Colloids Interfaces, Volume 9, Issue 6 (December 2025) – 11 articles

A detailed investigation of the structure–property relationships of three-antennary oligoglycines in aqueous solutions is performed. Two representatives of these substances are investigated: CH₃C(-CH₂-NH-Gly₅)₃ and CH₃C(-CH₂-NH-Gly₇)₃. The aim is to clarify the effect of molecular peculiarities and the concentration of the oligoglycines on bulk-solution performance and on adsorption-layer properties at the solution–air interface. This study is focused on the clarification of the conditions for the onset of bulk and interfacial supramolecular species in the aqueous environment. The presence of oligoglycine antennae attached to a common carbon-atom center allows the formation of highly coordinated intra- and intermolecular ‘click-clack’ interactions and presumes the possibility for the development of extended H-bonded networks, e.g., in the form of Polyglycine II motifs. A combined study protocol, including dynamic light scattering, profile analysis tensiometry, and microscopic thin-liquid-film techniques, is applied. The results allow the drawing of essential conclusions about the possible coupling mechanism of bulk and interfacial phenomena. The outcomes give grounds to advance the following hypothesis: due to the synchronized action of noncovalent interactions, three types of tectomeric structures may appear—dimers, gel-like elements, and disk-like supramolecular entities. Options for fine-tuning of the tectomer formation in aqueous solutions are presented, and possible application routes are outlined. Full article

This study systematically compares how three counterions (Na⁺, K⁺, NH₄⁺) regulate the interfacial properties, foaming behavior, and foam stability of lauroyl glutamate (LG) surfactants, and further examines how added NaCl modifies these properties in the sodium salt (SLG). The three counterions induce only slight variations in surface activity and foam generation. Their influence is more evident in foam stability, with the sodium salt exhibiting enhanced stability across a wider concentration range. For SLG, NaCl addition markedly lowers the critical micelle concentration and induces concentration-dependent changes in foaming behavior: 1% NaCl enhances foam generation, while higher salt levels diminish this effect. Foam stability is strongly affected in the sub-cmc regime, with 3% NaCl producing the most stable foams. Surfactant concentration and salt content are the main factors affecting foam performance. Full article

This study investigates the apparent surface-active and emulsifying behaviour of raw Albizia amara (AA) powder suspended in water, reflecting its traditional mode of use. AA suspensions (0.1–1% w/v) were prepared without extraction and evaluated for apparent surface tension, droplet size distribution, emulsification capacity, and emulsion stability. Increasing AA concentration reduced apparent surface tension from 57.13 ± 2.17 mN/m to 48.9 ± 0.06 mN/m, plateauing at higher concentrations. Both blending and high-shear mixing produced oil-in-water emulsions. Blending generated smaller initial droplets (1–10 µm), whilst high-shear mixing produced more uniform distributions (d₅₀ = 31.23 ± 0.95 µm). Emulsion capacity and stability increased with AA concentration, reaching 95.19 ± 3.39% and 89.81 ± 0.02% at 0.8% AA. As the system contains undissolved plant material, all measurements represent the apparent behaviour of a heterogeneous suspension. The specific molecular contributors to surface activity cannot be identified within this study. These findings provide a baseline physicochemical assessment of raw AA powder and support future work involving extraction, purification, and chemical characterisation to establish the mechanisms underlying its surface-active properties. Full article

The functional characteristics of Partial acylglycerols (PAGs) have attracted the attention of researchers in designing PAGs for food applications as a potential substitute for conventional fats/oils. Designing PA using enzymes has been of great interest due to the greater specificity of enzymes, giving high-quality products for food applications. The utilization of PA in fat-based products, such as bakery, dairy, and emulsion foods, exhibits superior functionalities and health-friendly characteristics. The PA can also be used for cooking/frying applications. However, exposure of PA to a higher temperature for a longer time shows inferior characteristics. The functional characteristics of PA, such as solid fat content, rheology, microstructure, crystal formation, and thermal behavior, make it a potential replacement for conventional fat. The present review focuses on a comparative assessment of synthetic routes, the functional characteristics of PA, food applications, and technological drawbacks in commercializing PA-based products. Furthermore, the future prospect focuses on supporting future research that will facilitate the incorporation of PA in food products at an industrial scale. Full article

Proton binding (i.e., charging) isotherms of halloysite nanotubes (HNT) were determined from cycled acid-base potentiometric titrations in KCl solution at constant ionic strengths (0.01, 0.10, 1.00 mol dm⁻³). The isotherms measured in the pH cycle from 3 to 11 and back exhibit a pronounced hysteresis with respect to the direction of pH change, which is accurately reproducible when the cycle is repeated. The hysteresis is absent if the cycled titration is performed within a narrow pH range between 5 and 9. These results align with the dissolution rates of alumina and silica, which form the two surfaces of the rolled kaolinite sheet in HNT, and clearly point to reversible partial dissolution-deposition processes in the HNT interior during a titration cycle, outside the above pH range (alumina dissolution below pH ≈ 5 and silica dissolution above pH ≈ 8.5). In the studied titration experiments, these processes produce partially dissolved surface-bound, rather than completely dissolved species (reversible surface etching). Under the applied conditions, reversible surface etching is less pronounced in the acidic part of the titration cycle. Charging isotherms recorded in the decreasing pH titrations at varied ionic strength exhibit a common intersection point very close to zero charge (point of zero charge) around pH ≈ 8.1, characteristic for an amphoteric solid surface. These isotherms were reasonably well fitted by applying the surface protonation model in the HNT interior, which invokes the Stern model of the electric double layer (EDL), by summing the surface charges calculated for alumina and silica as separate components (surfaces). The model surface charge isotherms for alumina surface in the HNT interior exhibit a point of zero charge at pH = 9.0, while the silica surface has a negative charge above pH > 8.5, which is in very good agreement with the values reported in the literature: as for these two surfaces, thus for kaolinite nanoparticles. The best-fit protonation site density for both surfaces is equal to 8.0 nm⁻², while the best-fit intrinsic pK_a for alumina and silica surfaces of HNT are equal to 9.0 and 8.5, respectively. The pH-dependence of electrophoretic mobility, measured by means of electrophoretic light scattering, reveals a more acidic behavior of the outermost silica surface than within the inner HNT phase, which is consistent with the literature result reported for kaolinite. The results reported herein confirm that the inner and outer surfaces of the HNT are oppositely charged below pH < 8.0 and negatively charged above that value, and importantly, they reveal new details about the protonation affinities and EDL parameters at active surfaces of HNT, important for the colloidal stability of HNT suspensions and the functionalization of HNT through the electrostatic binding of active molecules. Full article

The aim of this study was to investigate the nucleation, growth, and surface deposition of poly(2,2,2-trifluoroethyl methacrylate) [poly(TFEMA)] from the one-phase, cloud point, and two-phase regions of a supercritical CO₂–toluene solvent. A ternary mixture of 20 wt% toluene + 79 wt% scCO₂ + 1 wt% poly(TFEMA) at 40.0 °C was exposed to a fluorine-doped tin oxide (FTO) surface for 30 min at pressures placing the solution in (i) a one-phase region (15.86 MPa), (ii) the cloud point (12.37 MPa), and (iii) a two-phase region (8.96 MPa). Using the Altunin–Gadetskii–Haar–Gallagher–Kell (AG–HGK) equation of state (EOS), the corresponding CO₂ densities are 793.9, 729.2, and 477.8 kg m⁻³. Scanning electron microscopy (SEM) and particle-size analysis (sample sizes N = 852–1177) show particle-size distributions (PSDs) that are well described by the following lognormal form: the mean diameter increases monotonically with a decrease in pressure (1.767 μm → 2.605 μm → 2.863 μm), while dispersion tightens slightly near the cloud point (coefficient of variation, CV: ≈0.47 → 0.44) and then broadens strongly in the two-phase region (CV ≈ 1.02). Morphologies transition from sparse, compact islands (one-phase) to agglomerated, necked spheres (cloud point) and finally hierarchical populations containing hollow/pitted large particles (two-phase). These outcomes are consistent with a phase-state-controlled shift in nucleation pathways, as follows: from heterogeneous surface nucleation in the one-phase regime to homogeneous nucleation with agglomeration at the cloud point, and to homogeneous nucleation with coalescence and solvent capture in the two-phase regime. The results provide a mechanistic basis and practical design rules for pressure-programmable control of fluoropolymer coatings prepared from scCO₂/aromatic-cosolvent systems. Full article

This study investigated the flotation performance of W8, a blended xanthate collector containing ethyl, butyl, propyl, and amyl xanthates, combined with ammonium dibutyl dithiophosphate (ADD) for treating low-grade arsenopyrite-type gold ore from Golmud, Qinghai. Real ore flotation tests demonstrated the superior efficacy of the W8 + ADD system, achieving 84.06% gold recovery with 0.34 g/t tailings, outperforming conventional sodium amyl xanthate (SAX) + ADD and sodium propyl xanthate (SPX) + ADD systems. Systematic studies on pure arsenopyrite revealed a significant synergistic effect in the mixed SPX-SAX system (1:4 ratio), representative of W8 composition. At pH 9, the mixed collector achieved 73.5% recovery, substantially higher than individual SPX (37.5%) or SAX (45.8%). This enhanced performance was attributed to improved surface hydrophobicity (contact angle 47.68° vs. 36.92° for SAX), greater adsorption density (4.97 × 10⁻⁷ mol/g under depressant conditions), and extensive formation of molecular aggregates observed via AFM, which increased surface roughness to 28.95 nm. Flotation kinetics further confirmed the advantage of W8 + ADD, which reached 72.1% cumulative recovery in 420 s, exceeding both mixed SPX/SAX (69.5%) and single SAX (65.5%) systems. The synergistic interaction among different xanthate components in W8 enables efficient recovery of gold from this refractory ore. Full article

Carboxymethyl chitosan (CMCS) is ideal for active packaging due to its non-toxicity and degradability, but its poor film-forming performance (strong hydrophilicity, weak mechanical properties, and low antibacterial activity) limits practical use. This study prepared a new edible antibacterial presFervation film (SDEWL-CMCS) by adding salted duck egg white lysozyme (SDEWL) to CMCS (as the film-forming substrate). It investigated how SDEWL concentration affects the composite film’s properties (thickness, water solubility, moisture/oil resistance, mechanical properties, and antibacterial activity) and tested the film’s preservation effect on small nectarines. The results showed the composite film had significantly improved packaging and antibacterial properties: compared to pure CMCS film, it had higher tensile strength, lower water solubility, better oil resistance and water vapor barrier performance, and stronger antibacterial activity against Escherichia coli and Staphylococcus aureus (larger inhibition zone diameters). The SDEWL-CMCS film effectively preserved small nectarines by inhibiting surface bacteria, regulating the preservation environment, and delaying fungal decay. This study confirms the film’s potential as a sustainable fruit packaging alternative, providing a theoretical basis for developing new fruit/vegetable preservation packaging and reducing the food industry’s reliance on non-degradable petroleum-based packaging. Full article