Phys.org July 21, 2023 MOFs which possess a high degree of crystallinity and a large surface area with tunable inorganic nodes and organic linkers. The adsorption in MOFs changes the crystalline structure and elastic moduli. Thus, the coexistence of adsorbed/desorbed sites makes the host matrices elastically heterogeneous. To show the asymmetric role of elastic heterogeneity in the adsorption–desorption transition researchers in Japan constructed a minimal model incorporating adsorption-induced lattice expansion/contraction and an increase/decrease in the elastic moduli. They found that the transition was hindered by the entropic and energetic effects which become asymmetric in the adsorption process and desorption process, […]
Tag Archives: Soft materials
Better understanding soft material behavior
Science Daily May 1, 2023 The direct connections between the macroscopic flow/deformation and microscopic structure or dynamics has not been determined. An international team of researchers (USA – University of Illinois, Argonne National Laboratory, South Korea, Canada) They probed the microstructural yielding dynamics of a concentrated colloidal system by performing creep/recovery tests with simultaneous collection of coherent scattering data via X-ray Photon Correlation Spectroscopy (XPCS). This combination of rheology and scattering allowed for time-resolved observations of the microstructural dynamics as yielding occurred, which could be linked back to the applied rheological deformation to form structure–property relations. Under sufficiently small, applied […]
Soft semiconductors that stretch like human skin can detect ultra-low light levels
Science Daily December 15, 2021 An international team of researchers (USA – Georgia Institute of Technology, Chile) has demonstrated a new level of stretchability for a photodetector made from a synthetic polymer and an elastomer that absorbs light to produce an electrical current. It is up to 200% more stretchable than its original dimension without significantly losing its electric current. They found the right combination of chemical compounds to produce a super-soft material with the ability to generate and conduct electricity when exposed to light and the right ratio for all parts of the semiconductor layer to maintain high performance […]
Liquid crystals for fast switching devices
Phys.org December 6, 2021 In some liquid crystals the molecules self-assemble into helical structures which are characterized by pitch. Pitch determines how quickly they react to an applied electric field. An international team of researchers (Germany, Czech Republic, Russia) investigated a liquid crystalline cholesteric compound called EZL10/10 which had only one chiral center and it was only104 nanometres. Further analysis showed that in this material the cholesteric spirals form domains with characteristic lengths of about five pitches. According to the researchers the short pitch makes the material unique and promising for optoelectronic devices with very fast switching times, and the […]
Polymer that folds and unfolds under UV radiation
Phys.com November 30, 2021 An international team of researchers (Japan, Switzerland, UK) built the supramolecular polymer from monomers that formed six-membered rosettes stacked on top of one another to give an infinitely long chain. An intrinsic curvature generated along the stacked rosettes caused the nanofibers to twist up and fold into a helical structure. The folding could be removed by triggering a “light switch”. UV-light irradiation caused the monomer to bend, forming a kink in the molecule, reducing the rotation of the rosette, and unfolding the helical structure. A second switch which works using temperature prevented the entire polymer from […]
‘Super jelly’ can survive being run over by a car (with Video)
Phys.org November 25, 2021 The way materials behave is dependent upon the way molecules are joined by crosslinkers. Researchers in the UK used barrel-shaped molecules called cucurbiturils as crosslinking molecule, like molecular handcuff, which hold two guest molecules that prefer to stay inside the cavity for longer than normal keeping the polymer network tightly linked, allowing for it to withstand compression even at 80% water content. They found that the compressive strength could be easily controlled by simply changing the chemical structure of the guest molecule inside the cavity. To make their glass-like hydrogels, the team chose specific guest molecules […]