Synthesis and Characterization of Cationic Surfactants Based on N‐Hexamethylenetetramine as Active Microfouling Agents

Four cationic surfactants of quaternary hexammonium silane chloride based on hexamethylenetetramine and alkyl chloride were synthesized. The chemical structures of the prepared cationic surfactants were elucidated using Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. The surface and thermodynamic properties of the prepared surfactants were also studied. The performance of these cationic surfactants as microfouling agents against two strains of Gram‐negative bacteria, namely, Pseudomonas aeruginosa and Escherichia coli, and two strains of Gram‐positive bacteria, namely, Staphylococcus aureus and Bacillus subtilis, were evaluated as antimicrobial agents. The results showed that the maximum antimicrobial activity was detected for N‐hexamethylenetetramine‐N‐ethyl silane ammonium trichloride (Ah). The maximum and minimum antimicrobial activities were 73 and 60 % against S. aureus and E. coli, respectively, at a concentration of 5 mg/l, pH 7, and 37 °C.     

Synthesis and Inhibitory Activity of Schiff Base Surfactants Derived from Tannic Acid and Their Cobalt (II), Manganese (II) and Iron (III) Complexes Against Bacteria and Fungi

A series of tannic acid Schiff base surfactants and their iron, cobalt and manganese metal complexes were synthesized and their structures were elucidated by microelemental analysis, FTIR and ¹H-NMR data. The surface activities of the surfactants were increased by increasing the number of substituents, as represented from the surface tension measurements. The metal complexes showed higher critical micelle concentrations and surface tension reduction at critical micelle concentration. The antimicrobial activity in terms of inhibition zone diameter and minimum inhibitory concentrations showed increasing activity of the metal complexes over their parent compounds against Gram-positive, Gram-negative bacteria and fungi.     

Synthesis and Characterization of Multifunctional Surfactants in Oil-Field Protection Applications

A series of cationic surfactants was prepared using economical raw materials. The chemical structures of the prepared compounds were confirmed using elemental analysis, FTIR and ¹H-NMR spectra, and melting point determination. The synthesized surfactants were evaluated as oil-field protective additives. In this regard, several surface properties of the synthesized surfactants were studied including surface tension, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area. The results obtained from the surface activity measurements were correlated to their chemical structures. The emulsification power measurements for solutions of these surfactants showed their low emulsifying tendency towards paraffin and crude oil. The synthesized surfactants also exhibited high biocidal activity towards gram-positive and gram-negative bacteria and fungi. This activity was increased by increasing the hydrophobic chain length. The corrosion inhibition measurement of these surfactants for mild steel alloys in acidic media using a weight loss technique showed good protection of mild steel alloys against acidic environments. These properties qualify the synthesized compounds as economical oil-field protective additives.

Surface-Active Properties and Antimicrobial Study of Conventional Cationic and Synthesized Symmetrical Gemini Surfactants

Symmetrical gemini surfactants of cationic series α,ω-alkanediyl bis (dimethyl ammonium bromide) commonly referred as “m–s–m” have been synthesized. Spectral analysis was performed to confirm compound structures and purity. Conductivity and surface tension measurements provide better understanding of the micellization process. Their self-assembly behavior in aqueous solution is also discussed in detail. The antimicrobial efficacy was measured by bacterial and fungal growth inhibition expressed as minimal inhibitory concentration values against five strains of a representative group of microorganisms viz. Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, Salmonella paratyphi B and Aspergillus niger. All of the synthesized surfactants showed antimicrobial activity against them, but at different levels depending on their structures. The surfactants possessing longer alkyl chains (more hydrophobic environment) demonstrated better antimicrobial functionality. The antimicrobial potency was found to be dependent on the representative target microorganism (Gram-positive bacteria > fungi > Gram-negative bacteria), as well as on the ionic nature of the surfactant (cationic), alkyl chain length (m = 12, 16) and spacer length (s = 2, 4, 6) of the synthesized compounds. Gemini surfactants such as 12-2-12 and 12-4-12 were found to be weakly active whereas 16-2-16 and 16-4-16 compounds proved to be the most potent antimicrobial surface-active agents among the synthesized gemini homologues.     

Environmentally Friendly Nonionic Surfactants Derived from Tannic Acid: Synthesis, Characterization and Surface Activity

In order to discover new and safe surfactants with regard to the environment, new environmentally friendly nonionic surface active agents were synthesized by the reaction of tannic acid (as a natural product presents in several plants) and polyethylene glycol fatty acids containing different numbers of ethylene glycol units. The fatty acids were dodecanoic, hexadecanoic, octadecanoic and oleic acids. The chemical structures of the synthesized surfactants were confirmed using elemental analysis, infrared and ¹H-NMR spectroscopy. The molecular weights of the synthesized surfactants were determined using viscosity measurements and gel permeation chromatography. The surface properties of these surfactants were determined using surface tension measurements. The chemical structure?Csurface activity relationship of these surfactants showed a strong dependence of the surface activity on their chemical structures including the hydrophobic chains and the number of ethylene glycol units incorporated in the molecules. The free energy of micellization of the surfactants in their solutions showed their tendency towards micellization in the bulk of their solutions, while the free energy of adsorption showed their high tendency towards adsorption at the air?Cwater interface.     

Antimicrobial and Cytotoxic Properties of Bisquaternary Ammonium Bromides of Different Spacer Length

A group of cationic gemini surfactants (bisquaternary ammonium bromides) with different spacer chain lengths (8–6–8, 8–7–8, 8–8–8, 8–9–8) was investigated, paying special attention to antimicrobial and the cytotoxic properties as well as their antimicrobial activity during long‐term storage. It was shown that the compounds investigated exhibit excellent antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus) and Gram‐negative bacteria (Pseudomonas aeruginosa) as well as antifungal properties (Candida albicans). The gemini surfactants tested had the differential level of cytotoxicity against normal lymphocytes. It was shown that the spacer chain length plays an important role in antibacterial activity and influences the cytotoxicity. The gemini surfactants with shorter spacer chain length, that had higher critical micelle concentration, showed generally weaker antibacterial properties, but on the other hand, these exhibited lower level of cytotoxicity. Furthermore, the aqueous solution of gemini surfactants exhibited the same antimicrobial activity even after 3 months.     

Synthesis,Characterization, Surface,and Thermodynamic Studies of Alkyl Tetrachloroferrates: Performance Evaluation of Their Nanostructures as Biocides

Decyl and dodecylamino tetrachloroferrates were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), elemental analysis, X-ray diffraction (XRD), nuclear magnetic resonance (¹H-NMR), and atomic absorption spectroscopy (AAS). The surface properties of the cationic surfactants including critical micelle concentration, effectiveness, minimum surface area, and maximum surface excess were determined using surface tension measurements. The effectiveness of surface tension reduction (π_cmc) was found to increase as the hydrophobic chain length increases with values of 30 and 34 mN m⁻¹ for C₁₀ and C₁₂, respectively. Moreover, the effect of temperature on micellization was determined over the range of 35–55 °C. Thermodynamic parameters (ΔG°, ΔS°, and ΔH°) were calculated and the results indicate a spontaneous process for both micellization and adsorption. The nanoparticles (NC₁₀ and NC₁₂) of the prepared surfactants were obtained using the ball mill technique. The particle size and morphology of the nanoparticles were determined using transmission electron microscope measurements. The antibacterial study of the nanoparticle surfactants revealed their strong efficiency against fungi and different pathogenic bacteria compared with the original surfactants.     

Pyrazole Derived Cationic Surfactants and their Tin and Copper Complexes: Synthesis,Surface Activity,Antibacterial and Antifungal Efficacy

Five membered heterocyclic cationic 3-pyrazolium surfactants namely: 2-[2-(alkyloxy)-2-oxoethyl]-3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-3-pyrazolium bromide (decyl-; dodecyl-) and their copper and tin complexes were synthesized, their structures were confirmed using different spectroscopic tools. The IR spectra of the metal complexes showed that these compounds exhibit a tetrahedron structure with the transition metal ion (M²⁺) at the center and the cationic ligands arranged in the apexes, while the halide ions in the center. The synthesized compounds were evaluated as biocides against different types of bacteria and fungi. The biological activity data showed that the cationic surfactants exhibit moderate to high efficacy against the tested microorganisms (either bacteria or fungi). While, complexation of these cationic surfactants with Cu (II) and Sn (II) ions the antimicrobial activity was strongly increased. The surface activity of these compounds were discussed and correlated to their chemical structure and the type of substituents on the heterocyclic moiety. Meanwhile, the antimicrobial assay was correlated to the surface activities of the synthesized compounds.     

Synthesis and characterization of antimicrobial cationic surfactants: Aminopyridinium salts

Three antimicrobial 4-aminopyridinium salts were synthesized using two different processes in an effort to develop antimicrobial surface treatment agents for wool fibers. The structures of the salts were fully characterized using Fourier transform infrared, ¹H nuclear magnetic resonance (NMR), and ¹³C NMR analysis. In addition, their thermal stability was determined using differential scanning calorimetry and thermogravimetric analysis. The antimicrobial efficacy of these compounds was evaluated using minimum inhibitory concentration as an indicator. All of the synthesized aminopyridinium salts showed antimicrobial activity against gram-negative bacteria, but in different levels depending on their structures. The salts possessing longer alkyl chains demonstrated better antimicrobial function. The melting points of the salts decreases as the alkyl chain length increases.     

Synthesis,Surface and Antimicrobial Activities of Cationic Gemini Surfactants with Semi-Rigid Spacers

Four cationic gemini surfactants featuring semi-rigid spacers were synthesized via a two-step process. The surface-active properties of these surfactants were investigated through surface tension and electrical conductivity measurement. The thermodynamic parameters of micellization were evaluated from electrical conductivity measurements at temperatures ranging from 293 to 313 K. The aggregation behavior of these synthesized gemini surfactants in water were investigated using dynamic light scattering and transmission electron microscopy. Further, the antimicrobial activities of these synthesized gemini surfactants against both Gram-positive and Gram-negative bacteria were also investigated.     

Biocidal Activities of Cationic Surface Active Starch and Its Transition Metal Complexes Against Different Bacterial Strains

Starch alkyl triethanolammonium chloride derivatives and their metal complexes (Cu²⁺, Co²⁺ and Fe³⁺) were prepared and characterized using elemental analysis, FTIR, and ¹H-NMR spectra. The synthesized compounds were evaluated as antimicrobial agents against different microorganism including bacteria (gram +ve and gram −ve) and fungi. The effect of the chemical structure of the targeted cationic surfactants was discussed based on the surface parameters including surface tension and critical micelle concentration (CMC). Also, the effect of the structure of these surfactants and their metal complexes of Cu²⁺, Co²⁺ and Fe³⁺ on the cell membrane is discussed as well as their potent action on the targeted bacteria and fungi.     

Synthesis,Characterization, Surface and Biological Activity of Diquaternary Cationic Surfactants Containing Ester Linkage

Two series of diquaternary cationic surfactants designated as E9Nm and E11Nm having two different alkyl chains in their chemical structure were synthesized. The chemical structures of these surfactants were confirmed using elemental analysis, FTIR and ¹H‐NMR spectra. The surface activities of the different surfactants were determined using surface and interfacial tension at 25 °C. The surface parameters including: critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area were determined. The surface activities of the cationic surfactants were correlated with their chemical structure. The surface activities of the surfactants increased with increasing the hydrophobic chain length. The adsorption and micellization tendencies of the surfactants in solution were determined using the free energies of adsorption and micellization. The synthesized surfactants were evaluated as biocides against bacteria and fungi. Biocidal activity data showed that a gradual increase in the hydrophobic chain length of the surfactant molecules gradually increases the efficiency of these surfactants as biocides.     

Synthesis and Evaluation of Some Triazole Derivatives as Corrosion Inhibitors and Biocides

Three compounds namely; 5-(phenyl)-4H-1,2,4-triazole-3-thiol, 3-(decylthio)-5-phenyl-1H-1,2,4-triazole and 3-(benzylthio)-5-phenyl-1H-1,2,4-triazole) were synthesized. The chemical structure of the prepared compounds was confirmed using FTIR and ¹H-NMR analysis. The compounds were tested as corrosion inhibitors against the corrosion of carbon steel in 1 M HCl using weight loss, polarization and electrochemical impedance methods. The results revealed that these compounds have significant inhibiting effects on the corrosion of carbon steel. Polarization studies showed that the compounds act as mixed-type inhibitors which retard the anodic and the cathodic reactions with a predominant effect towards the cathodic reaction. The prepared compounds were evaluated as antimicrobial agents against sulfate-reducing bacteria using the serial dilution method, which showed good biocidal action.     

Antibacterial Activities of Five Cationic Gemini Surfactants with Ethylene Glycol Bisacetyl Spacers

A series of cationic gemini surfactants containing two dimethylalkylammonium chains linked by ethylene glycol bisacetyl spacers were synthesized [G_m‐AnA‐m, G = gemini surfactant, m = 12 (–C₁₂H₂₅), 14 (–C₁₄H₂₉), or 16 (–C₁₆H₃₃), A = acetyl, and n = 2, 3, or 4 is the number of ethylene glycol units in the spacers]. Because of the inductive effect of the oxygen atom in the spacer, acylation can take place using chloroacetyl chloride instead of bromoacetyl bromide which helps to limit the use of environmentally harmful reagents. Critical micelle concentrations were determined using conductivity measurements. The antibacterial activities of the surfactants against Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated from the minimum inhibitory concentration (MIC), minimum bacterial concentration, a time–kill study, and the inhibitory zone. Increasing the length of the spacer did not result in an obvious change of antibacterial activity. However, increasing the length of the alkyl chain apparently increased the antibacterial activity against S. aureus but decreased the antibacterial activity against E. coli. The G_{12‐A2A‐12} surfactant had the lowest CMC of 1.26 mmol L^?1 and exhibited the best antibacterial activity with a MIC of 32 μg mL^?1 toward S. aureus and 64 μg mL^?1 toward E. coli in the presence of 10⁵ CFU of bacteria. This work indicated that these cationic gemini surfactants have potential applications as antibacterial agents and emulsifiers.     

Synthesis and fabrication of high-potent antimicrobial polymeric ultrathin coatings

The development of antimicrobial coatings in various sectors is escalating nowadays. However, design, synthesis, and fabrication of simple antimicrobial polymer coatings with potent biocidal action against pathogenic microbes are necessary to emerge. The current article deals with fabrication of high efficient ultrathin coatings of synthesized polymer for controlling pathogenic bacteria and fungi. The article is intensified with simple synthesis, characterization, fabrication of ultrathin coatings and their antimicrobial studies. The polymer structure is elucidated by FTIR,¹HNMR, and ¹³CNMR, and the thermal properties are explained by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The antimicrobial activity of a polymer and their ultrathin coatings against Escherichia coli, Staphylococcus aureus, tubercular-variant Mycobacterium smegmatis, and Candida albicans are reported elaborately. The morphology of ultrathin coating and their interaction with microorganisms are studied using a scanning electron microscope and an atomic force microscope. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47893.     

The Effects of Amide Bonds and Aromatic Rings on the Surface Properties and Antimicrobial Activity of Cationic Surfactants

The cationic surfactants containing aromatic rings and amide bonds, N,N-dimethyl-N-dodecyl-2-pyrimidinylcarbamoylmethyl ammonium chloride ( a ), N,N-dimethyl-N-dodecyl-2-thiazolylcarbamoylmethyl ammonium chloride ( b ), and N,N-dimethyl-N-dodecyl-phenylcarbamoylmethyl ammonium chloride ( c ), were synthesized and characterized. The surface tension and conductivity values were employed to investigate the absorption and micellization behavior of the three cationic surfactants. The results showed that the synthesized surfactants have shown a low critical micelle concentration (CMC) and a high adsorption efficiency (pC₂₀) compared with the traditional cationic surfactant of N,N-dimethyl-N-dodecyl-N-benzyl ammonium chloride ( BAC-12 ). The aromatic rings of the a , b , and c molecular structures were analyzed using the ¹H NMR spectra for electrostatic repulsion effects between hydrophilic headgroups. The size distribution of the micelles was derived using dynamic light scattering (DLS) techniques. In addition, the foaming ability of a , b , c , and BAC-12 was investigated and the antimicrobial activity of a , b , c , and BAC-12 against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis was examined. The effects of amide bonds and aromatic rings on the surface properties and antimicrobial activity of a , b , and c were analyzed and compared with BAC-12 of the same alkyl chain length. The synthesized surfactants exhibited a high surface ability and better antibacterial activity compared with BAC-12 .     

Synthesis and Evaluation of Nonionic Surfactants Derived from Tannic Acid as Corrosion Inhibitors for Carbon Steel in Acidic Medium

Nonionic Schiff base surfactants were synthesized by chemical modification of tannic acid. The surface activities of the synthesized surfactants were determined using surface tension, interfacial tension, and emulsification properties. Thermodynamic parameters of adsorption and micellization of these surfactants showed their tendency towards the two processes with greater predominance of adsorption over micellization. Electrochemical polarization and impedance measurements showed that the surfactants exhibited good tendency towards inhibiting the dissolution of carbon steel in acidic medium. The inhibition efficiencies depend on the chemical structure and concentration of the compounds.     

Screening for Potential Antimicrobial Activities of Some Cationic Uracil Biocides Against Wide-Spreading Bacterial Strains

Eight novel uracil-based cationic surfactants containing Schiff base species were synthesized and characterized using elemental analysis, FTIR, ¹H-NMR and ¹³C-NMR spectroscopy. The surface activities of the synthesized Schiff bases and their cationic derivatives were determined based on interfacial tension measurements and partition coefficient values in water/octanol system. The synthesized Schiff bases and their cationic derivatives were evaluated as novel biocides against different bacteria and fungi strains. The results showed that the biocidal activity of the synthesized Schiff bases was considerably increased by quaternization. The influence of the cationic surfactants as biocides was increased by increasing the hydrophobic chain length and the presence of the methoxy groups. The biocidal activity was also increased by increasing the partition coefficient in water/octanol system. The structure and surface activity/biocidal activity of the different compounds were discussed.     

Bio-Wax Latex-Modified Paper as Antimicrobial and Water-Vapor-Resistant Packaging Material

Beeswax and carnauba wax latex particles grafted with antimicrobial agents polyhexamethylene guanidine hydrochloride and polyhexanide were prepared by coupling reaction using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride as a coupling reagent. As a bifunctional agent for the surface treatment of paper the modified bio-wax latex improved the property of water-vapor resistance and antimicrobial activities of paper significantly after coating. Compared with the control sample the water vapor transmission rate (WVTR) of the paper with coating weight of 12 g/m² was reduced significantly from 2788.8 g/m²/d to 222.0 g/m²/d (BW-Gly-PHGH) thus demonstrating excellent water vapor barrier performance. The shaking flask method was utilized to investigate the antimicrobial activity against E. coli. The results showed that antimicrobial performance was improved substantially when the amount of added modified bio-wax particles was higher than 20 mg/g fiber. The bacterial inhibition ring test indicated that the antimicrobial mode of the modified bio-wax particles was likely based on the contact mode.     

Novel Gemini Cationic Surfactants: Thermodynamic,Antimicrobial Susceptibility,and Corrosion Inhibition Behavior against Acidithiobacillus ferrooxidans

The Egyptian oil and gas industry is suffering from severe metal corrosion problems, particularly microbial-induced corrosion. There is limited knowledge on the corrosion inhibition of carbon steels in the presence of an acidophilic, iron-oxidizing bacterial species Acidithiobacillus ferrooxidans. Therefore, in this study, novel Gemini cationic surfactants, in three forms depending on variation in alkyl chains of 8, 12, and 16 carbon atoms named FHPAO, FHPAD, and FHPAH, respectively, were synthesized and characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopy. The surface parameters and the thermodynamic of the synthesized surfactants were evaluated at three different temperatures, 20, 40, and 60 °C. The synthesized Gemini cationic surfactants were tested as broad-spectrum antimicrobial, antibacterial and anticandida agents. They evaluated as biocides and corrosion inhibitors against Acidithiobacillus ferrooxidans. FHPAD showed higher adsorption ability at the solution interface and higher affinity to construct micelles than FHPAO and FHPAH. Both adsorption and micellization processes were hydrophobic and temperature dependent. FHPAO, FHPAD and FHPAH exhibited wide-spectrum antimicrobial activities, and the highest activity and the lowest minimum bactericidal/fungicidal inhibitory concentrations were attributed to FHPAD. Furthermore, synthesized FHPAD demonstrated the highest metal corrosion inhibition efficiency of 95.5% at 5 mM in comparison to 87.5% and 81.7% for FHPAO and FHPAH, respectively. In conclusion, this study provides novel synthesized cationic surfactants with many applications in the oil and gas industry, such as broad-spectrum antimicrobial, biocides, and corrosion inhibitors for acidophilic, iron-oxidizing bacterial species Acidithiobacillus ferrooxidans.