Facile Synthesis of Mechanically Flexible and Electrically Conductive Fluorosilicone Rubber Composites with Tunable Resistance Response for Efficient Organic Vapor Sensing

Conductive polymer composites have attracted considerable attention for gas sensing applications due to the easy fabrication, mechanical flexibility, and superior sensing capability at room temperature. Herein, fluorosilicone rubber (F-SiR) composites filled with vapor-grown carbon fibers (VGCFs) were fabricated, and the organic vapor sensing performance of the composites was investigated. Various F-SiR polymers with different contents (0, 50%, 100%) of trifluoropropyl groups were synthesized via ring-opening polymerization, and the addition of highly dispersed VGCF is effective in improving the electrical conductivity of F-SiR without affecting the mechanical flexibility. Consequently, the optimized VGCF/F-SiR composite film exhibits high sensitivity (>10⁴ resistance change), relatively rapid response time (∼34 s), and good reproducibility for detecting both static-saturated and low-concentration flowing organic vapors, superior to the traditional conductive silicone rubber composites. Notably, the composites with different trifluoropropyl groups present different organic vapor-responsive behaviors. Typically, the VGCF/50%F-SiR film-based gas sensor demonstrates good sensing selectivity for both hexane and ethyl acetate and maintains a stable gas-sensing behavior after 50 cyclic blending and twisting tests or under complex environments. Clearly, this work paves a rational method for developing advanced polymer composites as efficient organic vapor sensors by tailoring the molecular structure of silicone polymers.