Design of strong fluorosilicone composites via thermodynamic and kinetic regulation of SiO2

This study provides a pathway to optimize the mechanical properties of immiscible polymer composites through the thermodynamic and kinetic regulation of nano-SiO2. The nano-SiO2 premixed in silicone rubber (SR) preferentially thermodynamic migrated to the fluororubber (FKM)/SR interface and FKM phase, thereby assisting the chain entanglements at the interface and thus improving the interfacial compatibility. The surface modification of nano-SiO2 by silane coupling agents is envisioned to effectively facilitate rubber reinforcement, however, it would in turn weaken the thermodynamic driving force for their thermodynamic migration. As such, we reveal a fluorosilicone composite construction strategy (one-step method), in which the thermodynamic migration and surface modification of nano-SiO2 occur simultaneously. OS-P2F4S4-5%@K5% fabricated by one-step method has achieved the highest tensile strength of 7.6 MPa accompanied with the uncompromised stretchability (165%), which was higher than that of TS-P2F4S4-5%@K2% (5.9 MPa, 150%) and P2F4S4-0% (3.5 MPa, 113%).