January_February_2022_AMP_Digital

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 / F E B R U A R Y 2 0 2 2 8 METALS | POLYMERS | CERAMICS NeoGraf Solutions, Lakewood, Ohio, extended its range of graphite materials with the launch of Graf-X graphene nanoplatelets and precursors. Both materials impart enhanced strength, performance, and reliability to a broad range of thermoset and thermoplastic applications. neograf.com . Norman Noble Inc., Highland Heights, Ohio, achieved ISO 13485:2016 registration for its quality management system following a recertification audit by the British Standards Institute. The ISO standard is specific to the medical device industry. nnoble.com. BRIEFS COMPRESSION-RESISTANT HYDROGEL A soft material with significant re- sistance to compression was created by a research team at the University of Cambridge, U.K. The soft-yet-strong material looks and feels like a squishy jelly but acts like an ultra-hard, shatter- proof glass when compressed, despite its high water content. The non-water portion of the material is a network of polymers held together by reversible on/off interactions that control the ma- terial’s mechanical properties. The team used barrel-shaped mol- ecules called cucurbiturils tomake a hy- drogel that can withstand compression. The cucurbituril is the crosslinking mol- ecule which holds two guest molecules in its cavity—like a molecular handcuff. The researchers designed guest mole- cules that prefer to stay inside the cav- ity for longer than normal, which keeps Diagram of one sample of ceramic material showing that specimens gradually fell apart into a pile of powder. Courtesy of Gu et al., University of Minnesota and Kiel University. SHAPE-SHIFTING CERAMICS A new functional ceramic mate- rial class may now be possible due to a discovery made by an international team of researchers from the Univer- sity of Minnesota Twin Cities and Kiel University in Germany. The hypotheti- cally shape-shifting ceramic materials could improve everything frommedical devices to electronics. Leading up to their innovation, researchers utilized a formula that previously led to the dis- covery of new metallic shape memory materials, involving a delicate tuning of the distances between atoms by com- positional changes. They implemented this method but, instead of improving the deformability of the ceramic, they observed that some specimens explod- ed when they passed through the phase transformation. Others gradually fell apart into a pile of powder, a phenom- enon they termed “weeping.” With yet another composition, they observed a reversible transformation, easily trans- forming back and forth between the phases—much like a shape memory material. The mathematical conditions under which reversible transformation occurs can be applied widely and pro- vide a way forward toward the paradox- ical shape-memory ceramic. “We were quite amazed by our re- sults,” the team remarks. “Shape-mem- ory ceramics would be a completely new kind of functional material. There is a great need for shape memory actu- ators that can function in high tempera- ture or in corrosive environments. But what excites us most is the prospect of new ferroelectric ceramics. In these ma- terials, the phase transformation can be used to generate electricity from small temperature differences.” twin-cities. umn.edu , www.uni-kiel.de/en/. Researchers say this is the first time that significant resistance to compression has been incorporated into a so material. Courtesy of Zehuan Huang.