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A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 8 1 6 NANOTECHNOLOGY A NANO SPIN ON SPIDER SILK A team from the European Union’s Graphene Flagship discovered a nov- el way to create enhanced spider silk— feed the creepy critters graphene and carbon nanotubes. The modified silk exhibits up to three times the strength and 10 times the toughness of natural spider silk, which already possesses ex- cellent tensile strength, ultimate strain, and toughness, even compared to syn- thetic fibers such as Kevlar. To create the enhanced fiber, re- searchers sprayed the interior of the spiders’ enclosure with solutions of graphene and carbon nanotubes, which were ingested by the crea- tures. When the researchers collected and tested the resulting biocompos- ite silk, they found it possessed sig- nificant increases in strength, tough- ness, and elasticity compared to ref- erence silks previously collected from the same spiders. In fact, the stron- gest threads have a fracture strength of up to 5.4 GPa—comparable to that of the strongest carbon fibers—and a toughness modulus up to 2.1 GPa, the highest fiber toughness reported to date. These artificially modified silks could be used in high-performance or biodegradable textiles such as para- chutes or medical dressings. graphene- flagship.eu . GRAPHENE CLEANS UP An international group of scien- tists, including researchers at Shinshu University, Japan, and the director of Penn State’s ATOMIC Center, Universi- ty Park, Pa., invented a graphene-based coating for desalination membranes that is sturdier and more scalable than standard nanofiltration mem- brane technologies. The hybrid mem- brane uses a simple spray-on process to coat a mixture of graphene oxide and few-layered graphene in solution onto a backbone support membrane of poly- sulfone modified with polyvinyl alco- hol. The unique combination addresses several challenges in filtration technol- ogy. For example, the use of polyvinyl alcohol as an adhesive in the support membrane overcomes the water solu- bility of graphene oxide, allowing the hybrid to tolerate intense cross-flow and high pressure. The addition of few-layered graphene provides high re- sistance to chlorine, which is regularly used to mitigate biofouling but rapid- ly degrades the performance of current polymer membranes. In addition, the technology’s de- salination capabilities are promising. Porous graphene alone is predicted to have 100% salt rejection, and at its current stage of development, the hy- brid membrane rejects 85% of salt. Al- though these results are not yet pure enough for drinking water, the filter re- moves enough salt for agricultural pur- poses along with capturing 96% of dye molecules, a common industrial pol- lutant. The new technology could be used in protein separation, wastewa- ter treatment, and pharmaceutical and food applications, in addition to pro- viding clean water. www.shinshu-u.ac. jp/english, www.mri.psu.edu. BRIEF Engineers at the University of Maryland, College Park, developed a new use for nanofibrillated cellulose, joining it with carbon nanotubes via a 3D printing process to form robust, conductive microfibers. The fibers, which combine mechanical strength (247±5 MPa) and high electrical conductivity (216.7±10 S/cm), could be used in wearable elec- tronics, offering high performance and low cost. umd.edu . A scalable graphene-basedmembrane for producing clean water. Courtesy of Aaron Morelos-Gomez. Researchers at Graphene Flagship boosted the strength of spider silk using graphene- basedmaterials, paving the way for a novel class of high-performance bionic composites. Courtesy of F. Tomasinelli.