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

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 °C for 15 min. Thus, according to their composition, these obtained thermosetting resins are characterized by a relaxation temperature between 98 and 190 °C 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 = 280–300 °C increased to T_d = 315–340 °C). Their use as power module encapsulant can therefore be considered. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46105.