In multi-material composite sealing and functional integrated devices, the co-vulcanization of phenyl silicone rubber and ordinary silicone rubber often results in interface delamination and stress cracking due to differences in molecular chain polarity and mismatch in crosslinking kinetics, becoming a key bottleneck restricting product reliability. Phenyl raw rubber, with its unique "segment polarity matching" and "co-vulcanization kinetic synergy" mechanism, acts as a "molecular compatibilizer" at the co-vulcanization interface, constructing a "chemical bond bridge" across the two materials at the microscopic level.

The core of phenyl raw rubber's improved co-vulcanization compatibility lies in its "polar transition of phenyl groups" and "interpenetration of crosslinking networks." The non-polar methyl segments of ordinary silicone rubber (methyl vinyl silicone rubber) and the rigid phenyl segments of phenyl silicone rubber have different surface energies, easily forming a "phase separation interface" during vulcanization. Phenyl raw rubber, by introducing an appropriate amount of phenyl groups into its molecular chain, acts as a "molecular harmonizer." Its phenyl portion forms π-π interactions with phenyl silicone rubber, while the methyl portion generates van der Waals forces with ordinary silicone rubber. This reduces the solubility parameter difference (Δδ) between the two materials to within 1.5 (cal/cm³)⁰·⁵, achieving molecular-level compatibility. Simultaneously, the vinyl groups in its molecular chain react synchronously with the vulcanization systems (peroxide or platinum catalyst) of both rubber compounds, constructing an "interpenetrating network"—the rigid network of phenyl silicone rubber and the flexible network of ordinary silicone rubber interpenetrate each other, increasing the interfacial shear strength to over 2.5 MPa.

Furthermore, the excellent "vulcanization kinetic matching" of phenyl raw rubber allows it to coordinate the crosslinking rates of the two materials. The phenyl groups in its molecular chain, through steric hindrance, moderately reduce the attack rate of free radicals generated by peroxide decomposition, ensuring that the vulcanization induction period of phenyl silicone rubber highly coincides with the crosslinking peak temperature (ΔT<5℃) of ordinary silicone rubber. This avoids the interfacial defect of "the first vulcanized forming a hard shell, while the later vulcanized shrinks and cracks." From the polarity transition at the molecular level to the macroscopic interfacial fusion, phenyl raw rubber, with its synergistic mechanism of "compatibility regulation and network interpenetration," solves the co-vulcanization problem between phenyl silicone rubber and ordinary silicone rubber. It is not only a key binder for the reliable integration of composite materials, but also an invisible link for achieving "multi-material integration and synergistic performance" in functional devices.