Synthesis and properties of novel benzocyclobutene-functionalized siloxane thermosets

Two kinds of novel benzocyclobutene (BCB) functionalized monomers were synthesized through imidization of siloxane-containing dianhydride with 4-aminobenzocyclobutene. The BCB monomers obtained exhibited good solubility in various organic solvents. They were converted into crosslinked polymer via ring opening and the following Diels–Alder reaction at proper temperature. The curing kinetics were studied by non-isothermal differential scanning calorimetry. The BCB polymers showed good thermal stability, excellent dielectric properties, low water absorption and good planarization. Moreover, the thermal and mechanical properties of the BCB resins could be adjusted by the length of the siloxane unit. The BCB resins with a shorter siloxane chain exhibited higher glass transition temperature, higher modulus and lower coefficient of thermal expansion than BCB resins with longer chains. © 2013 Society of Chemical Industry