For solving the problem that adhesive layers have early damage in hot-end sensor package, metal-ceramic connection, and heat-resisting insulation connection when they touch acid medium and discontinuous heat, this paper puts forward a kind of organosilicon adhesive system which has many phenyl groups, can be solidified through vinyl groups, and includes zirconium coordination nodes. The study investigates the mechanism underlying its 500 ℃ heat resistance and its acid-heat synergistic aging behavior. Using phenyltriethoxysilane, methyltriethoxysilane, and vinyltriethoxysilane as copolymerization monomers. Through controlled hydrolytic condensation, a phenylated siloxane prepolymer retaining a certain amount of Si-OH groups was prepared. Acetone-coordinated n-propanol zirconium was then introduced to construct Si-O-Zr nodes, yielding five formulations (P0-P4). Free-standing films and lap joints were prepared using a PMHS/Pt addition curing system. A synergistic aging protocol consisting of one cycle of “8 h acid immersion at 80 ℃+4 h heat treatment at 250 ℃” was established to characterize the chemical structure, thermal stability, post-heat bonding strength, interfacial evolution, and residual phase formation. The results indicate that P3 exhibits the best comprehensive performance under conditions of Ph/Si=0.40 and Zr/Si=0.06. This formulation had a double bond conversion rate of 93.8%, with 5% and 10% weight loss temperatures reaching 438 ℃ and 476 ℃, respectively; the residual carbon content at 800 ℃ was 56.8%, and the lap shear strength at room temperature was 8.54 MPa, which remained at 2.73 MPa after 30 minutes of thermal exposure at 500 ℃. After 15 cycles of synergistic aging, P3 retained 59.2% of its initial strength, with a synergy factor of 1.18, lower than the 1.34 for P0 and 1.29 for P1. The phenyl group increased the proportion of the high-temperature residual phase, while the Si-O-Zr nodes delayed the main weight loss zone and promoted the formation of a continuous Si/O/Zr-enriched layer on the surface; the acidic medium preferentially induces Si-O-Si hydrolysis and silanol enrichment at the surface and interface defects; the subsequent thermal phase further triggers re-condensation, oligomer escape, and volume shrinkage, ultimately manifesting as outer-layer hardening, increased modulus gradient, and expansion of the interfacial gap. This paper presents a formulation window and an acid-thermal coupled failure map applicable to thermal exposure conditions at 500 ℃.
