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

above approach, the pendant group approach has also been extensively explored for the fabrication ofthermally self-healing polymers. Most of the examples 140-142 are based on the incorporation of furanmoiety as pendant groups (Figure – 1.24a) onto a thermoplastic or a thermoset polymer while a bis- ortrismaleimide (Figure – 1.24b) compound is added as reversible crosslinking agent. Additionally, directpolymerization of furan based methacrylates with other methacrylates using atomic transfer radicalpolymerization to obtain controlled molecular architectures has also been performed 143,144 . In a recentwork, a recyclable furan functionalized polyketone thermoset, crosslinked with bismaleimide waspresented 145 . The reversible gelation as a function of temperature was used as an indicator for DA andrDA reactions demonstrating the thermal reversibility of the system. The recyclability of the system wasproved by grinding a fractured sample and fabricating a new sample from it. The new sample performedas similar as the pristine sample in mechanical tests which led the authors to claim a 100 % healingefficiency in an otherwise different context.Figure – 1.24: Thermoreversible complex architectures made reaction of, a) Hydroxyethylcellulose furoate acetatewith, b) Bismaleimide to form, c) Crosslinked polymer having flexible structure with liquid crystalline properties 141Besides furan/maleimide combination, there are also other compounds like dicyclopentadiene 146-148 and anthracene 149 which have been used recently to fabricate thermally reversible polymers. Theadvantages of dicyclopentadiene is its cyclic nature which provides a favorable s-cis conformation forDiels-Alder reaction and its ability to self-react to form DA adduct rendering the need to use maleimideas a dienophile. For instance, in one example, a biscyclopentadiene end-functionalized PMMA wassynthesized and then crosslinked with a trifunctional pyridinyl dithioformate compound via hetero-DAreaction 150 (Figure – 1.25). Although no healing data in terms of mechanical properties or visual healingwas presented, the so called “bonding” at room temperature in 10 minutes and “debonding” at29