Soluble asymmetric bismaleimide with low molten viscosity and its high glass transition temperature polymer

A novel carbazole based bismaleimide monomer: Synthesis, characterization, thermal and optical properties

In this study, a novel bismaleimide monomer: Carbazole-Bismaleimide (Cz-BisMI) was introduced to the literature as a first. Cz-BisMI was synthesized by a catalytic cyclodehydration reaction of 3,6-bismalemic acid carbazole which is an intermediate product obtained by an imidization reaction of 3,6-diamino carbazole. Then, the chemical structure of Cz-BisMI was elucidated by FT-IR, 1H NMR, 13C NMR and LC-MS spectroscopies. The thermal properties of Cz-BisMI were investigated by DSC in comparison with a commercial bismaleimide monomer, 4,4-bismaleimidophenylmethane (DPM-BisMI). Cz-BisMI has a melting point of 192°C and also, the onset temperature of the exothermic curve was measured as 293°C. Furthermore, it was determined that Cz-BisMI has a 35.6 percent larger processing window than DPM-BisMI. The spin-coated films of Cz-BisMI showed a high refractive index in the range of 1.61 to 1.50 between 400 and 650 nm with good transparency of over 85%. On the other hand, a new poly(bismaleimide): P(Cz-BisMI)s containing carbazole units was prepared by the self-polymerization process of Cz-BisMI. P(Cz-BisMI)s showed a high thermal transition temperature of 356°C. In conclusion, Cz-BisMI is a viable choice as a bismaleimide monomer for the development of opto-electronic materials due to its enhanced optical properties and thermal behavior.

Asymmetric bismaleimide-based high-performance resins with improved processability and high Tg over 400 °C

Asymmetric 2-(4′-maleimido)phenyl-2-(4′-maleimidophenoxyl)phenylbutane (EBA-BMI) was successfully mixed with N, N′-(4,4′-diphenylmethane)bismaleimide (DDM-BMI) to prepare the matrix resins for high-temperature fiber-reinforced polymeric composites (glass transition temperature ( Tg) > 400°C). Experimental results imply that DDM-BMI/EBA-BMI (DE-BMIs) show excellent melting performance with wide processing temperature window and low molten viscosity, suggesting excellent compatibility between DDM-BMI and EBA-BMI. For example, the viscosity of DE-BMI41 (DDM-BMI/EBA-BMI, 4/1) is about 474–51 mPa·s in the temperature range of 148–180 °C. In addition, cured DE-BMIs represent remarkable thermal properties with Tg over 400°C, under which the storage modulus could still reach as high as 3.2 GPa. Meanwhile, the coefficient of thermal expansion of these cured resins is about 36–40 ppm °C−1 at 50–250°C, and the 5% weight loss temperature is about 470°C.