Semiconducting polymer blends that exhibit stable charge transport at high temperatures
We report a general strategy to make thermally stable high-temperature semiconducting polymer blends, composed of interpenetrating semicrystalline conjugated polymers and high glass-transition temperature insulating matrices. When properly engineered, such polymer blends display a temperature-insensitive charge transport behavior with hole mobility exceeding 2.0 cm2/V·s across a wide temperature range from room temperature up to 220°C in thin-film transistors. (Source: ScienceNOW)
Source: ScienceNOW - December 6, 2018 Category: Science Authors: Gumyusenge, A., Tran, D. T., Luo, X., Pitch, G. M., Zhao, Y., Jenkins, K. A., Dunn, T. J., Ayzner, A. L., Savoie, B. M., Mei, J. Tags: Chemistry, Materials Science reports Source Type: news
Building two-dimensional materials one row at a time: Avoiding the nucleation barrier
Assembly of two-dimensional (2D) molecular arrays on surfaces produces a wide range of architectural motifs exhibiting unique properties, but little attention has been given to the mechanism by which they nucleate. Using peptides selected for their binding affinity to molybdenum disulfide, we investigated nucleation of 2D arrays by molecularly resolved in situ atomic force microscopy and compared our results to molecular dynamics simulations. The arrays assembled one row at a time, and the nuclei were ordered from the earliest stages and formed without a free energy barrier or a critical size. The results verify long-stand...
Source: ScienceNOW - December 6, 2018 Category: Science Authors: Chen, J., Zhu, E., Liu, J., Zhang, S., Lin, Z., Duan, X., Heinz, H., Huang, Y., De Yoreo, J. J. Tags: Chemistry, Materials Science, Physics reports Source Type: news
Room-temperature cycling of metal fluoride electrodes: Liquid electrolytes for high-energy fluoride ion cells
We report a liquid fluoride ion–conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents. Pairing this liquid electrolyte with a copper–lanthanum trifluoride (Cu@LaF3) core-shell cathode, we demonstrate reversible fluorination and defluorination reactions in a fluoride ion electrochemical cell cycled at room temperature. Fluoride ion–mediated electrochemistry offers a pathway toward developing capacities beyond that of lithium ion technology. (Source: ScienceNOW)
Source: ScienceNOW - December 6, 2018 Category: Science Authors: Davis, V. K., Bates, C. M., Omichi, K., Savoie, B. M., Momcilovic, N., Xu, Q., Wolf, W. J., Webb, M. A., Billings, K. J., Chou, N. H., Alayoglu, S., McKenney, R. K., Darolles, I. M., Nair, N. G., Hightower, A., Rosenberg, D., Ahmed, M., Brooks, C. J., Mil Tags: Chemistry, Materials Science reports Source Type: news
Pushing 3D Printing Forward
Researchers and students have demonstrated that inks can be used instead of thermoplastic filaments to 3D print functional biomedical devices. Michael McAlpine, Benjamin Mayhugh Associate Professor of Mechanical Engineering at the University of Minnesota, described such advances in the ESC Minneapolis keynote, â3D Printing Functional Materials & Devices.â A lot of the inks McAlpineâs group uses are nanometer-scale particle inks printed at a line-width scale of 10 microns and above for printing devices at the macro level. They have developed software as well as a hig...
Source: MDDI - December 4, 2018 Category: Medical Devices Authors: Daphne Allen Tags: MD & M Minneapolis 3-D Printing Source Type: news
A research facility to drive forward technological progress
The European Spallation Source (ESS) will be the world's most powerful source of neutrons, a key tool in advancing materials science and technological progress. An EU-funded project has supported the development of ESS, which could lead to scientific breakthroughs that improve our quality of life. (Source: EUROPA - Research Information Centre)
Source: EUROPA - Research Information Centre - November 30, 2018 Category: Research Source Type: news
How Can Nanotechnologies Aid Implantable Drug-Delivery Systems?
Implantable technologies have come a long way over the years, and advancements in micro and nanotechnologies have helped device developers continue to push the envelope even further. Within the realm of drug delivery, advances in nanotechnologies have consistently improved patient outcomes by enabling sustained drug delivery to help treat chronic conditions. These scalable technologies have even offered localized drug delivery that can further improve bioavailability. While many of these technologies offer a variety of opportunities, weâre still eagerly awaiting to see the impact of these advancements onc...
Source: MDDI - November 29, 2018 Category: Medical Devices Authors: Kristopher Sturgis Tags: BIOMEDevice San Jose Implants Source Type: news
Colossal grain growth yields single-crystal metal foils by contact-free annealing
Single-crystal metals have distinctive properties owing to the absence of grain boundaries and strong anisotropy. Commercial single-crystal metals are usually synthesized by bulk crystal growth or by deposition of thin films onto substrates, and they are expensive and small. We prepared extremely large single-crystal metal foils by "contact-free annealing" from commercial polycrystalline foils. The colossal grain growth (up to 32 square centimeters) is achieved by minimizing contact stresses, resulting in a preferred in-plane and out-of-plane crystal orientation, and is driven by surface energy minimization durin...
Source: ScienceNOW - November 29, 2018 Category: Science Authors: Jin, S., Huang, M., Kwon, Y., Zhang, L., Li, B.-W., Oh, S., Dong, J., Luo, D., Biswal, M., Cunning, B. V., Bakharev, P. V., Moon, I., Yoo, W. J., Camacho-Mojica, D. C., Kim, Y.-J., Lee, S. H., Wang, B., Seong, W. K., Saxena, M., Ding, F., Shin, H.-J., Ruo Tags: Materials Science r-articles Source Type: news
Isostructural metal-insulator transition in VO2
The metal-insulator transition in correlated materials is usually coupled to a symmetry-lowering structural phase transition. This coupling not only complicates the understanding of the basic mechanism of this phenomenon but also limits the speed and endurance of prospective electronic devices. We demonstrate an isostructural, purely electronically driven metal-insulator transition in epitaxial heterostructures of an archetypal correlated material, vanadium dioxide. A combination of thin-film synthesis, structural and electrical characterizations, and theoretical modeling reveals that an interface interaction suppresses th...
Source: ScienceNOW - November 29, 2018 Category: Science Authors: Lee, D., Chung, B., Shi, Y., Kim, G.- Y., Campbell, N., Xue, F., Song, K., Choi, S.- Y., Podkaminer, J. P., Kim, T. H., Ryan, P. J., Kim, J.- W., Paudel, T. R., Kang, J.- H., Spinuzzi, J. W., Tenne, D. A., Tsymbal, E. Y., Rzchowski, M. S., Chen, L. Q., Le Tags: Materials Science, Physics reports Source Type: news
Electrically tunable low-density superconductivity in a monolayer topological insulator
Turning on superconductivity in a topologically nontrivial insulator may provide a route to search for non-Abelian topological states. However, existing demonstrations of superconductor-insulator switches have involved only topologically trivial systems. Here we report reversible, in situ electrostatic on-off switching of superconductivity in the recently established quantum spin Hall insulator monolayer tungsten ditelluride (WTe2). Fabricated into a van der Waals field-effect transistor, the monolayer’s ground state can be continuously gate-tuned from the topological insulating to the superconducting state, with cri...
Source: ScienceNOW - November 22, 2018 Category: Science Authors: Fatemi, V., Wu, S., Cao, Y., Bretheau, L., Gibson, Q. D., Watanabe, K., Taniguchi, T., Cava, R. J., Jarillo-Herrero, P. Tags: Materials Science, Physics reports Source Type: news
Multicomponent intermetallic nanoparticles and superb mechanical behaviors of complex alloys
Alloy design based on single–principal-element systems has approached its limit for performance enhancements. A substantial increase in strength up to gigapascal levels typically causes the premature failure of materials with reduced ductility. Here, we report a strategy to break this trade-off by controllably introducing high-density ductile multicomponent intermetallic nanoparticles (MCINPs) in complex alloy systems. Distinct from the intermetallic-induced embrittlement under conventional wisdom, such MCINP-strengthened alloys exhibit superior strengths of 1.5 gigapascals and ductility as high as 50% in tension at ...
Source: ScienceNOW - November 22, 2018 Category: Science Authors: Yang, T., Zhao, Y. L., Tong, Y., Jiao, Z. B., Wei, J., Cai, J. X., Han, X. D., Chen, D., Hu, A., Kai, J. J., Lu, K., Liu, Y., Liu, C. T. Tags: Materials Science reports Source Type: news
Templated nanofiber synthesis via chemical vapor polymerization into liquid crystalline films
Extrusion, electrospinning, and microdrawing are widely used to create fibrous polymer mats, but these approaches offer limited access to oriented arrays of nanometer-scale fibers with controlled size, shape, and lateral organization. We show that chemical vapor polymerization can be performed on surfaces coated with thin films of liquid crystals to synthesize organized assemblies of end-attached polymer nanofibers. The process uses low concentrations of radical monomers formed initially in the vapor phase and then diffused into the liquid-crystal template. This minimizes monomer-induced changes to the liquid-crystal phase...
Source: ScienceNOW - November 15, 2018 Category: Science Authors: Cheng, K. C. K., Bedolla-Pantoja, M. A., Kim, Y.-K., Gregory, J. V., Xie, F., de France, A., Hussal, C., Sun, K., Abbott, N. L., Lahann, J. Tags: Materials Science reports Source Type: news
Reversible self-assembly of superstructured networks
We report on hydrogels of peptide-DNA conjugates and peptides that organize into superstructures of intertwined filaments that disassemble upon the addition of molecules or changes in charge density. Experiments and simulations demonstrate that this response requires large-scale spatial redistribution of molecules directed by strong noncovalent interactions among them. Simulations also suggest that the chemically reversible structures can only occur within a limited range of supramolecular cohesive energies. Storage moduli of the hydrogels change reversibly as superstructures form and disappear, as does the phenotype of ne...
Source: ScienceNOW - November 15, 2018 Category: Science Authors: Freeman, R., Han, M., Alvarez, Z., Lewis, J. A., Wester, J. R., Stephanopoulos, N., McClendon, M. T., Lynsky, C., Godbe, J. M., Sangji, H., Luijten, E., Stupp, S. I. Tags: Chemistry, Materials Science reports Source Type: news
Light-driven fine chemical production in yeast biohybrids
Inorganic-biological hybrid systems have potential to be sustainable, efficient, and versatile chemical synthesis platforms by integrating the light-harvesting properties of semiconductors with the synthetic potential of biological cells. We have developed a modular bioinorganic hybrid platform that consists of highly efficient light-harvesting indium phosphide nanoparticles and genetically engineered Saccharomyces cerevisiae, a workhorse microorganism in biomanufacturing. The yeast harvests photogenerated electrons from the illuminated nanoparticles and uses them for the cytosolic regeneration of redox cofactors. This pro...
Source: ScienceNOW - November 15, 2018 Category: Science Authors: Guo, J., Suastegui, M., Sakimoto, K. K., Moody, V. M., Xiao, G., Nocera, D. G., Joshi, N. S. Tags: Materials Science, Molecular Biology reports Source Type: news
Wafer-scale single-crystal hexagonal boron nitride film via self-collimated grain formation
Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by e...
Source: ScienceNOW - November 15, 2018 Category: Science Authors: Lee, J. S., Choi, S. H., Yun, S. J., Kim, Y. I., Boandoh, S., Park, J.-H., Shin, B. G., Ko, H., Lee, S. H., Kim, Y.-M., Lee, Y. H., Kim, K. K., Kim, S. M. Tags: Materials Science reports Source Type: news
Suppressing corrosion in primary aluminum-air batteries via oil displacement
Primary aluminum–air batteries boast high theoretical energy densities, but negative electrode corrosion irreversibly limits their shelf life. Most corrosion mitigation methods are insufficient or compromise power and energy density. We suppressed open-circuit corrosion by displacing electrolyte from the electrode surface with a nonconducting oil during battery standby. High power and energy density are enabled by displacing the oil with electrolyte for battery discharge. The underwater-oleophobic wetting properties of the designed cell surfaces allow for reversible oil displacement. We demonstrate this method in an ...
Source: ScienceNOW - November 8, 2018 Category: Science Authors: Hopkins, B. J., Shao-Horn, Y., Hart, D. P. Tags: Chemistry, Materials Science reports Source Type: news
Controlled crack propagation for atomic precision handling of wafer-scale two-dimensional materials
Although flakes of two-dimensional (2D) heterostructures at the micrometer scale can be formed with adhesive-tape exfoliation methods, isolation of 2D flakes into monolayers is extremely time consuming because it is a trial-and-error process. Controlling the number of 2D layers through direct growth also presents difficulty because of the high nucleation barrier on 2D materials. We demonstrate a layer-resolved 2D material splitting technique that permits high-throughput production of multiple monolayers of wafer-scale (5-centimeter diameter) 2D materials by splitting single stacks of thick 2D materials grown on a single wa...
Source: ScienceNOW - November 8, 2018 Category: Science Authors: Shim, J., Bae, S.-H., Kong, W., Lee, D., Qiao, K., Nezich, D., Park, Y. J., Zhao, R., Sundaram, S., Li, X., Yeon, H., Choi, C., Kum, H., Yue, R., Zhou, G., Ou, Y., Lee, K., Moodera, J., Zhao, X., Ahn, J.-H., Hinkle, C., Ougazzaden, A., Kim, J. Tags: Engineering, Materials Science reports Source Type: news
Great honor for research on vehicle emissions
(Swiss Federal Laboratories for Materials Science and Technology (EMPA)) This year's Swiss Aerosol Award goes to Maria Mu ñ oz. The Empa researcher investigated the emission behavior of so-called GDI engines (gasoline-direct injection). Her results are alarming: GDI vehicles emit up to 17 times more carcinogenic substances than modern diesel vehicles. (Source: EurekAlert! - Biology)
Source: EurekAlert! - Biology - November 5, 2018 Category: Biology Source Type: news
Paul O ’Brien obituary
Materials chemist who perfected nanoscientific techniques and enabled important advances in electronicsIn 1995 the leading British materials chemist Paul O ’Brien, who has died aged 64 after suffering from brain cancer, began to use chemical synthesis to make quantum dots, which are tiny semiconductor particles, only nanometres across, that can be made to emit light of varying colours according to their size. Up to that point quantum dots had been di fficult to produce, requiring the use of hazardous metal alkyl precursors at high temperatures. O’Brien’s new method not only allowed them to be mass-produce...
Source: Guardian Unlimited Science - November 1, 2018 Category: Science Authors: David Lewis Tags: Materials science Nanotechnology Chemistry Physics People in science Higher education Electronics and electrical engineering Source Type: news
Soft magnetic materials for a sustainable and electrified world
Soft magnetic materials are key to the efficient operation of the next generation of power electronics and electrical machines (motors and generators). Many new materials have been introduced since Michael Faraday’s discovery of magnetic induction, when iron was the only option. However, as wide bandgap semiconductor devices become more common in both power electronics and motor controllers, there is an urgent need to further improve soft magnetic materials. These improvements will be necessary to realize the full potential in efficiency, size, weight, and power of high-frequency power electronics and high–rota...
Source: ScienceNOW - October 25, 2018 Category: Science Authors: Silveyra, J. M., Ferrara, E., Huber, D. L., Monson, T. C. Tags: Materials Science, Online Only review Source Type: news
Pushing the limits of electron ptychography
Source: ScienceNOW - October 25, 2018 Category: Science Authors: Lupini, A. R., Oxley, M. P., Kalinin, S. V. Tags: Materials Science, Physics perspective Source Type: news
Ethane/ethylene separation in a metal-organic framework with iron-peroxo sites
The separation of ethane from its corresponding ethylene is an important, challenging, and energy-intensive process in the chemical industry. Here we report a microporous metal-organic framework, iron(III) peroxide 2,5-dioxido-1,4-benzenedicarboxylate [Fe2(O2)(dobdc) (dobdc4–: 2,5-dioxido-1,4-benzenedicarboxylate)], with iron (Fe)–peroxo sites for the preferential binding of ethane over ethylene and thus highly selective separation of C2H6/C2H4. Neutron powder diffraction studies and theoretical calculations demonstrate the key role of Fe-peroxo sites for the recognition of ethane. The high performance of Fe2(O...
Source: ScienceNOW - October 25, 2018 Category: Science Authors: Li, L., Lin, R.-B., Krishna, R., Li, H., Xiang, S., Wu, H., Li, J., Zhou, W., Chen, B. Tags: Chemistry, Materials Science reports Source Type: news
Methylammonium-free, high-performance, and stable perovskite solar cells on a planar architecture
Currently, perovskite solar cells (PSCs) with high performances greater than 20% contain bromine (Br), causing a suboptimal bandgap, and the thermally unstable methylammonium (MA) molecule. Avoiding Br and especially MA can therefore result in more optimal bandgaps and stable perovskites. We show that inorganic cation tuning, using rubidium and cesium, enables highly crystalline formamidinium-based perovskites without Br or MA. On a conventional, planar device architecture, using polymeric interlayers at the electron- and hole-transporting interface, we demonstrate an efficiency of 20.35% (stabilized), one of the highest f...
Source: ScienceNOW - October 25, 2018 Category: Science Authors: Turren-Cruz, S.-H., Hagfeldt, A., Saliba, M. Tags: Materials Science, Physics reports Source Type: news
Hierarchically porous polymer coatings for highly efficient passive daytime radiative cooling
We present a simple, inexpensive, and scalable phase inversion–based method for fabricating hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene) [P(VdF-HFP)HP] coatings with excellent PDRC capability. High, substrate-independent hemispherical solar reflectances (0.96 ± 0.03) and long-wave infrared emittances (0.97 ± 0.02) allow for subambient temperature drops of ~6°C and cooling powers of ~96 watts per square meter (W m–2) under solar intensities of 890 and 750 W m–2, respectively. The performance equals or surpasses those of state-of-the-art PDRC designs, and the techni...
Source: ScienceNOW - October 18, 2018 Category: Science Authors: Mandal, J., Fu, Y., Overvig, A. C., Jia, M., Sun, K., Shi, N. N., Zhou, H., Xiao, X., Yu, N., Yang, Y. Tags: Physics, Applied, Materials Science reports Source Type: news
Aptamer-field-effect transistors overcome Debye length limitations for small-molecule sensing
Detection of analytes by means of field-effect transistors bearing ligand-specific receptors is fundamentally limited by the shielding created by the electrical double layer (the "Debye length" limitation). We detected small molecules under physiological high–ionic strength conditions by modifying printed ultrathin metal-oxide field-effect transistor arrays with deoxyribonucleotide aptamers selected to bind their targets adaptively. Target-induced conformational changes of negatively charged aptamer phosphodiester backbones in close proximity to semiconductor channels gated conductance in physiological buff...
Source: ScienceNOW - October 18, 2018 Category: Science Authors: Nakatsuka, N., Yang, K.-A., Abendroth, J. M., Cheung, K. M., Xu, X., Yang, H., Zhao, C., Zhu, B., Rim, Y. S., Yang, Y., Weiss, P. S., Stojanovic, M. N., Andrews, A. M. Tags: Chemistry, Materials Science reports Source Type: news
Latest Cornell dot features a new cancer weapon: Antibodies
(Cornell University) Ulrich Wiesner, the Spencer T. Olin Professor of Engineering in materials science and engineering at Cornell University, in collaboration with Dr. Michelle Bradbury of Memorial Sloan Kettering Cancer Center (MSKCC) and Weill Cornell Medicine, has proposed a novel approach to antibody-based imaging of cancer, using ultrasmall silica nanoparticles -- better known as 'Cornell dots' (or C dots) -- invented in his lab more than a dozen years ago. (Source: EurekAlert! - Cancer)
Source: EurekAlert! - Cancer - October 11, 2018 Category: Cancer & Oncology Source Type: news
Entropy-driven stability of chiral single-walled carbon nanotubes
Single-walled carbon nanotubes are hollow cylinders that can grow centimeters long via carbon incorporation at the interface with a catalyst. They display semiconducting or metallic characteristics, depending on their helicity, which is determined during their growth. To support the quest for a selective synthesis, we develop a thermodynamic model that relates the tube-catalyst interfacial energies, temperature, and the resulting tube chirality. We show that nanotubes can grow chiral because of the configurational entropy of their nanometer-sized edge, thus explaining experimentally observed temperature evolutions of chira...
Source: ScienceNOW - October 11, 2018 Category: Science Authors: Magnin, Y., Amara, H., Ducastelle, F., Loiseau, A., Bichara, C. Tags: Engineering, Materials Science reports Source Type: news
Key-and-lock commodity self-healing copolymers
We report that commodity copolymers, such as poly(methyl methacrylate)/n-butyl acrylate [p(MMA/nBA)] and their derivatives, can self-heal upon mechanical damage. This behavior occurs in a narrow compositional range for copolymer topologies that are preferentially alternating with a random component (alternating/random) and is attributed to favorable interchain van der Waals forces forming key-and-lock interchain junctions. The use of van der Waals forces instead of supramolecular or covalent rebonding or encapsulated reactants eliminates chemical and physical alterations and enables multiple recovery upon mechanical damage...
Source: ScienceNOW - October 11, 2018 Category: Science Authors: Urban, M. W., Davydovich, D., Yang, Y., Demir, T., Zhang, Y., Casabianca, L. Tags: Materials Science reports Source Type: news
Cross section: Mark Miodownik – Science Weekly podcast
What can a materials scientist learn from artists? How do you make robotic trousers? And what should we do about plastics?Hannah Devlin sits down with Mark Miodownik to find outAs a teenager,Mark Miodownik was stabbed with a razor blade, which penetrated his leather jacket, his school blazer and shirt before slicing his skin. The silver lining was that this harrowing event sparked a life-long fascination with materials science and engineering. A fascination that now sees him as Professor of Materials and Society, and director of theInstitute of Making at University College London.This week, Mark sits down in the studio wit...
Source: Guardian Unlimited Science - September 28, 2018 Category: Science Authors: Presented by Hannah Devlin and produced by Geoff Marsh Tags: Science Materials science Chemistry Physics Source Type: news
UCLA-led team develops new system for tracking chemicals in the brain
UCLA and Columbia University researchers have developed a new method for tracking the activities of small molecules in the brain, including the neurotransmitters serotonin and dopamine.“Understanding the fundamentals of how neurotransmission occurs will help us understand not only how our brains work, but what’s going on in psychiatric disorders,” said Anne Andrews, the study’s lead author, a UCLA professor of psychiatry and chemistry.The research, which was published in the journal Science, is part of the BRAIN Initiative, a collaboration among government, private industry, nonprofits, and colleges...
Source: UCLA Newsroom: Health Sciences - September 13, 2018 Category: Universities & Medical Training Source Type: news