4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

The diels-alder cycloaddition reaction was discovered in 1928 by Otto Diels and Kurt Alder (Figure– 1.21). The beauty of this reaction lies in its ability to form C – C bonds with little or no heat application.However the feature that makes it even more important for synthesis of self-healing materials is itsthermal reversibility, also known as reversible diels-alder reaction (rDA). Generally the rDA reactiontakes place at temperature higher than 100 o C and gives back the reaction precursors.Figure – 1.21: The Diels-Alder reactionA large number of publications have been published concerning the synthesis of polymersystems employing rDA chemistry, but their applicability for self-healing application and relevant datahas been reported quite lately. In general, most of such polymer systems either incorporatedienophile/diene as a pendant groups to the backbone chain or the backbone chain itself is formed dueto consecutive DA reactions between functionalized monomers. The Furan/Maleimide combination hasbeen the most explored DA-rDA chemistry system for the fabrication of thermally self-healed polymersalthough other dienophile/diene combinations have also been explored. In 1969, the earliestknown work as a patent on the synthesis of a thermally reversible polymer incorporatingFuran/maleimide moieties was reported. This was followed by a series of pioneering works 128-130 , inwhich these moieties were incorporated as pendant groups onto the polymer chains (Figure – 1.22).Figure – 1.22: Reversiblly crosslinked polymer via Diels–Alder cycloaddition reaction between pendent furan andmaleimide moieties 129 .27