Multi-benzocyclobutene functionalized siloxane monomers prepared by Piers-Rubinsztajn reaction for low-k materials

Abstract Two new multiarmed siloxane monomers of tri-benzocyclobutene monomer namely TriBS and tetra-benzocyclobutene monomer namely TetraBS have been successfully synthesized by Piers-Rubinsztajn (P-R) reaction. After cured at relevant temperature (>200 °C), the monomers converted to transparent highly-crosslinked bulk thermosets. TGA data showed that the crosslinked thermosets exhibited good thermostability with 5% weight loss temperature (Td5) at 451 °C and 518 °C, respectively. According to the results of dynamic mechanical analysis (DMA), the cured TriBS showed glass transition temperature (Tg) at 163 °C, while cured TetraBS showed no Tg under 400 °C. The two materials exhibited good dielectric properties with an average relative permittivity of about 2.42 and 2.54 in a range of frequencies from 100k to 1MHz, respectively. The cured TetraBS showed better thermostability, better thermomechanical performance and the cured TriBS showed lower permittivity. Overall, we have prepared low k polymer materials with excellent comprehensive performances such as low k value, extremely low dissipation, good thermostability and high Tg.