Synthesis and characterization of poly(aminobismaleimide)s obtained from solvent‐free mixtures

Abstract

A series of eight poly(aminobismaleimide)s containing aromatic units have been synthesized from a one-step nucleophilic addition reaction between diamine and bismaleimide, without exogeneous solvent, to provide encapsulant withstanding high temperature suitable for power electronics. To have a homogeneous medium at room temperature, the solid aromatic diamines are first mixed with different liquid aliphatic ones, and then mixed with bismaleimide. The syntheses were then carried out at 175 8C for 15 min. Thus, according to their composition, these obtained thermosetting resins are characterized by a relaxation temperature between 98 and 190 8C and a coefficient of thermal expansion between 20 and 150 ppm/K. All material surfaces are hydrophobic and their moisture uptake is lower than 2-3 wt %. Finally, as expected, the substitution of a part of the aliphatic diamine by an aromatic one improves the thermal stability under air atmosphere of the resulting materials (T d 5 280-300 8C increased to T d 5 315-340 8C). Their use as power module encapsulant can therefore be considered.

Flexible bismaleimide resins based on bio‐based diamine: Synthesis and properties

“…Table 8 shows the final water absorption of the cured F‐BMI films after being soaked in water for 30 days. The water absorption rate of all cured F‐BMI films after soaking for 30 days is less than 0.7%, which is better than other modified BMI resins, 42,43 such as the 1.09% water absorption rate of allyl benzoxazine/BD BMI resin blend‐modified material after soaking for 7 days (BD stands for 4,4′‐bismaleimido diphenyl‐methane (BMI)/2,2′‐Diallyl bisphenol A [DABPA]) 44 . The cured F‐BMI films with low water absorption are due to the surface free energy of long‐chain alkanes being extremely low 45,46…”