The researchers added an oil, an emulsifier and a hydrophobic silicon polymer called polydimethylsiloxane (PDMS) to wet concrete. With the help of the emulsifier, the oil formed many tiny droplets that contained PDMS. The team then dried and heated the concrete, evaporating the oil so that PDMS-coated pores were left behind. The resulting porous concrete was lightweight, yet mechanically strong. It repelled dust particles and liquids, including milk, beer, soy sauce, coffee and dyed water, and could be immersed in the liquids and removed without leaving any stains behind. Even with mechanical grinding, heat treatment and chemical exposure, the material remained superhydrophobic. The porous concrete also absorbed sounds and insulated against heat loss, two other attractive properties for building materials.
The authors acknowledge funding from the National Science Foundation of China, the China National Petroleum Corporation–Chinese Academy of Sciences Strategic Cooperation Research Program and the Open Foundation of the State Key Laboratory of Advanced Refractory Materials. (American Chemical Society)
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