Interface-Tunable Fluoropolymer Coatings Enabled by Surface-Engineered Recycled Tire Rubber

Fluoropolymer coatings demonstrate excellent chemical resistance and durability; however, their inherently low surface energy compromises adhesion and structural cohesion, particularly when exposed to aggressive environments. This study presents a scalable interfacial engineering strategy to enhance coating performance by integrating functionalized ground tire rubber (fGTR) into poly(vinylidene fluoride-<i>co</i>-hexafluoropropylene) (PVDF-HFP). Postconsumer GTR is transformed into high-performance fillers through surface-initiated grafting of poly(acrylic acid), introducing polar groups capable of improving dispersion in an organic bisolvent system and facilitating strong hydrogen bonding with the matrix. At an optimal filler content of 7 wt %, fGTR-containing composites exhibit nearly 3-fold higher elongation at break and over double the fracture energy of unmodified formulations while maintaining thermal and dielectric stability. Electrochemical impedance spectroscopy indicates sustained barrier performance, with low-frequency (0.1 Hz) impedance modulus remaining at approximately 1.3 × 10⁹ ohm·cm² after 30 days in salt solution. Finite element modeling and cyclic corrosion testing validate improved stress distribution and long-term durability. Overall, this approach establishes the first demonstration of surface-functionalized, radical-active GTR as an interface-tunable additive in thin-film fluoropolymer coatings, enabling a sustainable route to multifunctional, corrosion-resistant barrier systems.