Silicone resins with Si–O–Ar crosslinked networks prepared via the Piers-Rubinsztajn reaction for high thermal stability and low dielectric constant

A Si–OH‑containing silicone resin (R1) and a Si–H‑containing crosslinker (M1) were synthesized and used to construct silicone resin networks through the Piers-Rubinsztajn(P-R) reaction. The hydroxyl content of R1 was quantified by chemical end-capping followed by1H NMR analysis, providing a stoichiometric basis for calculating the required amount of M1. By tuning the loading of M1, cured networks with different contents of Si–O–Ar-containing segments were prepared. The P-R reaction effectively introduced rigid Si–O–Ar linkages into the crosslinked network. Compared with the conventionally cured resin, the P-R-cured resins showed improved thermo-oxidative, hydrophobic, and dielectric properties. In particular, the one with the highest Si–O–Ar content exhibited a 5% weight-loss temperature of 521 °C in nitrogen and 508 °C in air, with char yields of 86.10% and 60.40% at 800 °C, respectively. It also showed a reduced water uptake of 0.18%, low dielectric constant (Dk) of 2.49, and improved hardness. These results demonstrate that P-R curing is an effective strategy for preparing silicone resin dielectric materials for high-frequency electronic packaging applications.