Preparation and characterization of superhydrophobic and oleophobic surfaces as precursors for boiling applications

Superhydrophobic and oleophobic surfaces have drawn global interest over the past decade for their potential in heat transfer and thermal management applications. This study examines the combined effects of mechanical surface treatments and silane coatings in developing such surfaces, as well as the influence of each treatment method and duration on wettability. Sandblasting and electrolytic etching were applied to create micro- and nano-scale roughness on aluminum surfaces, followed by the application of fluorinated silane coatings: heptadecafluoro-1,1,2,2-tetrahydrodecyl triethoxysilane (HT) and heptadecafluoro-1,1,2,2-tetrahydrodecyl trimethoxysilane (HDFS). Testing with water and low surface tension liquids showed that HDFS-treated surfaces exhibit higher oleophobicity, with oil (n-hexadecane) contact angles reaching 137.8°, while HT treatment demonstrated superior hydrophobicity, with water contact angles of 164.7°. Linear relationships were observed between surface tensions of the low-surface-tension liquids and their static contact angles on HT- and HDFS-treated micro-, nano-, and micro-nano surfaces. The study also revealed that etching duration strongly affects wettability, with optimized nanoscale roughness being a crucial factor to enhance oleophobicity. These findings provide a systematic approach for fabricating micro-/nano-structured surfaces and lay the foundation for developing advanced engineered materials with controllable wettability. • Hierarchical micro/nano structures form via sandblasting, electrolytic etching, silanization. • Combined mechanical and chemical methods yield aluminum with high water/oil repellency. • Water and oil (n-hexadecane) contact angles reach 164.7° and 137.8°, respectively. • Optimal etching time balances roughness and integrity for maximum oleophobicity. • Contact angle correlates linearly with surface tension across five low-surface-tension oils. • First direct comparison of superhydrophobic and oleophobic regimes from different silanes