Understanding the influence of interfacial interaction and fluorine content on the mechanical properties and oil resistance in composites of fluorosilicone rubber/silica

Fluorosilicone rubber (FSR) has become an indispensable sealing material due to its exceptional adaptability to extreme temperatures and non-polar media environments. In this study, the influence of interfacial interactions and fluorine content in FSR composites on their mechanical properties and oil resistance was investigated. Three modified M5s (@M5) were firstly prepared by surface modification of fumed silica M5 using three fluorinated silane coupling agents with different chain lengths. Among them, though 13F@M5 and 17F@M5 exhibit weaker interfacial interactions with the FSR matrix, they exhibit remarkable hydrophobicity (water contact angle >142°) and dispersibility. Additionally, among the three @M5/FSR composites, 13F@M5/FSR and 17F@M5/FSR exhibit excellent tensile strength (>11.1 MPa) and elongation at break (>490 %), while 3F@M5/FSR shows superior oil resistance, with only a 5.1 % decrease in tensile strength after 48 h of immersion in IRM 901 at 150 °C. The analysis of the interfacial structures reveals that interfacial interactions play a decisive role in the oil resistance of FSR composites, whereas the fluorine content indirectly affects the oil resistance by preventing the oil molecules from immersing into the interphase. The present study not only provides a comprehensive understanding of interfacial interactions and the influence of fluorine content on the properties of FSR composites, but also offers valuable insights for the design of high-performance composite interfaces. [Display omitted] •The hydrophobicity of M5 is greatly enhanced by fluorinated silane coupling.•Strong interfacial interaction is the primary reason to enhance oil resistance.•The fluorine content indirectly enhances oil resistance by protecting the interface.