Low-Temperature Adaptive Dual-Network MXene Nanocomposite Hydrogel as Flexible Wearable Strain Sensors.

Flexible electronic devices and conductive materials can be used as wearable sensors to detect human motions. However, the existing hydrogels generally have problems of weak tensile capacity, insufficient durability, and being easy to freeze at low temperatures, which greatly affect their application in the field of wearable devices. In this paper, glycerol was partially replaced by water as the solvent, agar was thermally dissolved to initiate acrylamide polymerization, and MXene was used as a conductive filler and initiator promoter to form the double network MXene-PAM/Agar organic hydrogel. The presence of MXene makes the hydrogel produce more conductive paths and enforces the hydrogel's higher conductivity (1.02 S·m-1). The mechanical properties of hydrogels were enhanced by the double network structure, and the hydrogel had high stretchability (1300%). In addition, the hydrogel-based wearable strain sensor exhibited good sensitivity over a wide strain range (GF = 2.99, 0-200% strain). The strain sensor based on MXene-PAM/Agar hydrogel was capable of real-time monitoring of human movement signals such as fingers, wrists, arms, etc. and could maintain good working conditions even in cold environments (-26 °C). Hence, we are of the opinion that delving into this hydrogel holds the potential to broaden the scope of utilizing conductive hydrogels as flexible and wearable strain sensors, especially in chilly environments.

Synthesis of γ Phase and Amorphous Solid Dispersion of Glycine from α-Glycine During the Solvent-Free Ball Milling Process.

Nano α-glycine crystals, γ-glycine crystals, and amorphous solid dispersion (ASD) of glycine were prepared through solvent-free ball milling of commercial α-glycine. The solid-state polymorph conversion of glycine from α to γ was completely realized by ball milling with 0.2 wt.% NaCl for 1 h or by ball milling with 0.02 wt.% NaCl for 1 h with subsequent storage for one week. The ASD of glycine was prepared by ball milling α-glycine with an equal amount of CaCl2 for 1 h. We studied the effect of inorganic salt types and their concentrations on the extent of polymorph conversion and amorphization of glycine in our experiments. This solvent-free ball milling method could be used for the synthesis of polymorphs and amorphous phase of drugs and other organic materials.

A study of composition effects on the bandgaps in a series of new alkali metal aluminum/gallium iodates.

Four new alkali metal aluminum/gallium iodates, namely A2M(IO3)4(H0.5IO3)2 (A = K, Rb and M = Al, Ga), have been successfully synthesized via a hydrothermal reaction and structurally characterized through single-crystal X-ray diffraction analysis. These compounds are isostructural and crystallize in the P1[combining macron] space group (no. 2) with one formula unit in each unit cell. The rare half-protonated H0.5IO3 building units were identified, and their structure feature isolated [M(IO3)4(H0.5IO3)2]2- anions, which are separated by alkali metal cations. The optical diffuse reflectance spectroscopy measurements associated with the Tauc analysis showed direct energy gaps, which are in good agreement with the theoretical calculation prediction. Moreover, this study also indicates that the electronic properties of these compounds are mainly determined by the IO3 and H0.5IO3 anionic units, and the alkali metal cations show a remarkable effect on their energy gap values, whereas the impacts of the group 13 elements aluminum and gallium are insignificant.