Colloid and Polymer Science最新文献

Three kinds of multiblock polyethylene oxide-polypropylene oxide (PEOm-PPOn for short) were synthesized using ethylene glycol as the initiated core via the living anionic polymerization. Respectively, the multiblock polyethers were named E340, E540, and E740 based on the block number (3, 5, 7) and the content of ethylene oxide (EO, 40 wt%), which were confirmed by the Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC). Moreover, their bulk and solution properties, including dynamic modulus, rheological characteristic, viscosity, aggregation behavior, surface tension, steady-state fluorescence, solubility, and microemulsion performance were determined. The test results of rheological properties showed that these multiblock copolyethers behaved as the pseudo-plastic non-Newtonian fluids. Furthermore, it was found that their solubility and surface tension were gradually decreased with an increase of block numbers. Nevertheless, the dynamic modulus tended contrary trends. Research on the aggregation and micro-emulsion properties in aqueous solutions indicated that the value of critical micelle concentration (CMC) increased, and meanwhile the ability of solubilization and micro-emulsion formation deteriorated with increasing block numbers. In conclusion, their aggregation mechanism in aqueous solution was also given.

Graphical Abstract

An investigation is proposed for the Buongiorno model nanofluid flow within a converging as well as diverging channel which is inclined with the plane walls. The impact of magnetization is reported for the imposed of applied magnetic field along the normal direction of the flow. Additionally, the behavior of thermal radiation and the effect of binary chemical ration are implemented in the energy and concentration equation respectively. It is superimposed that both the channel walls are uniformly heated, and it is also assumed that concentration of the nanoparticles near the walls is considered as constant. However, the Cartesian coordinate system is imposed to describe the proposed designed flow problem. The formulated problem governed by nonlinear coupled partial differential equations is generalized and renovated to corresponding nondimensional form by implementing appropriate similarity rules. Further, the transformed equations are solved numerically using Runge-Kutta fourth order accompanied by shooting technique. The physical behavior of the standard factors involved in the problem is displayed graphically. Validation of the result is presented with an earlier study which shows a good correlation as well as convergence analysis of the proposed methodology. Further, the important outcomes of the proposed study are deployed as follows: the velocity distribution retards for the enhanced Reynolds number significantly; however, the Brownian motion is treated as a controlling parameter for the fluid temperature and reverse impact observed in case of fluid concentration.

Graphical Abstract

• The Buongiorno model nanofluid flow within a converging and diverging channel inclined with the plane walls is analysed.

• The behaviour of not only thermal radiation but also the effect of binary chemical ration is implemented.

• It is superimposed that both the channel walls are uniformly heated and it is also assumed that concentration of the nanoparticles near the walls is considered as constant.

• The transformed equations are solved numerically using Runge-Kutta fourth-order accompanied by shooting technique.

To investigate the impact of plasticizer functional groups on starch plasticization, three distinct plasticizers were selected in this study: ethylene glycol (EG), ethylenediamine (EDA), and ethylenebisformamide (EBF). Three models of the plasticizer/starch system were constructed using molecular dynamics (MD) simulations, and the analysis encompassed the computation of mean square displacement (MSD), radial distribution function (RDF), and hydrogen bonding energy for each system. Additionally, the proportions of simulation were used to prepare thermoplastic starch films, which were subsequently subjected to examinations such as DSC, XRD, FT-IR, SEM, and mechanical property testing. Comparative analysis of the simulation data from the three systems and the properties of the manufactured thermoplastic starch (TPS) established that the diverse functional groups of plasticizers significantly influenced starch plasticization. In different plasticizer functional group types, it was observed that hydroxyl groups in EG and amino groups in EDA predominantly form hydrogen bonds with hydroxyl groups in starch molecular chain. In contrast, amide groups in EBF can establish hydrogen bonds not only with hydroxyl groups of starch but also with ether bonds on the starch main chain, thereby resulting in more effective starch plasticization.

Graphical Abstract

To improve the efficiency of hydrophilic polymers in oil reservoirs, a method encapsulates the polymer within a protective shell, safeguarding the core polymer and enabling controlled release in demanding, high-temperature conditions. Poly(N-isopropylacrylamide) nanoparticles are encapsulated with polystyrene shells through emulsion polymerization in this study. Varying the amounts of shell monmer and crosslinking agents resulted thick, sphere-shaped shells with homogeneous morphology, which protects the core polymer and enabling controlled release. Structural and morphological properties are characterized using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (H¹NMR), dynamic light scattering (DLS), and scanning electron microscope (SEM) imaging. Increasing the styrene amounts lead to larger particles, while higher crosslinker amounts result in a narrower size distribution. Thermal testing indicates heat resistance up to 300 °C, suitable for enhanced oil recovery (EOR) applications. Rheological tests determine an optimal 30-day release for the PNIPAM core, with the CS polymer showing increased viscosity under harsh conditions. The colloidal stability model estblished by Derjaguin, Landau, Verwey, and Overbeek (DLVO theory) and experimental results demonstrate good stability and energy barriers at room temperature, but decreased stability and increased agglomeration at higher temperatures. Thickening the styrene shell leads to particle agglomeration and unsuitable stability. The study confirms the effectiveness of the model in analyzing CS colloidal latex systems.

Graphical Abstract

We embarked on an investigation with potential implications for studying blood flow within the cardiovascular system; keeping this application in mind, this investigation aims to provide numerical evaluations for a complex problem involving MHD flow, chemical reactivity, and energy transfer of a Maxwell fluid within a channel. The governing equations for momentum, concentration, and energy are renovated into ODEs for concentrated analysis using a similarity transformation. Dimensionless velocity, temperature, and concentration fields corresponding to steady motions of Maxwell fluid over a channel are numerically recognized using the bvp4c inbuilt software in MATLAB. We validated our results with existing work to check the gained results and got an excellent agreement. The impression of physical parameters on fluid motion is plotted and debated. The quantitative outcome of this study is that the Deborah number surges, and both velocity and temperature experience enhancement while the concentration within the fluid diminishes. This knowledge can be applied to various fields, such as material processing, biomedical engineering, and environmental sciences, to optimize processes and design systems accordingly. The outcomes and key findings of this study indicate that concentration distribution declines with the introduction of a chemical reaction and a complex Schmidt number. Additionally, the quantitative results of this learning are that the impression of the magnetic parameter is observed, resulting in reduced velocity and temperature profiles, while concentration profiles exhibit an increase across the entire domain. Furthermore, the rise in the Reynolds number corresponds to an escalation in the temperature outline.

Graphical Abstract

Copper is abundant and has good conductivity, corrosion resistance, and malleability. These properties affect the behavior of nanofluids by contributing to the interaction between nanoparticles and the magnetic field. This work aims to assess the thermal transfer characteristics of a Cu-water nanofluid filled in an enclosure having vertical wavy walls under the influence of natural convection. The system also experiences the existence of a constant inclined magnetic field and features an inner heated rectangular baffle. In this study, a comprehensive analysis is conducted on several thermo-physical parameters, including the Rayleigh number (({10}^{3} le {text{Ra}} le {10}^{5})), Hartmann number ((0 le {text{Ha}} le 150),) nanoparticle concentration ((0.00 le phi le 0.09),) and porosity ((0.2 le varepsilon le 0.8)). The Galerkin finite element method (GFEM) is employed in this study to conduct calculations, enabling a comprehensive analysis of streamlines, isotherms, entropy generation, and mean Nusselt numbers. The key findings demonstrate that raising the number of Rayleigh and porosity raises the velocity profile within the enclosure. For the various angles of the inner rectangular baffle ((theta =0^circ ,30^circ ,60^circ ,mathrm{ and} 90^circ )) at ({text{Ra}}={10}^{3}- {10}^{5}), the calculated maximum increase in ({{text{Nu}}}_{{text{avg}}}) are (77.5%, 78.3%), (81.9% ,) and (82.2%,) respectively. Furthermore, significant rise in the value of (({S}_{{text{Total}}})) up to (96.1%, 11.1%), and (8.8%) is experienced when (left(Raright), left(phi right),) and ((varepsilon )) increase, while (19.5%) decrement is observed when (({text{Ha}})) increases. Additionally, the average Bejan number (({{text{Be}}}_{{text{avg}}})) grows as the fraction volume of nanoparticle ((phi )) climbs and the Hartmann number (({text{Ha}})) declines. The geometry configurations employed in this research have real-world applications across different engineering fields, such as energy storage, chemical processing equipment, biomedical systems, solar collectors, heat exchangers, and cooling systems for electronic devices.

In this work, the morphology of zirconia, alumina, and silicas was studied, and static sorption of the repellents N, N-diethyl-3-methylbenzamide and ethyl-3-[acetyl(butyl)amino]propionate on these oxides was carried out. ZrO₂, Al₂O₃, and SiO₂ phenyl were shown to have high sorption activity to the repellents N, N-diethyl-3-methylbenzamide (239 mg/g for SiO₂ phenyl) and ethyl-3-[acetyl(butyl)amino]propionate (251 mg/g for ZrO₂). Pointedly, it was found that despite having the largest pore volume and high specific surface area (compared to the other studied oxides), SiO₂ C2 has a significantly inferior sorption capacity in respect to other oxides, in particular SiO₂ phenyl, which can be explained by the presence of the phenyl group in the latter that has chemical affinity for repellent molecules. Obtained isotherms of SiO₂ 300 also confirm the low sorption activity towards N, N-diethyl-3-methylbenzamide. The sorption equilibrium for both repellents, in most cases, is described by the Langmuir monomolecular adsorption model. The obtained results suggest that the studied zirconia, alumina, and silica can be used as carrier components of repellents.

Graphical abstract

The interactions of polyelectrolyte poly (sodium styrene sulfonate or NaPSS) and anionic surfactants, sodium glycodeoxycholate (SGDC) and sodium tetradecyl sulfate (STS), as well as their combination (SGDC + STS) at different mole fraction ratios, were investigated using surface tension analysis. In the SGDC + STS binary mixture, when the amount of NaPSS (0.005–0.03%) increased from ({alpha }_{{text{SGDC}}}) 0.0 to 1.0, increasing the critical micellization concentration (cmc) of the mixtures. The minimum cmc values were found from 0.833 to 1.480 mmol L⁻¹ in the presence of 0.03% of NaPSS. Clint, Rubingh, Motomura, and Rodenas approaches were used to evaluate the ideal cmc, activity coefficients (f_i), interaction parameter (–β), micellar compositions (x), and ideal micellar composition of (x^id) of SGDC + STS mixtures. Synergism has been demonstrated by the experimental values of c_0m being lower than the ideal values in water. Moreover, by adding NaPSS from 0.005 to 0.03%, the synergism interaction was eliminated and antagonism behavior was developed. The standard Gibb’s free energy of micellization (({Delta G}_{m}^{0})) and surface excess (Γ) and surface area per absorbed molecules (A_min) was decreased or increased depending on NaPSS amount in the SGDC + STS mixture with varying ({a}_{{text{SGDC}}}).

In this research, hydrogels based on chitosan, pectin, and salt (NaCl) were synthesized through the formation of polyelectrolyte complexes (PECs). The synthesis parameters, including pH, salinity, and polymer concentration, were varied to explore their influence. Weight and texture analysis revealed differences in hydrogel morphology. Swelling behavior studies showed hydrogels synthesized at pH 4 exhibiting higher swelling capacities. Additionally, the presence of salt affected the formation process. Thermal characterization showed a first decomposition step occurring around 180–224 °C. Morphological testing using SEM highlighted differences in pore size and distribution, notably when salt was included in the formulation (pore wall diameter without NaCl, 2.2 ± 1.1 um, with NaCl, 4.7 ± 1.2 um). Physico-chemical tests, including Zeta potential, FTIR, and XRD, provided insights into interactions within the hydrogels: hydrogen bonds and electrostatic interactions. Moreover, antibacterial tests demonstrated efficacy against Escherichia coli and Staphylococcus aureus, with varying inhibition degrees correlated with NaCl content (halo for E. coli without NaCl, 8 and 10 mm; with NaCl, 10 and 15 mm). Further assessments, including water vapor transmission rate (WVTR) and lidocaine release assays, highlighted hydrogel potential for wound dressing applications, with suitable moisture retention properties and controlled drug release capabilities. The release percentage achieved by the hydrogel with 0.15 M NaCl was higher than without salt (111.1% ± 9.5% and 31.16% ± 15.13%, respectively). Preliminary in vivo wound healing studies showed promising results. Overall, our findings emphasize the tunable properties of these hydrogels and their potential for wound dressings.