This study deals with the impact of a microgel particle-laden drop of the water–agar solution onto nanofiber mats of different wettability at Weber numbers in the range of 14–502 and initial velocities in the range of 0.32–1.83 m/s. We examined the effects of inertia and the competition between the wetting and antiwetting pressures within the liquid impalement on the hydrodynamic behavior of drops in the spreading and contraction phases. Hydrophilic mat representing a full water absorption coating is manufactured by electrospinning from a mixture of polycaprolactone and polyvinylpyrrolidone; hydrophobic—from polytetrafluoroethylene. The micro- and nanoscale characteristics of nanofiber mats are analyzed by scanning electron microscopy and atomic force microscopy, respectively. A physical model of liquid flow under an impacting microgel particle-laden drop along and inside the micro- and nanostructures of nanofiber mats is proposed. Empirical expressions for the prediction of drop impact hydrodynamics are derived. By introducing the impalement factor, which is physically close to the Euler number, they take into account the difference between wetting and anti-wetting pressures in addition to inertia. Microgel particle-laden drop deposition accounting for the effect of liquid impalement inside nanofiber materials with different wettability is expected to enhance the efficiency of bioprinting polymer layers in tissue engineering.

Electrospun poly(ε-caprolactone) (PCL)-based scaffolds are widely used in tissue engineering. However, low cell adhesion remains the key drawback of PCL scaffolds. It is well known that nitrogen-doped diamond-like carbon (N-DLC) coatings deposited on the surface of various implants are able to enhance their biocompatibility and functional properties. Herein, we report the utilization of the pulsed vacuum arc deposition (PVAD) technique for the fabrication of thin N-DLC coatings on the surface of electrospun PCL scaffolds. The effect of N-DLC coating deposition under various nitrogen pressures on the morphological, mechanical, physico-chemical, and biological properties of PCL scaffolds was investigated. It was established that an increase in nitrogen pressure in the range from 5 × 10⁻³ to 5 × 10⁻¹ Pa results in up to a 10-fold increase in the nitrogen content and a 2-fold increase in the roughness of the PCL fiber surface. These factors provided the conditions for the enhanced adhesion and proliferation of human mesenchymal stem cells (MMSCs) on the surface of the modified PCL scaffolds. Importantly, the preservation of N-DLC coating properties determines the shelf life of a coated medical device. The elemental composition, tensile strength, and surface human MMSC adhesion were studied immediately after fabrication and after 6 months of storage under normal conditions. The enhanced MMSC adhesion was preserved after 6 months of storage of the modified PCL-based scaffolds under normal conditions.

Electrospray is a promising method for fabricating semipermeable polytetrafluoroethylene (PTFE) membranes. PTFE membranes are attractive for filtration and separation in harsh environments, but their mechanical properties depend strongly on crystallinity and thermal history. In this work, PTFE/poly(ethylene oxide) (PEO) membranes were fabricated by electrospraying aqueous solutions with PTFE/PEO ratios of 98.8/1.2, 97.5/2.5, 95/5, and 90/10 wt.%. Increasing the PEO content increased the solution viscosity from 43–78 to 124 mPa·s and caused a transition from sphere-based to mixed fiber–sphere morphology. After sintering at 330 °C, PEO was completely removed and the membrane architecture was preserved. Annealing (slow cooling) produced a more developed folded surface, higher crystallinity, and greater shrinkage, whereas quenching (rapid cooling) retained a less ordered structure, lower shrinkage, and generally higher tensile strength and relative elongation. The highest tensile strength (4.12 ± 0.25 MPa) was obtained for the quenched 97.5/2.5 wt.% membrane, and the highest relative elongation (259 ± 16%) for the quenched 90/10 wt.% membrane. Exposure to nitric acid, potassium hydroxide, dimethyl sulfoxide, motor oil, and distilled water at 100 °C for 48 h caused no statistically significant changes in tensile strength or relative elongation. These results demonstrate that electrosprayed PTFE membranes offer tunable morphology and mechanical properties together with high chemical resistance, making them promising for aggressive-media filtration and separation.

Electrospray is a promising method for fabricating semipermeable polytetrafluoroeth-ylene (PTFE) membranes. These membranes exhibit high hydrophobicity and a large specific surface area. They can be used in various sectors, including the chemical and energy industries, aerospace, and microelectronics manufacturing. In this study, we investigated the effect of different spray solution compositions, heat treatment re-gimes, and exposure to various media on the physicochemical properties of these membranes. We used scanning electron microscopy to determine the optimal range of spray solution compositions for electrospraying. We found that quenching the mem-branes after electrospraying reduced shrinkage, increased tensile strength, and in-creased relative elongation. This was attributed to a decrease in the degree of crystal-linity in the quenched membranes. We also investigated the effects of various aggres-sive media, including concentrated acids, alkalis, organic solvents, and mineral oil, on the tensile strength and relative elongation of the membranes. No significant changes in tensile strength or relative elongation were observed after immersion for 48 h at 100 °C, indicating the high chemical stability and operational reliability of the elec-trosprayed PTFE membranes.