Thermal frontal polymerization with a thermally released redox catalyst

Parrinello, Claudio Attardo; Bounds, C. O.; Liveri, Maria Liria Turco

doi:10.1002/pola.26013

Cited by 11 publications

(14 citation statements)

References 47 publications

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“…Iodonium and sulfonium salts are widely used in industry for the cationic polymerization of oxirane monomers under light. Originally used to photochemically cure thin layers of epoxides, these onium salts have been recently used for thick material curing . Indeed, among the recent works devoted to dual‐cure initiating systems, some efforts have been especially focused on epoxide curing by photoinduced thermal frontal polymerization .…”

Section: Introductionmentioning

confidence: 99%

Versatility of Pyrylium Salt/Vinyl Ether Initiating System for Epoxide Dual‐Cure Polymerization: Kick‐Starting Effect of the Coinitiator

Lecompère

Allonas

Maréchal

et al. 2017

Macromol. Rapid Commun.

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redox reaction mediated via radicals in depth, where the light does not penetrate anymore. In such case, the possible on-demand curing afforded by the photochemistry is an additional and attractive benefit. Indeed, these systems open new opportunities in industry where the cycle time becomes a more and more challenging task. In addition, the versatility of dual-cure initiating systems is intended to provide greater flexibility in the industrial processes.Recently, pyrylium salts have been reported as a new photothermal initiator for epoxide monomers under irradiation or by thermal heating. [15,16] In this paper, the versatility of pyrylium-based initiating systems combined with vinyl ethers as coinitiators is discussed. It is shown that 2,4,6-triphenylpyrylium tetrafluoroborate (TPP + ) behaves as a very effective cationic thermal initiator in the presence of small amounts of vinyl ether. Similarly, the photoinitiation ability of TPP + is slightly increased in the presence of vinyl ethers. These two features open the possibility to use this system as a dual-cure initiating system for cycloaliphatic epoxides. Moreover, a kickstarting effect is observed, which enables to tune the thermal reactivity of the initiating system. These results Pyrylium salts combined with vinyl ethers are shown to act as new versatile dual-cure initiating systems for both photochemical and thermal initiation of oxirane monomers. The combination of both possibilities allows the curing of thick samples through photoinduced frontal polymerization. On the basis of quantum calculations and photochemical experiments, some clues are given about the reaction mechanisms involved. Interestingly, a sequential kick-starting effect is observed in the presence of vinyl ether enabling the curing of oxetane monomers. Thereby, this communication presents a short overview of potential of pyrylium salts in cationic polymerization of oxiranes.

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Section: Introductionmentioning

confidence: 99%

Versatility of Pyrylium Salt/Vinyl Ether Initiating System for Epoxide Dual‐Cure Polymerization: Kick‐Starting Effect of the Coinitiator

Lecompère

Allonas

Maréchal

et al. 2017

Macromol. Rapid Commun.

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“…Parrinello et al recently presented a thermal-FP with thermally released redox catalysts by integrating cobalt-containing polymer with cumene hydroperoxide. 26 More recently, we reported 27 remarkable self-propagating polymerization after irradiation due to the persistent interaction of produced longeval amine with peroxides in thin materials. Thus, we speculate that the photocaged amine species in the redox initiator combination can exert more control over the redox FP.…”

mentioning

confidence: 97%

Photo-triggered redox frontal polymerization: A new tool for synthesizing thermally sensitive materials

Huang

Zeng

et al. 2013

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

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A novel approach of photo-triggered redox frontal polymerization (FP) by integrating photocaged superbase (QA-DBU) with a peroxide initiator (dibenzoyl peroxide, BPO) is presented for the synthesis of thermally sensitive materials. Under photo-irradiation at a localized region, the regenerated superbase can diffuse into unirradiated regions and effectively actuate redox FP in a diffusion-controlled manner. Moreover, the redox FP can be conducted at a much lower front temperature with enhanced front velocity. Astonishingly, the front temperature can be well-modulated by changing the concentration of latent superbase. The prepared thermally sensitive fluorescent polymer composites exhibit enhanced fluorescence emission intensity compared to that of conventional thermal FP. V C 2013

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“…The front velocity seemed to be independent of the calcium carbonate loading but the front temperature showed an increasing trend with the increasing filler content. In earlier studies, the front temperature reached as high as 280 °C when 20 phr Kaolin was used as filler and cumene hydroperoxide as an initiator . However, these samples were monolithic (0.70 cm thick).…”

mentioning

confidence: 97%

“…In earlier studies, the front temperature reached as high as 280 °C when 20 phr Kaolin was used as filler and cumene hydroperoxide as an initiator. 21 However, these samples were monolithic (0.70 cm thick). Increasing kaolin content more than 20 phr was found to reduce front temperature.…”

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confidence: 99%

Frontal Polymerization of a Thin Film on a Wood Substrate

Bansal

Quadir

2020

ACS Macro Lett.

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Frontal polymerization has been explored as a technique to form two-dimensional thin films (<0.5 mm) on wood. We used trimethylolpropane triacrylate with a thermal free-radical initiator. The viscosity of the resin was adjusted by incorporating fumed silica within the formulation. As filler materials, either calcium carbonate or graphene nanoplatelets was used to evaluate the effect of filler type and content on front propagation. We observed that resin viscosity and film thickness critically affected the qualitative and quantitative propagation of the thermal front resulting in the formation of the coating. A workable coating was formed at a viscosity of 0.6 Pa·s, which was obtained when 3 phr (parts per hundred resin) of fumed silica was used in the resin formulation. Wet film thickness for this resin system was also found to have a limiting value, and full propagation of the front to result in a conformal coating required at least 15 mil (1 mil = 25 μm) of wet film thickness. Filler materials affected film propagation as a function of particle size and thermal properties. While 15 phr calcium carbonate could be incorporated with the resin, only 5 phr graphene nanoplatelets could be loaded within the matrix to ensure complete propagation of the front. Interestingly, for graphene fronts, velocity and temperature reduced systematically as a function of filler content. Filler type and content affected porosity and roughness of the coating, which was quantified by computerized tomography to understand the relationship between porosity and adhesion of the coated film with the wood substrate.

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Thermal frontal polymerization with a thermally released redox catalyst

Cited by 11 publications

References 47 publications

Versatility of Pyrylium Salt/Vinyl Ether Initiating System for Epoxide Dual‐Cure Polymerization: Kick‐Starting Effect of the Coinitiator

Versatility of Pyrylium Salt/Vinyl Ether Initiating System for Epoxide Dual‐Cure Polymerization: Kick‐Starting Effect of the Coinitiator

Photo-triggered redox frontal polymerization: A new tool for synthesizing thermally sensitive materials

Frontal Polymerization of a Thin Film on a Wood Substrate

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