Spray-Based Fabrication of Uniform Superhydrophobic Coating Using Surface-Modified SiC Nanoparticles

Superhydrophobic (SH) coatings have received considerable attention for their potential use in water-repellent, anti-corrosion, and anti-icing applications. However, conventional spray-based SH coatings often suffer from non-uniform hierarchical structures due to uncontrollable nanoparticle aggregation during solvent evaporation, which significantly limits their practical performance and scalability. In this study, we developed a surface chemistry-based strategy to improve the uniformity of SH coatings by precisely controlling the surface polarity and functional group density of the nanoparticles. Specifically, silicon carbide (SiC) nanoparticles, which originally exhibit very low surface hydroxyl content, were chemically modified via acid treatment followed by the grafting of hydroxyl-terminated polydimethylsiloxane (H-PDMS) to tune their surface polarity and interparticle interactions. The modified SiC nanoparticles formed aggregates with optimized size which significantly enhanced uniformity during the spray deposition process, resulting in robust and uniform hierarchical surface structures. Compared to unmodified SiC and conventional SiO<sub>2</sub> nanoparticles, the coatings fabricated with modified SiC exhibited a high water contact angle of 163.5<sup>o</sup> as well as remarkably reduced contact angle variation across the coated area, confirming the improvement in spatial uniformity. This work demonstrates that precise control over nanoparticle surface functionalization is critical for achieving uniform and scalable superhydrophobic surfaces and provides a foundational strategy for overcoming aggregation-induced non-uniformity, thereby advancing the industrial applicability of spray-deposited SH coatings.