National Research Tomsk State University

Metal-organic frameworks (MOFs) are of great interest for application in sorption, catalysis, and other fields due to their unique properties and the possibility of wide variation of their structures and functional characteristics. However, the use of MOFs is limited by their powder form and difficulty of molding. Therefore, it is necessary to develop ways for additional stabilization of MOFs, in particular on the surface of primary substrates. Here we studied the formation of copper-containing metal-organic framework HKUST-1 in the structure of cotton and polyethylene terephthalate fabrics using three approaches differing in the way of introduction of copper ion precursor into the reaction mixture. Pre-impregnation of the fabrics with a solution of a metal ion precursor salt followed by assembly of MOF in an aqueous ethanol solution of trimesic acid was shown to be the optimal approach for the self-assembly of HKUST-1 on the surface of cotton and polyethylene terephthalate fabrics. The specific surface area and HKUST-1 contents in the obtained materials were 198–259 m2/g and 12–15.8 wt

The water vapor sorption and desorption kinetics of the cucurbit[n]uril (CB[n]) homologues (n = 5–8) were investigated. Kinetic analysis revealed that the water uptake capacity varies as a function of cavity size with CB[5], CB[6], CB[7] and CB[8] exhibiting sorption of 8, 12, 18 and 17 mol H2O per mol of host, respectively. The corresponding sorption equilibria were attained over 270, 320, 210 and 300 min, while complete desorption required 270, 390, 450 and 400 min, respectively. Experimentally derived rate constants for sorption (ksorp) and desorption (kdes) were determined as follows: CB[5] ksorp = 0.0172 min− 1, kdes = 0.0101 min− 1; CB[6] ksorp = 0.013 min− 1, kdes = 0.0047 min− 1; CB[7] ksorp = 0.0195 min− 1, kdes = 0.039 min− 1; CB[8] ksorp = 0.0129 min− 1, kdes = 0.0063 min− 1. Notably, the highest sorption rate constants were observed for CB [5] and CB [7], which also demonstrate comparatively greater aqueous solubility, suggesting a possible correlation between hydration affinity and solubility behavior.

Synthesis, printing, and sintering processes of W–Cu composite materials produced by additive manufacturing were investigated in an integrated manner. A W–Cu powder obtained by electrical explosion of wire, providing high purity and particle uniformity, was used as the starting material. To prepare the feedstock, the powder was mixed with a polymer binder, and extrusion parameters, including temperature, feed rate, and pressure, were optimized to minimize porosity in printed samples. Particular attention was given to the rheological properties of the feedstock, which strongly influence print quality. Debinding and sintering were carried out in a reducing Ar–H2 atmosphere to prevent oxidation of the components. Sintering at 1050–1100°C results in high material density with a uniform distribution of tungsten particles in the copper matrix. Mechanical testing shows that the microhardness of the samples is 144 ± 16 HV and the flexural strength reaches 320 ± 12 MPa. Anisotropy of tribological properties is observed due to the orientation of layers during printing, which must be taken into account in design. The results demonstrate the potential of additive manufacturing for producing W–Cu composites with tailored properties, opening prospects for applications in electronics, aerospace, and other high-technology fields. Further work may focus on optimization of feedstock composition and investigation of the effect of post-processing on functional properties.

The influence of low-pressure (LP) air plasma treatment on the surface morphology of aramid fibers (AFs) in Kevlar fabric and on the physicomechanical properties of laminated composites with a polyphenylene sulfide matrix reinforced with this fabric has been investigated. The change in the AF surface morphology (increase in roughness) is most pronounced after LP plasma treatment for 30 min. Energy dispersive X-ray spectroscopy data are used to discuss the probability of chemical modification of the AF surface as a result of LP plasma treatment, namely, the introduction of –OH and –COOH functional groups, which additionally improves the interlaminar adhesion. After LP plasma treatment for 30 min, the interlaminar shear strength of the laminated composites is 30.2 MPa, which is 55

Precise structural design is vital for advancing high-performance birefringent crystals used in mid-infrared polarizing devices. Mixed anion systems, particularly chalcohalides, present a promising avenue by synergistically combining the broad infrared transparency of chalcogenides with the band gap-widening capability conferred by halide ions. Guided by this approach, a novel chalcohalide birefringent crystal, Ba4CdGa2S6F4, was successfully designed and synthesized by the cation and anion cosubstitution strategy. This compound was derived from the parent phase Ba5Ga2S8 by partially replacing one Ba2+ cation with one Cd2+ cation and two S2- anions with four F- anions. Optical characterization via the UV-vis-NIR diffuse reflectance measurement reveals that Ba4CdGa2S6F4 exhibits a large optical band gap of 3.78 eV. And the broad infrared transparency of Ba4CdGa2S6F4 is confirmed for the material via both Raman and Fourier transform IR spectroscopy. First-principles calculations indicate that Ba4CdGa2S6F4 has moderate birefringence with a value of 0.057 at 1064 nm, representing a 26.6% increase over the parent compound Ba5Ga2S8. This work not only reports a promising infrared birefringent crystal with large band gap but also demonstrates that the cation and anion cosubstitution is an effective strategy for designing novel functional crystalline materials.