A novel approach to raspberry-like particles for superhydrophobic materials

A new strategy was developed to prepare raspberry-like particles by introducing poly(acrylic acid) (PAA)-functionalized polystyrene (PS) particles into hydrolysis reaction of tetraethoxysilane (TEOS). The monodisperse PAA-functionalized PS particles were used as cores and nanosized silica particles were then assembled on the surface of PS particles to construct raspberry-like particles during the hydrolysis process. With the increase of PAA content from 11% to 20% (wt) at the surface of latexes, the diameter of the silica particles assembled at the surface of cores decreased from 124 nm to 36 nm. The structure, morphology and constitution of the PAA-functionalized PS particles and the raspberry-like particles were characterized by Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). In addition, the particulate films were constructed by assembling these raspberry-like particles on glass substrates. After surface modification with dodecyltrichlorosilane, superhydrophobic surfaces can be obtained and the contact angle of water on the dual-sized structured surface can be adjusted by the scale ratio of the micro/nano surface structure of raspberry-like particles.