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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 | N O V E M B E R / D E C E M B E R 2 0 1 9 1 2 NEW BIO-BASED MATERIAL MIMICS PLASTIC Inspired by nature, researchers at Aalto University and the VTT Technical Research Center of Finland recently cre- ated a truly new bio-based material by gluing together wood cellulose fibers and the silk protein found in spider web threads. The result is a very firm and resilient material which could be used as a possible replacement for plastic, as part of bio-based composites, and in medical applications, surgical fibers, textile industry, and packaging. The spider web silk used by Aalto University researchers is not actually taken from spider webs but is instead produced by the researchers using bac- teria with synthetic DNA. According to researchers, this work demonstrates new and versatile pos- sibilities of protein engineering. They are currently developing new compos- ite materials as implants, impact re- sistance objects, and other products. www.aalto.fi/en , www.vttresearch.com. DIAMOND-LIKE SUPERHARD CARBON Scientists use superhard materials to create scratch-resistant coatings and to slice, drill, and polish other objects. Now, researchers are using computa- tional techniques to identify 43 pre- viously unknown forms of carbon that are thought to be stable and super- hard—including several predicted to be slightly harder than or nearly as hard as diamonds. Each new carbon variety consists of carbon atoms arranged in a distinct pattern in a crystal lattice. Researchers at the University at Buffalo, N.Y., combined computational predictions of crystal structures with machine learning to hunt for novel ma- terials in their theoretical work. The hardest structures the scien- tists found tended to contain fragments of diamond and lonsdaleite—also called hexagonal diamond—in their crystal lattices. EMERGING TECHNOLOGY Scientists at the University of Leeds, U.K., have created a new form of gold which is just two atoms thick—the thinnest unsupported gold ever created at just 0.47 nanometers. The materi- al is regarded as 2D because it comprises just two layers of stacked atoms. www.leeds.ac.uk. BRIEF The techniques used in the re- search could be applied to identify oth- er superhard materials, including ones that contain elements other than car- bon. buffalo.edu . METAL-ORGANIC FRAMEWORK DESIGN Scientists from the University of Amsterdam are demonstrating design strategies for adjusting the thermal ex- pansion behavior of microporous metal- organic frameworks (MOFs). The ability to realize negative thermal expansion coefficients is of great relevance to the potential MOF applications, e.g., at ma- terial interfaces where they could pre- vent cracking and peeling. MOFs are predicted to exhibit wide-spread negative thermal expan- sion (NTE), due in part to their nano-po- rosity and flexible framework. They are particularly intriguing as NTE materials since they offer great design flexibility. A fundamental understanding of MOF thermal expansion is crucial to ad- vancing their use in a wide range of po- tential applications that include coated monoliths,microcantilever sensors, and electronic devices. www.uva.nl/en. Silk is a natural protein but can also be synthetically produced. Courtesy of Eeva Suorlahti. Artificially colored gold nanosheet. Illustration of three of the new superhard carbon structures. Blue indicates sections that are structurally related to diamond. Courtesy of Bob Wilder/University at Buffalo. Metal-organic frameworks are the key to new design strategies. Courtesy of HIMS.