Examining the kinetics of the thermal polymerisation behaviour of epoxy resins initiated with a series of 1-ethyl-3-methylimidazolium based ionic liquids

Binks, Fiona C.; Cavalli, Gabriel; Henningsen, Michael; Howlin, Brendan J.; Hamerton, Ian

doi:10.1016/j.tca.2018.02.015

Cited by 16 publications

(15 citation statements)

References 26 publications

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“… 33 and Binks et al 78 As an example, one can mention ionic liquid with imidazolium-based cation for which the reported activation energy is E a = 19 kJ/mol. 33 Moreover, the activation barriers E a = 72.7 and 72.4 kJ/mol estimated for curing DGEBA with [(MOB)IM][Sal] are in perfect agreement with the respective value for the system reported in ref ( 78 ) (where E a = 74 kJ/mol). As shown, the values of E a are closely connected to the applied monomers, which also affect the dominant curing mechanism.…”

Section: Resultsmentioning

confidence: 99%

Impact of Imidazolium-Based Ionic Liquids on the Curing Kinetics and Physicochemical Properties of Nascent Epoxy Resins

et al. 2020

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We investigated the influence of anion type (salicylate, [(MOB)MIm][Sal], vs chloride, [(MOB)MIm][Cl]) of imidazolium-based ionic liquid (IL) and its content on the curing kinetics of bisphenol A diglicydyl ether (DGEBA of molecular weight M n = 340 g/mol). Further physicochemical properties (i.e., glass transition temperature, T g , and conductivity, σ dc ) of produced polymers were investigated. The polymerization of the studied systems was examined at various molar ratios (1:1, 10:1, and 20:1) at different reaction temperatures ( T reaction = 353–383 K) by using differential scanning calorimetry (DSC). Interestingly, both DGEBA/IL compositions studied herein revealed significantly different reaction kinetics and yielded materials of completely distinct physical properties. Surprisingly, in contrast to [(MOB)MIm][Cl], for the low concentration of [(MOB)MIm][Sal] in the reaction mixture, an additional step in the kinetic curves, likely due to the combined enhanced initiation activity of anion (salicylate)–cation (imidazolium-based), was noted. To thoroughly analyze the kinetics of all studied systems, including the two-step kinetics of DGEBA/[(MOB)MIm][Sal], we applied a new approach that relies on the combination of the two phenomenological Avrami equations. Analysis of the determined constant rates revealed that the reaction occurring in the presence of the salicylate anion is characterized by higher activation energy with respect to those with the chloride. Moreover, DGEBA/[(MOB)MIm][Sal] cured materials have higher T g in comparison to DGEBA polymerized with [(MOB)MIm][Cl] independent of the IL concentration. This fact might indicate that, most likely, the products of hardening are highly cross-linked (high T g ) or oligomeric linear polymers (low T g ) in the former and latter cases, respectively. Such a change in the chemical structure of the polymer is also reflected in the dc conductivity measured at the glass transition temperature, which is much higher for DGEBA cured with [(MOB)MIm][Cl]. Herein, we have clearly demonstrated that the type of anion has a crucial impact on the polymerization mechanism, kinetics, and properties of produced materials.

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Section: Resultsmentioning

confidence: 99%

Impact of Imidazolium-Based Ionic Liquids on the Curing Kinetics and Physicochemical Properties of Nascent Epoxy Resins

et al. 2020

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“…Our previous publications [23,24] highlighted the importance of the acidic hydrogen atom and the role of the anion in combination with the cation when employed as initiators for the polymerisation of epoxies. Several different reaction pathways have been proposed for the initiation reaction with a di-epoxy is proposed to occur via a carbene route, an imidazole route or a nucleophilic route (Fig.…”

Section: Resultsmentioning

confidence: 99%

On the use of benzaldehyde to improve the storage stability of one-pot, epoxy ionic liquid formulations

Binks

Cavalli

Henningsen

et al. 2019

European Polymer Journal

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. On the use of benzaldehyde to improve the storage stability of one-pot, epoxy ionic liquid formulations.

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“…Imidazoles and their derivatives have been widely used as either the curing accelerators or main curing agents owing to their efficient activity for initiating the ring‐opening polymerization (ROP) of epoxy resins, along with the expected mechanical performance and insulating property of the cured resins . The curing mechanism of imidazoles/epoxy resins system is rather complex and has been reported a lot previously . It is now generally acknowledged that pyridine‐type nitrogen and pyrrole‐type nitrogen are crucial to curing reaction.…”

Section: Introductionmentioning

confidence: 99%

Thermal latent curing agent for epoxy resins from neutralization of 2‐methylimidazole with a phosphazene‐containing polyfunctional carboxylic acid

Wei

Sun

et al. 2020

Polymers for Advanced Techs

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A novel thermal latent curing agent, 2MZS, was obtained through the reaction of 2-methylimidazole (2MZ) and a symmetrically carboxyl-functionalized star-shaped molecule based on cyclotriphosphazene (N 3 P 3 -COOH). In the complex, the resonance of N 3 P 3 -COOH reduced the activity of lone electron pairs on the pyridine-type nitrogen atom of imidazole ring, suppressing the nucleophilic attack and crosslinking reaction between 2MZ and epoxy resin. As a result, the storage stability was improved distinctly for the one-pot epoxy compound, which could be steadily stored at room temperature for nearly 1 month. Nonisothermal DSC revealed a delayed initiation curing mechanism of the prepared one-pot system, and which could undergo rapid curing reaction upon raising the temperature. Moreover, the introduction of terminally polyfunctional star-shaped phosphazene derivative could promote the curing process at elevated temperature, as well as improve the chain rigidity of the cured resin by chemical incorporation into the cross-linked network, thus endowing the cured resin with enhanced glassy storage modulus. The epoxy thermoset exhibited the highest glass transition temperature and thermal degradation temperature when 20 wt% of 2MZS was used. It is suggested that the novel latent curing agent is potential for high-performance one-pot epoxy compound, particularly recommended for application in electronic packaging fields. K E Y W O R D Scuring agent, epoxy resin, imidazole, latent, phosphazene

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Examining the kinetics of the thermal polymerisation behaviour of epoxy resins initiated with a series of 1-ethyl-3-methylimidazolium based ionic liquids

Cited by 16 publications

References 26 publications

Impact of Imidazolium-Based Ionic Liquids on the Curing Kinetics and Physicochemical Properties of Nascent Epoxy Resins

Impact of Imidazolium-Based Ionic Liquids on the Curing Kinetics and Physicochemical Properties of Nascent Epoxy Resins

On the use of benzaldehyde to improve the storage stability of one-pot, epoxy ionic liquid formulations

Thermal latent curing agent for epoxy resins from neutralization of 2‐methylimidazole with a phosphazene‐containing polyfunctional carboxylic acid

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