Mussel-inspired direct immobilization of nanoparticles and application for oil-water separation

Immobilization of various nanoparticles onto complex 2D or 3D macroscopic surface is an important issue for nanotechnology, but the challenge remains to explore a facile, general and environmentally friendly method for achieving this goal. Taking inspiration from the adhesion of marine mussels, we reported here that oxide nanoparticles of different compositions and sizes were directly and robustly anchored on the surface of monolithic foams ranging from polymer to metals in an aqueous solution of dopamine. The effective immobilization of the nanoparticles was strongly dependent on the oxidation of dopamine, which could be tuned by either pH or by adding n-dodecanethiol. Interestingly, the thiol addition not only allowed the immobilization to take place in a wide pH range, but also led to superhydrophobicity of the resulting foams. Application of the superhydrophobic foams was illustrated by fast and selective collecting oils from water surface. Because catecholic derivatives exhibit high affinity to a variety of substances, the present strategy might be extendable to fabricate hybrid nanomaterials desirable for self-cleaning, environmental protection, sensors and catalysts, and so forth.