl polymers, is a general concern not only for environmental sustainability, but also for biomedical applications. In recent years, there has been a significant effort to develop reversible polymerization approaches in those well-established controlled polymerization systems. Reversible polymerization typically involves two steps, including (i) forward polymerization, which converts small monomers into macromolecule; and (ii) depolymerization, which is capable of regenerating original monomers. Furthermore, recycled monomers can be repolymerized into new polymers. In this perspective, we highlight recent developments of reversible polymerization in those controlled polymerization systems and offer insight into the promise and utility of reversible polymerization systems. More importantly, the current challenges and future directions to solve those problems are discussed. We hope this perspective can serve as an “initiator” to promote continuing innovations in this fairly new area.

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Photo-triggered solvent-free metamorphosis of polymeric materials

Cited by 55 publications

References 42 publications

Recyclable Heterogeneous Radical Generators Toward In‐Flow Polymer Elaboration System

Recyclable Heterogeneous Radical Generators Toward In‐Flow Polymer Elaboration System

Synthesis of star‐shaped poly(n‐butyl acrylate) oligomers with coumarin end groups and their networks for a UV‐tunable viscoelastic material

A Perspective on Reversibility in Controlled Polymerization Systems: Recent Progress and New Opportunities

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