Colloid and Polymer Science最新文献

Pickering emulsion stabilized by lignin particles has many advantages such as high flexibility, natural non-toxicity, anti-oxidation, and anti-ultraviolet. In order to promote the application of industrial lignin in the field of Pickering emulsions, this study has done comparatively systematic and basic research on Pickering emulsions stabilized by lignin particles. The emulsification effects of lignin particles on cyclohexane and n-decanol which have opposite polarity were compared firstly under different oil-water ratios. It was found that stable emulsions formed when the three-phase contact angle of oil/water/lignin was closer to 90°. The weakly polar cyclohexane could be well-emulsified by lignin particles, while the strong polar n-decanol could not. Cyclohexane was used as the oil phase to discuss the emulsification ability of lignin particles under different concentrations or with different particle sizes. The results show increasing the concentration of lignin particles or reducing the particle size can improve the emulsification performance.

Poly(octamethylene citrate) (POC) is a promising bioelastomer material in tissue engineering field. However, its thermosetting characteristic reveals a big challenge to manufacture fibrous membranes via electrospinning. Herein, an Pickering emulsion, with dimethyl carbonate solution of POC prepolymer (pre-POC) as a dispersed oil phase (o), Pullulan (Pull) aqueous solution as a continuous water phase (w), and chitin nanocrystal (ChiNC) as a particle-type emulsifier, was successfully constructed and electrospun to form POC/Pull core/shell structured fibers, in which the ChiNCs did not merely reside on the core/shell interface, but moved into the POC core layer to reinforce the POC matrix. On the one hand, the core/shell structured fiber mat could be used as a double-layer drug release system to release hydrophilic drugs from outer layer and hydrophobic drugs from core layer. On the other hand, after washing off the Pull shell layer, a pure POC elastomer fiber mat was obtained, of which the mechanical properties were comparable to that of the ChiNC reinforced POC dense films.

In this brief report, omitting the step of dissolving sodium alginate with water, directly mixing sodium alginate powder with calcium chloride powder sufficiently, and gelatinizing sodium alginate by the impregnation method improve the characteristics of sodium alginate gel which is in the form of jelly and has poor mechanical properties. In this paper, micron-sized gel particles were prepared by slow impregnation method using mixed powder of sodium alginate and calcium chloride. The preparation method is simple and low-cost, and can be used for the recovery of rare earth ions from aqueous solutions. The SAG-2 gel prepared at a mass ratio of sodium alginate to calcium chloride of 1:1 showed the best adsorption performance; the particle size varies from 50 to 200 µm. The adsorption capacities of SAG-2 for La(III), Ce(III), Pr(III), and Nd(III) were 334.1, 349.8, 360.1, and 364.5 mg g⁻¹ at pH = 5. The adsorption equilibrium was reached in 35 min. The kinetic study showed that the adsorption process was chemisorption and the adsorption isotherm was well fitted with the Freundlich model. The adsorption mechanism was explored using FTIR and XPS characterization, indicating that both -OH and -COOH functional groups were involved in adsorption. The desorption of rare earths by different eluents was explored and the recyclability of the adsorbent was examined.

The present article deals with the theoretical development of the electrophoresis of core-shell structured soft particles in which the inner rigid core is decorated with a fluid and ion-permeable polymeric shell layer. Note that such a particle resembles several biocolloids (e.g., bacteria, virus, humic acid), functionalized nanoparticles, and environmental entities, to name a few. For such a structured particle, the conventional (zeta)-potential concept loses its meaning, and an extensive theory is required to analyze the electrohydrodynamics of the particle considering the penetration of ionized liquid across the shell layer. Note that the dielectric permittivity of the shell layer is often lower than that of the bulk aqueous medium, which induces the ion partitioning effect. Besides, in several practical situations, the hydrodynamic slipping may occur along the slipping plane. In addition, the slipping plane may not always be located along the surface of the inner core due to grafting of a polymeric shell layer along its surface, and thus, it may be assumed to be located somewhere within the surface polymeric layer. The slipping plane separates two regions with different Brinkman parameters. The region outside the slipping plane the Brinkmann screening length takes a finite value, which allows fluid flow across this region. In the region inside the slipping plane, the Brinkman parameter may practically be equal to infinity, but electrolyte ions still can penetrate this region. Considering all the physical aspects indicated above, we have proposed a simple model to study the electrophoresis of soft particles within the flat-plate regime. Based on the weak charge limit, we adopt the Debye-Hückel linearization to simplify the governing equations, and the explicit form of electrophoretic mobility is derived. Several closed-form analytic expressions are further deduced from the general mobility expressions valid under various limiting situations. We have illustrated our findings graphically to highlight the impact of pertinent parameters on the electrophoretic mobility of such a particle. In addition, we have further provided an estimate of the parametric range in which the particle may attain a zero mobility. Overall, the analytical results presented in this study will be helpful to the experimentalists to analyze their findings.

Graphical Abstract

Hyaluronic acid (HA) is a mucopolysaccharide alternately linked by glucuronic acid and n-Acetylglucosamine as disaccharide units. This study prepared HA derivative (DA-HA) by modifying sodium hyaluronate with dopamine (DA). DA-HA had unique surface activity. By optimizing the reaction conditions systematically, DA-HA could prepare the emulsion with uniform droplets successfully. When n (COOH) /n (EDC) /n (NHS) was 1/2/4, n (HA) /n (DA) was 1/5, the reaction pH was 5.5, and the molecular weight of HA was 1350 KDa, the emulsion particles were relatively uniform. The chemical structure of DA-HA was characterized, and the results showed that DA was grafted on the HA chain through the amide bond. In addition, the effect of formula composition on the emulsifying performance of DA-HA was studied. The particle size of emulsion decreased as the concentration of DA-HA increased. When the oil-water ratio was 4/6 or 5/5, the emulsion droplets were small and uniform. When the aqueous phase was in an acidic or weakly alkaline condition, the particle size of the emulsion was smaller. The introduction of high salinity will destroy the stability of the emulsion. Meanwhile, DA-HA also had good moisturizing property and biosafety, which greatly expanded the application of HA in cosmetics.

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The enormous rise in population, urbanization, industrialization, and improvement in people’s living conditions over the past few decades have led to an increase in the consumption of fossil fuels. While there are several strategies to overcome it, such as afforestation, increasing the number of natural sinks, trapping the produced carbon dioxide in exhausted oil wells, and sorption of CO₂ on absorbers, all of these are only short-term remedies. However, a long-term solution would be conversion of CO₂ into another type of substance. Thereby, reduction of CO₂ to generate short chain hydrocarbons like CH₃OH, CH₄, C₂H₆, etc. can act as a renewable strategy to produce green energy sources. Reduction of CO₂ can be achieved following several pathways which include pyrolysis, chemical-catalysis, electrocatalysis and/or photocatalysis, etc. Among these routes, photocatalytic pathway is more appealing as it is an inherently green approach where solar light can directly convert CO₂ to value-added products. During molecular photocatalytic CO₂ reduction, typically Ru- or Ir-based photosensitizers are commonly used in presence of a cocatalyst. In this context, metal chalcogenides photocatalysts including CdS, CuS, MoS₂, ZnS, ZnTe, and their heterostructures like CdSe/CdS, CdS/CeO₂, etc. are made of earth-abundant metals and have received a considerable attention towards CO₂ reduction due to their notable photocatalytic efficiency. As it is well known, it is nearly impossible to concurrently satisfy the various performances in a one-step excitation system utilizing a single photocatalyst. As a result, the idea of composite photocatalysts which combine the advantages of many materials emerged, and this trend has become essential and foreseeable. This compact review highlights the application and the engagement of metal chalcogenides which due to their unique properties not only helps in the reduction of CO₂ but also plays a vital role in reducing environmental pollution and hence seen as a potential remedy towards the concerned problem.

Graphical Abstract

This compact review highlights the application and engagement of metal chalcogenides which due to their unique properties not only helps in the reduction of CO₂ but also plays a vital role in reducing environmental pollution. Various metal chalcogenides photocatalysts including CdS, CuS, MoS₂, ZnS, ZnTe, and their heterostructures like CdSe/CdS, CdS/CeO₂, etc. are made of earth-abundant metals and have received a considerable attention towards CO₂ reduction due to their notable photocatalytic efficiency.

By enabling the development of complex structures with adaptable qualities, techniques for additive manufacturing have opened new routes for material development and research. In this research, silicon nitride (Si₃N₄) ceramic nanoparticles are incorporated into polypropylene (PP) matrices. Various loading levels and standardized test specimens that adhere to ASTM criteria are created. The main goal is to thoroughly characterize these composites with an emphasis on their mechanical capabilities. The rheological, thermomechanical, and morphological properties of 3D-printed PP/Si₃N₄ composites created using material extrusion (MEX) 3D printing are examined. Thermogravimetric analysis and differential scanning calorimetry are exploited to study thermal stability and phase transitions in composite materials. Mechanical testing is conducted to determine mechanical qualities, such as flexural and tensile strength and modulus of elasticity. For detailed characterization of the nanocomposites, scanning electron microscopy, and Raman spectroscopy are also performed. The results provide insight into the impact of Si₃N₄ nanoparticles on the mechanical properties, thermal stability, and rheological behavior of PP/Si₃N₄ composites. The 2 wt% Si₃N₄ filler showed overall the best performance improvement (21% in the tensile modulus of elasticity, 15.7% in the flexural strength, and high values in the remaining properties assessed). The nanocomposite with the maximum Si₃N₄ loading of wt% showed a 33.6% increased microhardness than the pure PP thermoplastic, showing a promising wear resistance for the parts built with it. This research reveals the ability of Si₃N₄ ceramic nanoparticles to improve the mechanical characteristics of PP-based compounds produced by MEX 3D printing.

Graphical Abstract

Polymer dielectrics possessing the superiorities of easy processing and high power density are widely used in pulsed power and power electronics. However, the low energy storage density (U_e) of polymer dielectrics limits their application in the modern electronic industries. In this work, we present the sea-island structure multilayered composites based on polymethylmethacrylate (PMMA) matrix and polyvinylidene fluoride (PVDF) nanoparticles, which is constructed by the solution blending with typical solubility differences method and the layer-by-layer solution casting method. The PVDF/PMMA composite incorporated with high PVDF content is placed in the middle of the sandwich-structured composite as a non-traditional intermediate polarization layer. The PVDF/PMMA composite with low PVDF loading is placed in the outer layer to improve the insulating property of the composite. The results show that the PVDF/PMMA composites with inner and outer PVDF volume content of 30% and 10%, respectively, obtained an excellent dielectric constant value (ε_r ~ 4.35), which is 45% higher than that of PMMA (ε_r ~ 3). Meanwhile, the maximum U_e (~ 4.95 J cm⁻³) of the PVDF/PMMA composites at an electric field of 422.48 MV m⁻¹ was obtained, which is 207% higher than that of PMMA (U_e ~ 1.61 J cm⁻³). The improved energy storage capability could be attributed to the introduction of highly polarizing particles, the increased number of heterogeneous interfaces, and the multilayered construction of composite. This work provides a strategy for the preparation of advanced all-organic dielectrics with a higher discharge energy density.

In this study, a novel molecularly imprinted polymer (MIP) was synthesized with attapulgite (ATP) and acrylamide (AM) and ethyl methacrylate (MMA) for controlled release carrier of 5-fluorouracil (5-FU). The MIPs (PAM-PMMA) were characterized by XRD, FESEM, HRTEM, and FTIR. The drug loading and in vitro controlled release ability of MIP on 5-FU was investigated by adsorption property analysis and in vitro release analysis. MIPs (PAM-PMMA) reached a maximum drug loading of 12 mg/g and a maximum release of 80% at an ATP dosage of 0.2 g (0.4%), an initial concentration of 5-FU of 100 mg/L, and an adsorption time of 240 min. Cytotoxicity analysis showed that the maximum inhibition of cells could reach 25% at 72 h of cell culture time under the above conditions. The results showed that MIPs synthesized with ATP as the substrate and AM and MMA as the functional monomers were successfully synthesized and could be used as a drug delivery system for 5-FU.

Graphical Abstract

Natural pigment violacein exhibits many pharmaceutical properties which include antimicrobial, anticancer and antioxidant activities. However, limited solubility of violacein in water has restricted its application. Hence, in this study, the violacein nanoparticles were synthesised via sonication technique with the aid of surfactants as dispersing and stabilising agent. Experimentally, the effect of surfactant and violacein concentrations on the production, size and stability of violacein nanoparticles was studied. The location of the violacein in the surfactant micelle was studied using computational study. Violacein nanoparticles were successfully produced at optimized parameters, surfactant concentration of 1 mM, concentration of violacein of 50 µg/mL and sonication time of 10 min. The smallest violacein nanoparticles were 131.5 ± 2.001 nm, with PDI of 0.180 ± 0.018, which indicated a monodispersed violacein nanoparticle distribution. The violacein nanoparticles were stable upon dispersion in water, with a zeta potential of − 49.8 ± 3.49 mV. Violacein was located in the hydrophobic tail region of SDS surfactant micelle after 92 ns. The violet colour of the nanoparticles was maintained at pH from 3 to 11, temperature up to 60 °C and under dark condition, despite its nanoscale size. Higher degradation rate was observed at high temperature and upon light illumination, with k = 6.51 × 10⁻³ h⁻¹, t_1/2 = 106 h and k = 6.75 × 10⁻⁴ h⁻¹, t_1/2 = 1027 h, respectively, following the first-order kinetics. As conclusion, the violacein nanoparticles were able to be produced using water as a medium for green approach, and the nanoparticle colour remained stable at various conditions. This study provides an insight into the molecular mechanism of violacein-surfactant interaction for its solubility and stability in water.