The fabrication of robust superhydrophobic 3D porous materials is of great importance for both academic research and industrial applications. The main challenge is the poor adhesion between porous substrates and superhydrophobic coatings. In this study, a robust superhydrophobic polysiloxane layer was coated onto the surface of 3D porous polyurethane sponges through a one-step solution immersion method.The durability of the resulting sponges was investigated by repeated mechanical compressions, ultrasonication in polar solvents, and strong acid/alkali attacks. Results revealed that the superhydrophobic sponges showed excellent elasticity, high mechanical durability and good chemical stability. By combining the special wettability and high porosity, the sponges exhibited high oilabsorption capacity and high selectivity when they were employed as absorptive materials for cleaning oils on the water surface. More importantly, the superhydrophobic sponges could be reused for oil-water separation for more than 300 cycles without losing their superhydrophobicity, exhibiting the highest reusability and durability among the reported counterparts. Therefore, the present study offers a simple and low-cost strategy for large-scale fabrication of robust superhydrophobic 3D porous materials that might be applied to the cleanup of oil spills on the water surface.

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Ultralow-density (<10 mg cm(-3)) materials have many important technological applications; however, most of them were fabricated using either expensive materials or complicated procedures. In this study, ultralight magnetic Fe2O3/C, Co/C, and Ni/C foams (with a density <5 mg cm(-3)) were fabricated on the centimeter scale by pyrolyzing commercial polyurethane sponge grafted with polyelectrolyte layers based on the corresponding metal acrylate at 400 °C. The ultralight foams consisted of 3D interconnected hollow tubes that have a diameter of micrometer and nanoscale wall thickness, forming hierarchical structures from macroscopic to nanometer length scales. More interesting was that the wall thickness and morphology of the microtubes could be tuned by controlling the concentrations of acrylic acid and metallic cations. After modification with low-surface-energy polysiloxane, the ultralight foams showed superhydrophobicity and superoleophilicity, which quickly and selectively absorbed a variety of oils from a polluted water surface under magnetic field. The oil absorption capacity reached 100 times of the foams' own weight, exhibiting one of the highest values among existing absorptive counterparts. By controlling the composition and conformation of the grafted polyelectrolyte layers, the present approach is extendable to fabricate a variety of ultralow-density materials desirable for absorptive materials, electrode materials, catalyst supports, etc.

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.

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