Colloid and Polymer Science最新文献

This study delves into the reaction mechanism of neutralization precipitation and the kinetics of precipitation, as well as the equilibrium of adsorption of germanium. The investigation examines the impact of various experimental parameters, including reaction temperature, reaction duration, iron-germanium mass ratio, and the final pH of the reaction, on the rate of germanium precipitation. The findings suggest that optimal precipitation conditions are attained at a reaction temperature of 60 °C, a precipitation duration of 120 min, an iron-germanium mass ratio of 40:1, and a pH of 5.5 at the reaction endpoint. Under these conditions, the precipitation efficiency can achieve 99.42%. Kinetics and adsorption equilibrium were analyzed, revealing that the germanium precipitation reaction adhered to the pseudo-second-order model for kinetics and the Freundlich adsorption isothermal model for adsorption equilibrium. Based on theoretical analysis and detection of precipitate, the precipitation reactions can be divided into three parts: (1) GeO₂ reacts with water to form small amounts of germanic acid, which then hydrolyzes to form colloidal precipitates; (2) colloidal ferric hydroxide, adsorbing germanium, precipitates spontaneously; (3) due to the addition of NaOH to adjust pH both at the outset and during the experiment, a portion of the solution will have a high pH region for a certain period of time, leading to the presence of germanium in the forms of HGeO₃⁻ and GeO₃²⁻ within these localized areas. The HGeO₃⁻ and GeO₃²⁻ at this point will form a small amount of colloid in the reaction.

In high-temperature and high-salt environments, emulsions stabilized by surfactants are susceptible to instability phenomena, such as droplet coalescence, thereby limiting their utility in tertiary oil recovery. Addition of nanoparticles to the emulsion systems is able to improve the stability of emulsions by several mechanisms. In this paper, two kinds of SiO₂ nanoparticle stabilized emulsions, i.e., the electrostatic repulsion stabilized emulsions (ERS) and the Pickering emulsions, are investigated to clear their potential for enhancing oil recovery. The ERS emulsions are prepared by adding SiO₂ nanoparticle to a SDS stabilized emulsion. It is found that the critical surfactant concentration for forming emulsions is reduced from 0.06 to 0.006%, and the ERS emulsions are stable at salinity lower than 1% NaCl with no oil phase releasing. The cryo-SEM experiments show that the nanoparticles mainly disperse in the aqueous phase and prevent the droplets from coalescence by electrostatic repulsion. On the other hand, Pickering emulsions are prepared using nonionic surfactant modified SiO₂ nanoparticles. By adjusting a surfactant-to-nanoparticles ratio (such as 0.1%:1.0%), the hydrophilic-lipophilic equilibrium is obtained. Laser confocal and cryo-scanning electron microscopy results indicated that SiO₂ nanoparticles in Pickering emulsions are dispersed at the oil–water interface, forming a network structure between the emulsion droplets. Further experiments indicates that the ERS emulsions are effective at salinity lower than 1% NaCl, and the Pickering emulsions adapt to salinity lower than 4% NaCl. In the visual 2-D oil displacement experiments, the ERS emulsion and the Pickering emulsion contribute to 8% and 15% oil recovery, respectively, since the droplets of the Pickering emulsions may aggregate and plug large pores.

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In recent years, the topic of additive manufacturing of polymer materials has gained high acceleration in terms of scientific aspects due to the perfect prototyping capacity, clean production ability, and fast manufacturing opportunity of layer-by-layer fabrication technology. However, the majority of the studies have been directed to the exploration of the mechanical performance of three-dimensional (3D)-printed materials according to changing production variables. Different from the previous efforts, this experimental work is the first initiative to comprehend the low and high-speed mechanical performance of two different thermoplastic materials depending on the shifting test temperatures in a comparative manner. For polylactic acid (PLA) and polyamide 6 (PA6), the combined effect of the infill rate and high-speed drop weight deformation was analyzed for the first time in the technical literature. For this purpose, low-speed tensile tests, differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) analyses, drop-weight impact tests, and damage inspections were made elaboratively. The results showed that PLA samples had superior mechanical responses at 25 °C, but the case was the opposite and in favor of PA6 above the glass transition. Specific absorbed energy values increased with decreasing infill rates both for PLA and PA6. Furthermore, PA6 samples remained united after the drop-weight deformation at higher temperatures, while PLA lost its integrity.

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Block copolymers (BCPs) have recently been explored in spherical confinement to form internally structured microparticles. While the behavior of AB diblock copolymers in confinement is comparably well studied, knowledge on confined ABC triblock terpolymers is still rather sparse. The latter are especially interesting as the third block allows the formation of a broader variety of multicompartment microparticles (MMs), but their synthesis is often realized through sequential polymerization, which can be work intensive and challenging. Here, we demonstrate that blending linear ABC triblock terpolymers with homopolymers is a versatile and straightforward method to tune the microphase behavior in MMs. We systematically blend polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM or PS-b-PB-b-PM) with homopolymers of hPS, hPB, or hPM, to study the feasibility of this approach to replicate specific morphologies or access new ones. We utilize Shirasu Porous Glass (SPG) membrane emulsification and evaporation-induced confinement assembly (EICA) to produce narrowly size-dispersed MMs with defined inner structure. We analyze the MMs with dynamic light scattering (DLS), as well as transmission and scanning electron microscopy (TEM, SEM). We show that the resulting blend morphologies can be identical to those of the unblended SBM at same composition and that, depending on the location in the ternary microphase diagram, one SBM morphology can be converted into multiple different morphologies.

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The study of the aggregation of anionic surfactant, sodium dodecyl sulfate (SDS) with an antibiotic drug, ofloxacin (OFC) has been performed employing conductivity measurement technique in different aq. hydrotropes (HDTs) media. The aqueous solutions of four HDTs (two anionic HDTs (sodium benzoate (NaBenz) and sodium salicylate (NaSal)) and two non-ionic HDTs (p-aminobenzoic acid (PABA) and resorcinol (ReSC))), having different compositions, were used to investigate their effect on the micellization phenomena of the SDS + OFC mixture. The micelle formation of the SDS + OFC mixture has been detected to be reliant on the nature and composition of additives as well as the temperature variation. At lower concentration (1.00 mmol kg⁻¹) of HDTs in aq. media, the CMC values of the working system followed the following order: CMC_PABA > CMC_NaBenz > CMC_ReSC > CMC_NaSal, and the CMC values increased with the rising concentration of HDTs. An increase in temperature at a fixed composition of OFC and HDTs resulted in the elevation of CMC values. The extent of counterion binding (β) values exhibited to be reduced with an increase of both concentration of HDTs and temperature. The negative free energy change (({Delta G}_{m}^{0})) for the micellization processes across all temperatures and investigated media indicates spontaneous micellization. The enthalpy change (({Delta H}_{m}^{0})) of micellization of the SDS + OFC mixture was obtained to be positive (endothermic) and negative (exothermic) at lower and higher temperatures in all media studied. The entropy change ({(Delta S}_{m}^{0})) of micellization is positive even with varying temperatures in all the working additive media. The molar heat capacity (({Delta C}_{m,p}^{0})), transfer properties, and enthalpy-entropy compensation have been evaluated and explained with appropriate reasoning for the examined systems.

For the first time, functionalized okra gum with multi-aldehyde groups (OG-CHO) and carboxymethyl chitosan (CMCh) is used to create injectable hydrogels (IHs) via Schiff base reaction at 37 °C. Gelation time is optimized based on the ratio of aldehyde groups of OG-CHO to amine groups of CMCh (9 ± 3 to 2 ± 1 min). Physical characteristics such as gel content (84 ± 2) and porosity (66 ± 3) are assessed. The syringeability, injectability, and self-healing properties are evaluated qualitatively and quantitatively using a rheometer. Structural analysis is carried out by FT-IR and ¹H-NMR spectroscopy, while surface morphology and pore size (80 ± 5 µm) are examined via SEM. The swelling ratio is studied in the gel state of the IH in phosphate buffer saline (PBS) at varying pH levels of 5.5, 7.4, and 8.5, revealing a decrease in swelling ratio with increasing pH from 5.5 to 7.4 (75 ± 24 to 635 ± 20%), followed by an increase in swelling at pH 8.5 (724 ± 18.5%). Ciprofloxacin is employed as a model drug for release assays, and drug release behavior in gel forms of IH across different wound pH ranges is evaluated. The swelling and drug release behavior is described using the Korsmeyer–Peppas model, which shows non-Fickian diffusion. Furthermore, biocompatibility (cell viability > 90%), antibacterial assay, and in vitro degradation (~ 98%) are also assessed.

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The microplastic pollution caused by traditional agricultural mulch had been revealed. The application of biodegradable mulch is one of the potential ways to solve this problem. Therefore, it is significant to investigate the hydrothermal aging behavior of poly(butylene adipate-co-terephthalate) (PBAT) mulch. In this study, thermoplastic starch (TPS), TPS/talc, and talc-filled PBAT mulch were prepared. A 28-day hydrothermal aging test was conducted, and the mechanical properties, light transmission, water vapor barrier properties, hydrophobic performance, viscosity-average molecular weight, and characterization of the PBAT mulch were detected. The results showed that the original TPS-filled PBAT mulch had excellent mechanical properties, and its tensile strength and elongation at break reached 29.67 MPa and 1166.52%, respectively. The mechanical properties of the PBAT mulch were greatly reduced after hydrothermal aging. Hydrothermal aging would reduce the light transmittance of PBAT mulch to visible light, while the hydrolysis of starch would cause the opposite result. The hydroxyl group in TPS would reduce the water vapor barrier performance of the PBAT mulch. After hydrothermal aging, the viscosity-average molecular weight of the PBAT mulch decreases and the surface of the PBAT mulch was destroyed, which meant that the PBAT mulch was hydrolyzed. FTIR showed that hydrothermal aging could cause the fracture of ester groups. The TG spectral curve showed that the proportion of TPS in PBAT mulch decreased after hydrothermal aging, which meant that TPS was more easily hydrolyzed than PBAT. The results would promote the wide application of PBAT mulch.

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Fused filament fabrication (FFF) is a rapidly growing additive manufacturing technique. It is widely used in various industrial applications due to its ability to efficiently produce functional parts with complex geometrical features. Estimating the mechanical properties and dimensional accuracy is essential for the functional testing of objects fabricated using the FFF process. Several process variables influence the mechanical qualities and dimensional accuracy of objects manufactured using FFF technology. Selecting the optimal set of parameters is crucial for achieving the desired properties in the final parts. This research investigated the influence of four crucial process variables, layer thickness, extrusion temperature, printing speed, and extrusion width, on the impact resistance and shear strength of polycarbonate parts printed using the fused filament fabrication (FFF) technique. A hybrid modelling approach involving dimensional analysis (DA)–based mathematical modelling and regression-based machine learning (ML) modelling was adopted to predict the two output responses and determine the correlation between the process parameters and mechanical properties. A comparison based on various error metrics and the performance of the models suggested that ML models have higher prediction performance and accuracy than DA models. The developed prediction models exhibited significant agreement with the observed values and may be used to forecast the mechanical characteristics of FFF components while manipulating the input parameters. The findings revealed that a maximum impact strength of 66.37 J/m and shear strength of 50.43 MPa were obtained when the layer height, extrusion temperature, printing speed, and extrusion width were 320 µm, 280 °C, 20 mm/s, and 0.56 mm, respectively.

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The combination of conducting polymer and nanogold represents a cutting-edge approach in the development of efficient drug release control systems, particularly leveraging molecular imprinting technology. In this work, a conductive molecularly imprinted polymer (MIP) was electro-synthesized from 1,8-diaminonaphthalene monomers in the presence of amoxicillin as target molecule on gold nanoparticles (AuNPs). AuNPs play a crucial role in supporting the polymerization process and facilitating the characterization of material properties through various analytical techniques. Furthermore, the conductive MIP facilitates fabrication control through electrochemical parameters, enabling the specific and reversible capture and release of amoxicillin. A comprehensive drug release kinetic study was conducted, revealing a significant departure from the conventional release profile of commercial amoxicillin capsules. While typical capsules release the drug over 1 h, our conductive MIP material demonstrated a substantially prolonged release time, extending up to approximately 8 h. This prolonged-release duration holds promising implications for drug delivery applications, potentially offering improved therapeutic outcomes and patient adherence.

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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%.

Graphical Abstract

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