Research Progress and Applications of Benzocyclobutene‐Based Functional Polymers

Benzocyclobutene (BCB) stands out as a compound of remarkable structural distinction, featuring a thermodynamically stable benzene ring coupled with a kinetically dynamic four‐membered ring. This unique structure allows for ring‐opening reactions under specific conditions, leading to the formation of crosslinking products. The primary initiation for the ring‐opening of the four‐membered ring in BCB is heat, although mechanical stress and light exposure can also trigger this transformation. This ability has catapulted it to prominence in the field of polymer material development. It has spurred the creation of a vast array of polymers that incorporate BCB groups either in their main chains or side chains, showcasing BCB's extensive applicability as a crosslinking agent. Additionally, BCB‐based polymers (BCB polymer) exhibit a suite of desirable properties, such as exceptional dielectric characteristics, chemical and thermal resilience, minimal thermal expansion, and low moisture uptake. These attributes render them particularly suitable for a range of applications, including electronic packaging, silicon‐based photonic integration, flat panel display technology, biomedical devices, and beyond. This paper delves into the various methods of inducing ring‐opening crosslinking in BCB, summarizes the recent advancements in performance enhancement of BCB polymer materials, and examines their wide applications in different fields.