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.

Carborane-containing bismaleimide resins with excellent heat resistance and dimensional stability

Novel carborane-containing bismaleimides with excellent heat resistance and dimensional stability for advanced composites are presented. First, a new kind of carborane-containing mono-maleimido-terminated monomer 1-(4-tolyl)-2-(4-maleimido phenyl)- o-carborane (CB-MI) was synthesized and characterized by FT-IR and 1H-NMR. Then, it was used as a modifier for bismaleimide resin 4,4’-bismaleimidodiphenylmethane (BDM) with different weight fraction of CB-MI. The curing behavior and thermal property of the CB-MI/BDM resin systems were studied and presented here. Results displayed that a wide processing window and low curing temperature provided a good processability for the CB-MI/BDM resin system. Due to the effect of carborane groups, the char yield at 600°C of the cured resin systems tended to be increased with the addition of CB-MI. Moreover, the coefficient of thermal expansion of the resin was found to be reduced with the increase of CB-MI, indicative of a remarkable dimensional stability. This study might open up great opportunities for the preparation and design of various novel bismaleimides in a simple and feasible way and the resins with good thermal property and processability at the same time.

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.

Synthesis and properties of bismaleimide resins containing phthalide cardo and cyano groups

Two novel n ≈ 1 oligomeric bismaleimide monomers containing phthalide cardo and cyano groups (PCBMI and MCBMI) were designed and synthesized. The chemical structures of the monomers were confirmed from proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. Both BMIs exhibit good solubility in common organic solvents, enabling easy solution processing. Thermal curing behaviors of the monomers were investigated by differential scanning calorimetry, displaying broad exothermic peaks and large thermal processing windows. Furthermore, PCBMI/carbon fiber composites were prepared, with their thermal stability and mechanical properties investigated. Thermogravimetric analysis and test of interlaminar shear strength indicated that the thermal polymerization of cyano groups improved the heat resistance of BMI resins and enhanced the interfacial adhesion at higher temperature.

Thermal curing of novel carborane-containing phenylethynyl terminated imide oligomers

The thermal behavior of novel carborane-containing phenylethynyl terminated imide model compound and resultant resin systems was studied in this paper.