Polydopamine-assisted synthesis of raspberry-like nanocomposite particles for superhydrophobic and superoleophilic surfaces

Abstract

Inspired by nature, we combine the easy decoration of polydopamine with the attractive biomimetic silification to develop a facile synthetic route toward raspberry-like nanocomposite particles, and further lead to the superhydrophobic and superoleophilic surfaces by mimicking the lotus leaf surface structures in the usage of these particles. In this approach, monodisperse polystyrene (PS) particles are used as the template particles, and then, follows with a subsequent polydopamine (PDA) coating step through the self-polymerization of dopamine in a weakly alkaline aqueous environment (pH = 8.5). The obtained core–shell PS/PDA particles are used as the active substrates for the biomimetic silification under the ambient conditions, allowing a well-controlled synthesis of raspberry-like PS/SiO2 nanocomposite particles with a tunable surface roughness. Upon adjusting the concentration of silica precursor, the surface geometry and the coverage degree of silica nanoparticles of PS/PDA composite particles can be easily tailored. The whole procedure is carried out in a mild environment, no intricate instruments or toxic reagents are involved. In addition, these raspberry-like PS/SiO2 nanocomposite particles self-assemble onto the glass slides driven by capillary force during drying, forming a hierarchical dual-sized rough structure, which is analogous to the surface morphology of lotus leaf in nature. Making full use of this hierarchical surface, superhydrophobic and superoleophilic surfaces can be successfully achieved via a rational surface modification of this lotus leaf-like surface structure. The superhydrophobic performances can be readily adjusted by varying the scale ratio of the micro/nano surface structures.