Polymers最新文献

Laser-induced graphene (LIG) is most often produced from commercial Kapton; the properties of LIG are inherently linked to those of the polymer substrate, which results in a limited field of applications for LIG on Kapton. This study demonstrates that tailored properties of LIG, including nitrogen doping, which is favorable for electronic applications, can be achieved by using synthesized cross-linked polyimides (PIs) as substrates for graphene induction. Three amorphous polyimides containing 4-[(4-aminophenyl)sulfonyl]aniline (PI-APSA), 1,2-diaminoethane (PI-EDA), and urea (PI-Urea), as crosslinkers, were prepared from different diamines and maleic anhydride, and subsequently used as substrates to produce in situ nitrogen-doped LIG. The resulting materials were comprehensively characterized and compared with LIG on Kapton. Raman spectroscopy confirmed lower defect densities and higher crystallinity than in LIG on Kapton, while sheet resistance was up to three times smaller. The LIG with PI-EDA showed the highest nitrogen content and a specific areal capacitance of 3.1 mF/cm², which is more than an order of magnitude higher than that of LIG/on Kapton, highlighting its strong potential for energy storage devices. PI-APSA-based LIG exhibited the best adhesion and lowest sheet resistance, making it suitable for wearable electrodes, whereas PI-urea-based LIG maintained hydrophilicity. Thus, chemically tailored polyimides enable the formation of nitrogen-doped LIG with tunable interfacial properties, higher structural order, and improved electrical and electrochemical performance compared to commercial Kapton.

A new series of polyamides (PAs) employing two phenolic natural compounds as starting materials, eugenol and chavicol, has been successfully prepared. The synthesis was carried out through a solvent-free protocol using the environmentally friendly organocatalyst 1,5,7-triazabicyclo[4.4.0]dec-3-ene (TBD). The obtained materials have been properly characterized. Moreover, the prepared materials, all of them amorphous, showed a wide range of transition temperatures (T_gs) depending on the structure of the diester counterpart used in the polymerization reaction. In addition, the influence of the methoxy group present in eugenol on the thermal properties of the resulting polyamides was studied. The synthesized polyamides demonstrated excellent thermal stability, high hydrophobicity, and great dimensional integrity. Furthermore, the obtained polymers could be depolymerized under alkaline hydrolysis conditions to yield, with good to excellent recovery ratios, the corresponding starting diamine monomer, which could eventually be used in the synthesis of new polymers. Closed-loop chemical recycling emerges as a sustainable alternative to conventional end-of-life management strategies for discarded polymers, while also constituting a promising pathway to mitigate the accumulation of polyamide (PA) waste.

This study aimed to evaluate the individual and combined effects of mechanical, plasma-based, and laser-based surface treatments, along with short- and long-term thermal aging, on the surface morphology, surface energy, and resin cement bond strength of CAD/CAM monolithic zirconia. Significant numerical differences were observed among the treatment groups. Surface roughness increased from 0.22 µm (control) to 0.98 µm after sandblasting, 1.12 µm after sandblasting + plasma, and 1.07 µm after laser treatment, while plasma alone produced a moderate increase (0.31 µm). Wettability improved most notably in the plasma group, where the contact angle decreased to 43.27° compared with 67.00° in the control. The highest shear bond strength after 5000 thermal cycles was recorded in the sandblasting + plasma group (14.80 ± 1.53 MPa), whereas laser treatment demonstrated the best long-term stability, showing no significant decrease after 10,000 cycles (12.48 → 12.02 MPa). From a practical perspective, these findings indicate that sandblasting followed by plasma treatment provides high initial bond strength, making it suitable for clinical situations requiring strong immediate adhesion of zirconia restorations. Conversely, femtosecond laser treatment offers superior resistance to aging-related degradation, suggesting its potential value in cases where long-term durability is critical, such as high-stress posterior restorations or patients with parafunctional habits.

Urgent demand for wound healing treatments has driven rapid advancement in electronic skin technology. As a promising wound healing approach, electronic skin offers advantages such as flexible conformability, autonomous sensing, and intelligent regulation. However, mainstream electronic healing patches face significant challenges in complex wound applications, including insufficient coordination, delayed response, limited healing efficiency, and inadequate feedback. Therefore, developing innovative wound healing technologies that integrate high efficiency, multi-module drive, and closed-loop feedback is imperative. The advanced development of electronic skin for wound healing is urgently needed to be systematically reviewed. Here, first, the structural innovations and design strategies for biomimetic thermotherapeutic electronic skins based on thermoelectric polymer composites and interactive temperature biomimetic regulation are summarized. Subsequently, several emerging bioelectrically active electronic skins are reviewed, including drug-delivery electronic skins, multifunctional hydrogel-integrated electronic skins, and photoelectric synergistic stimulation electronic skins, along with an analysis of their advanced designs and innovative advantages. Last but not least, potential challenges facing the future development of electronic skin are explored. Practical solutions are proposed for advancing low-cost, clinically applicable, and scalable electronic skin development, aiming to drive breakthrough progress in therapeutic wound healing.

Phthalates (PAEs), commonly incorporated into materials such as polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC), are easily to migrate readily into the surrounding environment, which have become a matter of increasing concern. Traditional PAEs extraction methods have been prevented by long extraction times and high costs, requiring substitute to accelerate the extraction speed while reducing extraction costs. Ultrasonic-assisted extraction facilitates the release and dissolution of target compounds through the combined effects of acoustic cavitation and molecular vibration acceleration, which could be an effective means to overcome the limitations of traditional extraction methods. Herein, we have developed a four-frequency composite ultrasonic extraction technology for PAEs, with a recovery of 95.2%, approximately 38.2% higher than mode MU 20 kHz. Besides, an in-depth study on the mechanism of ultrasound-assisted extraction with sequential multi-frequency was conducted and we confirm that stepped-frequency ultrasound could achieve precise control of cavitation effects by dynamically adjusting frequency distribution, ensuring high extraction efficiency while maximally protecting the PVC matrix structure, providing a new technical path for efficient and green recovery of plasticizers.

In the late stage of oilfield water flooding, the rapid increase in water cut of produced fluids significantly reduces oil well productivity. To tackle the challenge of excessive water production in ultra-high-temperature (150 °C) reservoirs, this study introduces a copolymer (acrylamide/vinylpyrrolidone copolymer, acrylamide/2-acrylanmido-2-methylpropanesulfonic acid copolymer)-based gel system. The gelation performance of copolymers with varying compositions and molecular weights was systematically investigated at 150 °C using gelation visualization codes, mechanical strength tests, microstructural analysis, thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR) spectroscopy. These approaches provide insights into the thermal and mechanical behavior of the gel under high-temperature conditions. Experimental results show that under optimized conditions-specifically with a vinylpyrrolidone (NVP) content of 30-40% in the copolymer and a copolymer concentration of 1.0 wt%-the gel system exhibited the best performance: a gelation time of 9.5-11 h, storage modulus (G') of 14.7-16.0 Pa, and stability exceeding 6 months at 150 °C. Moreover, increasing the molecular weight from 1.78 × 10⁶ to 3.82 × 10⁶ shortened the gelation time from 18.5 h to 14 h and raised the gel strength code from F to G. Although higher molecular weight led to a finer microstructure lattice and somewhat lower chemical structure stability, it also reduced the gel's water-binding capacity compared to lower-molecular-weight analogues. The copolymer gel system developed in this work offers a promising technical solution for improving water flooding efficiency in ultra-high-temperature reservoirs.

The use of carbon fiber-reinforced plastic (CFRP) components has increased significantly in civilian aviation, necessitating effective maintenance and repair strategies to ensure durability and performance. While prior studies have focused on composite repair methods, such as stepped scarf patch and bolted joint repairs, these were limited to specimen and panel levels without addressing full-scale wing models. This study bridges that gap by evaluating stepped-lap repairs on a full-scale composite wing model under realistic loading conditions and exploring various repair scenarios. To reduce computational cost, two-dimensional shell elements were employed to simulate repairs, with results validated using experimental tensile test data from stepped-lap repaired specimens. Numerical models were developed for single regions and two closely located repair regions. For single-region repairs, adding up to two extra layers enhanced mechanical strength, but three extra layers increased strain, diminishing performance. For two closely located repairs, additional layers improved strength, though less effectively than single-region repairs. Square-shaped repairs exhibited higher strain due to stress concentrations at the corners, while circular repairs showed more uniform stress and strain distribution. These findings emphasize the importance of optimizing repair geometry and layer configurations using numerical simulations to ensure optimal structural performance of CFRP components.

This study presents the fabrication and optimization of eco-efficient epoxy composites reinforced with ground natural stone fillers, namely pebble, sandstone, and marble, at loadings of up to 15.6 wt.%. Low content of a bio-based modifier, modified castor oil (MCO ≈ 0.5 wt.%), is incorporated to improve filler dispersion, processing behavior, and matrix-filler interfacial compatibility. The composites are designed to enhance mechanical, thermal, and dielectric performance using low-cost, abundant, and environmentally sustainable constituents. An experimental optimization approach is employed to evaluate and optimize bulk density, Shore D hardness, thermal conductivity, dielectric constant, and tensile strength. The results demonstrate that pebble-reinforced composites exhibit the highest tensile strength (≈30 MPa) and surface hardness (≈82 Shore D), which are attributed to the angular morphology and high intrinsic rigidity of pebble particles. Marble-filled systems show superior thermal stability, with residual mass increasing from approximately 2.5 wt.% for neat epoxy to over 11 wt.% at 550 °C, owing to the thermally stable calcium carbonate phase. In contrast, sandstone-reinforced composites exhibit the lowest dielectric constant (≈3.2), indicating enhanced electrical insulation capability. Fourier-transform infrared spectroscopy (FTIR) results confirm that the epoxy network structure is preserved upon filler incorporation, while MCO promotes improved interfacial interactions through physical interactions. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) reveal enhanced thermal resistance, reduced microvoid formation, and improved filler-matrix adhesion at optimal filler contents of approximately 3.5 wt.%.

This study provides a comprehensive analysis of peanut shell (PnS) combustion behavior using combined physicochemical characterization and non-isothermal thermogravimetric kinetics. To evaluate its potential as a sustainable solid biofuel, PnS was characterized for its proximate and ultimate composition, with its fiber structure analyzed via Van Soest methods and functional groups identified via FTIR spectroscopy. Thermogravimetric analysis (TGA) was performed at high heating rates (20,40,60, and 80 K min-1) to investigate combustion stages under oxidative conditions. The results established PnS as a high-potential energy source, revealing a significant volatile matter content (65.30 wt%) and an exceptionally high heating value (20.87 MJ kg-1), which surpasses many standard agricultural residues. The proximate analysis also indicated a moisture content of 9.61% and an ash content of 6.59%. TGA profiles displayed distinct decomposition stages, with the primary devolatilization occurring between 500 and 700 K. Kinetic analysis was conducted using six model-free methods: Friedman (FR), Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink (STK), Kissinger (K), and Vyazovkin (VY) and the Coats-Redfern model-fitting method. The apparent activation energy Ea was found to vary with conversion (α), reflecting the complex degradation of the lignocellulosic matrix (47.86% cellulose, 28.4% lignin). The activation energy values ranged from approximately 23 kJ mol-1 (VY method at low conversion) to 187 kJ mol-1 (FR method at α=0.5). Model-fitting analysis identified the three-dimensional diffusion (D3) model as the governing reaction mechanism. Thermodynamic analysis indicated positive enthalpy (ΔH:70.7-181.8 kJ mol-1) and Gibbs free energy (ΔG: 116.2-216.7 kJ mol-1), with predominately negative entropy (ΔS), confirming the endothermic and non-spontaneous nature of the reaction activation.

The design and optimization of immobilized metal affinity chromatography (IMAC) media are crucial to enhancing the purification efficiency of recombinant proteins. In this study, the agarose-based microspheres are prepared by using a three-factorial Box-Behnken design followed by NTA-Ni²⁺ agarose-based microspheres (ABM) preparation by the "one-step" crosslinking of epichlorohydrin (ECH)-nitrilotriacetic acid (NTA) to efficiently couple the NTA ligand to the surface of the matrix. After preparation, various sophisticated techniques, including SEM, AFM, DSC, FTIR, and SDS-PAGE, were used to analyze the morphological structure, thermal stability, and chemical composition of NTA-Ni²⁺ ABM. The optimal conditions are identified as an emulsifier PP concentration of 8.12 wt%, a stirring speed of 1624.46 rpm, and an oil-phase temperature of 53.86 °C, giving a span value (Y) of 0.50684. SEM, AFM, DSC, and FTIR results showed that the fabricated NTA-Ni²⁺ ABM were structurally stable and had a uniform cross-linking network for up to 8 h of coupling reaction time. The performance results showed that the beads had a high binding capacity for His-tagged proteins (15.2 ± 0.8 mg/mL), and SDS-PAGE results demonstrated the efficient purification ability for target proteins. These findings provide the theoretical basis and a practical solution for the rational design and application of IMAC medium.