AB maleimide benzocyclobutene

These same authors also reported on several other types of AB maleimide benzocyclobutene monomers. The syntheses of these materials are shown in Fig. 42 [103],... 

AB maleimide benzocyclobutene monomers and polymers have also been actively studied and developed by researchers at the Dow Chemical Co. The first AB maleimide type benzocyclobutene monomer prepared and polymerized by Kirchhoff was the benzocyclobutenyl maleamic acid 106 [6]. The detailed synthesis of 106 is shown in Fig 44. 

Another approach to the preparation of AB maleimide benzocyclobutenes was to use the parent hydrocarbon as the primary building block. One of the first monomers prepared directly from the hydrocarbon was 17, which was a material that was later reported on by researchers at Air Force Wright Laboratories [103]. 

Several different AB maleimide benzocyclobutenes were prepared and Table 21 lists these monomers and homopolymers along with their thermal and... 

The use of benzocyclobutene as the source of the diene in a Diels-Alder polymerization offers a unique solution to the problems described above. Benzocyclobutene containing monomers can be stored indefinitely at room temperature without concern for further advancement of the molecular weight. It is only when benzocyclobutene is heated to temperatures of approximately 200 °C that the reactive diene, o-quinodimethane, is formed at a significant rate and enters into reaction with the dienophile. The only requirement of the dienophile is that it must be stable at these temperatures and not undergo reaction with itself. The most common dienophiles that have been successfully used in the formation of polymers from AB type benzocyclobutene monomers have been acetylenes, olefins and maleimides. 

Fig. 8. Formation of AB benzocyclobutene maleimide 17 from hydrocarbon 1 by Friedel-Crafts benzoylation...

The third major area of AB benzocyclobutene technology has dealt with the reaction of benzocyclobutene with maleimide to form a substantially linear... 

As before, the homopolymer forming reaction involved the generation of an o-quinoidimethane from benzocyclobutene which in turn reacted with the double bond of a maleimide functionality on a second monomer to give chain extended AB material via a Diels-Alder pathway. The polymers prepared to date using this type of approach have been shown to have excellent thermal and mechanical properties and have been considered as potential candidates for use as matrix resins for advanced composites. This area has been investigated by the researchers at both the Air Force Wright Laboratories and the Dow Chemical Co. 

Table 21. Properties of AB benzocyclobutene maleimide homopolymers derived from ...

Of all of the AB benzocyclobutene maleimide homopolymers prepared, 114a appeared to have the best combination of thermal and mechanical properties as well as ease of fabrication (Table 21). This monomer/polymer was used as a... 

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