The Surface of a PMP Hollow Fiber Membrane Was Modified with a Diamond-like Carbon Film to Enhance the Blood Compatibility of an Artificial Lung Membrane.

The contact between the blood and the surface of medical materials causes a series of rejection reactions. In this process, the plasma protein is adsorbed to the surface of materials within seconds and binds to glycoprotein receptors on platelets, causing platelet activation, coagulation cascade, and complement activation to form thrombus, which greatly limits the application of medical materials. In our work, the surface of poly(4-methyl-1-pentene) hollow fiber membranes (PMP HFMs) was coated with a diamond-like carbon (DLC) film by the ion plating method. The blood compatibility of the DLC coating was evaluated by protein adsorption, platelet adhesion, clotting time, red blood cell (RBCs) hemolysis, dynamic coagulation, and extracorporeal blood circulation tests. Compared with the unmodified PMP membrane, the DLC film could effectively reduce protein adsorption and platelet adhesion and prolong the coagulation time. The DLC coating showed BSA adsorption of as low as 0.53 µg/cm2 as well as a long activated partial thromboplastin time (APTT) value of 71.84 s. Furthermore, the PMP membrane modified with the DLC coating was used for extracorporeal blood circulation without thrombosis forming within 28 days. The DLC coating is one of the most promising medical coatings as an artificial lung membrane in extracorporeal membrane oxygenation (ECMO) equipment.

Multifunctional Superamphiphobic Coating Based on Fluorinated TiO2 toward Effective Anti-Corrosion.

The application of superamphiphobic coatings improves the surface's ability to repel fluids, thereby greatly enhancing its various functions, including anti-fouling, anti-corrosion, anti-icing, anti-bacterial, and self-cleaning properties. This maximizes the material's potential for industrial applications. This work utilized the agglomeration phenomenon exhibited by nano-spherical titanium dioxide (TiO2) particles to fabricate 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) modified TiO2 (TiO2@fluoroPOS) fillers with low surface energy. This was achieved through the in-situ formation of protective armor on the surface of the agglomerates using the sol-gel method and fluorination modification. Polyvinylidene fluoride-tetrafluoropropylene (PVDF-HFP) and TiO2@fluoroPOS fillers were combined using a spraying technique to prepare P/TiO2@fluoroPOS coatings with superamphiphobicity. Relying on the abundance of papillae, micropores, and other tiny spaces on the surface, the coating can capture a stable air film and reject a variety of liquids. When the coatings were immersed in solutions of 2 mol/L HCl, NaCl, and NaOH for a duration of 12 h, they retained their exceptional superamphiphobic properties. Owing to the combined influence of the armor structure and the organic binder, the coating exhibited good liquid repellency during water jetting and sandpaper abrasion tests. Furthermore, the coating has shown exceptional efficacy in terms of its ability to be anti-icing, anti-waxing, and self-cleaning.

Effect of TiC Content on Microstructure and Wear Performance of 17-4PH Stainless Steel Composites Manufactured by Indirect Metal 3D Printing.

In order to improve the performance of 17-4PH under wear conditions (e.g., gears, etc.) and reduce the cost of metal additive manufacturing, TiC needs to be added to 17-4PH to improve its wear resistance. Micron-sized TiC-reinforced 17-4PH stainless steel composites with different contents (0-15 wt%) have been prepared by fused filament fabrication 3D printing for the first time. The effects of TiC content on the structure and properties of composites were studied by XRD, SEM, and sliding wear. The obtained results show that the microstructure of TiC-reinforced 17-4PH stainless steel composites mainly consists of austenite. With the increase in TiC content, the grain size is obviously refined, and the average grain size decreases from 65.58 µm to 19.41 µm. The relative densities of the composites are maintained above 95% with the addition of TiC. The interfaces between TiC particles and the 17-4PH matrix are metallurgical bonds. The hardness of the composites increases and then decreases with increasing TiC content, and the maximum hardness (434 HV) is obtained after adding 10 wt.% of TiC content. The wear rate of the composites was reduced from 2.191 × 10-5 mm3 /(N‧m) to 0.509 × 10-5 mm3 /(N‧m), which is a 3.3-fold increase in wear resistance. The COF value declines with the addition of TiC. The reasons for the significant improvement in the composites' performance are fine grain strengthening, solid solution strengthening, and second phase strengthening. The wear mechanisms are mainly abrasive and adhesive wear. Compared to the 10 wt% TiC composites, the 15 wt% TiC composites show limited improvement in wear resistance due to more microcracks and TiC agglomeration.

Tribology Performance of Surface Texturing Plunger.

Plunger pumps are widely used in oil pumping units around the world. The water content of the wellbore is increasing along with the development progress, so the lubricating capacity of the well fluids between the plunger and barrel is decreasing correspondingly. Commonly, the substrate material of the plunger and barrel are stainless steel, and the plunger surface is usually covered with nickel-based coating. Therefore, the performance of the plunger and barrel has been affected due to poor lubrication and eccentric wear. Non-smooth surfaces have been proven to improve the tribology performance in many cases. A surface texturing plunger covered with specific dimples has been prepared by using laser surface texturing technology. The morphology of the surface texturing plunger was characterized and analyzed. The tribology performance of surface texturing plunger samples was tested using standard friction and wear test machines with oil and water lubrication, respectively. The results indicated that surface texturing could effectively reduce the coefficient of friction, and the wear resistance of the surface textured samples has been improved to some extent.

Comparison of oxidation resistance of UHMWPE and POM in H2O2 solution from ReaxFF reactive molecular dynamics simulations.

The oxidation mechanism of ultra-high-molecular-weight polyethylene (UHMWPE) and polyoxymethylene (POM) in hydrogen peroxide solution was investigated by molecular dynamics (MD) simulations via reactive force field (ReaxFF) method. MD results from ReaxFF suggested that UHMWPE provided better antioxidation activity at high temperature (>373 K) than its POM counterpart in the same concentration of hydrogen peroxide solution. Furthermore, POM was relatively more susceptible to erosion and swelling because of the infiltration of H2O2 solution. Calculations of the diffusion coefficient at different temperatures permit further understanding of the chemical phenomena involved in the level of oxidation in the course of MD simulations. Results of the simulations are generally consistent with the previous experimental available in literature. The simulations also provide new insights into understanding the mechanism resulting oxidation products among the interested polymers.