Synthesis, properties of novel benzocyclobutene-functionalized siloxane thermosets

A new kind of BCB-functionalized monomer is synthesized through imidization between 4-aminoBCB and siloxane-containing dianhydride. The synthesized BCB monomer exhibits an excellent solubility in organic solvents such as ethanol, acetone and dichloromethane etc. At elevated temperature, the monomer is converted into highly cross-linked resins via ring opening reaction. The curing kinetic parameters, including the apparent activation energy (E_a), the frequency factor (A) and the reaction order (n), are obtained by non-isothermal DSC. The DMA result suggests that the cured BCB resin has a high glass transition temperature of 263°C and modulus of 2.7 GPa, and the TGA result shows the thermal decomposition temperature of the cured resin is higher than 450°C. Moreover, the cured resin demonstrates a low dielectric constant of 2.7 at 1 MHz and low water absorption (<; 1.2wt % after submersion in water for 5 days). The cured films prepared from spin-casting the acetic acid solution of Si-BCB show a well planarization (maximum height difference <; 5 nm).