Defect-Dominated Superhydrophobicity: Unraveling Failure Mechanisms for Scalable and Durable Coating Applications.

Abstract

Superhydrophobic (SH) coatings hold immense potential for industrial applications, yet their widespread adoption has been hindered by fast performance degradation under real-world conditions. This study investigates multiscale defect formation and its performance implications in SiC whisker/silicone resin/PTFE nanoparticle SH coatings, serving as a model for the widely used nanoparticle-based SH composites. By varying PTFE content (1-10 parts), we identified that though micrometer-scale inhomogeneities affected initial wettability, localized regions with low nanoscale roughness ("defects") governed long-term SH stability. The optimized formulation (4:2:8 mass ratio) with a uniform nanoscale morphology (Ra = 71.6 nm) exhibited exceptional performance metrics, including a highly stable Cassie state against rainfall flushing (167 mL/s) and waterjet impinging (24.13 m/s, We ≈ 21000), a low ice adhesion strength of 0.8 kPa at -15 °C, and a prolonged plastron stability of >24 days and up to a 96-fold improvement over unoptimized compositions under shear slurry-pot flow (Re ≈ 4200000). These findings provide both fundamental insights into defect-dominated failure mechanisms and practical guidelines for the scalable manufacturing of robust superhydrophobic surfaces.