Bulletin of Materials Science最新文献

Polymer electrolytes are increasingly recognized for their potential in energy storage applications such as batteries and supercapacitors, owing to their mechanical flexibility, thermal stability, and safety advantages over liquid counterparts. This study explores a nanocomposite polymer electrolyte system based on chitosan (CS), methyl cellulose (MC), sorbitol, TiO₂ nanoparticles, and ammonium trifluoromethanesulfonate (NH₄CF₃SO₃), with glycerol added at varying concentrations (9–45 wt.%) to enhance ion mobility. Five samples (EX1–EX5) were fabricated via solution casting and systematically analyzed. XRD revealed a semicrystalline structure with crystallinity decreasing from 31.84% to 23.38% as glycerol content increased, indicating enhanced amorphous character. FTIR spectra confirmed strong hydrogen bonding and polymer–plasticizer interactions, while EIS measurements showed a sharp reduction in bulk resistance from 16.55 kΩ (EX1) to 182 Ω (EX5), resulting in a conductivity increase from 0.209 µS cm⁻¹ to 27.11 µS cm⁻¹, an over 129-fold improvement. AC conductivity and dielectric analyses demonstrated increased permittivity and reduced relaxation times, reflecting faster ion dynamics and improved segmental mobility. Electrical modulus studies further supported enhanced local ionic transport and reduced dielectric relaxation time. These results underscore the effectiveness of glycerol as a plasticizer in promoting ion transport and optimizing electrochemical performance in CS–MC-based polymer electrolytes for advanced energy storage technologies.

Gelatin methacrylamide (GelMA) is a widely used bioink for three-dimensional (3D) bioprinting owing to its tunable mechanical properties and excellent biocompatibility. Sterilization is an essential terminal step in both biomedical device manufacturing and the preparation of bioinks for 3D bioprinting. Ethylene oxide (EtO) sterilization is a widely used method for sterilizing medical devices. However, its effects on biomaterials such as GelMA must be evaluated to ensure effective sterilization while preserving the physicochemical properties required for bioink performance. In this study, the effects of EtO sterilization at two temperatures (37 °C and 55 °C) on a GelMA bioink containing an antioxidant (GelMA-AO) were investigated with respect to its structural integrity, crosslinking efficiency, and three-dimensional (3D) printability. Changes in chemical functional groups, rheological properties, printability, crosslinking efficiency, compressive strength, and cytotoxicity were evaluated before and after EtO sterilization. The rheological analysis showed that sterilization at 55 °C altered the viscosity of the GelMA-AO formulation. In contrast, sterilization at 37 °C preserved the chemical, rheological, and mechanical properties of the GelMA-AO bioink while ensuring sterility and non-cytotoxicity. These findings demonstrate the importance of carefully optimizing EtO sterilization conditions to maintain the performance and functionality of GelMA-based bioink formulations for 3D bioprinting applications.

Praseodymium selenide nanoparticles (NPs) were fabricated via two hydrothermal approaches: in situ β-cyclodextrin citrate incorporation (method 1) and post-synthesis coating (method 2). X-ray diffraction confirmed tetragonal crystallinity, while transmission electron microscopy revealed rod-like particles averaging 13±5 nm in length (width≈5±2 nm) in method 1 and 425±50 nm in length (width≈59±10 nm) in method 2. Infrared, X-ray photoelectron and thermogravimetric analyses verified successful surface functionalization, with organic contents of ~38% (method 1) and ~32% (method 2). Both systems achieved high 5-fluorouracil (5-FU) encapsulation efficiencies (90% and 88%, respectively) and pH-responsive release, with >90% drug liberation under mildly acidic conditions within 48 h. Cytotoxicity assays against MCF-7 breast cancer cells yielded IC₅₀ values of 14.1±3.2 µg/mL (empty) and 9.4±0.4 µg/mL (drug-loaded) in method 1, and 35.0±3.1 µg/mL (empty) and 8.7±0.4 µg/mL (drug-loaded) in method 2. Enhanced activity correlated with increased reactive oxygen species (ROS) generation, mitochondrial membrane depolarization and nuclear condensation, indicative of apoptosis. Non-cancerous 3T3 fibroblasts displayed minimal susceptibility (IC₅₀>100 µg/mL in method 2). These results position β-CD-citrate-modified Pr₂Se₃ nanoparticles as tunable, biocompatible and highly effective drug delivery platforms for targeted breast cancer therapy.

This study investigates the formation of titanium boride (TiB₂/TiB) layers on Ti₆Al₄V alloy to enhance its surface hardness and wear resistance. Boride layers were synthesized via powder-pack boriding under an inert atmosphere at 1373 K for 10, 15, and 20 h. Under these parameters, a titanium diboride (TiB₂) layer with a maximum thickness of 9.7 ± 0.4 µm was obtained, achieving a total boride depth of 19.7 ± 0.4 µm. X-ray diffraction (XRD) corroborated the formation of the TiB₂ phases. Progressive scratch tests (1–60 N) identified Hertzian cracking, chipping, and spalling as the main damage mechanisms. The onset of Hertzian cracking was significantly delayed by increasing the thickness of the boride layer from 5.5 ± 0.1 to 24 ± 0.5 N, although the critical load for chipping decreased from 45 ± 0.3 to 39 ± 0.2 N due to the release of stored elastic strain energy. Multi-pass scratch tests showed 84% reduction in wear rate, achieving a minimum value of (3.7 ± 0.3) × 10⁻⁶ mm³ N⁻¹ m⁻¹ with friction coefficients below 0.05. Ultimately, the treatment fundamentally shifted the dominant wear regime from severe plastic deformation and galling to a milder regime of localized cracking, where the deep reinforcement provided by the titanium monoboride (TiB) whisker zone effectively stiffened the subsurface, preventing localized substrate collapse and conferring a superior load-bearing capacity to the thicker borided systems.

The nylon 6-based manganese phosphate (NMP) composite membrane was synthesized using the die-mold casting process. This cation exchange membrane is designed to improve electrochemical behavior and stability. To attain a membrane with superior stability and selectivity, various polymer-to-inorganic salt ratios were evaluated through comparative analysis of ion exchange capacity, porosity, membrane potential, and chemical stability. Nylon 6 polymer and NMP inorganic material were combined in a ratio of 25% and 75%, respectively, to create the synthetic composite membrane. The inorganic material was created using the sol-gel method of material synthesis. Comprehensive characterization of the membrane was performed using SEM, XRD, FTIR, and EDX to confirm its surface morphology, crystalline structure, functional groups, elemental composition, ion transport behavior, etc. The synthesized membrane showed appropriate porosity (0.012%), ion-exchange capacity (0.8 mmol/g), high stability, reproducibility, and selectivity for salts and heavy metal ions. The electrical potentials measured across the composite membrane in contact with 1:1 electrolytes (KNO₃, NaNO₃, and LiNO₃) showed that LiNO₃ had the highest membrane potential values, followed by NaNO₃ and KNO₃ (LiNO₃ > NaNO₃ > KNO₃). The transport numbers and mobility ratio increased with decreasing concentration of electrolytes and followed the order KNO₃ > NaNO₃ > LiNO₃. Based on the excellent results, the developed membrane is cost-effective, environmentally friendly, and can be effectively used for the separation of brackish water and for industrial wastewater treatment applications.

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One-dimensional (1D) TiO₂ nanostructures such as nanorods, nanowires, and nanotubes (NTs) are attractive for applications in solar cells, photocatalytic solar energy conversion, photoelectrochemical cells, gas sensors, and biomedical sensors due to their high surface-to-volume ratio, fast charge carrier transport, high catalytic activity, and superior chemical stability. In this study, highly ordered, vertically aligned TiO₂ NTs were fabricated by two-electrode electrochemical anodization of titanium foils. The surface morphology, crystal structure, and chemical bonding of the NTs were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy measurements. Non-enzymatic glucose sensing properties of NTs have been investigated using cyclic voltammetry (CV), amperometric measurements, and electrochemical impedance spectroscopy. TiO₂ NTs demonstrated sensitivity of 81.56 µA mM⁻¹ cm⁻² in the linear detection range 0.005–3.325 mM with a detection limit of 71.5 nM. The sensor exhibited excellent selectivity towards glucose in the presence of common interfering substances such as ascorbic acid, uric acid, urea, dopamine, and K⁺, Na⁺, Mg²⁺, and Cl⁻ ions. Furthermore, self-powered glucose-sensing performance of the NTs was evaluated under light and dark conditions without any external bias. The sensor achieved a self-powered glucose sensitivity of 7.749 µA mM⁻¹ cm⁻². The fabricated sensor also successfully demonstrated non-enzymatic detection of salivary glucose, achieving a sensitivity of 0.0963 µA cm⁻² μM⁻¹.

The stability and thermal degradation kinetics of a nanofluid critically govern its use. Herein, the stability and thermal degradation kinetics of three variants of graphene oxide-based nanofluids are investigated, considering the nanoparticle size and pH of the medium. For this, graphene oxide (GO)-, amine-functionalized graphene oxide (f-GO)-, and reduced graphene oxide (rGO)-based nanofluids with different particle sizes were prepared at a concentration of 0.1 wt.% and at various pH values ranging from 3 to 9. It was found that f-GO nanofluids with a particle size of approximately 55 nm remained stable for up to 90 days at pH 7 and showed higher thermal conductivity, i.e., 0.698 W m⁻¹ K⁻¹ at 25°C, than the other variants. Additionally, at the same pH, f-GO-3 nanofluid showed a higher photothermal response than the other nanofluids. An optimum transparent insulating material thickness (TIM) of 2 mm was obtained for improved photothermal behavior. Analysis of thermal degradation kinetics revealed that rGO showed better thermal stability and higher activation energy (E_a) at higher temperatures than GO and f-GO nanoparticles. Thus, f-GO and rGO nanofluids with a particle size of around 50 nm may be chosen depending on the application requirements involving high temperatures or long-duration storage.

Alumina fibers are high-performance ceramic fibers renowned for their mechanical strength, high elastic modulus, thermal stability, and superior creep resistance. Their applications are in aerospace thermal protection systems, thermal insulation for nuclear reactors, and structural reinforcement for high-temperature industrial equipments. However, the complex multiaxial loading conditions prevalent in the automotive and construction sectors, fibers are susceptible to intricate failure mechanisms including transverse stress concentration and torsional buckling. Consequently, their intrinsic brittleness limits their broader applicability. To overcome this limitation, a flexible composite coating was formulated using polyurethane (PU) adhesive as the matrix, 3-glycidoxypropyltrimethoxysilane (KH560) as the compatibilizer, and tetrahydrofuran (THF) as the solvent. The primary objective of this study is to enhance the mechanical performance of alumina fibers, by ameliorating their inadequate torsional resistance. The effects of this coating on fiber microstructure and mechanical behavior were evaluated using scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, INSTRON universal testing machine, and a dedicated torsion tester. The results demonstrated that the PU–THF coating increased the static torsional twist angle of alumina fibers from 20–40 wt%. Mechanistic analysis reveals that the coating enhanced fiber performance through two key mechanisms: Filling inherent surface defects and forming robust chemical bonds at fiber-coating interface. These results indicated that the PU–THF coating effectively improved the mechanical integrity of the alumina fibers. This work presents a viable strategy for surface modification and toughening of ceramic fibers, providing novel insights into the design of multifunctional coatings for high-performance inorganic fiber reinforcements.

A hydrothermal approach was employed to achieve bismuth intercalation into rhombohedral 3R-MoS₂, offering a viable strategy for engineering the structural, electronic, and surface characteristics of the MoS₂ polytype. X-ray diffraction confirms retention of the 3R phase with a systematic leftward shift in 2θ and c-axis expansion (18.42 to 18.89 Å), along with a 50% reduction in microstrain, indicating lattice relaxation induced by Bi³⁺ intercalation. FE-SEM reveals a transformation to a hierarchical microsphere morphology with filamentous projections, while HR-TEM confirms an expanded interlayer spacing (0.68–0.72 nm). EDS and XPS demonstrate uniform Bi³⁺ distribution, sulphur-vacancy passivation, and partial oxidation states. TGA-DTG displays a modified two-stage decomposition, reflecting enhanced thermal resilience. Most notably, BET analysis reveals a 6.6-fold increase in surface area (1.60–10.58 m²/g), a ~3.7- to 4.7-fold increase in pore volume, and pore diameter refinement (47.37 nm to 19.19 nm) within the mesopore regime. Room-temperature I-V measurements reveal a transition from non-ohmic to nearly ohmic behaviour, attributed to expanded interlayer spacing and improved surface accessibility. This work systematically analyses the effect of Bi³⁺ intercalation in 3R-MoS₂, providing new insights into defect passivation and phase stability. Altogether, these results establish Bi-MoS₂ as a promising multifunctional material with promising avenues for energy storage, catalysis, and adsorption applications.

Achieving thermal actuation in shape memory alloys (SMAs) requires subjecting the material to cyclic thermal processing. This process involves carefully regulating the heating and cooling of the material to trigger the desired superelasticity and shape memory effect (SME) in the SMA. To investigate the influence, the temperature rate, and constant stress on the thermal actuation behavior of NiTi and NiTiHf alloys, this study used molecular dynamics (MD) simulations on equiatomic NiTi and a Ni-rich NiTiHf high-temperature shape memory alloy (HTSMA). Transformation temperatures for both alloys were first determined to define the temperature range used during actuation. The constant stress applied during actuation was based on the plateau stress associated with the martensitic transformation under loading. Thermal actuation was then simulated on thick plate models at various temperature rates. The results demonstrated that while the actuation strain remains largely unaffected by the temperature rate, a decrease in temperature rate leads to significantly narrower thermal hysteresis in the strain–temperature response.