Kinetics of the epoxy–thiol click reaction initiated by a tertiary amine: Calorimetric study using monofunctional components

Loureiro, Roi Meizoso; Amarelo, Tánia Carballeira; Abuín, Senén Paz; Soulé, Ezequiel Rodolfo; Williams, Roberto J. J.

doi:10.1016/j.tca.2015.08.012

Cited by 30 publications

(61 citation statements)

References 20 publications

(30 reference statements)

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“…Both reactions are depicted in Scheme (right‐hand side). The reaction mechanisms of nucleophile‐initiated thiol–epoxy polymerization and epoxy homopolymerization have been recently discussed in detail elsewhere . Because the kinetics of the second process are much slower than the first one, it has been possible to develop recently a new family of dual‐curable thermosetting materials that have found, so far, an application in shape‐memory devices …”

Section: Resultsmentioning

confidence: 99%

“…The scenario that is simulated is the processing of composite parts by resin transfer moulding, focusing only on the curing stage. Given that thiol–epoxy systems have a long induction period at room temperature and that initial viscosity at room temperature is low, we consider that the injection can be decoupled from the curing process . In order to simplify the scenario, we will neglect the injection time.…”

Section: Resultsmentioning

confidence: 99%

“…This is of special importance in the case of thicker composite parts. In addition, the curing of thiol–epoxy formulations is highly sensitive to preparation, so that the time elapsed between mixing and curing (or analysis) is also a critical factor . A pre‐reacted sample would have a shorter induction during processing, so that a temperature runaway might occur during preheating, following the same optimized curing schedule obtained for a fresh sample.…”

Section: Resultsmentioning

confidence: 99%

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Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Romero

Fernández‐Francos

Ramis

2018

Polymer International

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The sequential heat release (SHR) taking place in dual‐curing systems can facilitate thermal management and control of conversion and temperature gradients during processing of thick composite parts, hence reducing the appearance of internal stresses that compromise the quality of processed parts. This concept is demonstrated in this work by means of numerical simulation of conversion and temperature profiles during processing of an off‐stoichiometric thiol–epoxy dual‐curable system. The simulated processing scenario is the curing stage during resin transfer moulding processing (i.e. after injection or infusion), assuming one‐dimensional heat transfer across the thickness of the composite part. The kinetics of both polymerization stages of the dual‐curing system and thermophysical properties needed for the simulations have been determined using thermal analysis techniques and suitable phenomenological models. The simulations show that SHR makes it possible to reach a stable and uniform intermediate material after completion of the first polymerization process, and enables a better control of the subsequent crosslinking taking place during the second polymerization process due to the lower remaining exothermicity. A simple optimization of curing cycles for composite parts of different thickness has been performed on the basis of quality–time criteria, producing results that are very close to the Pareto‐optimal front obtained by genetic algorithm optimization procedures. © 2018 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Romero

Fernández‐Francos

Ramis

2018

Polymer International

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“…Other typical hardeners of epoxy resins are polythiols [156][157][158][159] and polyisocyanates [160][161][162][163]. Like carboxylic acids, their nucleophilicity is usually much lower than amines or dihydrazides and base-catalyzed conditions must be used to observe adequate curing rates.…”

Section: Thiols and Isocyanatesmentioning

confidence: 99%

Control of reactions and network structures of epoxy thermosets

Vidil¹,

Tournilhac²,

Musso

et al. 2016

Progress in Polymer Science

282

252

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Recent advances in macromolecular chemistry have revolutionized the way we perceive the synthesis of polymers. Polymerization, to be modern, must be "controlled", which usually means capable of producing macromolecules of well-defined structure. The purpose of this review is to examine how the chemistry of epoxy resins, an almost century-old chemistry, is also involved in this movement. Epoxy resins are characterized by both the flexibility of implementation and the qualities of the polymers obtained. Key materials in health-, mobility-and energy related technologies, these resins are heavily present in high-performance composites, electronic boards, adhesives and coatings. Currently, a large number of resins and hardeners are available on the market or described in the literature and an interesting point is that almost any combination of the two is possible. Common to all these recipes and processes is that a liquid (or soluble) resin at some point becomes insoluble and solid. It is very important to know how to manage this transition, physically known as the gel point, as it is the point after which the shape of the object is irreversibly set. Taking into account the variety of epoxy polymerization processespolyaddition, anionic or cationic polymerization-we detail a number of methods to program the occurrence of the gel point and how this type of control affects the structure of the growing network.

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“…Of all the various "click" systems, the thiolepoxy mechanism is particularly interesting because hydroxyl and thioether groups can be formed in a single step and then further transformed into other polymeric structures (Carlborg et al 2014;Flores et al 2013). Tertiary amines are commonly used to catalyzse the thiol-epoxy reaction (Jin et al 2015;Loureiro et al. 2015) but they are usually too reactive to prepare stable one-pot formulations.…”

Section: Mtdm9322_deltamentioning

confidence: 99%

Network structure dependence on unconstrained isothermal-recovery processes for shape-memory thiol-epoxy “click” systems

Belmonte

Fernández‐Francos

Flor

et al. 2016

Mech Time-Depend Mater

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The shape-memory response (SMR) of "click" thiol-epoxy polymers produced using latent catalysts, with different network structure and thermo-mechanical properties, was tested on unconstrained shape-recovery processes under isothermal conditions. Experiments at several programming temperatures (Tprog) and isothermal-recovery temperatures (Tiso) were carried out, and the shape-memory stability wasere analysed through various consecutive shape-memory cycles. The temperature profile during the isothermal-recovery experiments was monitored, and it showed that the shape-recovery process takes place while the sample is becoming thermally stable and before stable isothermal temperature conditions are eventually reached. The shaperecovery process takes place in two different stages regardless of Tiso: a slow initial stage until the process is triggered at a temperature strongly related with the beginning of network relaxation, followed by the typical exponential decay of the relaxation processes until completion at a temperature below or very close to Tg. The shape-recovery process is slower in materials with more densely crosslinked and hindered network structures. The shape-recovery time (tsr) is significantly reduced when the isothermal-recovery temperature Tiso increases from below to above Tg because the network relaxation dynamics accelerates. However, the temperature range from the beginning to the end of the recovery process is hardly affected by Tiso; at higher Tiso it is only slightly shifted to higher temperatures. These results suggest that the shape-recovery process can be controlled by changing the network structure and working at Tiso < Tg to maximize the effect of the structure and/or by increasing Tiso to minimize the effect but increasing the shape-recovery rate.

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Kinetics of the epoxy–thiol click reaction initiated by a tertiary amine: Calorimetric study using monofunctional components

Cited by 30 publications

References 20 publications

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Sequential heat release: an innovative approach for the control of curing profiles during composite processing based on dual‐curing systems

Control of reactions and network structures of epoxy thermosets

Network structure dependence on unconstrained isothermal-recovery processes for shape-memory thiol-epoxy “click” systems

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