Synthesis and Performance of Double-Chain Quaternary Ammonium Salt Glucosamide Surfactants

Highly Effective and Broad-Spectrum Antimicrobial Quaternary Ammonium Salts Containing Camphene Structure: Preparation, Surface-Active Properties, and Bioassay

A series of novel quaternary ammonium salts (QASs) (4a-4n) comprising a camphene moiety were synthesized for the first time. Fourteen examples were prepared from camphene through Prins reaction, halogenation, and quaternarization, successively. The structures of the synthesized QASs were analyzed by Fourier transform infrared spectroscopy, 1H NMR, 13C NMR and high-resolution mass spectrometry. Surface-active properties, emulsifying abilities, and foaming properties of the investigated compounds were then studied. The antimicrobial activities of these QASs against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), and fungi species (Candida albicans, Candida tropicalis, and Aspergillus niger) were determined by the microdilution method. The results showed that the chemical structural factors, including types of substitutes and alkyl chain length, might be correlated with the lipid-water partition coefficient (cLog P), which played a critical role in the antimicrobial process. Compounds with alkyl chain lengths (N) in the range of 10-14 were relatively more active, while compounds bearing pyridinium, benzyl, methylimidazolium groups, or varied alkyl chain lengths (N < 5 and N > 16) were almost inactive. Compound 4k possessing a dodecyl group exhibited the most effective and broad-spectrum antimicrobial activity against almost all tested bacteria and fungi with the minimal inhibitory concentration values ranging from 0.24 to 0.98 μg/mL.

Preparation and Performance Study of Microemulsion Acid for Comprehensive Plugging Removal in Carbonate Reservoir

Matrix acidification is one of the most effective stimulations to dissolve scales and remove damage in carbonate reservoirs. However, existing acid systems are difficult to dissolve organic and inorganic scales simultaneously, and complex multi-stage alternative injection often introduces new precipitation and damages the reservoir. Here, based on the retardation ability of emulsified acid and the stable structure of microemulsion, an oil-phase solvent was preferably selected, and the surfactant and cosurfactant were optimized to prepare an acid-in-oil type microemulsion acid capable of dissolving both organic and inorganic scales and high solubilizing for hydrochloric acid. Based on the rotating disc experiment, scale dissolution experiment and acid driving experiment, the acid-rock reaction kinetics, scale dissolution ability and acidizing and plugging removal performance of microemulsion acid in a carbonate reservoir were systematically studied and compared. The results show that Solvesso 150 (aromatic solvent) has the advantages of low toxicity, high flash point and high-scale dissolving ability. At NP-4: OP-10: A (cosurfactant) = 3:3:4, the microemulsion acid system has the strongest ability to solubilize hydrochloric acid and can solve the problem of low H⁺ concentration. The particle size of microemulsion acid is smaller compared to emulsified acid. At 60 °C, the mass transfer coefficient of microemulsion acid is 3.2 × 10^-8 cm²/s, which is one order of magnitude less than that of emulsified acid. Microemulsion acid shows good solubility performance in dissolving organic and inorganic scales, and the comprehensive solubility of mixed scales can reach 98.28%. The stronger scale solubilization ability and lower acid-rock reaction rate enable microemulsion acid to form a thin and straight main wormhole, thus enhancing the acidizing and plugging removal effect. This study can solve the problem of poor hydrochloric acid solubilization ability of microemulsion acid to a certain extent, which provides theoretical and data support for the research and development of microemulsion acid and the efficient plugging removal technology for carbonate reservoirs.

One-Step Synthesis of Self-Stratification Core-Shell Latex for Antimicrobial Coating

Herein, we describe a one-step method for synthesizing cationic acrylate-based core-shell latex (CACS latex), which is used to prepare architectural coatings with excellent antimicrobial properties. Firstly, a polymerizable water-soluble quaternary ammonium salt (QAS-BN) was synthesized using 2-(Dimethylamine) ethyl methacrylate (DMAEMA) and benzyl bromide by the Hoffman alkylation reaction. Then QAS-BN, butyl acrylate (BA), methyl methacrylate (MMA), and vinyltriethoxysilane (VTES) as reactants and 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) as a water-soluble initiator were used to synthesize the CACS latex. The effect of the QAS-BN dosage on the properties of the emulsion and latex film was systematically investigated. The TGA results showed that using QAS-BN reduced the latex film's initial degradation temperature but improved its thermal stability. In the transmission electron microscopy (TEM) photographs, the self-stratification of latex particles with a high dosage of QAS-BN was observed, forming a core-shell structure of latex particles. The DSC, TGA, XPS, SEM, and performance tests confirmed the core-shell structure of the latex particles. The relationship between the formation of the core-shell structure and the content of QAS-BN was proved. The formation of the core-shell structure was due to the preferential reaction of water-soluble monomers in the aqueous phase, which led to the aggregation of hydrophilic groups, resulting in the formation of soft-core and hard-shell latex particles. However, the water resistance of the films formed by CACS latex was greatly reduced. We introduced a p-chloromethyl styrene and n-hexane diamine (p-CMS/EDA) crosslinking system, effectively improving the water resistance in this study. Finally, the antimicrobial coating was prepared with a CACS emulsion of 7 wt.% QAS-BN and 2 wt.% p-CMS/EDA. The antibacterial activity rates of this antimicrobial coating against E. coli and S. aureus were 99.99%. The antiviral activity rates against H₃N₂, HCoV-229E, and EV71 were 99.4%, 99.2%, and 97.9%, respectively. This study provides a novel idea for the morphological design of latex particles. A new architectural coating with broad-spectrum antimicrobial properties was obtained, which has important public health and safety applications.

Quaternary Ammonium Salts: Insights into Synthesis and New Directions in Antibacterial Applications

The overuse of antibiotics has led to the emergence of a large number of antibiotic-resistant genes in bacteria, and increasing evidence indicates that a fungicide with an antibacterial mechanism different from that of antibiotics is needed. Quaternary ammonium salts (QASs) are a biparental substance with good antibacterial properties that kills bacteria through simple electrostatic adsorption and insertion into cell membranes/altering of cell membrane permeability. Therefore, the probability of bacteria developing drug resistance is greatly reduced. In this review, we focus on the synthesis and application of single-chain QASs, double-chain QASs, heterocyclic QASs, and gemini QASs (GQASs). Some possible structure-function relationships of QASs are also summarized. As such, we hope this review will provide insight for researchers to explore more applications of QASs in the field of antimicrobials with the aim of developing systems for clinical applications.

Structural Significance of Hydrophobic and Hydrogen Bonding Interaction for Nanoscale Hybridization of Antiseptic Miramistin Molecules with Molybdenum Disulfide Monolayers

This paper reports an easy route to immobilize the antiseptic drug miramistin (MR) molecules between the sheets of molybdenum disulfide, known for excellent photothermal properties. Two hybrid layered compounds (LCs) with regularly alternating monolayers of MR and MoS₂, differing in thickness of organic layer are prepared and studied by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations and quantum theory of atoms in molecules (QTAIM) topological analysis. The obtained structural models elucidate the noncovalent interaction network of MR molecules confined in the two-dimensional spacing surrounded by sulfide sheets. It emerged that the characteristic folded geometry of MR molecule previously evidenced for pure miramistin is preserved in the hybrid structures. Quantification of the energetics of bonding interactions unveils that the most important contribution to structure stabilization of both compounds is provided by the weak but numerous CH…S bonding contacts. They are accompanied by the intra- and inter-molecular interactions within the MR layers, with dominating bonding effect of intermolecular hydrophobic interaction. The results obtained in the models provide a comprehensive understanding of the driving forces controlling the assembly of MR and MoS₂ and may lead towards the development of novel promising MoS₂-based photothermal therapeutic agents.

Magnetic CuFe2O4 Nanoparticles with Pseudocapacitive Properties for Electrical Energy Storage

This investigation is motivated by increasing interest in the development of magnetically ordered pseudocapacitors (MOPC), which exhibit interesting magnetocapacitive effects. Here, advanced pseudocapacitive properties of magnetic CuFe₂O₄ nanoparticles in negative potential range are reported, suggesting that CuFe₂O₄ is a promising MOPC and advanced negative electrode material for supercapacitors. A high capacitance of 2.76 F cm^-2 is achieved at a low electrode resistance in a relatively large potential window of 0.8 V. The cyclic voltammograms and galvanostatic charge-discharge data show nearly ideal pseudocapacitive behavior. Good electrochemical performance is achieved at a high active mass loading due to the use of chelating molecules of ammonium salt of purpuric acid (ASPA) as a co-dispersant for CuFe₂O₄ nanoparticles and conductive multiwalled carbon nanotube (MCNT) additives. The adsorption of ASPA on different materials is linked to structural features of ASPA, which allows for different interaction and adsorption mechanisms. The combination of advanced magnetic and pseudocapacitive properties in a negative potential range in a single MOPC material provides a platform for various effects related to the influence of pseudocapacitive/magnetic properties on magnetic/pseudocapacitive behavior.