Colloid and Polymer Science最新文献

The phase transition temperature dependence of polymer dispersed liquid crystals (PDLCs) leads to a narrow operating temperature range, especially in low-temperature environments prone to transparency anomalies or a significant increase in the drive voltage and other issues, which seriously limits its promotion in outdoor displays, automotive dimming glass, and other wide-temperature range applications. The narrow working temperature range is one of the significant factors limiting the wide applications of PDLC. In this paper, we have prepared a surfactant (Span-80)-doped PDLC. The different concentration of Span-80 has a significant impact on the electro-optical properties of PDLC at different temperatures. Based on the experimental results, doping of Span-80 can reduce the driving voltage and shorten the recovery time of PDLC at low temperatures. This innovation not only enhances the operational stability of PDLC devices at low temperatures, but also provides a sustainable optoelectronic architecture with minimized power consumption and accelerated switching dynamics, which is particularly beneficial for smart windows operating in low-temperature environments. In addition, a ball lubrication model is proposed, and the results of the ideal model agree with the experimental results.

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Panax notoginseng saponins (PNS) is a natural medicine known for its ability to promote blood circulation, remove blood stasis, reduce swelling, and relieve pain. However, obtaining high-purity PNS from the crude extract of the medicinal plant Sanqi is a challenging and important task. In this study, a novel rosin-based diatomite polymer microsphere (RDPMs) was synthesized, and its physical and chemical properties were characterized using various analytical techniques. The adsorption capacity of RDPMs for PNS was 273.69 mg·g⁻¹, with an increase in PNS content from 44.38 to 79.59%. The process was spontaneous, endothermic, and multilayered, controlled by physical and chemical factors. Quantum chemical calculations revealed that there are van der Waals forces, H-bonding, and electrostatic interactions between RDPMs and PNS. Overall, RDPMs is an effective and reusable bioadsorbent with potential for isolating PNS from Sanqi extract.

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This study investigates the use of PAN/EPI-DMA-bentonite composite fibers, synthesized through electrospinning, for the efficient adsorption of anionic azo dye, amido black (AB), in wastewater treatment. The composite fibers were developed by incorporating epichlorohydrin dimethylamine (EPI-DMA) modified bentonite into a polyacrylonitrile (PAN) matrix, enhancing the surface’s positive charge and increasing adsorption sites. Characterization using SEM–EDX, FTIR, and BET analyses confirmed successful bentonite integration, increased fiber diameter, and enhanced surface area, contributing to improved dye affinity. Adsorption experiments revealed that a 3 wt% EPI-DMA-bentonite dosage achieved optimal AB dye removal, with the composite demonstrating a maximum adsorption capacity of 1829 mg/g at 200 ppm dye concentration. Acidic conditions (pH 2–4) significantly improved adsorption efficiency, reaching up to 92% dye removal due to increased electrostatic attraction between the anionic dye and cationic sites on the composite fibers. Isotherm and kinetic studies indicated that the adsorption process adheres to the Langmuir isotherm model and pseudo-second-order kinetic model, suggesting monolayer adsorption and chemisorption mechanisms. Compared to conventional adsorbents, the PAN/EPI-DMA-bentonite composite exhibited superior adsorption capacity, highlighting its potential as an effective and scalable solution for industrial dye-laden wastewater treatment.

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Radiation skin injury (RSI) is a common side effect of radiation therapy for cancer patients, and bacterial infection at the RSI site usually hinders the healing process of the radiation skin injury, thus affecting the subsequent treatment regimen of the patient. To address this issue, we developed a dual network hydrogel containing the natural phenolic antioxidant curcumin. The hydrogel possesses good mechanical and swelling properties to effectively isolate radioactive skin wounds from the external environment, while curcumin released from the hydrogel can effectively inhibit bacterial infections in RSI. In addition, curcumin is able to regulate intracellular redox balance by affecting GSH transferase homologs in cell membranes, thereby reducing the inflammatory response at the wound site. The synergistic effect of antibacterial/anti-inflammatory action produced by the hydrogel effectively accelerates the rate of healing of RSI, providing valuable insights into the clinical management of radiation dermatitis.

The reduced graphene oxide (rGO), a two-dimensional nanomaterial with a large aspect ratio, exhibits good chemical stability and electrical conduction. Its applicability could be boosted by making its water-dispersible composite with metallic nanostructures like silver nanoparticles (SNPs). This study focuses on the synthesis and characterization of sustainable SNP-decorated reduced graphene oxide (SNP@rGO) nanosheets for poly(vinyl alcohol) (PVA) nanocomposite films having opto-mechanical potential. The SNP@rGO nanofillers were synthesized using eco-friendly reductants, including sodium citrate and chitosan, through a hydrothermal approach. The resulting nanofillers were characterized using advanced analytical techniques. The XRD analysis revealed that the resultant SNP@rGO nanocomposites retained the face-centered cubic crystal structure for metallic silver. The use of sodium citrate as a reductant resulted in highly crystalline SNP@rGO nanocomposites. SEM images confirmed the successful impregnation of spherical SNPs on the rGO nanosheets. FTIR results indicated interactions between SNPs and residual oxygen functionalities on the rGO nanosheets. The SNP@rGO-mediated PVA nanocomposites demonstrated superior performance, exhibiting up to 97% UV-blockage and a remarkable superoxide dismutase activity of 7.2 U/mg with enhanced mechanical strength and antibacterial properties compared to pristine PVA and SNP-loaded PVA films. Incorporating SNP@rGO into PVA enhanced its optical properties, rendering it suitable for optical applications. This investigation paves the way for using SNP@rGO/PVA nanocomposites in cutting-edge fields such as optical devices, biomedical coatings, and packaging materials.

The escalating release of carcinogenic azo dyes into aquatic environments necessitates the urgent development of efficient adsorbents. This study addresses this challenge by synthesizing two poly(N-vinyl imidazole)-based nanocomposite hydrogels, VMG (non-ionic crosslinking) and VDG (cationic crosslinking via 3, 3′ -divinyl-1, 1′ (1, 6-hexanediyl) di-imidazolium dibromide), incorporating 4.0 wt% of N-doped graphene quantum dots (NGQDs) to potentially enhance adsorption capacity. Characterization was performed using FTIR, XRD, SEM–EDS, BET, TEM, zeta potential (ZP), and swelling tests. VDG was selected for anionic dye adsorption studies due to its higher swelling and porous structure. ZP measurements of the adsorbent indicated that the ZP value was influenced not only by the solution pH but also by the presence of NGQDs in the nanocomposite. BET results indicated that the resulting VDG exhibited a high surface area of 245.02 m²/g. Batch experiments demonstrated highly efficient removal of model anionic dyes, Congo red (CR) and Methyl orange (MO), achieving maximum adsorption capacities of 454.54 and 400.0 mg/g at pH 7.0- and 60-min contact time, conditions likely favoring electrostatic interactions. The adsorption isotherm and kinetic data best fit the Langmuir for both CR and MO, pseudo-first order model for CR and Elovich model for MO, suggesting monolayer adsorption and a predominantly chemisorption-controlled process. The thermodynamic data indicated that dyes adsorption onto the VDG was endothermic and spontaneous. These findings highlight the VDG nanocomposite as a promising and potentially high-capacity adsorbent for the effective removal of anionic dyes from wastewater.

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This study develops an optimized nanoemulsion for efficient oil-based drilling fluid (OBDF) removal, and the unique removal mechanisms of nanoemulsion are studied. Compared to surfactant solutions, the nanoemulsion exhibits enhanced wettability on solid surfaces and lower interfacial tension against oil phases (< 0.1 mN·m⁻¹), synergistically facilitating OBDF detachment through three mechanisms: low interfacial tension, wettability enhancement, and disjoining pressure effects. Enhanced emulsification produced monodisperse micron droplets under shear, overcoming Laplace resistance through pre-organized interfacial films. The synergistic combination of enhanced wettability (contact angle reduction to 25.4°) and nanoscale droplet dimensions (147 nm) significantly improves nanoemulsion permeation through OBDF filter cakes. These combined properties improve the removal effect of OBDF, while interfacial bonding strength at cement-casing (3.02 MPa) and cement-formation (2.74 MPa) interfaces matched pristine samples. These elucidated mechanisms provide theoretical guidance for formulating and optimizing nanoemulsion-based flushing fluids, while also facilitating their broader applications in fields such as enhanced oil recovery and environmental remediation.

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Metal oxide nanoparticles are widely used in various biomedical applications due to their ability to reach unique target positions within the body. In the present work, nickel cobaltite (NiCo₂O₄) nanoparticles (NPs) embedded into sodium alginate/gum arabic polymeric hydrogel beads for controlled release of bioactive agents were prepared. These hydrogel beads are comprehensively examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. XRD confirmed the generation of NiCo₂O₄ NPs and integration of NPs into the hydrogel matrix. The TEM studies revealed that the size of NPs is between 25 and 30 nm. Swelling studies revealed that hydrogel beads exhibit pH-dependent behaviour, which is suitable for controlled drug release in various physiological conditions. In vitro release tests revealed a higher release rate at pH 7.4 compared to pH 2.0. Using doxorubicin as a model drug, cytotoxic effects on human breast cancer cells were examined. The developed NPs-loaded hydrogel beads effectively prevent the growth of breast cancer cells, such as Michigan Cancer Foundation-7 (MCF-7) cells with a viability of 9.5%. Furthermore, the biocompatibility of NPs and sodium alginate/gum arabic hydrogel beads conducted with 3T3 fibroblast cells has shown that cell viability is more than 80%, indicating the biocompatibility of hydrogel beads. These hydrogel beads need to warrant further development as carriers for pH-responsive and controlled release of bioactive agents.

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The study investigates the electrical and dielectric properties of polar and non-polar polymer-based composites and Si-based composite varistors across a range of temperatures. Current-voltage characteristics (CVC) were measured, and the real (ε′) and imaginary (ε″) components of the dielectric constant were calculated at different frequencies. The results show that the CVC exhibits non-linearity over the entire measured temperature range, with the breakdown voltage shifting to lower electric fields as temperature increases. The polar polymer-based composites exhibit a current flow approximately five times higher than non-polar composites under the same applied voltage. For polar polymer composites, the dielectric constant (ε) increases monotonically with rising temperature, whereas non-polar polymer composites show a sharp decline in ε with temperature. A decrease in ε″ and loss tangent (tgδ) was observed with increasing temperature. The electrical conductivity (σ) of polar polymer composites decreases monotonically as temperature increases. In contrast, for non-polar polymer composites, σ decreases sharply at low voltages (<50 V) with increasing temperature, while at higher temperatures, σ increases. These findings highlight the contrasting behaviors of polar and non-polar polymer composites under varying thermal and electrical conditions, offering insights into optimizing materials for advanced dielectric and varistor applications.

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We present a simple analytic expression for the electrophoretic mobility of a weakly charged oil drop in an aqueous electrolyte solution, where the drop acquires its surface charge through ion adsorption. The derivation is based on a simplified Baygents-Saville model, in which no ions are present inside the drop. This model incorporates the Marangoni effect arising from interfacial tension gradients. The resulting analytic expression shows excellent agreement with the numerical results of Baygents and Saville for low zeta potential values, validating the accuracy of the approximation. It is found that, under the assumption of no internal ions, the electrophoretic mobility of the drop is independent of its internal dielectric permittivity. This behavior stands in contrast to the case of an oil drop with a uniform, constant surface charge density, where the mobility depends on the drop's internal dielectric permittivity. However, it is similar to the case of rigid particles, as shown by O’Brien and White. Furthermore, it is found that in the analytic expression for the electrophoretic mobility of a mercury drop, the leading term proportional to κa (where κ is the Debye–Hückel parameter and a is the drop radius) completely cancels out for an oil drop due to the tangential Maxwell stress and the Marangoni effect—both of which are absent in the case of a mercury drop. As a result, the electrophoretic mobility of an oil drop does not increase linearly with increasing κa when plotted at a fixed zeta potential.

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