Effect of curing reaction types on the structures and properties of acetylene-containing thermosets: towards optimization of curing procedure

High-temperature thermosets are usually prepared from resins containing alkynyl groups, and their properties depend much upon the curing process containing various types of curing reactions. However, how the curing process affects the properties remains unclear due to the complicated curing reactions. We used molecular dynamics simulations to investigate the effect of curing reaction types, including cyclotrimerization, Diels-Alder reaction, and radical reaction, on the structures and properties of imide oligomers terminated with alkynyl groups. The results show that the cycloadditions such as cyclotrimerization and Diels-Alder reaction endow the thermosets with rigid structures and high moduli. Compared with the cycloadditions, the radical reaction enables the formation of flexible cured structures, which can enhance the toughness of thermosets. The differences in thermal and mechanical properties caused by different curing types were elucidated by the relaxation processes of fragments in these cured systems and were explained by the variation of torsion energy in different curing forms. As this work aims to optimize the curing procedure to obtain high-performance resins with desired properties, different curing procedures were finally designed according to the theoretical studies, and the obtained cured polymers show significant differences in the properties from different curing ways. The results can guide the preparation of desired thermosetting resins by tuning the curing procedure.

Automated summary

The study investigates the effect of different curing reaction types on imide oligomers, finding that cycloadditions like cyclotrimerization and Diels-Alder reaction lead to rigid structures and high moduli in thermosets, while radical reactions enhance toughness. By using molecular dynamics simulations and theoretical studies to design various curing procedures, significant differences in properties of cured polymers from different curing ways were observed, providing guidance for optimizing the preparation of high-performance resins.