ADVANCED MATERIALS & PROCESSES | JANUARY/FEBRUARY 2024 1 1 PROCESS TECHNOLOGY MULTI-METAL MIXING TECHNIQUE BREAKTHROUGH Researchers at The Institute of Materials Science of Barcelona developed a breakthrough mixing technique that enables them to systematically blend many different metals into metal- organic frameworks (MOFs). Their approach relies on specially designed organic linker molecules that gently coax the different metal ingredients to uniformly mix within the MOF structure. By blending together eight different rare-earth metals, the researchers were able to custom-tune the thermal, optical, and magnetic traits of the resulting MOF. section is the conventional cotton: flexible and strong enough for everyday use, and the other side is the conductive material. The cotton can support the conductive material which can provide the needed function.” While intrinsically conductive, polyaniline is brittle and by itself, cannot be made into a fiber for textiles. To solve this, researchers dissolved cotton cellulose from recycled t-shirts into a solution and the conductive polymer into another separate solution. These two solutions were then merged together side-by-side, and the material was extruded to make one fiber. “We wanted these two solutions to work so that when the cotton and the conductive polymer contact each other, they mix to a certain degree to kind of glue together,” Liu says. “But we didn’t want them to mix too much, otherwise the conductivity would be reduced.” Researchers tested the fibers with a system that powered an LED light and another that sensed ammonia gas. Their goal is to integrate fibers like these into apparel as sensor patches with flexible circuits, which could be part of hazardous exposure-detecting uniforms for workers who handle chemicals, such as firefighters or soldiers. Other applications could include health monitoring or exercise shirts that can do more than current fitness monitors. wsu.edu. The key was their specialized organic linker molecule, which contains molecular clusters called carboranes. Carboranes are excep- tionally stable 3D carbon-boron molecules shaped like a soccer ball. The researchers connected two carborane balls together using a rigid rod-like linker. The bulky carborane balls gently pushed apart the different rare-earth metals, while the rod-shaped linker coaxed them to line up in a uniform mixed chain within the MOF. After systematically testing different rare-earth metal combinations, the team succeeded in blending together eight metals with different sizes—a first for MOFs. Analyses showed that the different metals were evenly distributed throughout the MOF crystal, rather than clumping together. Remarkably, the intricate MOF retained the distinct optical, magnetic, and thermal traits contributed by the individual ingredient metals. The MOF displayed versatile magnetic behaviors stemming from the different rare-earth metals, showcasing their potentially tunable functionalities. Two of the metals, terbium and dysprosium, endowed the MOF with single- molecule magnet behavior useful for data storage. The metal-mixing technique could potentially yield a sweeping range of previously inaccessible applications. www.icmab.es. SMART TEXTILES WITH CONDUCTIVE FIBER Using polyaniline, scientists at Washington State University (WSU) developed a single strand of fiber that has the flexibility of cotton and the electric conductivity of a polymer. The newly synthesized material shows promising potential for wearable e-textiles. Researcher Hang Liu explains: “We have one fiber in two sections—one Example of possible outcome from the formation of crystals with various bimetallic combinations and rod-shape secondary building units, resulting in preferential partial segregation. Hang Liu views an image of the new fibers showing their mix of cotton and polyaniline polymer. Courtesy of Dean Hare, WSU Photo Services. Caldera Holding, the owner of Missouri’s Pea Ridge iron mine, entered a nonexclusive R&D licensing agreement with Oak Ridge National Laboratory (ORNL) to apply a membrane solvent extraction technique (MSX) developed at ORNL to mined ores. MSX efficiently separates rare earth elements from mixed mineral ores. ornl.gov. BRIEF
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