Low Critical Micelle Concentration Research Articles

Effect of surfactant's charge properties on behavior, physiology, and biochemistry and the release of microcystins of Microcystis aeruginosa

Surfactant pollution is escalatitheng in eutrophic waters, but the effect of surfactant charge properties on the physiological and biochemical properties of toxin-producing microalgae remains inadequately explored. To address this gap, this study explores the effects and mechanisms of three common surfactants―cetyltrimethylammonium bromide (CTAB, cationic), sodium dodecyl sulfate (SDS, anionic), and Triton X-100 (nonionic)―found in surface waters, on the agglomeration behavior, physiological indicators, and Microcystin-LR (MC-LR) release of Microcystis aeruginosa (M. aeruginosa) by using UV-visible spectroscope, Malvern Zetasizer, fluorescence spectrometer, etc. Results suggest that charge properties significantly affect cyanobacterial aggregation and cellular metabolism. The CTAB-treated group demonstrates a ∼5.74 and ∼9.74 times higher aggregation effect compared to Triton X-100 and SDS (300 mg/L for 180 min) due to strong electrostatic attraction. Triton X-100 outperforms CTAB and SDS in polysaccharide extraction, attributed to its higher water solubility and lower critical micelle concentration. CTAB stimulates cyanobacteria to secrete proteins, xanthohumic acid, and humic acids to maintain normal physiological cells. Additionally, the results of SEM and ion content showed that CTAB damages the cell membrane, resulting in a ∼90% increase in the release of intracellular MC-LR without cell disintegration. Ionic analyses confirm that all three surfactants alter cell membrane permeability and disrupt ionic metabolic pathways in microalgae. This study highlights the relationship between the surface charge properties of typical surfactants and the dispersion/agglomeration behavior of cyanobacteria. It provides insights into the impact mechanism of exogenous surfactants on toxic algae production in eutrophic water bodies, offering theoretical references for managing surfactant pollution and treating algae blooms.

Glycidyl methyl ether: A safer alternative to ethylene oxide for designing ethoxy-free non-ionic surfactants

Ethoxylated surfactants have recently raised alarm because small amounts of dioxane, a Substance of Very High Concern (SVHC), are formed during their synthesis and degradation, with some of it ending up as traces in drinking water. This awareness has prompted a quest for alternative non-ionic surfactants free of ethoxylates yet offering a tuneable molecular structure and amphiphilic behaviour akin to polyethoxylated alcohols, CiEj. In this perspective, we performed oligomerization of Glycidyl Methyl Ether (GME) on fatty alcohols to yield branched isomers of CiEj surfactants. The amphiphilic properties of the resulting well-defined ethoxy-free surfactants were systematically compared to their polyethylene glycol counterparts. The introduction of branching in the polar head led to decreased hydrophilicity, as quantified by PIT-slope measurements. Furthermore, these branched surfactants exhibited cloud points with a reduced dependence on the oligomerization degree and lower Critical Micelle Concentrations (CMC). Consequently, these findings position them as promising alternatives to ethoxylated non-ionic surfactants. Finally, the COSMO-RS theory was strategically applied for the first time to rigorously rationalize the amphiphilic properties exhibited by these novel surfactants by precisely quantifying hydrophilic-lipophilic tendencies.

Synthesis of narrow-distributed Guerbet dodecyl alcohol ethoxylates on Ca(OAc)2 catalyst and theirs surface properties

Despite significant breakthroughs that have been made in the application performance of traditionally distributed Guerbet alcohol ethoxylates (GAEO), research on the characteristics of their narrow distribution products remains relatively limited. Herein, a series of hydrophilic and hydrophobic nonionic surfactants have been synthesized via the ethoxylation of 2-butyl-octanol with ethylene oxide. Ca(OAc)2 was employed as a narrow distribution (NRD) catalyst, while KOH served as a broad distribution (BRD) catalyst. The synthesized products were characterized using Fourier-transform infrared (FT-IR), 1H and 13C nuclear magnetic resonance (1H, 13C NMR) spectroscopy. In addition, a comprehensive assessment of the physicochemical and surface properties of the NRD GAEO surfactants was conducted through systematic investigations. The results were then compared to conventionally distributed GAEO surfactants. The study has demonstrated that NRD GAEO surfactants exhibited lower critical micelle concentration (CMC) values, which have the higher efficiency of the surfactant application. In addition, the NRD products have superior wettability performance, reduced foaming capacity in foam properties, and improved rapid defoaming capacities. In regarding their other properties, they closely mirrored the performance of BRD products. These findings will contribute to a comprehensive understanding of the properties of NRD ethoxylates and have substantial practical implications in optimizing personal care and household cleaning products.

Synthesis of PEGylated amphiphilic block copolymers with pendant linoleic moieties by combining ring-opening polymerization and click chemistry.

This study focused on synthesizing and characterizing PEGylated amphiphilic block copolymers with pendant linoleic acid (Lin) moieties as an alternative to enhance their potential in drug delivery applications. The synthesis involved a two-step process, starting with ring-opening polymerization of ε-caprolactone (CL) and propargylated cyclic carbonate (MCP) to obtain PEG-b-P(CL-co-MCP) copolymers, which were subsequently modified via click chemistry. Various reaction conditions were explored to improve the yield and efficiency of the click chemistry step. The use of anisole as a solvent, N-(3-azidopropyl)linoleamide as a substrate, and a reaction temperature of 60°C proved to be highly efficient, achieving nearly 100% conversion at a low catalyst concentration. The resulting copolymers exhibited controlled molecular weights and low polydispersity, confirming the successful synthesis. Furthermore, click chemistry allows for the attachment of Lin moieties to the copolymer, enhancing its hydrophobic character, as deduced from their significantly lower critical micelle concentration than that of traditional PEG-b-PCL systems, which is indicative of enhanced stability against dilution. The modified copolymers exhibited improved thermal stability, making them suitable for applications that require high processing temperatures. Dynamic light scattering and transmission electron microscopy confirmed the formation of micellar structures with sizes below 100 nm and minimal aggregate formation. Additionally, 1H NMR spectroscopy in deuterated water revealed the presence of core-shell micelles, which provided higher kinetic stability against dilution.

Surface-active ionic liquids as drug carriers: A physico-chemical study

This work evaluates the potential of two surface active ionic liquids (SAILs) 1-dodecyl-3-methylimidazolium bromide and 1-tetradecyl-3-methylimidazolium bromide as drug carrier for ciprofloxacin (CPF) and compares them with their conventional counterparts dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide using spectroscopic and electrochemical techniques. Different physico-chemical parameters including critical micelle concentration (CMC), binding constants, partition coefficients and their corresponding free energy changes, thermodynamic parameters of micellization and redox behavior of micelle-drug systems were investigated. Both the SAILs demonstrated higher solubilization powers and binding constants owing to the less polar nature of imidazolium ring. Lower CMCs indicated relatively stronger hydrophobic forces existing in all SAILs-CPF systems tested. The cyclic voltammetry displayed shifting of oxidation peaks towards higher positive potential in the micellar region indicating the protection of CPF against oxidation. This work demonstrates the benefits of using SAILs as drug carriers due to their lower CMCs, improved binding and partition coefficients, and favorable electrochemical results.

Multi-functional Chitosan Polymeric Micelles for improving the oral bioavailability of Paclitaxel based on synergistic effect.

A novel multi-functional micelle delivery system was developed for enhancing the oral absorption of paclitaxel (PTX). The delivery carriers were constructed by modifying chitosan-stearic acid (CS-SA) micelles with L-carnitine (LC) and co-encapsulating quercetin (Que), and the PTX-loaded micelles were prepared by film-sonication dispersing technique. The as-prepared micelles showed homogeneous spherical shapes with a small particle size of 148.3 ± 1.7nm, high drug loading of 7.05% and low critical micelle concentration (CMC) of 16.89µg/ml. Compared to the in-house PTX formulation similar to the commercial injection Taxol™, the target PTX-loaded micelles had obvious sustained-release effects and exhibited an oral relative bioavailability of 168.08%. The cellular uptake studies of Caco-2 cells confirmed the micellar modification of LC and the co-loading of Que played important roles in promoting the absorption of drug loaded in micelles. The CYP3A4 enzyme test demonstrated the micelles had an inhibitory effect on the metabolic enzyme due to the presence of Que. These findings confirmed the potential of the multi-functional chitosan polymeric micelles based on synergistic effect as an effective oral delivery system.

Synthesis of pH/redox-double-responsive ferrocene-containing diblock copolymers and their application in controlled release

A novel pH/redox-double-responsive ferrocene-containing diblock copolymer of poly(ethylene glycol)-block-poly[2-(2-((2-ferrocenyl ethyl ester) (methyl) amino) ethoxy) ethyl methacrylate] [mPEG113-b-P(Fe–N-EOMA)] was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. mPEG113-b-P(Fe–N-EOMA) is amphiphilic with PEG as hydrophilic block and the part containing ferrocene as hydrophobic block. For comparison, three other diblock copolymers were prepared by changing the molecular weight of the hydrophilic block and the microstructure of the hydrophobic block. The diblock copolymers have a critical pH in solution and increases with the increase of the hydrophilicity of the copolymers. The redox-response was confirmed by the shift of characteristic peak of ferrocene in the UV/vis absorption spectrum after adding FeCl3/VC. The self-assembly behavior of these diblock copolymers in solution were then investigated. It shows that they have low critical micelle concentration (cmc), and the cmc decreases as the hydrophobicity of copolymers increases. Their morphology is varied, including sphere, lamella, aggregated sphere, and can be reversible changed by the stimulation of pH and redox. Finally, mPEG113-b-P(Fe–N-EOMA) was applied to the release of Nile Red (NR), which showed a good release efficiency. The prepared diblock copolymers have sensitive and reversible response properties, which provided ideas for the design of multistimuli-responsive polymers, and have good application prospects in drug-release.

Development of a highly efficient solubilization method for mass spectrometric analysis of phospholipids in living single cells.

Phospholipids are vital constituents of the cell membrane and aid in signal transduction. Phospholipid profiles vary distinctively with the cell type. Notably, specific phospholipid molecules are present in significantly higher or lower concentrations in cancer cells versus normal cells. In this study, live single-cell mass spectrometry (MS) was developed for analyzing phospholipids at the single-cell level. This method facilitates rapid molecular analysis of cells under microscopic observation. For nanoelectrospray ionization, phospholipids were extracted from single cells isolated in a glass capillary through a high-efficiency process. Cell-derived phosphatidylcholines were detected with high sensitivity when trehalose C14 was added as a solubilizing reagent. Trehalose C14 can solubilize cells at low concentrations owing to its low critical micelle concentration, and exerts minimal matrix effects (such as suppressing ionization and causing peak overlap) in the MS analysis of cellular molecules. Analyses of phospholipids in Raji and HEV0070 cells using the developed method revealed specific peaks of phosphatidylcholine and sphingomyelin in the respective cells. The developed technique not only affords phospholipid profiles at the single-cell level, but also holds promise for identifying biomarkers associated with various diseases, particularly cancer.

Influence of cationic dimeric and trimeric-type surfactants on the aggregation behavior of water-soluble phthalocyanine: A combined experimental and computational study

The aggregation behavior of the water-soluble phthalocyanine, namely zinc 2,9,16,23–tetra(tert–butyl)–29H,31H–phthalocyanine tetrasulphonic acids (ZnPcS4), has been examined in the presence of dimeric and trimeric-type cationic surfactants and their conventional counterpart cetyltrimethylammonium bromide (CTAB). The absorption and fluorescence studies of ZnPcS4 in water showed a different feature than that in methanol suggesting the formation of aggregated ZnPcS4 in an aqueous medium. The fluorescence studies of ZnPcS4 in the presence of examined dimeric-type cationic surfactants showed lower critical aggregation concentration (CAC = 0.62–13.6 µM) compared to that of CTAB (CAC = 16 µM). It was found that the position of the substituents affected the critical micelle concentration (CMC) value, and the ortho-dimeric surfactant had a lower CMC value compared to those surfactants with meta, and para-dimeric surfactant. It was interesting to see that the CMC for the dimeric surfactant with two groups at the para position (13.6 µM) decreased significantly (0.04 µM) by removing the (O-CH2) groups attached to the benzene which can be explained by structural parameters determined by theoretical calculations. By changing the surfactants from dimers to cationic trimers surfactants, a significant decrease in the CAC values was observed (0.04 µM for Trimer-12 with two dodecyl groups and 0.39 µM for Trimer-8 with two octyl groups). This finding indicates that the increase in tail length by four methylene groups of Trimer-12 compared to Trimer-8 results in a decrease in CAC by about one order of magnitude. These new findings suggest that the trimeric-type cationic surfactants are remarkably superior to conventional and dimeric-type surfactants, which could have a profound impact on many applications of ZnPCS4 including, but not limited to, medical, organic electronics, light harvesting, photonics, and optical sensors.

PH sensitive adriamycin-incorporated nanoparticles self-assembled from amphiphilic chitosan derivatives with enhanced antioxidant and antitumor activities

Development of secure and efficient drug delivery systems to overcome physicochemical challenges in cancer clinical treatment is one of the most active fields, and novel drug carriers are actively sought. In this work, the successful synthesis of amphiphilic chitosan derivatives containing pyridine cations and folic acid (TMACMCF) was confirmed by FTIR and 1H NMR spectroscopy. The critical micelle concentration (CMC) of TMACMCF was studied, and the results indicated that it possessed a relatively low CMC (0.186 mg/mL). Self-assembled nanoparticles (TMACMCF-ADM NPs) for the entrapment and delivery of adriamycin (ADM) were synthesized based on TMACMCF, and the morphology, particle size, zeta potential, sustained release performance, antioxidant and antitumor activities, and cytotoxicity were investigated. The particle size of TMACMCF-ADM NPs was 163.79 ± 7.31 nm, and the morphology observed by SEM and TEM showed spherical or oval particles. TMACMCF-ADM NPs showed excellent entrapment of ADM with entrapment efficiency and drug loading efficiency of 65.04 ± 1.20 % and 22.73 ± 0.40 %, respectively. The release performance results showed that in vitro release profiles of ADM from NPs exhibited pH-sensitive controlled and sustained release properties. The assay of antioxidant activity exhibited that TMACMCF-ADM NPs possessed significantly improved scavenging ability against three kinds of radicals (Superoxide-radical, DPPH radical, and ABTS radical). Moreover, the assay of antitumor activity by CCK-8 test exhibited that nanoparticles led to statistically significant enhancement in inhibition index for four kinds of cancer cells (BGC-823, MCF-7, HEPG-2, and A549). This work provides a promising carrier for secure and effective entrapment and delivery of ADM.

An investigation on the hydrophobic binding stability of Azithromycin to the hydrocarbon chains of Tween: Based on micellization thermodynamics

Based on micellization thermodynamics, the difference in hydrophobic binding stability between Azithromycin and the hydrocarbon chain of Tween was investigated. Initially, the critical micelle concentration (CMC) of AZM-loaded Tween micelles was determined by measuring surface tension, followed by subsequent analysis and discussion of the associated parameters of micellization thermodynamics. The findings indicated that AZM-loaded Tween 20 and AZM-loaded Tween 80 micelles both exhibited a lower CMC value, enhanced stability at the air/water interface, and a more pronounced tendency towards micellization. This suggested that Azithromycin exhibited a stronger affinity towards the hydrophobic hydrocarbon chains of Tween 20 and Tween 80, leading to a more robust hydrophobic binding between them, thereby promoting the formation of AZM-loaded micelles. Subsequently, the transmittance, particle size, and in vitro release of each micelle system were assessed. The findings demonstrated that both AZM-loaded Tween 20 and AZM-loaded Tween 80 micelles exhibited excellent physical stability. Furthermore, in terms of antibacterial activity, AZM-loaded Tween 20 and AZM-loaded Tween 80 micelles exhibited stronger antibacterial efficacy. In summary, the variation in the hydrocarbon chain of Tween exerts an influence on the stability of the hydrophobic binding between Tween and Azithromycin, consequently impacting the pertinent attributes of drug-loaded micelles. This finding offers a valuable point of reference for the investigation of hydrophobic drug micelles in academic research.

Imidazolium surface-active ionic liquids as antifungal agents in wood protection

This research focuses on five newly surface-active ionic liquids (SAILs) whose commitment to sustainable chemistry allows for their utilization as effective wood protection agents alternatives to traditional surfactants. The synthesis yields were above 93 %, while the purity ranged from 97 to 99 %. Also, a series of properties such as surface activity, wettability, antifungal properties were studied. The demonstrated relationship between critical micelle concentration (CMC) and elongation on alkyl chain length of the investigated imidazolium SAILs aligns with expectations. Moreover, it was shown that all tested SAILs exhibited lower CMC values (ranged from 0.34 to 8.46 mmol⋅L−1) than conventional surfactants such as didecyldimethylammonium chloride (DDAC) and decyltrimethylammonium bromides (CTAB) proving that the synthesized compounds can serve as substitutes for surfactants. 3-Decyloxymethyl-1-methylimidazolium dicyanamide (SAIL-3) showed the best antifungal properties, which does not translate into contact angle (CA) values. The mechanical properties measured for the impregnated wood samples were consistently inferior to those of the control wood samples. However, wood treated with SAIL-3, in contrast, exhibited a reduced uptake of free water compared to the untreated control wood. The results presented validate our hypothesis regarding the distinctive nature of SAILs and affirm their suitability for wood impregnation.

Effect of Surface Modification on the Luminescence of Individual Upconversion Nanoparticles.

Lanthanide-doped upconversion nanoparticles (UCNPs) hold promise for single-molecule imaging owing to their excellent photostability and minimal autofluorescence. However, their limited water dispersibility, often from the hydrophobic oleic acid ligand during synthesis, is a challenge. To address this, various surface modification strategies' impact on single-particle upconversion luminescence are studied. UCNPs are made hydrophilic through methods like ligand exchange with dye IR806, HCl or NOBF4 treatment, silica coating (SiO2 or mesoporous mSiO2 ), and self-assembly with polymer of DSPE-PEG or F127. The studies revealed that UCNPs modified with NOBF4 and DSPE-PEG exhibited notably higher single-particle brightness with minimal quenching (3% and 8%, respectively), followed by SiO2 , F127, IR806, mSiO2 , and HCl (84% quenching). HCl disrupted UCNPs's crystal lattice, weakening luminescence, while mSiO2 absorbed solvent molecules, causing luminescence quenching. Energy transfer to IR806 also reduced the brightness. Additionally, a prevalence of upconversion red emission over green is observed, with the red-to-green ratio increasing with irradiance. UCNPs coated with DSPE-PEG exhibited the brightest single-particle luminescence in water, retaining 48% of its original emission due to a lower critical micelle concentration and superior water protection. In summary, the investigation provides valuable insights into the role of surface chemistry on UCNPs at the single-particle level.

Impact of the Hydrocarbon Chain Length of Biodegradable Ester-Bonded Cationic Gemini Surfactants on Self-Assembly, In Vitro Gene Transfection, Cytotoxicity, and Antimicrobial Activity.

Gemini surfactants, due to their unique structural features and enhanced properties compared to conventional surfactants, are becoming more popular in the domain of colloid and interface science, drug delivery, and gene delivery science. This distinct class of surfactants forms a wide range of self-assembled aggregates depending on their chemical structure and environmental conditions. The present work aims to develop Gemini with three distinct chain lengths linked through the ester group and quaternary nitrogen head groups that can bind DNA molecules and ultimately serve as vectors for DNA transfection. Thus, we synthesized three distinct cationic Gemini with 12, 14, and 16 carbons in their tails and studied the effect of the hydrocarbon chain length on their physicochemical properties and biological applications. The self-assembly of these Geminis in aqueous solution was investigated by a number of techniques, including surface tension, electrical conductivity, fluorescence probe, calorimetry, dynamic light scattering, and atomic force microscopy. All three Gemini were extremely surface active and self-assembled above a very low critical micelle concentration. Calorimetric studies suggested the formation of thermodynamically favorable aggregates in an aqueous medium. Chain length dependence was observed in the size as well as the morphology of the aggregates. These Gemini ions were found to bind DNA strongly, as indicated by the high binding constant values. In vitro gene transfection studies using the RAW 264.7 cell line suggested that all three cationic Gemini had transfection efficiencies comparable to that of commercial standard turbofectamine. MTT assay was also performed for concentration selection while using these Gemini as transfection vectors. Overall, it was observed that Gemini had very little cytotoxicity within the investigated concentration range, highlighting the significance of the ester link within the structure. When compared with known antimicrobials such as kanamycin and ampicillin, all three Gemini furnished excellent antimicrobial activity in both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms.

Rheology of high-temperature resistant fracturing fluids formed by VES, acids and oxidants for enhancing CO2 injection in deep coal seams

To address the low efficiency of CO2 injection into deep coal seams due to coal adsorption-induced swelling and low permeability, this study proposes the use of a CO2 injection enhancement fracturing fluid (IEFF) to increase injection efficiency, which is composed of viscoelastic surfactant (quaternary ammonium Gemini surfactant, 18-3-18), organic acids (acetic acid, C2H4O2) and oxidants (hydrogen peroxide, H2O2). The rheology and micelle morphology of the IEFF were investigated in terms of temperature and substance ratios. In addition, comparative study was conducted with monomeric surfactants (STAB). The results demonstrated that compared to STAB, 18-3-18 exhibited a two orders of magnitude lower critical micelle concentration (CMC), a lower surface tension (γCMC), and formed a system with favorable rheology at lower concentrations. Moreover, the viscosity of the IEFFs increased as the substance ratio of C2H4O2 to H2O2 decreased. Inflection points in the IEFFs were observed at 313.15 K, 323.15 K, and 333.15 K, where the viscosity exceeded 25 mPa·s. At 323.15 K, a shear rate of 170 s−1, and a substance ratio of 1:1.5, the IEFF reached its maximum viscosity of 40.390 mPa·s, with a micelle size of 109.56 nm, and the intertwined wormlike micelles formed a robust network structure. The results can provide a reference for optimizing fracturing fluid and promoting the efficiency of CO2 injection into deep coal seams.

Influence of Surfactant Structure on Polydisperse Formulations of Alkyl Ether Sulfates and Alkyl Amidopropyl Betaines.

Surfactants provide detergency, foaming, and texture in personal care formulations, yet the micellization of typical industrial primary and cosurfactants is not well understood, particularly in light of the polydisperse nature of commercial surfactants. Synergistic interactions are hypothesized to drive the formation of elongated wormlike self-assemblies in these mixed surfactant systems. Small-angle neutron scattering, rheology, and pendant drop tensiometry are used to examine surface adsorption, viscoelasticity, and self-assembly structure for wormlike micellar formulations comprising cocoamidopropyl betaine, and its two major components laurylamidopropyl betaine and oleylamidopropyl betaine, with sodium alkyl ethoxy sulfates. The tail length of sodium alkyl ethoxy sulfates was related to their ability to form wormlike micelles in electrolyte solutions, indicating that a tail length greater than 10 carbons is required to form wormlike micelles in NaCl solutions, with the decyl homologue unable to form elongated micelles and maintaining a low viscosity even at 20 wt % surfactant loading with 4 wt % NaCl present. For these systems, the incorporation of a disperse ethoxylate linker does not enable shorter chain surfactants to elongate into wormlike micelles for single-component systems; however, it could increase the interactions between surfactants in mixed surfactant systems. For synergy in surfactant mixing, the nonideal regular solution theory is used to study the sulfate/betaine mixtures. Tail mismatch appears to drive lower critical micelle concentrations, although tail matching improves synergy with larger relative reductions in critical micelle concentrations and greater micelle elongation, as seen by both tensiometric and scattering measurements.

Differences in the structural properties of three OSA starches and their effects on the performance of high internal phase Pickering emulsions

The emulsifying properties of emulsions are significantly influenced by the structural properties of octenyl succinic anhydride (OSA) starch. The purpose of this work was to elucidate the effect of the structure of OSA starch on its performance as an emulsifier to stabilize Pickering high-internal-phase emulsions (HIPEs). The degrees of substitution (DS) of the three OSA starches were 0.0137, 0.0177 and 0.0236, and their degrees of branching (DB) were 13.96 %, 14.20 % and 14.32 % measured by 1H NMR, which were sequentially labeled as OSA1, OSA2, and OSA3. The OSA3 starch with higher DS and DB had a lower critical micelle concentration (CMC) (0.11 mg/mL). Its emulsification activity (EAI) and emulsion stability (ES) were 61.8 m2/g and 72.5 min, respectively, which were higher than OSA1 and OSA2 starches. The contact angle of the three OSA starches increased from 45.35° to 80.03° with increasing DS and DB. Therefore, it is hypothesized that OSA3 starches have better emulsification properties. The results of physical stability of HIPEs confirmed the above results. These results indicated that DS and DB have a synergistic effect on emulsion properties, and OSA starch with higher DS and DB values were more conducive to the construction of stable HIPEs systems.

Quaternary ammonium-based and imidazolium-based gemini surfactants: A comparison study

Gemini surfactants have aroused significant attention since their discovery due to their unique properties that arise from the particular molecular structure. However, the effect of a CC double bond in the spacer has seldom been considered, and common quaternary ammonium-based gemini surfactants have seldom been compared with imidazolium-based ones. In this work, four gemini surfactants, denoted as 12–4-12, 12–4u-12, C12im-4-C12im, and C12im-4u-C12im were synthesized and characterized, and the effects of CC double bond in the spacer and hydrophilic headgroup on the fundamental properties were investigated. The results showed that imidazolium-based gemini surfactants (C12im-4-C12im and C12im-4u-C12im) have lower critical micelle concentration (cmc), greater efficiency and effectiveness in reducing surface tension, and superior ability to generate micelles compared to the corresponding quaternary ammonium-based ones, but showed comparatively lower salt resistance, foaming, and antibacterial activity. The introduction of CC in the spacer further decreased the cmc and the Gibbs free energy of micellization, and enhanced the antibacterial activity, but barely affected interfacial adsorption, the efficiency in reducing surface tension, micelle size, or foaming. None of the four gemini surfactants alone was capable of decreasing the interfacial tension to an ultra-low value. The incorporation of sodium cetanol polyoxyethylene ether carboxylate not only significantly decreased the interfacial tension (<10−2 mN·m−1), but also remarkably enhanced the salt resistance capacity up to 80,000 mg·L−1. This information may be helpful for designing new gemini surfactants tailored for different potential applications.

A novel erucic acid derived surfactant: Experimental and theoretical study

Erucic acid is still a difficulty to utilize efficiently as a byproduct of grease processing. An effective strategy is to develop novel surfactants derived from erucic acid. Adamantyl trimethyl ammonium erucate, (AdEr) is an ionic liquid anionic surfactant derived from erucic acid. In this study, a combination of experimental and theoretical calculations was used to compare its physical characteristics and aggregation behaviors with the previously reported choline erucate (ChEr). The physical chemical properties were evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis, surface tension and dynamic light scattering (DLS). The introduction of adamantane enhanced thermal stability and increased the melting point, while maintaining the excellent water-solubility. In comparison with ChEr, AdEr has a lower critical micelle concentration (CMC) and lager micellar aggregation sizes, exhibiting better micellization ability. Density functional theory (DFT) calculations suggests that AdEr has less intramolecular activity and a more stable molecular structure. Molecular dynamic (MD) simulations verified that AdEr preferred to aggregate to form micelles and had a larger aggregation size than ChEr using parameters such as conformation snapshots, radius of gyration (Rg) and mean square displacement (MSD). According to radial distribution function (RDF) analysis, this is owing to the smaller occupied area due to lower hydration of COO− groups of AdEr, and the difference hydration extent of the cations (Ad+ and Cho+). These findings clearly suggest that AdEr can be used as a potential alternative to conventional surfactant derived from erucic acid for various applications.

Transformation of Highly Hydrophobic Triarylphosphines into Amphiphiles via Staudinger Reaction with Hydrophilic Trichlorophenyl Azide.

Owing to its hydrophobic properties and reactivity, triarylphosphines (PAr3 ) are promising precursors for the development of new amphiphiles. However, an efficient and reliable synthetic method for amphiphiles based on highly hydrophobic PAr3 is still required. Herein, a straightforward transformation of highly hydrophobic PAr3 into amphiphiles via the Staudinger reaction is reported. By simply mixing PAr3 and a hydrophilic trichlorophenyl azide containing two hydrophilic chains, amphiphiles bearing a N=P bond (i. e., an azaylide moiety) were quantitatively formed. The obtained azaylide-based amphiphiles were remarkably water-soluble, enabling their spontaneous self-assembly into 2 nm-sized micelles composed of 4-5 molecules in water with a low critical micelle concentration (up to 0.05 mM or less) due to the effective intermolecular interactions among the hydrophobic surfaces. Although the azaylide moiety is easily hydrolyzed in the presence of water, the azaylide in the amphiphiles displayed notable stability in water even at 60 h, which stems from the LUMO modulation induced by the presence of three electron-withdrawing chloro groups and two twisted alkoxycarbonyl groups, according to DFT calculations. An amphiphile having a large hydrophobic surface solubilized various hydrophobic organic dyes through efficient intermolecular interactions, resulting in the dyes exhibiting either monomer or excimer emissions in water.