Phys.org September 11, 2023 Radical type mechanophores (RMs), molecules that can undergo small-scale chemical reactions upon exposure to a mechanical stimulus are studied due to their potential application in the fabrication of highly functionalized polymers. However, the lack of a rational design concept with pre-determined properties limits their development. Researchers in Japan have developed a rational design strategy of RMs with high thermal tolerance while maintaining mechanoresponsiveness. Through experimental and theoretical analysis, they found that the high thermal tolerance of RMs is related to the radical-stabilization energy (RSE) as well as the Hammett and modified Swain–Lupton constants at the para-position. […]
Tag Archives: Advanced materials
Revolutionizing lithium production on a string
Science Daily September 7, 2023 A team of researchers in the US (Princeton University, University of Maryland) has developed an efficient and self-concentrating crystallization method for the selective extraction of lithium from both brine and seawater. The sequential and separable crystallization of cation species with different concentrations and solubilities was enabled by a twisted and slender 3D porous natural cellulose fibre structure via capillary and evaporative flows. The process exhibited an evaporation rate as high as 9.8 kg m−2 h−1, and it selectively concentrated lithium by orders of magnitude. They characterized the composition and spatial distribution of crystals, and a transport model deciphered […]
Growing triple-decker hybrid crystals for lasers
Phys.org August 31, 2023 Although two-dimensional organic semiconductor-incorporated perovskites are a promising family of hybrid materials for optoelectronic applications, tuning their structures and specific properties has remained challenging. By choosing the right solvent a team of researchers in the US (Purdue University, Duke University, Lawrence Berkeley National Laboratory) has developed a general method to tune the dimensionality of phase-pure organic semiconductor-incorporated perovskite single crystals during their synthesis. They showed that the length of the conjugated semiconducting organic cations and the dimensionality of the inorganic layers could be manipulated at the same time. The energy band offsets and exciton dynamics at […]
Nano-thin ‘liquid-like’ coatings may pave the way for a ‘self-cleaning’ world
Nanowerk August 17, 2023 Slippery covalently attached liquid surfaces (SCALS) with low contact angle hysteresis (CAH) and nanoscale thickness display impressive anti-adhesive properties, like lubricant-infused surfaces. Their efficacy is generally attributed to the liquid-like mobility of the constituent tethered chains. However, the precise physico-chemical properties that facilitate this mobility are unknown. An international team of researchers (Australia, Germany) quantified the chain length, grafting density, and microviscosity of a range of polydimethylsiloxane (PDMS) SCALS, elucidating the nanostructure responsible for their properties. They used three methods to produce SCALS, with characterization carried out via single-molecule force measurements, neutron reflectometry, and fluorescence correlation […]
Chromium replaces rare and expensive noble metals
Science Daily August 14, 2023 Researchers in Switzerland developed chromium compounds, very similar to those used in the past, that can replace the noble metals osmium and ruthenium. When irradiated with a red lamp the new chromium compounds the energy from the light could be stored in molecules which could serve as power source. They demonstrated it by building the chromium compounds into a stiff organic molecular framework consisting of carbon, nitrogen, and hydrogen. The stiff framework ensured that the chromium atoms were well packaged. The tailor-made environment minimized energy losses due to undesired molecular vibrations and to optimize the […]
New method simplifies the construction process for complex materials
MIT News August 2, 2023 Cellular metamaterials are small scale, tileable structures that can be architected to exhibit many useful material properties. But their “architectures” vary widely making it difficult to explore them using existing representations. An international team of researchers (USA – MIT, Austria) created a technique to include many different building blocks of cellular metamaterials into one, unified graph-based representation using which engineers can quickly and easily model metamaterials, edit the structures, and simulate their properties. Their procedural graph succinctly represents the construction process for any structure using a simple skeleton annotated with spatially varying thickness. To express […]
Extraordinarily strong, lightweight material combines DNA and glass
Nanowerk July 25, 2023 Continuous nanolattices are an emerging class of mechanical metamaterials that are highly attractive due to their superior strength-to-weight ratios, which originate from their spatial architectures and nanoscale-sized elements possessing near-theoretical strength. Rational design of frameworks remains challenging below 50 nm because of limited methods to arrange small elements into complex architectures. A team of researchers in the US (Columbia University, Brookhaven National Laboratory, University of Connecticut) fabricated silica frameworks with ∼4- to 20-nm-thick elements using self-assembly and silica templating of DNA origami nanolattices and performed in situ micro-compression testing to examine the mechanical properties. They observed […]
Self-healing plastic becomes biodegradable
Science Daily July 27, 2023 Mineral plastics are a promising class of bio-inspired materials that have properties, like self-heal ability, stretchability, hardness, and non-flammability, they can be reshaped easily. However, current mineral plastics are hardly biodegradable, and thus persistent in nature. Researchers in Germany have developed the next generation of mineral plastics, which are bio-based and biodegradable. Physically cross-linked (poly)glutamic-acid (PGlu)-based mineral plastics using various alcohol-water mixtures, metal ion ratios and molecular weights. The rheological properties were easily adjusted using these parameters. The general procedure involved addition of equimolar solution of CaCl2 to PGlu in equal volumes followed by addition […]
Some alloys don’t change size when heated, and we now know why
Phys.org July 31, 2023 The low thermal expansion of Fe–Ni Invar has long been associated with magnetism, but to date, the microscopic underpinnings of the Invar behaviour have eluded both theory and experiment. An international team of researchers (USA – Caltech, Boston College, Argonne National Laboratory, Israel) applied thermodynamic Maxwell relation to nuclear resonant X-ray scattering measurements of the phonon and magnetic entropies under pressure to obtain the separate phonon and magnetic contributions to thermal expansion. They found that the Invar behaviour stems from a competition between phonons and spins. In particular, the phonon contribution to thermal expansion cancelled the […]
Intelligent rubber materials
Nanowerk July 18, 2023 Researchers in Germany have developed intelligent humidity-programmed hydrogel patches with high stretchability and tunable water-uptake and -release by copolymerization and crosslinking of N-isopropylacrylamide and oligo(ethylene glycol) comonomers. The intelligent elastomeric patches strongly responded to different humidities and temperatures in terms of mechanical properties which made them applicable for soft robotics and smart skin applications where autonomous adaption to environmental conditions was a key requirement. Beyond using the hydrogel in the conventional state in aqueous media, the new patches could be controlled by relative humidity. The humidity programming of the patches allowed to tune drug release kinetics, […]