bismaleimides

Bismaleimides are a class of organic compounds characterized by having two maleimide functional groups connected to a common central spacer, typically an aromatic or aliphatic moiety. The structure allows them to act as highly reactive crosslinking agents in high-temperature resin systems. In practical use, bismaleimides are the key components of bismaleimide (BMI) resins, which form thermosetting networks upon curing.

Most BMI compounds are prepared by linking two maleimide units to a difunctional spacer, such as a diaryl or polyaryl core. The curing chemistry involves reactions of the maleimide double bonds with curing agents (for example diamines or latent modifiers) or with dienes in a Diels–Alder-type process, leading to a crosslinked network. Some BMI formulations also undergo Michael-type additions or co-react with epoxy or other co-monomers to tailor properties.

Applications of BMI resins and BMI-based composites include aerospace and electronics, where high thermal stability and mechanical performance are essential. BMI resins are often used in prepregs, high-temperature adhesives, coatings, and glue formulations. They offer high glass transition temperatures, excellent thermal and dimensional stability, good chemical resistance, and strong dielectric properties. Limitations can include relatively high processing temperatures, potential brittleness, and sensitivity to moisture in certain formulations.

Safety and handling considerations align with typical thermosetting polymers: use appropriate protective equipment, work in well-ventilated areas, and follow material safety data sheet recommendations. BMI systems are selected when elevated service temperatures and robust mechanical performance are required.