STUDY OF SELF-HEALING FULLY REVERSIBLE DIELS-ALDER THERMOSETTING SYSTEMS

Research output: Unpublished contribution to conferencePoster

Abstract

An efficient mechanism of an intrinsic self-healing polymer network is based on dynamic covalent bonding by the introduction of thermoreversible Diels-Alder (DA) cycloadditions. The cycloadduct single bonds are preferentially broken in case of material damage, but also reversibly reform, leading to a repeatable healing cycle and an increased lifetime for many applications, such as sustainable coatings [1-3]. However, for coating applications sufficient thermo-mechanical stability is required for surface protection, requiring a network material exhibiting a high glass transition (Tg). As such, these materials are usually used in their vitrified state. The potential self-healing reactions will thus occur under diffusion-controlled instead of kinetically controlled conditions. Little information can be found in literature regarding the study of diffusion-controlled reversible network formation, as opposed to their irreversible analogues.

This work focuses on the effect of vitrification on Diels-Alder reaction kinetics, using model systems formed by furan-functionalized Jeffamines and bismaleimides. These fully reversible systems exhibit a Tg high enough to efficiently study the vitrification effect at low temperatures. Using (MT)DSC measurements, vitrification is followed through isothermal and non-isothermal measurements based on the evolution of the heat capacity, while isothermal measurements from microcalorimetry give information on the heat flow evolution.

These results are compared to a kinetic model, taking into account the stereochemistry of the system based on literature values [4]. In addition, rheology complements these measurements, allowing the construction of a time-temperature-transformation (TTT) diagram.

This work is the first systematic study of diffusion-controlled reversible Diels-Alder network formation in the perspective of self-healing applications. The Diels-Alder reaction is proven to proceed both under kinetically and diffusion-controlled conditions, allowing self-healing of the material even in mobility-restricted conditions. The self-healing ability of the vitrified Diels-Alder model networks is demonstrated.
Original languageEnglish
Publication statusPublished - 27 May 2019
EventBPG 2019 annual meeting - Houffalize, Belgium
Duration: 27 May 201928 May 2019

Conference

ConferenceBPG 2019 annual meeting
CountryBelgium
CityHouffalize
Period27/05/1928/05/19

Bibliographical note

[1] M.M. Diaz, J. Brancart, G. Van Assche, B. Van Mele, Polymer 153 (2018) 453–463.
[2] A. Cuvellier, R. Verhelle, J. Brancart, B. Vanderborght, G. Van Assche, H. Rahier, Polym. Chem. 10 (2019) 473-485.

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