Dynamic Ionic Crosslinking Polypropylene-based Elastomers with Excellent Mechanical Properties and Antibacterial Performance

It is still challenging in obtaining an insulation material with high thermal conductivity and excellent mechanical properties, while suppressing the distribution of space charges. In this article, exfoliated hexagonal boron nitride nanosheets (BNNS) were introduced into low-density polyethylene (LDPE) to optimize the electrical, thermal and mechanical properties of LDPE-based composites. The results show that the obtained LDPE/BNNS composites possess enhanced thermal conductivity, suppressed space charge distribution, higher breakdown strength and excellent mechanical properties. The nanoscale interfaces (about 2.0 nm) between BNNS and LDPE in the composites are detected by small angle X-ray scattering (SAXS) technique and in-situ SAXS is employed to investigate the variation of interface during stretching process. Acquired information suggests that the strong interface interaction is beneficial to suppressing space charge distribution, enhancing breakdown strength and improving mechanical properties of the composites except increasing interface thermal resistance. This work would provide a candidate insulation material and present a new recognition of the role of interface in enhancing the properties of LDPE-based composites.

Fabrication of high strength-ductility aluminum alloy heterogeneous plates using additive manufacturing and hot rolling process

Titanium alloys such as Ti-6Al-4V are widely used in biomedical implants due to their excellent mechanical properties and biocompatibility, but their bioinert nature limits osseointegration and antibacterial performance. This study proposes a multifunctional surface coating system integrating a thermally oxidized TiO2 interlayer with a hydroxyapatite (HAp) top layer synthesized via a green route using Hylocereus undatus extract. The HAp was deposited by electrophoretic deposition (EPD), enabling continuous coverage and strong adhesion to the pre-treated Ti-6Al-4V substrate. Structural, morphological, chemical, and electrical characterizations were performed using XRD, SEM, EDS, Raman spectroscopy, and impedance spectroscopy. Bioactivity was assessed through apatite formation in simulated body fluid (SBF), while antibacterial properties were evaluated against Staphylococcus aureus. The results demonstrated successful formation of crystalline TiO2 (rutile phase) and calcium-rich HAp with good surface coverage. The HAp-coated surfaces exhibited significantly enhanced bioactivity and strong antibacterial performance, likely due to the combined effects of surface roughness and the bioactive compounds present in the plant extract. This study highlights the potential of eco-friendly, bio-inspired surface engineering to improve the biological performance of titanium-based implants.

Effect of different sintering additives type on Vat photopolymerization 3D printing of Al2O3 ceramics

Cytocompatible chitosan based multi-network hydrogels with antimicrobial, cell anti-adhesive and mechanical properties

In order to develop a promising bio-applicable body-centered-cubic multi-principal element alloy (BCC MPEA) with excellent mechanical and biological properties, Tantalum (Ta) was introduced into TiNbZr alloy based on lattice distortion design, and heterogeneous structure was subsequently constructed. The widespread hetero-structured interfaces alter planar slip mode in recrystallized grains (RGs) via emission and multiplication of geometrically necessary dislocations (GNDs), which generate significant heterogeneous deformation induced (HDI) stress effect. Plentiful subgrains and nano-sized dislocation cells in unrecrystallized grains (UGs, i.e., textures) enable extensive dislocation behavior including annihilation, activation and interaction, effectively alleviating stress concentration in RGs and strain gradient across the interfaces. This process results in an optimal balance of yield strength reaching 925.2MPa and fracture elongation of 26.1%. In vitro experiments demonstrate that TiNbZr0.7Ta0.3 alloy exhibits enhanced cell adhesion, proliferation and osteogenic response compared to TC4 alloy. The remarkable mechanical properties and biocompatibility render it a highly promising candidate for orthopedic implants. This study provides new insights for the design and optimization of biomedical MPEAs with excellent mechanical properties.

Materials with excellent comprehensive mechanical properties (e.g., strength and toughness, stiffness and damping, fatigue etal.) are highly desirable for engineering applications, while it is still challenged for design. Tooth enamel is a typical biomaterial with outstanding mechanical properties that originate from its multiscale and gradient structure. Some composites with enamel-like multiscale structures are successfully synthesized, but mimicking the gradient structure of tooth enamel is still difficult to realize. Here, an enamel analog is fabricated with a gradient structure similar to inner enamel based on the crisscross assembly of aligned hybrid nanowires through a magnetic-assisted freeze casting and subsequent mechanical compression strategy. The gradient enamel-mimetic composites exhibited high strength and toughness surpassing the natural tooth enamel, and simultaneously high stiffness and damping comparable to those of enamel, as well as high fatigue resistance. The interface reinforcement of gradient structure, crystal/amorphous and organic/inorganic, fundamentally accounted for high mechanical performance. The gradient design strategy provides an avenue for the engineering of structural materials with excellent mechanical properties.

Wearable flexible sensors based on dual-network ionic hydrogels with xanthan gum/sodium alginate/polyacrylamide/gallium indium alloy.

Hydrogels with excellent flexibility, conductivity, and controllable mechanical properties are the current research hotspots in the field of biomaterial sensors. However, it is difficult for hydrogel sensors to regain their original function after being damaged, which limits their practical applications. Herein, a composite hydrogel (named SPBC) of poly(vinyl alcohol) (PVA)/sodium alginate (SA)/cellulose nanofibers (CNFs)/sodium borate tetrahydrate was synthesized, which has good self-healing, electrical conductivity, and excellent mechanical properties. The SPBC0.3 hydrogel demonstrates rapid self-healing (<30 s) and achieves mechanical properties of 33.92 kPa. Additionally, it exhibits high tensile strain performance (4000%). The abundant internal ions and functional groups of SPBC hydrogels provide support for the good electrical conductivity (0.62 S/cm) and electrical response properties. In addition, the SPBC hydrogel can be attached to surfaces such as fingers and wrists to monitor human movements in real time, and its good rheological property supports three-dimensional (3D) printing molding methods. In summary, this study successfully prepared a self-healing, conductive, printable, and mechanically superior SPBC hydrogel. Its suitability for 3D-printing personalized fabrication and outstanding sensor properties makes it a useful reference for hydrogels in wearable devices and human motion monitoring.

Aerogels emerge as captivating contenders within the realm of high-temperature thermal resistance and thermal insulation. Nevertheless, their practical applications are usually constrained by their inherent brittleness when subjected to rigorous conditions. Herein, employing hafnium dichloride oxide octahydrate (HfOCl2·8H2O) as the hafnium source and resorcinol-formaldehyde (RF) as the carbon precursor, hafnium carbide (HfC) aerogels are fabricated via the sol-gel method complemented with carbothermal reduction reaction. Investigations are conducted into the effects of various molar ratios, duration, and temperatures of calcination on the microstructural features and physico-chemical characteristics of the as-prepared HfC aerogel. The aerogel shows a high BET-specific surface area (601.02 m2/g), which is much larger than those of previously reported aerogels. Furthermore, the HfC aerogel exhibits a low thermal conductivity of 0.053 W/(m·K) and a compressive strength of up to 6.12 MPa after carbothermal reduction at 1500 °C. These excellent thermal insulation and mechanical properties ensure it is ideal for the utilization of high-temperature thermal resistance and thermal insulation in the fields of aerospace.

Monodomain liquid crystal elastomer bionic muscle fibers with excellent mechanical and actuation properties

Synthesis and thermal degradation mechanism of a semi-aromatic copolyamide from renewable sources

Polymer matrix composites with lightweight, low dielectric constant (ε) and dielectric loss tangent (tan δ), high‐temperature resistance, and excellent mechanical properties are urgently needed in the fields of aviation, aerospace, transportation, and wireless communication services. In this work, 3D woven spacer Kevlar/polyimide composites (3DKPC) with excellent dielectric properties and robust mechanical properties were designed and obtained by combining 3D weaving technology and thermal imidization process. Results show that the volume density of the prepared composites is as low as 0.24 g·cm −3 , but its compressive strength can be up to 6.24 MPa. The dielectric constant and loss tangent of 3DKPC at room temperature are extremely low, with the value of ~1.32 and 6.9 × 10 −3 , respectively. Moreover, the compressive strength retention rate is more than 96% and the dielectric constant can be consistently lower than 1.36 when the temperature increases from 25 to 300°C, demonstrating the outstanding mechanical and dielectric stability of 3DKPC. In addition, as an application example of resulting composites, a microstrip antenna with 3DKPC as the substrate material was designed, followed by the simulation of its electromagnetic properties via High Frequency Structural Simulator. The results display that the gain of the microstrip antenna is 6.2 dB, which is superior to those of many other reported microstrip antennas, indicating that the 3DKPC proposed here has great application potential in aerospace, wireless communication, and other fields.

A new pseudo binary strategy to design eutectic high entropy alloys using mixing enthalpy and valence electron concentration

Polyurea-crosslinked cationic acrylate copolymer for antibacterial coating