Interplay between bulk aggregates, surface properties and foam stability of nonionic surfactants

Salt-induced gelation of nonionic sucrose ester dispersions

HYPOTHESIS

The dispersions of nonionic sucrose ester surfactants in water exhibit a highly negative zeta-potential, though its origin remains controversial. The addition of electrolytes to these dispersions may influence their zeta-potential, thus potentially affecting their physicochemical properties.

EXPERIMENTS

The electrolyte- and pH- driven gelation of aqueous dispersions of commercial sucrose stearate (S970) containing ca. 1:1 monoesters and diesters was studied using optical microscopy, rheological and zeta-potential measurements, and small-angle X-ray scattering techniques.

FINDINGS

At low electrolyte concentrations and pH ≳ 5, 0.5-5 wt% S970 dispersions exhibited low viscosities and behaved as freely flowing liquids. The addition of electrolytes of low concentrations, e.g. 9 mM NaCl or 1.5 mM MgCl2, induced the formation of a non-flowing gels. This sol-gel transition occurred due to the partial screening of the diesters particles charge, allowing the formation of an attractive gel network, spanning across the dispersion volume. Complete charge screening, however, led to a gel-sol transition and phase separation. Gel formation was observed also by pH variation without electrolyte addition, whereas the addition of free fatty acids had negligible impact on dispersion properties. These findings support the hypothesis that the negative charge in sucrose ester dispersions arises from hydroxyl anions adsorption on particles surfaces. Gels were formed using just 1.3 wt% surfactant, and the critical electrolyte concentration for gelation was found to scale approximately with the square of the cation charge, in agreement with the low surface charge density theory. The biodegradable sucrose esters gels offer a sustainable alternative for structuring personal and home care products, replacing the wormlike micelles of synthetic surfactants typically used at much higher surfactant and salt concentrations.

Advances in surfactants for photolithography

The advancement of dense integrated circuits requires the miniaturization of feature sizes, which has driven continuous progress in photolithography. However, there are still some challenges in achieving a high patterning resolution for photolithography such as surface contaminants, defect formation, pattern collapse, etc. Surfactants have been extensively investigated for several decades as essential wet chemicals to resolve these issues due to their outstanding performance in reducing surface tension, enhancing wettability, and improving solubility. Recently, it has been revealed that surfactants with diverse chemical structures can exhibit distinct functionalities at various stages of the photolithography process, yet comprehensive discussions on their structures, performance, and mechanisms remain limited. In this review, we first address the structure-performance relationships for anionic, cationic, nonionic, and zwitterionic surfactants and then provide a general introduction to photolithography from a historical and technological perspective. Specifically, various surfactants used as additives in cleaners, developers, etchants, and strippers for photolithography are thoroughly summarized and discussed, where their key parameters, used concentrations, and underlying mechanisms have been introduced to provide a valuable guide for future research. Finally, we propose three strategic directions for the development of innovative surfactants to address emerging challenges and drive sustainable progress in photolithography: (1) high-performance surfactants, (2) switchable surfactants, and (3) bio-based surfactants.

Isolating and Purification Technologies for Glycyrrhizic Acid

Glycyrrhizic acid (GA) is the primary active component of the traditional Chinese medicinal herb licorice. It possesses antimicrobial, anti-inflammatory, and antitumor activities. In addition, due to its unique sweetness, it can also be used as a food additive. Traditional Chinese medicines are typically used directly as drugs. However, the chemical composition of Chinese medicinal materials such as licorice is complex, containing not only effective components but also ineffective and even toxic substances. To efficiently exert their medicinal value and minimize the side effects of harmful substances, the extraction and separation of the active components is an important means to achieve the modernization of traditional Chinese medicine utilization. This article focuses on the extraction of GA, summarizes the current technologies related to the extraction and separation of GA, reveals the underlying chemical principles, and evaluates the advantages and disadvantages of the corresponding technologies. On this basis, it proposes challenges faced in the separation of GA and provides corresponding solutions. The author believes that with the continuous introduction of precise chemical synthesis and other methods in separation, the extraction and separation of the active substance will become greener and more efficient. It will also provide a reference for the extraction of other effective components of traditional Chinese medicine.

Pure drug nanomedicines - where we are?

Pure drug nanomedicines (PDNs) encompass active pharmaceutical ingredients (APIs), including macromolecules, biological compounds, and functional components. They overcome research barriers and conversion thresholds associated with nanocarriers, offering advantages such as high drug loading capacity, synergistic treatment effects, and environmentally friendly production methods. This review provides a comprehensive overview of the latest advancements in PDNs, focusing on their essential components, design theories, and manufacturing techniques. The physicochemical properties and in vivo behaviors of PDNs are thoroughly analyzed to gain an in-depth understanding of their systematic characteristics. The review introduces currently approved PDN products and further explores the opportunities and challenges in expanding their depth and breadth of application. Drug nanocrystals, drug-drug cocrystals (DDCs), antibody-drug conjugates (ADCs), and nanobodies represent the successful commercialization and widespread utilization of PDNs across various disease domains. Self-assembled pure drug nanoparticles (SAPDNPs), a next-generation product, still require extensive translational research. Challenges persist in transitioning from laboratory-scale production to mass manufacturing and overcoming the conversion threshold from laboratory findings to clinical applications.

Enzymatic synthesis of some sugar-lauric acid esters by lipase from Candida antarctica and their functionalities as emulsifiers and antibacterial agents

To investigate the regioselectivity of lipase-catalyzed synthesis of important sugar-laurate esters and their functionalities as emulsifiers and antimicrobial agents, glucose, galactose, mannose, maltose and trehalose were used. 6-O-lauryl glucose (Glu-L), 6-O-lauryl galactose (Gal-L), 6-O-lauryl mannose (Man-L), 6'-O-lauryl maltose (Mal-L) and 6-O-lauryl trehalose/6'-O-lauryl trehalose (Tre-L) were synthesized using lipase from Candida antarctica. The Glu-L and Man-L achieved the highest yields (65.49 % and 58.16 %, respectively). The synthesized esters produced smaller-particle-size (1.9-3.1 μm), but less stable emulsions than the commercial sucrose esters (4.2-8.1 μm). The zeta-potential data revealed Man-L and Gal-L had higher surface coverage than the Glu-L on the oil droplets, while the Mal-L and Tre-L had similar surface coverage. The Man-L, Mal-L and Tre-L demonstrated the superior foamability and foam stability. The Gal-L, Man-L, Mal-L, and Tre-L inhibited E.coli 12024 (MIC 1-4 mg/mL), while only Man-L, Mal-L, and Tre-L inhibited B.subtilis 5009 (MIC 0.5-2.0 mg/mL).

Recent Advances in the Properties and Applications of Polyglycerol Fatty Acid Esters

Although polyethylene glycol (PEG)-based surfactants are widely used in various industries due to their wide range of hydrophile-lipophile balance (HLB) values, their possible by-product, 1,4-dioxane, has been listed as a reasonably anticipated human carcinogen, which may limit their applications in fields closely related to the human body. Polyglycerol fatty acid esters (PGFEs), a class of surfactants based on polyglycerol (another polyether), also have a wide range of HLB values that can be adjust by varying the degree of polymerization of the polyglycerol, the length of the fatty acid carbon chain, or the degree of esterification, but do not have the risks caused by 1,4-dioxane. In addition, all the raw materials (glycerol and fatty acids) required for the preparation of PGFEs can be obtained via hydrolysis of renewable vegetable oils. Therefore, PGFEs, as new eco-friendly and biodegradable non-ionic surfactants, have been proposed as potential green alternatives to PEG-based non-ionic surfactants. This review summarizes the properties of PGFEs specifically including their HLB, surface properties, phase behaviors, stabilizing effect on foams and emulsions, and stability, and highlights their potential applications in food, cosmetics, and pharmaceuticals observed in the last decade.

Synthesis and Properties of Isononyl-Extended Multibranched Alcohol Polyether Nonionic Surfactants

Isononanol, a branched aliphatic alcohol, is derived from isobutylene upgradation, encompassing dimerization and hydroformylation. Branched surfactants exhibit lower surface tension, superior wettability, and rapid defoaming compared to linear surfactants. Isononanol (C9-OH) with abundant methyl branching can serve as a hydrophobic tail of branched surfactants, suffering from insufficient lipophilicity due to its short effective chain length. This paper proposes a strategy to extend the hydrophobic tail by grafting one propylene oxide (P1) or butylene oxide (B1) to increase chain length and branching degree with the aim of synthesizing extended multibranched alcohols C9P1-OH and C9B1-OH with purities of 95.3 and 97.2%, respectively. Subsequently, a series of extended multibranched alcohol polyether nonionic surfactants (C9P1En and C9B1En) were synthesized by ethoxylation, with their structures confirmed by Fourier-transform infrared (FT-IR) and 1H NMR and their surfactant properties systematically investigated. The findings indicate that C9P1En and C9B1En exhibited lower γCMC values compared to the isononanol polyether surfactant (C9En), which allows for rapid wetting on a hydrophobic surface, especially C9B1E6 with an initial contact angle of only 54° compared to 80° for C9E6. Also remarkable is the rapid defoaming performance, with C9B1E6 having less than 0.1% of the initial foam volume but C9E6 having up to 50.1% foam volume after 30 s. These surfactant performances provide significant benefits for the potential application of branched nonionic surfactants in the industrial cleaning field.

Experimental and computational studies of cationic Gemini surfactants as corrosion inhibitors for carbon steel in 15% HCl

In the process of oil and gas exploration, the corrosion of carbon steel pipes results in substantial economic losses, numerous casualties, environmental contamination, and resource waste. The advancement of highly efficient and stable corrosion inhibitors holds significant importance for protecting carbon steel from corrosion during oil and gas exploitation. In this study, two new cationic Gemini surfactants (2CncoesT, where n = 12, 14) were synthesized through a straightforward two-step reaction. Weight-loss tests demonstrated that the inhibition efficiency (ηw%) increases with the increase in temperature. Specifically, the maximum ηw% values for 2C12coesT and 2C14coesT were 98.0% and 98.3% respectively at 85 °C. The adsorption of these surfactants conformed to the Langmuir adsorption isotherm. Electrochemical measurements suggested that the two surfactants functioned as mixed-type inhibitors. The findings obtained from scanning electron microscopy (SEM) were consistent with the experimental outcomes that 2C12coesT and 2C14coesT are efficient corrosion inhibitors for the metal in an acidic environment. The quantum chemical investigation and molecular dynamics simulation (MD) further substantiated the experimental results and offered insights for a deeper comprehension of the inhibition mechanism of Gemini surfactants.

Colloid, interface, and foam properties of water-soluble polyglycerol esters solutions

HYPOTHESIS

Polyglycerol esters of fatty acids are generated via the esterification of a polydisperse mixture of polyglycerol with naturally derived fatty acids. The polymerization process of polyglycerol results in the production of various oligomers, ranging from di-, tri-, and higher-order forms, which contribute to the complexity of final products. The combination of complementary experimental techniques and adequate theoretical interpretations can reveal the wide variety of their physicochemical properties.

EXPERIMENTS

The colloid and interface properties of polyglyceryl mono-laurate, mono-stearate, mono-oleate, and a mixture of mono-caprylate and mono-caprate esters solutions were characterized by measurements of the electrolytic conductivity, static and dynamic surface tension, aggregate and micelle sizes and distributions, thin liquid film stability and stratification, and solubility in aqueous and in oil phases. The formation, stability, and bubble size distribution of foams generated from polyglycerol esters aqueous solutions were systematically investigated.

FINDINGS

The low concentrations of double-tail molecules and fatty acids in polyglycerol esters affect considerably their micellar, aggregation, and vesicle formations in aqueous solutions. The theoretical data interpretation of polyglycerol esters isotherms and thin liquid films data provide information on the adsorption energies, excluded areas per molecule, interaction parameters of molecules at interfaces, surface electrostatic potential, and the size of micelles. Polyglyceryl mono-oleate exhibits spontaneous emulsification properties. Short chain length polyglycerol esters have excellent foaming ability but relatively low foam stability. The optimal weight fractions of the short-chain polyglyceryl esters and polyglyceryl mono-stearate mixtures with respect to good foaminess and foam stability upon Ostwald ripening are obtained. The reported physicochemical characterization of the water-soluble polyglycerol esters could be of interest to increase the range of their applicability in practice.

Investigating the Potential of Ufasomes Laden with Nintedanib as an Optimized Targeted Lung Nanoparadigm for Accentuated Tackling of Idiopathic Pulmonary Fibrosis

Background/objectives: Idiopathic pulmonary fibrosis (IPF) is a prevalent interstitial lung disease that typically progresses gradually, leading to respiratory failure and ultimately death. IPF can be treated with the tyrosine kinase inhibitor, nintedanib (NTD), owing to its anti-fibrotic properties, which ameliorate the impairment of lung function. This study aimed to formulate, optimize, and assess NTD-loaded ufasomes (NTD-UFSs) as a nanosystem for its pulmonary targeting to snowball the bioavailability and therapeutic efficacy of the drug. Methods: To investigate the influence of numerous factors on NTD-UFSs assembly and to determine the optimal formulation, Box-Behnken statistical design was implemented with the assistance of Design-Expert® software. The thin-film hydration strategy was employed to fabricate NTD-UFSs. The optimum NTD-UFSs formulation was subsequently selected and subjected to additional evaluations. Also, using a rat model, a comparative pharmacokinetic analysis was scrutinized. Results: The optimal NTD-UFSs elicited an accumulative release of 65.57% after 24 h, an encapsulation efficiency of 62.51%, a zeta potential of -36.07 mV, and a vesicular size of 364.62 nm. In addition, it disclosed remarkable stability and a continuous cumulative release pattern. In vivo histopathological studies ascertained the tolerability of NTD-UFSs administered intratracheally. According to the pharmacokinetic studies, intratracheal NTD-UFSs administration manifested a significantly higher AUC0-∞ value than oral and intratracheal NTD suspensions, by approximately 5.66- and 3.53-fold, respectively. Conclusions: The findings of this study proposed that UFSs might be a promising nanoparadigm for the non-invasive pulmonary delivery of NTD.

Adsorption, Aggregation, and Application Properties of Green Pluronic Aliphatic Alcohol Ether Carboxylic Acids and Nonionic/Amphoteric Surfactants in Water

In the realm of colloid and interface science, new types of green surfactants, including anionic Pluronic alcohol ether carboxylate (AEC), branched alkyl glucoside (IG), and zwitterionic coconut oil amide propyl betaine (CAB), have been identified and merit further exploration. AEC, characterized by its inclusion of 5 EO and 3.5 PO units, was synthesized, and its behavior in aqueous solutions with IG and CAB was meticulously examined. Their performance in applications such as foam generation, wetting, and the dispersion and stabilization of graphene was also evaluated. At αAE5P3C = 0.5, AE5P3C/CAB exhibited superior surface and interfacial properties compared to AE5P3C/IG. In these hybrid systems, the self-assembly of micelles is predominantly influenced by hydrogen bonding, electrostatic interactions, and hydrophobic forces. Kinetic analysis further confirmed that the driving force for micelle formation in these hybrid systems is enthalpy, with the adsorption process involving a mixed diffusion-kinetic adsorption mechanism. AE5P3C/CAB demonstrated enhanced foaming ability, foam stability, and wetting properties compared to AE5P3C/IG. Intriguingly, the optimal dispersion and stabilization of graphene were achieved with AE5P3C/IG at αAE5P3C = 0.2, providing a foundational basis for its potential application in graphene-based systems. A thorough examination of the synergistic mechanisms and application potential of these three distinct surfactants in aqueous solutions was presented, taking into account various charged ions and the specific hydrophilic and hydrophobic groups of EO and PO. This study not only provides fundamental insights into their intrinsic properties but also offers a fresh perspective for the ongoing exploration of green surfactants.

Low-Foaming Nonionic Gemini Surfactants Containing Hydrophilic Poly(oxyethylene) Chain and Hydrophobic Di-tert-pentylbenzenes Groups

Low-foaming nonionic gemini surfactants have a wide range of applications in industrial cleaning and photoresist development. In this study, three low-foaming nonionic gemini surfactants (S1, S2, and S3) with different poly(oxyethylene) chain lengths have been synthesized by using methoxy poly(ethylene glycol) and 2,5-di-tert-pentylhydroquinone. The chemical structures of the novel surfactants are confirmed by 1H NMR, Fourier transform infrared, and gel permeation chromatography (GPC), and their properties such as surface tension, wetting properties, emulsifying properties, and foaming properties are investigated. The surface tension values of S1, S2, and S3 at the critical micelle concentration are 40.29, 37.14, and 41.64 mN/m, exhibiting good surface activity. When the surfactant concentration is higher than 2 mM, the contact angles of S1 and S2 no longer change and can maintain 62 and 64°, showing good wetting properties. In addition, S3 can keep an emulsion state for 2 months at high concentrations, exhibiting good emulsion stability. Furthermore, all the prepared surfactants show good low-foaming properties. The initial foaming volumes of S1 are very low, less than 0.1 mL at various concentrations, less than 2% of the conventional surfactant sodium dodecyl sulfate. For S2, the initial foaming volumes at the concentration of 0.1, 1, 2, and 3 g/L are 1, 0.5, 0.55, and 0.45 mL, respectively. For S3, the initial foaming volumes show a general trend of increasing with concentration. The surfactants with longer poly(oxyethylene) chains possess more initial foaming volumes at the same concentration, which is because the greater cohesion between the surfactant molecules can increase the elasticity of the bubble film. Our study enriches the design rationales for low-foaming surfactants and motivates researchers to develop more advanced surfactants for industrial cleaning and photoresist development.

Cyclodextrin-based metal-organic framework materials: Classifications, synthesis strategies and applications in variegated delivery systems

Metal-organic frameworks (MOFs) are coordination compounds that possess an adjustable structure and controllable function. Despite their wide applications in various industries, the use of MOFs in the fields of food and biomedicine is limited mainly due to their potential biological toxicity. Researchers have thus focused on developing biocompatible MOFs to address this issue. Among them, cyclodextrin-based metal-organic frameworks (CD-MOFs) have emerged as a promising alternative. CD-MOFs are novel MOFs synthesized using naturally carbohydrate cyclodextrin and alkali metal cations, and possess renewable, non-toxic, and edible characteristics. Due to their high specific surface area, controllable porosity, great biocompatibility, CD-MOFs have been widely used in various delivery systems, such as encapsulation of nutraceuticals, flavors, and antibacterial agents. Although the field of CD-MOF materials is still in its early stages, they provide a promising direction for the development of MOF materials in the delivery field. This review describes classification and structural characteristics, followed by an introduction to formation mechanism and commonly used synthetic methods for CD-MOFs. Additionally, we discuss the status of the application of various delivery systems based on CD-MOFs. Finally, we address the challenges and prospects of CD-MOF materials, with the aim of providing new insights and ideas for their future development.

Multibranched Molecule Defoamers Based on Methyl Gallate for Highly Effective Defoaming and Antifoaming

Bubbles or foams appear in many industrial processes, bringing inconvenience; yet, efficient capture or removal of them is still challenging. In this study, we report the synthesis and properties of multibranched molecule defoamers based on methyl gallate derivatives (Mb-GDs), which adopt methyl gallate (M-G) as the parent structure, by incorporating alkyl groups from alkyl isocyanates (A-I) with different chain lengths (C12 and C18) to replace R-OH in the M-G structure and further by linking two Mb-GDs into one Gemini-type multibranched derivative (Gt-Mb-GD) by transesterification to construct a defoamer material with a larger spatial volume. The surface properties and interfacial activity of molecular defoamers in aqueous solutions were studied, and the structure-property relationships of the multibranched gallate molecule defoamers based on Mb-GDs and Gt-Mb-GDs were further investigated by comparing the defoaming and antifoaming performance in four typical surfactant foams and foaming solutions with two kinds of commercial defoamers. The foam experiments indicated that the defoamers with a longer branched chain length (C18) showed more effectiveness in defoaming and antifoaming for four surfactant foams or foaming solutions, even at very low dosages, which were far stronger than the commercial high-carbon alcohol defoamer with a linear structure and comparable to branched silicone-based emulsion-type defoamers. Compared with Mb-GD defoamers, Gt-Mb-GD defoamers with a larger branched structure showed a higher defoaming performance. The study found the great potential of materials with multibranched structures for practical applications as the core components of high-performance defoamers.

A lipid toolbox of sugar alcohol fatty acid monoesters for single-component lipid nanoparticles with temperature-controlled release

This study aimed to prepare single-component LNPs with sugar alcohol fatty acid monoesters for temperature-controlled release. In total, 20 kinds of lipids with a series of sugar alcohol head groups (ethylene glycol, glycerol, erythritol, xylitol and sorbitol) and fatty acyl tails (12:0, 14:0, 16:0 and 18:0) were synthesised via lipase-catalysed esterification. Their physicochemical properties and upper/lower critical solution temperature (LCST/USCT) were analysed. Two groups of mixed lipids, 78 % ethylene glycol lauric acid monoester + 22 % sorbitol stearic acid monoester (LNP-1) and 90 % ethylene glycol lauric acid monoester + 10 % xylitol myristic acid monoester (LNP-2), had LCST/USCT of approximately 37 °C, which formed empty LNPs using the emulsification-diffusion method. These two mixed lipids were prepared for LNPs loaded with curcumin, showing high encapsulation (>90 %), mean particle sizes of approximately 250 nm and low polydispersity index (≤0.2). These lipids have the potential for tailor-made LNPs achieving thermo-responsivity in delivering bioactive agents and drugs.

Adsorption and volumetric properties of some nonionic surfactants and their mixtures with quercetin and rutin

The adsorption and volumetric properties of the Triton X-114 (TX114), Tween 80 (T80), quercetin (Q) and rutin (Ru) at the different temperatures in relation to above properties of the TX114 and T80 mixtures with quercetin and rutin in the absence and presence of alcohol were discussed based on the studies reported in the literature. The adsorption isotherms of the mixtures of the nonionic surfactants with flavonoids in the presence and absence of alcohol were analyzed based on the isotherms of the surface tension of the particular mixture components and thermodynamic parameters of the adsorption of these components at the water-air interface. The surface tension isotherms of the particular component of the mixtures were taken into account while considering the surface tension isotherms of the mixtures and the composition of the mixed surface layer at the water-air interface. Different ways of the mixed surface layer composition determination were shown. The values of the surface tension and composition of the mixed surface layers obtained using different methods were discussed in the light of the intermolecular interactions and their contribution to the surface tension of the surfactants mixture with flavonoids and alcohol. The composition of the mixed monolayer and the bulk phase were compared and the differences between them were explained. The behaviour of the nonionic surfactants and flavonoids in the presence and absence of alcohol was analyzed in relation to the micelle formations and molar volumes of the mixtures and their components. Moreover, the micelles composition and their size as well as the thermodynamic parameters of the micellization process were analyzed.

Bubble Evolution under the Action of Polycarboxylate and Air-Entraining Agent and Its Effects on Concrete Properties-A Review

In order to improve the performance of concrete, it is of great significance to have a better understanding the mechanism and main influencing factors of concrete bubble evolution under the action of polycarboxylate and air-entraining agents. In the present review, with respect to the generation, growth, stability, and rupture of concrete bubbles under the action of polycarboxylate and air-entraining agents, this paper discusses the influence of bubble characteristics on concrete performance and studies bubble regulation by air-entraining agents and polycarboxylate (PCE) superplasticizer. The results show that the acid-to-ether ratio, sulfonic acid group, ester group, and the type of air entraining agent of the polycarboxylate acid structure have a significant impact on the bubbles. The bubble size, specific area, spacing factor, and bubble content have a significant impact on the rheological properties and related mechanical properties of fresh concrete and also affect the appearance quality of concrete. The problems with the experimental methods and theoretical models of concrete bubble research were analyzed, and future research ideas were put forward.