Superhydrophobization of hydrophilic silica via solid phase reaction enhances dispersion in deproteinized natural rubber

Superhydrophobic silica is crucial for many industries due to its outstanding water repellency and broad application potential. These materials are defined by water contact angles above 150° and very low sliding angles, allowing droplets to roll off easily. Conventionally, superhydrophobicity is achieved by combining a low-surface-energy chemical coating with micro/nano-scale surface roughness. However, there is a lack of solid-phase surface treatment methods for silica, which limits large-scale production. Here, we demonstrate a solvent-free solid-phase reaction between silica and sodium dodecyl sulfate (SDS) at 200 °C to fabricate superhydrophobic silica particles. The resulting material achieves a water contact angle of 159.1°, surpassing previous methods, and this simple approach can be scaled up for industrial production. To preliminarily assess the applicability of this material, we chose to mix it with deproteinized natural rubber (DPNR) to indirectly evaluate dispersion through vulcanization process parameters and tensile strength. Indirect results suggest that Si-SHPB has better dispersion in DPNR compared to Si-HPL.