Fabrication of raspberry SiO 2/polystyrene particles and superhydrophobic particulate film with high adhesive force

We report a facile and novel strategy on the fabrication of well-defined raspberry SiO ₂/polystyrene (SiO ₂/PS) particles via radiation miniemulsion polymerization. Starting from methacryloxypropyltrimethoxysilane (MPS)-functionalized SiO ₂ particles (176 nm), raspberry SiO ₂/PS particles (257 nm) with a submicron SiO ₂ core decorated by nano-sized PS latex particles (58 nm) are obtained after γ-ray induced miniemulsion polymerization of styrene (St). It is found that MPS grafted density on the surface of submicron SiO ₂ particles, the weight ratio of St to SiO ₂ particles (W _St/o-SiO2), as well as the surfactant concentration will affect the morphology and wettability of the resultant SiO ₂/PS hybrid particles. When the well-defined raspberry SiO ₂/PS particles are deposited on a blank glass substrate, a dual-size roughness surface topology was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). This film has a static water contact angle as high as 151°. However, this film exhibits a large contact angle hysteresis (∼116°) and strong adhesion to water. Furthermore, this kind of superhydrophobic particulate film can be used as a "mechanical hand" for transportation of small water droplets without loss, thus it may have potential applications in industrial fields. © The Royal Society of Chemistry 2012.