Bisbenzocyclobutene-bismaleimide mixtures

Early reports by Kirchhoff, Hahn, Tan and Arnold describe the use of polybenzocyclobutene monomers in Diels-Alder type polymerizations [10,13]. For the most part, these early studies focused on the thermal characterization of mixtures of polybenzocyclobutenes and bismaleimides. Several reports describe the thermal analysis of mixtures of the bisbenzocyclobutene 41 with either the bismaleimide 44 or the diacetylenes 42 and 43 as shown in Fig. 19 [13,79,81, 90-93]. 

The advantage of using free radical inhibitors to facilitate the copolymerization of a bisbenzocyclobutene with a bismaleimide was first noted in a patent to Bartmann [78]. Subsequent to this, Corley in a series of patents described some detailed experiments on the copolymerization of bisbenzocyclobutenes with bismaleimides both with and without the addition of a free radical inhibitor [33, 34]. The structures of the bisbenzocyclobutenes used in this study are shown in Fig. 33. The bismaleimide component that was used was a mixture of three different bismaleimides in the molar ratio shown in Fig. 34. The individual bisbenzocyclobutenes were blended at elevated temperature with varying amounts of the bismaleimide composition. In some of the experiments, the free radical inhibitor phenothiazine was added at a 0.5 mole % level. The various monomer mixtures were then copolymerized using one of the cure schedules described in Table 14. The copolymers were then physically characterized using a variety of techniques. Table 14 shows the results obtained from copolymers... 

Mixtures of bisbenzocyclobutene and bismaleimide such as shown below were also polymerized to form stable polymers. 

---