Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Abstract

This study focuses on the synthesis of new liquid aromatic bismaleimide monomers in order to improve self-curing on demand (SCOD) systems previously based on aliphatic bismaleimides. These SCOD systems are based on Diels-Alder (DA)/retro-DA reactions. The syntheses of new different aromatic bismaleimides with ester and amide bonds are presented. These maleimides have been protected using DA reaction and characterized by 1 H NMR analysis to determine protection rate and diastereomer ratios. The retro-DA reactions of both aromatic and aliphatic DA adducts in presence of thiol molecules were studied. Kinetic analysis was monitored by 1 H NMR and compared to model study.Finally, both aromatic and aliphatic bismaleimides-based polymers were synthesized with 2-mercaptoethyl ether and thermal properties of polymers were compared. The glass transition temperature values ranged from -20°C to 14°C and very good thermal stabilities were observed (up to 300°C).

Trends in the Diels–Alder reaction in polymer chemistry

“…Moreover, we also observed the presence of the exo isomer that needed to reach 110 °C to be unlocked. Further, aromatic and aliphatic bismaleimides were compared to optimize the retro DA reaction (Figure 14) [161]. Aromatic maleimides led to the best compromise to reach a good conversion and easy process.…”