Recent Progress in Benzocyclobutene Related Polymers

The developing history of polymer materials tells that the invention of novel polymers with excellent performance is generally originated from the synthesis of new polymerizable monomers. Among kinds of monomers, benzocyclobutene (BCB) has attracted much interest because of its unique molecular structure and polymer properties (1-2). The structure of BCB is shown as following with the numbering system, the CA name of which is bicyclo[4,2,0]octa-1,3,5-triene. In terms of the four-membered ring structure, BCBs are able to transform into the reactive o-quinodimethane, also known as o-xylylene, upon heating at around 200 oC. This very reactive specie readily undergoes interand intramolecular DielsAlder reaction with various dienophiles to produce polycyclic compounds with high stability, such as cyclooctadiene. On the other hand, the polymerization of oquinodimethane similar to that of 1,3-diene would give linear polymers. Additionally, the reaction of BCB does not require any catalyst and release any small molecules, thus hardly introducing any impurities into materials. These features undoubtedly offer BCB based materials several superiorities in several specific applications, such as microelectronic applications, optic applications, electrical applications, etc.