Bismaleimide resins modified by bi- or tri-allyl-functionalized azo chromophores for second-order optical nonlinearity

Several novel azo dye chromophores with allyl groups at one or two ends of the molecules were synthesized. Differential scanning calorimetry and thermogravimetric analysis tracing showed that these chromophores can be thermally cured with bismaleimidodiphenyl methane to afford a series of crosslinked, and chromophore-modified bismaleimide resins without any appreciable decomposition up to >300 °C, while IR spectra analysis indicated that it is not a trivial task to achieve highly-crosslinked BMI resins due to decomposition of the azo dye chromophores. The effects of different chromophores on the curing conditions and thermal stability of these modified BMI resins are discussed. It is noticeable that incorporating a chromophore into the network of BMI resins by its reactive groups at both ends facilitates improvement of the thermal stability of the materials.