Piers-Rubinsztajn reaction for BCB functionalized silphenylene/silbiphenylene siloxane oligomers to highly crosslinked low-k thermosets

[Display omitted] •Two BCB functionalized siloxane oligomers (PhBVSi and BPBVSi) were prepared.•Piers-Rubinsztajn reaction: A facile method for the post-curable siloxane oligomers.•TMA in penetration mode were utilized to characterize the thermosets’ rigidity.•Good thermostability with Td5 > 490 °C and extremely low dissipation loss 490 °C in nitrogen). Tan δ curve of the cured PhBVSi and BPBVSi appears peaks with small dissipation factor of 0.05 at 134 °C and 148 °C, respectively, which refers to unconventional glass transition proved by the penetration mode TMA. In addition, both thermosets show well dielectric property with low dielectric constants (