Volume 62, Issue 3

Nanomaterials with precisely controlled size and shape have attracted considerable attention over the past two decades due to their diverse applications in pharmaceuticals, oil recovery, energy production and storage, wastewater treatment, and advanced magnetic devices. Among the various synthesis techniques, water-in-oil (W/O) microemulsions have emerged as a superior strategy for the preparation of nanoparticles with well-defined morphology and minimal aggregation. These self-assembled colloidal dispersions act as nanoscale reactors, offering exceptional control over nanoparticle growth and structural evolution. This review critically examines the role of W/O microemulsions in tailoring nanoparticle size, geometry, and crystallinity by modulating key physicochemical parameters such as surfactant architecture, cosurfactant-to-surfactant molar ratio, and water-to-surfactant molar ratio. The influence of surfactant head group charge, hydrophobic tail length, and cosurfactant selection on nanoparticle synthesis is systematically analyzed, highlighting the versatility of anionic, cationic, and nonionic surfactants. Despite significant progress, critical gaps remain, including the underutilization of ionic liquid-based microemulsions and the limited exploration of amines as cosurfactants. Additionally, the potential of biosurfactants as sustainable alternatives for nanoparticle synthesis remains largely untapped. By consolidating extensive research findings, this review provides a comprehensive framework for optimizing W/O microemulsion systems and offer valuable insights for future advances in nanomaterial synthesis and applications.

The oxidation of amino acids is interesting due to the different molecules generated by different oxidants. This research is crucial to understand the role of amino acids in redox processes and to identify the active species of Ru(III) and diperiodatocuprate(III) (DPC). The purpose of the present research is to analyze the effect of cationic surfactant on the Ru(III) catalysed oxidation of l -tyrosine ( l -Tyr) by DPC. The progression of the reaction was evaluated using the pseudo-first-order scenario as a metric for [OH − ], [DPC], ionic strength, [ l -Tyr], [Ru(III)], [IO 4 − ], [surfactant], and temperature. Over the range of concentrations studied, the observed reaction exhibits a kinetic order less than one with respect to both [OH − ] and [ l -Tyr], a negative fractional order with respect to [IO 4 − ], and a first-order dependence on [Ru(III)] and [DPC]. The observed constancy of the oxidation rate with electrolyte addition suggests a zero salt effect. The oxidation rate is markedly increased by Ru(III) solution acting as a catalyst at ppm concentration. The micellar media of cetylpyridinium chloride (CPC) significantly accelerates the rate of the desired reaction, achieving a fourfold increase. The compatibility of CPC with Ru(III) for the oxidation of l -Tyr using DPC is particularly noteworthy.

This study investigates the novel interaction dynamics between the biosurfactant rhamnolipids, saponin (reetha or sapindus saponin), and the conventional surfactant cetylpyridinium chloride (CPC) with the anionic organic dye, Xylenol Orange (XO), in aqueous micellar media. Absorption spectroscopy revealed the strong interactions between XO and CPC, especially in the premicellar concentration range. The formation constants for the dye-surfactant complexes were calculated, shedding light on the nature and strength of these interactions. A comprehensive analysis using DLS, SEM, zeta potential measurements and surface tension experiments further confirmed the complexation, with CPC exhibiting robust electrostatic interactions with XO, as indicated by notable changes in hydrodynamic size and surface morphology. In contrast, saponin exhibited much weaker interactions with XO, as evidenced by minimal spectral shifts and slight increases in hydrodynamic size. Rhamnolipids, which exhibited intermediate interactions, formed weaker complexes than CPC, but stronger than saponin. The study clearly demonstrates that CPC-XO interactions are the most efficient for complex formation, positioning CPC as the optimal choice for applications targeting XO removal from aqueous solutions. This research significantly contributes to the development of sustainable surfactant-based solutions for environmental management and highlights CPC as a key player in the extraction and removal of dyes from contaminated water.

A series of nonionic surfactants, polyoxyethylene(n) monodehydroabietates (PEGylated DHAAs), were synthesized by an addition polymerization reaction between dehydroabietic acid (DHAA) and ethylene oxide (EO). The structures of PEGylated DHAAs were characterized by FTIR, UV–Vis and 1 H NMR, and their hydrophilic-lipophilic character and surface activities were evaluated by water titration and surface tension measurement, respectively. Meanwhile, the degree of polymerization of the PEG chain in the structure of PEGylated DHAAs was determined according to the results of 1 H NMR analysis, and its influence on the hydrophilic-lipophilic character and performance of the surfactant in aqueous solution was systematically investigated. The experimental results showed that the degree of polymerization of the PEG chain has a significant influence on the hydrophilic-lipophilic character, the critical micelle concentrations (CMCs) of PEGylated DHAAs and their surface tensions at CMC ( γ CMC ), while it had little effect on their minimum of surface tensions ( γ min ).

Organic montmorillonite, a typical clay mineral, has been used as a high temperature grease thickener. Although naturally occurring montmorillonite (MMT) is commercially available, a readily synthesizable alternative is needed to achieve uniform elemental composition and controllable physical and chemical properties. Synthetic MMT with a crystal structure similar to that of naturally occurring MMT was prepared by a one-step hydrothermal method. Different organic MMT samples were subjected to alkyl chain intercalation by dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride and octadecyl trimethyl ammonium chloride (OTAC-MMT). Synthetic MMT greases were prepared using the four alkyl chains intercalated organic MMT samples as thickeners. Due to the longest alkyl chain of OTAC, OTAC-MMT with the smallest particle size had the most different arrangement of interlayer molecules, the largest basal spacing, the highest hydrophobicity and the highest organic content. The rheological behaviour and tribological results showed that OTAC-MMT grease had the best mechanical stability, colloidal stability and thermal stability among the four synthetic MMT greases. In addition, OTAC-MMT had stable and good anti-wear and anti-friction properties under high temperature and high load conditions. This study is expected to promote the expansion of synthetic MMT applications in grease manufacturing and related potential applications in the near future.

A novel, pH-sensitive ‘fatty acid-amino acid conjugate’ (L-arginine oleoyl acid amide) was synthesized. The conjugate was evaluated for its suitability as a carrier in the development of a biocompatible and pH-responsive vesicular system for tumor-targeted delivery of pazopanib hydrochloride (PHC). Prepared vesicles exhibited high drug encapsulation efficiency (83.3 %) and a pH-dependent phase transition at the acidic pH of the tumor microenvironment. Formulated vesicles showed a high rate of PHC release in the acidic media (pH 5 > 6.8 > 7.4) similar to the pH of the tumor site, indicating more accurate and selective drug delivery. The vesicles showed a PHC concentration-dependent effect on the viability of ACHN/A498 human renal cancer cells and significantly high intracellular uptake of PHC (83.07 %). Therefore, the developed pH-activated vesicular drug delivery system with predetermined fatty acid-amino acid composition in conjugate could serve as a promising controlled and targeted delivery approach for PHC and other anticancer drugs.

An economically viable route towards doubled headed alkyl triazole glycoside surfactants (ATG) is reported. The approach applies common industrial precursors leading to reasonable product yields. The interface-dominating hydrophilic domain favors curved assemblies over lamellar analogs, thereby enhancing the water solubility of the surfactants. In terms of assembly behavior, the double headed ATG matched corresponding chain analogs of alkyl polyglucosides (APG), thereby implying a compensation of the triazols’ hydrophobic effect by the parallel head groups. Likewise, the foaming behavior matched ATG analogs, suggesting comparable application potential. Differing emulsion behavior of Y-shape ATGs suggests π-stacking cohesion between triazoles with C 3 -spacer, whereas a shorter C 2 linker prevents these, leading to better emulsion stability, reflected in substantially smaller droplet size for oil-in-water.

The problem of excessive foam in industrial production and everyday chemical processes causes significant problems, including compromised product quality, equipment damage and waste of water resources. Undoubtedly, the use of low-foaming surfactants represents a highly effective method to control foam formation. In this work, we have developed two novel silicone-based surfactant molecules by combining hydrosilylation reactions with metathesis reactions. These molecules use allyl diglycol carbonate, trisiloxane, sodium bisulfite and calcium chloride as primary reactants. Sodium trisiloxane sulfonate (TSS) was synthesized by hydrosilylation and sulfonation reactions, followed by a metathesis reaction with calcium chloride to form calcium trisiloxane sulfonate (TCS). The structures of the target products were characterized by FTIR and 1 H NMR. Analysis of interfacial properties showed that both surfactants have excellent surface activity, with a minimum surface tension of 22 mN m −1 for TSS. Foam performance tests showed that these two surfactants have good foam disrupting and suppressing properties in three foam systems: anionic SDBD, cationic CTAB and non-ionic AEO-9. Therefore, these two structures have the potential to be developed into defoamers to meet complex industrial challenges.

In this study, the grinding and flotation of quartz were conducted in the presence of either a quaternary amine (QA) as a cationic surfactant or sodium dodecyl sulfonate (SDS) as an anionic surfactant. Both reagents were investigated to determine their suitability for sequential use as a grinding aid and a flotation collector. The results showed that although SDS was not an effective collector for quartz, it performed better than QA as a grinding aid. In contrast, the quaternary amine is efficient in both grinding and flotation. The effectiveness of SDS as a grinding aid is attributed to its ability to provide higher dispersion, which allows direct particle-grinding ball collisions to result in better grinding. However, the contamination of the quartz surface by cations, such as iron, which are predominantly present in a grinding mill, increases the floatability of quartz when SDS is used at the expense of its effectiveness as a grinding aid, as the dispersion becomes minimal. On the other hand, while the chemical affinity of QA to the quartz surface improves its flotation performance but slightly reduces the dispersion status.

In this work, Curcuma longa L. essential oil (CEO) was loaded into the modified chitosan/hydroxyapatite (PMCH) biomimetic material and the PMCH/CEO was characterized by FTIR, SEM, XRD and BET. The main components of CEO were ar-tumerone (21.97 %), ar-curcumene (13.00 %), β-sesquiphellandrene (13.00 %) and curlone (8.57 %), which was analyzed by GC-MS. The stability of PMCH/CEO was investigated at different relative humidities (33 % and 96 %) and temperatures (60 °C and 80 °C) conditions. The ability of CEO and PMCH/CEO to scavenge DPPH radicals and ABTS radicals is used to evaluate the antioxidant acivity. The concentration of the sample was determined by the CCK-8 method, and the lipopolysaccharide-induced RAW264.7 cell inflammation model was established to evaluate the anti-inflammatory effect. CEO and PMCH/CEO showed good antioxidant activity. CEO and PMCH/CEO also had significant inhibitory effects on NO, IL-6 and TNF-α, and the inhibition rates were 85.62 %, 55.82 % and 27.7 %, respectively. This study shows that CEO-loaded PMCH has potential development prospects in food, medicine and other related fields.