Synthesis, characterization, and curing kinetics of novel bismaleimide monomers containing fluorene cardo group and aryl ether linkage

Two novel bismaleimide (BMI) monomers containing fluorene cardo group and aryl ether linkage, that is, 9,9-bis[4-(4-maleimidophenoxy)phenyl] fluorene (PF-BMI) and 9,9-bis[4-(4-maleimidophenoxy)-3-methylphenyl] fluorene (MPF-BMI) based on 9,9-bis(4-hydroxyphenyl)fluorene and its derivative were designed and synthesized. The chemical structures of the monomers were confirmed from 1H NMR, 13C NMR spectroscopy, and Fourier transform infrared spectroscopy. Both monomers obtained are readily soluble in common organic solvents, such as acetone, dichloromethane, and chloroform, enabling an easy solution processing. The thermal curing behavior of the monomers and their non-isothermal thermal curing processes were investigated using differential scanning calorimetry, displaying that both monomers have lower melt points and broad thermal processing windows. The corresponding kinetic data, for example, activation energy (Ea), pre-exponential factor (A), and the order of the reaction (n), were obtained by the Kissinger and Ozawa method. The BMI resins based on these new monomers have good thermal stability seen from the thermogravimetric analysis results.