Robust superamphiphobic coatings in confined and chemically inert tubular geometries enabled by a dynamic circulation coating strategy.

Fabricating robust superamphiphobic coatings on the inner surfaces of narrow tubes remains a long-standing challenge due to restricted mass transport, geometric confinement, and limited interfacial reaction efficiency. Despite extensive progress in planar superamphiphobic surfaces, achieving durable liquid repellency in confined tubular systems-particularly on chemically inert substrates-has remained essentially unsolved. Herein, we report a versatile dynamic circulation coating (DCC) strategy for constructing robust superamphiphobic coatings on both planar substrates and, more importantly, the inner walls of narrow and chemically inert tubes. In the DCC process, a peristaltic pump precisely controls precursor delivery, enabling uniform coating under confined geometry. The coatings are fabricated through co-deposition of tannic acid and dopamine with silica microparticles as a primer layer with abundant hydroxyl groups on chemically inert substrates, followed by confined self-assembly of silicone nanofilaments with vinyl groups and subsequent covalent fluorination via thiol-ene click chemistry, forming a hierarchical micro-/nanostructure with ultralow surface energy. The resulting coatings exhibit exceptional superamphiphobicity, an outstanding static/dynamic pressure resistance of up to 2.0 MPa, and excellent chemical/mechanical durability. This work overcomes the critical barrier of applying high-performance superamphiphobic coatings to confined geometries, paving the way for their use in microfluidics, medical devices, industrial tubing, etc.