Hierarchically Reinforced PDMS-Silica Coatings for Durable Superhydrophobicity

Robust, self-cleaning surfaces were fabricated by embedding dual-sized silica nanoparticles (SiO₂, 100 and 500 nm SNPs) into a poly-(dimethylsiloxane) (PDMS) matrix and coating the resulting composite onto a solid substrate. The incorporation of nanoparticles generated a hierarchical surface texture that promoted the emergence of superhydrophobicity. Scanning electron microscope (SEM) analysis confirmed the successful embedding and uniform distribution of the SNPs within the PDMS matrix. To further enhance the mechanical stability of the coating, glass beads (GBs) of different sizes were introduced, providing additional microscale topography and reinforcing the coating against physical damage. This multiscale structuring amplified the water repellency effect. Scratch tests showed that GBs reinforced coatings maintained higher hydrophobicity than their bead-free counterparts. The optimized coating exhibited a water contact angle exceeding 159° and a sliding angle of around 15°, indicating considerable water repellency. Overall, this study demonstrates the role of hierarchical architecture and mechanical reinforcement in developing durable superhydrophobic surfaces suitable for practical applications.