Researchers in Switzerland say they have punched precisely shaped holes in films of graphene, a two-dimensional sheet of linked carbon atoms. Their development means graphene, a material that is lightweight and strong, can be made into the thinnest possible membrane with pores of exact size to exclude specific molecules.
Engineers at ETH Zurich created the membrane out of two graphene sheets pressed together. Their prototypes were 100,000 times thinner than a human hair.
"With a thickness of just two carbon atoms, this is the thinnest porous membrane that is technologically possible to make," said Jakob Buchheim, a nanoscience doctoral student in the university’s Department of Mechanical and Process Engineering. He is a lead author of the study published today in the journal Science.
Along with major applications like filtering water, separating gaseous mixtures and removing impurities from liquids, graphene membranes could be a game changer in rain gear and waterproofing. The researchers say the material could be manufactured to make a coating that excludes liquids while letting gases right on through.
A new water-repellant concrete impregnated with tiny superstrong fibers promises to leave roads and bridges free of major cracks for up to 120 years.
University of Wisconsin-Milwaukee civil engineers have developed a concrete mix that is durable and superhydrophobic. They call it Superhydrophobic Engineered Cementitious Composite (SECC). Preventing normally porous concrete from absorbing water means that liquid can’t get inside, freeze and cause it to crack. The concrete’s unusual characteristics, including being significantly more ductile than traditional concrete, means that cracks that do form do not propagate and cause failure.
“Our architecture allows the material to withstand four times the compression with 200 times the ductility of traditional concrete,” said associate professor Konstantin Sobolev, whose lab created SECC.