Colloid and Polymer Science最新文献

Enhancing the compatibility of immiscible polymer blends is crucial to achieving optimized performance for polymer materials. This work presents a comprehensive investigation into the effect of copolymer-tethered nanoparticles (NPs) on the compatibilization of immiscible polystyrene/polymethyl methacrylate (PS/PMMA) blends. The morphology, rheological behavior, and mechanical properties of the blends were analyzed to compare the compatibilization effects of NPs tethered with block, random, and graft copolymers. Our findings indicate that block copolymer-tethered NPs exhibited superior compatibilization efficiency in contrast to random and graft copolymer-tethered NPs. Moreover, by achieving an optimized balance in selective molecular entanglement, the incorporation of 3 wt% block copolymer-tethered NPs with extended PS and PMMA blocks demonstrated the most efficient compatibilization, decreasing the size of dispersed phases from 6.42 ± 9.66 µm to 1.25 ± 0.73 µm while boosting the tensile strength of blends by 78%.

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This work presents a comprehensive investigation into the effect of copolymer-tethered nanoparticles on the compatibilization of immiscible polystyrene/polymethyl methacrylate (PS/PMMA) blends.

In this study, three polycarboxylic acids with varying numbers of carboxyl groups were employed to crosslink polyvinyl alcohol (PVA): malonic acid as a diacid (MA), citric acid as a triacid (CA), and 1,2,3,4-butane tetracarboxylic acid as a tetraacid (BTCA). The crosslinking abilities of these acids were compared using physical, chemical, mechanical, morphological, thermal, and swelling measurements to assess their impact on the physicochemical properties of the resulting films. Based on the degree of crosslinking, mechanical strength, and thermal stability, tetra acid demonstrated superior crosslinking performance compared to di and tri acids. The highest strength was observed in the tetra acid crosslinked film, which exhibited a 127% increase over neat PVA. Regarding thermal stability, the decomposition temperature followed the order of tetraacid (450 °C) > triacid (378 °C) > diacid (350 °C). However, in terms of swelling behavior, triacid-crosslinked film, i.e., P-CA, exhibited the highest swelling. Further, the tetra acid-crosslinked film exhibited the lowest crystallinity and a higher contact angle (104.9°) than diacid and triacid crosslinked films. Additionally, the crosslinked films displayed enhanced elasticity compared to pure PVA, with the elasticity order being diacid > triacid > tetraacid, possibly due to differences in available crosslinking sites among the crosslinkers.

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With the extensive use of manufactured sand and admixtures, it has been observed that as the shear rate increases, the shear rate–shear stress curve of some fresh wet shotcrete materials increasingly deviates from a linear correlation. It is necessary to study the rheological properties of wet shotcrete using a nonlinear model due to the large error when utilizing the Bingham model to describe the concrete. The torque-velocity curve of wet shotcrete was determined using an ICAR rheometer in this study. The experimental data was fitted using the Bingham model, Herschel-Bulkley (H-B) model, and modified Bingham (M-B) model, resulting in the determination of the associated rheological parameters. The M-B model exhibits the most optimal fitting effect, followed by the H-B model and the Bingham model. As the shear rate reaches a specific value, the M-B model consistently represents a higher degree of divergence from linearity compared to the H-B model. Furthermore, considering the limitations of the H-B model which includes varying dimension parameters, this study enhanced the calculation approach for determining the equivalent plastic viscosity based on Larrard et al.’s (Mat Struct 31:494–498, 1998) research. Ultimately, the impact of the mix parameters on the yield stress and plastic viscosity of the three rheological models was analyzed through the range approach. This study is beneficial for enhancing the comprehension of the rheological characteristics of wet shotcrete.

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The presence of numerous drugs in effluents poses the multiple challenges of removing them from effluents, quantifying them, and developing models to describe the adsorption process. In this manuscript, we present our work on the competitive sorption of sodium cromoglicate (CG) and sodium diclofenac (DF) on crosslinked chitosan particles (C-CHIT). In the Supplementary Material of this manuscript, we provide a method for simultaneously determining the concentrations of these drugs in effluents using trivial UV–Vis spectrophotometric measurements. This method was used to build sorption isotherms for the competitive sorption of these two drugs. Competitive sorption is evident in the sorption isotherms in the form of two regimes: in the first stage, the surface is saturated with CG, and after a sharp discontinuity, adsorption is governed by DF. These ternary solution two-step isotherms can be mathematically described as composed of isotherms derived from the sorption of binary solutions on C-CHIT, with the discontinuity related to their Gibbs free energies of adsorption and lateral interaction parameters. To our knowledge, there are no descriptions of competitive sorption of this kind reported in the literature.

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Phenol–formaldehyde resin can be used to improve oil recovery; its key lies in its aggregation behavior and blocking strength. However, the traditional phenol–formaldehyde resin used in the petroleum field is all prepared by phenol and formaldehyde. In order to get rid of the dependence on fossil resources and make full use of renewable biomass resources, we used the abandoned walnut shells of the unique agricultural and forestry crops in Gansu province, which contains lignin partially replaced phenol to synthesize the new sulfonated lignin-based phenol–formaldehyde resin (SLPFR). The results showed that the optimum conditions for microwave polymers were polystyrene substitution rate of 20 wt%, decomposition temperature of 160 ℃, decommissioning time of 20 min, and sodium hydroxide concentration of 0.3 mol/L. Infrared spectroscopes and scanning telescopes have shown that after disintegration, there was an increased concentration of phosphorus, which had more active spots and was more suitable for replacing phenylphenol-synthetic formaldehyde resins. LC–MS indicated the molecular mass of SLPFR and the possible structure of molecules, indicating the successful synthesis of SLPFR. In this work, the aggregation behavior and dispersion stability of SLPFR were investigated from the composition of formation water. The effects of metal cations (Na⁺, Mg²⁺, Ca²⁺) on the dispersion stability of SLPFR in formation water were determined by turbidimetry, and the effects of metal cations on the particle size and zeta potential of the SLPFR system were measured by dynamic light scattering method and electrophoretic light scattering method. The stability of the aggregate structure of the SLPFR system was calculated by combining the fractal dimension. In this paper, the surfactant + SLPFR system and partially hydrolyzed polyacrylamide (HPAM) + SLPFR system were designed for the specific conditions of oil reservoirs, and the effects of metal cations on the aggregation behavior and dispersion stability of these two systems were studied. Based on the above comprehensive analysis, aggregation models were constructed to describe the aggregation behavior and dispersion stability of the HPAM + surfactant + SLPFR system. This makes it possible to predict in real time the migration and plugging of SLPFR aggregates in formation water.

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Surface conductivity can have a significant impact on the determination of the zeta potential, but it is normally not accounted for when applying the Helmholtz-Smoluchowski or Henry models. In this study, we investigate concentrated polymer dispersions using electroacoustics and both standard models. We also pay particular attention to the influence of surface conductivity, which is characterized by conductivity measurements of the dispersion and dispersion medium. The Dukhin number as a measure of surface conductivity is calculated according to Maxwell–Wagner-O’Konski theory. Zeta potentials were determined by means of colloid vibration current (CVI) and electrophoretic light scattering (ELS) methods. It has been found that neglecting surface conductivity in standard electrokinetic models can lead to large measurement errors of up to 100% with increasing particle volume fraction. In this study, the surface conductivity is now correctly taken into account by using the conductivities of the dispersion and the dispersion medium. Alternatively, this influence can also be considered using the Dukhin number. The zeta potentials resulting from the CVI measurement are then in excellent agreement with ELS reference measurements over a wide volume fraction range.

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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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Hydrogel-based soft materials have attracted significant attention in various fields due to their high water content, good biocompatibility, and variable mechanical strength. However, due to the hydrophilic properties of hydrogel networks, most of the hydrogel-based soft materials are easy to swell in water and have monotonous surface wettability. Here, taking advantage of the intrinsic hydrophobicity of siloxane, novel heteronetwork organohydrogels were synthesized by covalently integrating reactive siloxane monomers into the hydrophilic hydrogel networks via emulsion polymerization. The surface of the heteronetwork organohydrogels exhibited adaptive wettability owing to the rearrangement of the surface chemistry induced by varying solvent conditions. Moreover, the heterogeneous networks endowed organohydrogels with excellent anti-swelling abilities in water or oil (n-heptanes). The potential application of the prepared organohydrogels in the field of oil/water separation was also preliminarily explored. The idea and method of integrating polysiloxane into hydrogels in this study might provide a new insight to develop high-performance polysiloxane-based heteronetwork gel materials.

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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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