Studies on Hydrophobic Silica/Silicone Rubber Composite Microspheres with Dual-Size Microstructures

In this study, a series of microsphere composites were prepared by the hydrosilylation of nanospherical SiO₂ and silicon rubber microspheres. The influence of different host-guest size ratios on the wettability of the SiO₂/silicone rubber composite microspheres was explored. The structures and performance of the composite microspheres were investigated using scanning electron microscopy and contact angle testing. The results showed that the prepared SiO₂/silicone rubber composite microspheres had a raspberry-like structure and exhibited a rose petal effect. When the SiO₂ content was 30%, the water contact angle of the SiO₂/silicone rubber composite microspheres reached a maximum, and 30% was used as the optimal ratio for compounding SiO₂ having different particle diameters with silicone rubber microspheres. Wettability calculations and analyses were performed for the surface with the composite microspheres. The results indicated that the structure with dual-size roughness could significantly improve surface hydrophobicity. As the ratio of the host-guest size increased, the contact angle of the water phase also increased. However, the surface structures of the composite microspheres were not uniform because of the surface chemical composition and the uncontrollable distribution of the small spheres on the surface of the large spheres during compounding. As a result, water droplets appeared in the Cassie-impregnated state on the composite microsphere particle coating, resulting in the phenomenon of high hydrophobicity and high adhesion.