Colloid and Polymer Science最新文献

Triboelectric nanogenerators (TENGs) made from biocompatible materials serve as promising integrated power sources for portable wearable electronics due to many advantages such as lightweight, high flexibility, simple technique, and excellent breathability. In this work, we report the fabrication of electrospun polycaprolactone micro-nanofiber films (s-PCL) and convex-microdome-patterned polydimethylsiloxane (c-PDMS) utilizing electrospinning and micromolding techniques. These materials, s-PCL and c-PDMS, are utilized as positively and negatively charged tribosurfaces, respectively, in the development of a bioTENG device. The developed TENG device can generate a superior power output of 2 mW with an open-circuit voltage (V_OC) of 188 V and short-circuit current (I_SC) of 18.5 µA, even under a low triggering frequency of 5 Hz. In addition, TENG possesses outstanding durability and output performance stability over a continuous operation of nearly 16,000 cycles. Furthermore, the TENG demonstrates its capacity to harvest mechanical energy and convert it into electricity, capable of directly illuminating more than 100 LEDs. The electrospun s-PCL- and c-PDMS-based TENG can be considered for self-powdered wearable devices attached to fingers, wrists, feet, and other human body parts.

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Glycidyl methacrylate (GMA) was grafted onto diatomite (DE) to improve the interfacial bonding between GMA and rubber using “one-step”/“two-step” methods, respectively. The hydroxyl group on DE and the amine group on γ-aminopropyltriethoxysilane (KH550) react with the epoxy group on GMA in a ring-opening reaction during the process. The modified diatomite was characterized and analyzed by using Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence spectrometer (XRF), X-ray diffraction patterns, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Natural rubber/diatomite (NR/DE) composites were also prepared using a wet mixing method and investigated the interfacial interactions between different DE and NR in detail using dynamic mechanical analysis (DMA) and rubber process analyzer (RPA). The result showed the improved mechanical properties of NR/DE composites for both “one-step” and “two-step” methods; however, the “two-step” method is found to be more effective. Compared with the unmodified NR/DE composites, the “two-step” modified NR/DE composites exhibited an increase in 37.8% tensile strength, 25.1% tear strength, 11.7% abrasion resistance, and 24% wet slip resistance, respectively. In addition to these, GMA has minimal effect on the elongation at break retention of the rubber composites after aging. These results showed valuable insights for the further application of diatomite in rubber.

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In order to overcome the drawback of poor mechanical and rheological properties and potentially extend the poly(butylene adipate-co-butylene terephthalate) (PBAT) application market, in this work, we developed PBAT blend with excellent comprehensive performance through blending with biodegradable poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA). Two-step melt blending and constant polylactide (PLA) content were devised to prepared PBAT blend. The effect of PDLA on the crystallization properties, rheological properties, miscibility, morphological structure, and mechanical properties of blend was investigated. According to torque-time curve and DSC results, PLA stereocomplex (SC-PLA) crystallites were formed in blend system. DMA results confirmed that the compatibility between PBAT and PLLA was not changed when PDLA was introduced. SEM results showed that the phase morphology of PBAT/20PLLA/0PDLA blend displayed typical sea-island structure and the particle size of dispersed phase decreased accompanying by agglomeration when PDLA was added. Rheological results showed that percolation SC-PLA network structure had formed and a much denser crystallite network could be formed with high PDLA content, which significantly enhanced rheological properties of blend. The mechanical results demonstrated that the addition of PDLA could significantly enhance mechanical properties. The blend with 6 wt% PDLA presented yield strength, elongation at break, and modulus about 13.3 MPa, 307%, and 221.2 MPa, respectively, the yield strength and modulus increased by 141.7% and 54.7% compared with the pure PBAT.

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Considering the carcinogenic and mutagenic properties of azo anionic dyes on the environment and human health, the development of efficient adsorbents for the removal of these water pollutants is very important. Therefore, the main aim of this research is to develop cost-effective and efficient melamine-formaldehyde (MF) microspheres for the removal of anionic dyes from wastewater. MF nanocomposite (MF-NGQD) microspheres were prepared using varying amounts of N-doped graphene quantum dots (NGQDs) through a simple polycondensation method. According to the SEM images, the MF-NGQD microspheres contain up to 10 wt% monodisperse, with an average diameter of 427 nm, which is smaller than the MF microspheres with a diameter of ⁓2.1 μm. The measurement of zeta potential (ZP) as a function of solution pH showed that the amount of ZP is significantly affected not only by the pH of the solution but also by the content of NGQDs in the microspheres. BET results revealed higher surface area and larger pore volume of nanocomposite microspheres (11.40 m² g⁻¹ and 0.030 cm³ g⁻¹) compared to MF microspheres (5.40 cm³ g⁻¹ and 0.017 cm³ g⁻¹). Batch adsorption experiments were carried out to investigate the adsorption properties of microspheres on Congo Red (CR). The results indicated that MF-NGQD microspheres with an amount of 0.05 g/25 mL were able to remove CR up to 97% at pH 6.0 with C₀ of 50 mg L⁻¹ in 45 min with an adsorption capacity of 91.74 mg g⁻¹. Adsorption processes were further analyzed through isotherm and kinetic studies, which showed a better fit with the Freundlich model and pseudo-second-order model, respectively. In conclusion, our finding demonstrates that MF-NGQD-10 microspheres are highly effective adsorbents for the removal of anionic dyes such as Congo Red from textile effluents, offering a promising solution for wastewater treatment. Future studies should explore the scalability and real-world application of these microspheres.

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Polyvinyl alcohol (PVA) and chitosan (CS) were mixed with purple tomato anthocyanins (PTA), and then nano zinc oxide (nano-ZnO) or calcium chloride (CaCl₂) were added to prepare PVA/CS/PTA/ nano-ZnO (PCP-ZnO) or PVA/CS/PTA/CaCl₂ (PCP-CaCl₂) films. The effects of nano-ZnO and CaCl₂ on the morphology, pH response, color stability, color reversibility, antibacterial activity, antioxidant activity, mechanical properties, water vapor permeability and UV absorption characteristics of films were studied. In addition, its application in intelligent packaging to monitor the freshness of pork was also studied. It was found that both nano-ZnO and CaCl₂ can reduce the transmittance of the film in the visible light region, and the film with addition of nano-ZnO was more sensitive to pH. During the 14 day storage period, the film modified with CaCl₂ exhibited better color stability. SEM images indicate that the addition of nano-ZnO or CaCl₂ alters the microstructure of the film. The mechanical, antibacterial and antioxidant properties and also the application as freshness indicator of PCP-CaCl₂ film were superior to those of PCP-ZnO film. Those indicated that the prepared PCP-CaCl₂ film is a potential candidate for active and intelligent packaging applications.

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This study describes the development of ulvan films blended with selected concentrations of carnauba (Copernicia prunifera) wax (0%, 5%, 10% and 15% w/w) to modify its hydrophilic nature. The effects of carnauba wax on the physical, chemical, and mechanical properties of the films were studied. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrum evidenced the presence of uronic acid carboxyl groups, ester sulfate groups, and the vibrational modes associated with C-O groups in the glycosidic linkage between rhamnose and glucuronic acid, which constitute the characteristic ulvan bands. Higher wax concentrations led to lower intensity of transmission peaks in the range of 3500 cm^-1 to 3200 cm^-1, indicating an increase in the films' hydrophobicity. This enhanced hydrophobicity is further supported by contact angle measurements, where the wax-free film (CC0) exhibited a contact angle of 51.85 ± 1.61° (hydrophilic), while the film with 15% wax (CC15) showed a contact angle of 66.64 ± 2.15° (hydrophobic). Additionally, a maximum reduction in the solubility of films with 10% carnauba wax compared to wax-free films. Meanwhile, both tensile strength and elongation at break show negligible changes regardless of carnauba wax presence. The findings indicate that carnauba wax-enriched ulvan films enhance hydrophobicity without compromising mechanical integrity, highlighting its potential for use in food packaging applications.

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The study of steady natural convection Couette flow is vital in designing as well as the optimization of microfluidic devices, geothermal energy systems, cooling of electronic devices and systems, etc., due to several recent applications. The present investigation aims to analyze radiative heat transfer and dissipative energy in the free convection of Couette flow within a vertically positioned channel. Incorporating carbon nanotubes (CNTs), specifically single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs), into the base fluid water enhances the flow phenomena. Additionally, the explanation of heat source/sink on the energy phenomenon encounters various properties. Further, suitable similarity variables are employed for the transformation of the governing equations. However, the homotopy perturbation method (HPM), an analytical approach, is used for the solution of the coupled ordinary differential equations. The thermophysical parameters and their impact are depicted through graphs, and the comparative analysis is presented via tables.

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• Explore the combined effects of CNT nanoparticle concentrations on the Couette flow through a vertical channel.

• The inclusion of radiating heat on free convection of nanofluid enriches the flow phenomena.

• The adaptation of various thermophysical properties, i.e., in particular, the thermal conductivity, shows its effectiveness on the heat transport phenomenon.

• Clarify different contributing parameters by using the homotopy analysis method.

The objective of this study was to enhance the anticancer potential of curcumin (CR)-loaded niosomal formulation against human myeloid leukemia cell lines and its antioxidant activity by the incorporation of amphiphilic palmitoyl-modified arginine (PL-ARG) serving as a positively charged amphiphile. PL-ARG was synthesized by using palmitoyl chloride (PL) and l-arginine (ARG) followed by characterization through ESI–MS, ¹H-NMR, and FT-IR. The proportion of niosomal constituents including Tween 80/20 and cholesterol was optimized using experimental design to achieve small size vesicle with enhanced encapsulation of CR, and the optimized proportion was then used for the development of niosomal formulation functionalized with synthesized PL-ARG (PL-ARG-CR-NSMs). For the comparison, non-functionalized CR-loaded niosomes (CR-NSMs) were also prepared. The developed niosomal vesicles were characterized for encapsulation efficiency, size, PDI, zeta potential and surface morphology, and in vitro drug release. CR was encapsulated in niosomes with entrapment efficiency of 78.94 ± 5.16% (PL-ARG-CR-NSMs) and 65.82 ± 3.52% (CR-NSM) and provided a sustained drug release profile. Interestingly, when compared to CR-NSMs, the PL-ARG-CR-NSMs demonstrated enhanced growth inhibition of human myeloid leukemia cell lines supporting the antitumor efficacy of CR delivered from PL-ARG-CR-NSMs against human myeloid leukemia cell lines as well as the feasibility of arginine modified niosomes as a sustainable cancer treatment approach.

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The assembly of colloids at fluid interfaces followed by their transfer to solid substrates represents a robust bottom-up strategy for creating colloidal monolayers over large, macroscopic areas. In this study, we showcase how subtle adjustments in the transfer process, such as varying the contact angle of the substrate and controlling deposition speed and direction, enable the realization of all five two-dimensional Bravais lattices. Leveraging plasmonic core–shell microgels as the building blocks, we successfully engineered non-close-packed plasmonic lattices exhibiting hexagonal, square, rectangular, centered rectangular, and oblique symmetries. Beyond characterizing the monolayer structures and their long-range order, we employed extinction spectroscopy alongside finite difference time domain simulations to comprehensively investigate and interpret the plasmonic response of these monolayers. Additionally, we probed the influence of the refractive index environment on the plasmonic properties by two methods: first, by plasma treatment to remove the microgel shells, and second, by overcoating the resulting gold nanoparticle lattices with a homogeneous refractive index polymer film.

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