Colloid and Polymer Science最新文献

Abstract

Three direct –NSO₃H functionalized Brønsted acidic ionic liquids of 2-alkyl-1,3-disulfo imidazolium chloride with varied sizes of alkyl substituents (Me-, Et-, nBu-) were utilized to explore the effects of ionic liquids on aggregation behavior of anionic surfactant sodium dodecyl sulfate in aqueous media at various concentrations of ionic liquids and temperatures (288.15 K, 293.15 K, 298.15 K, 303.15 K, and 308.15 K). Critical micelle concentrations (CMCs) of the IL-surfactant systems obtained from conductivity measurement were found to be in good agreement with the CMC values of surface tension and UV–visible spectroscopy techniques. These CMCs values were used to calculate the thermodynamic parameters of IL-surfactant solutions such as standard free energy of micellization (ΔG°_m), standard enthalpy of micellization (ΔH°_m), and standard entropy of micellization (ΔS°_m). Continuous decrease of the CMC values was observed with increasing concentrations of the ILs as well as temperatures. Packing parameters calculated from the surface tension measurement displayed small spherical shape for all the mixed micellar systems. Structural changes of the IL-surfactant solutions were also observed using FT-IR spectroscopic method. Increased positive inductive effect (+ I) of 2-alkyl substituent of the imidazolium cation of ionic liquid showed stabilizing effect on the micelle formation by lowering of more negative zeta potential values of the IL-surfactant systems.

The effects of liquid properties, such as pH and conductivity, on the thermal stability of electrostatically interacting colloidal silica crystals generated from heterogeneous nuclei were investigated mainly by measuring relative reflection spectra. The melting behavior of the colloidal crystals was also investigated. The melting points of both negatively and positively charged 3-aminopropyltriethoxysilane (APS)-treated substrates with different surface charges increased or decreased with increasing or decreasing pH. For both substrates, pH 5.5 was the modulation point of the crystal melting, and the melting point increased with increasing pH. For the negatively charged substrate, the melting point increased slowly as the pH decreased from pH 5.5. Meanwhile, the melting point of the APS-treated substrate increased more with decreasing pH from 5.5 than that of the negatively charged substrate. The cationisation of the substrate increased with decreasing pH, resulting in stronger electrostatic interactions with the negatively charged colloidal crystals and enhanced thermal stability. Next, we investigated the size of colloidal crystal grains in sample bottles for different liquid properties, and the results show that at the higher pH, the smaller crystal grains, indicating that pH affects both the substrates and crystals. Moreover, the binding effect of the APS-treated substrate on the crystals became stronger at lower pH, thereby enhancing the thermal stability of the crystals.

Graphical Abstract

Today, additive manufacturing methods have received attention in various fields due to simplicity of the process, high production speed, as well as good physical and mechanical characteristics of printed parts. In this research, the effect of parameters such as the stacking angle, infill extrusion width, layer thickness, and bed temperature on the tensile strength, tensile force, impact energy, and flexural strength of PLA printed samples was investigated. To achieve the relationship between the input and output variables as well as the optimal conditions of the process parameters, the response surface methodology and the desirability function technique were used. The results showed that the tensile strength, tensile force, impact energy and flexural strength can be improved at stacking angle of 13.5º, infill extrusion width of 145%, layer thickness of 0.2 mm and bed temperature of 110 º C. In addition, when the optimal conditions of the process parameters are applied, the tensile strength, tensile force, impact energy and flexural strength are improved to 38.43 MPa, 1.48 kN, 1.86 J and 32.36 MPa, respectively.

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Abstract

This paper thoroughly examines the complex dynamics of non-Newtonian electro-osmotic flow (EOF) across micro-parallel plates, which is crucial for the advancement of micro-fluidic technology. Our research focuses on investigating the effects of Joule heating and exothermic reactions on flow characteristics and temperature distributions in these systems. The Debye-Hückel approximation and a Nahme-type law are employed to, respectively, model the Poisson-Boltzmann body force and temperature-dependent fluid viscosity. Efficient and robust computational algorithms based on the finite difference methods (FDM) are implemented to obtain the numerical solutions. The solutions are qualitatively discussed, highlighting the sensitivity to variations in various embedded flow parameters. The results of our study demonstrate that the combination of Joule heating and exothermic reactions significantly influences the electro-osmotic flow (EOF), resulting in major variations in fluid velocity and temperature distributions.

In this research work, the authors have presented a water-ethylene glycol-based hybrid nanofluid flow which contains MoS₂ and GO nanoparticles on a stretching surface. The fluid flow has been examined under the consequences of velocity and thermal slip conditions, magnetic field, and exponential heat source/sink. The hybrid-based fluid flow is composed of 50% water and 50% ethylene glycol. The purpose of this investigation is to propose a comparative analysis among the pure fluid, GO nanofluid, and hybrid nanofluid. A suitable set of variables has been used to convert the leading equation to dimensionless notation. The bvp4c Matlab built-in package is utilized to compute a numerical solution of the suggested model. A comparison of the resultant data with published results exhibits a significant agreement. The outcomes of the present work show that GO nanofluid flow has a greater velocity profile than the hybrid nanofluid and base fluid. Temperature panels, skin friction, and thermal flow rate are much greater in the case of hybrid nanoparticles in contrast to single GO nanofluid and base fluid. Further, it has been noticed that the impact of the porosity factor and magnetic and rotation factors drops the velocity distribution, while the opposite impacts of the porosity and magnetic factors have been found on the radial velocity.

Magnetic nanoparticles attached to hydrophilic polymer brushes containing immobilized Fe³⁺ ions were synthesized and used as a new strategy for phosphopeptide enrichment from digested tryptic proteins. To test the performance of nanoparticles in phosphopeptide enrichment, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used. Magnetic nanoparticles with the following features such as high adsorption capacity (about 360 mg/g), easy control and transfer by external magnetic field (high magnetic saturation, about 50 emu/g), excellent phosphopeptide recovery (93.4%) and no shadow effect (due to their non-porous structure), were synthesized. It has been shown that the presence of other proteins in high concentrations does not affect on the performance of nanoparticles. Furthermore, the lowest concentration of digested β-casein phosphopeptides detectable by nanoparticles was determined to be approximately 0.5 fmol µL^− 1. The function of synthesized nanoparticles to enrich phosphopeptides in complex biological samples was also demonstrated by isolating four endogenous phosphopeptides from human serum.

Graphical Abstract

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.

Abstract

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