Synthesis, Surface and Thermodynamic Properties of Substituted Polytriethanolamine Nonionic Surfactants

Three series of nonionic surfactants derived from polytriethanolamine containing 8, 10, and 12 units of triethanolamine were synthesized. Structural assignment of the different compounds was made on the basis of FTIR and ¹H‐NMR spectroscopic data. The surface parameters of these surfactants included critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), surfactant concentration required to reduce the surface tension of the solvent by 20 mN m^?1 (pC₂₀), maximum surface excess (Γ_max), and the interfacial area occupied by the surfactant molecules (A_min) using surface tension measurements. The micellization and adsorption free energies were calculated at 25 °C.     

Novel Biobased Nonionic Surfactants: Synthesis,Surface Activity and Corrosion Inhibition Efficiency Against Aluminum Alloy Dissolution in Acidic Media

Four nonionic surfactants were prepared from the reaction of propylene oxide with oleic acid, linoleic acid, and the free fatty acid mixture from hydrolysis of jatropha oil. The chemical structures of the prepared surfactants were confirmed using IR and NMR spectroscopy. The surface activities of the prepared surfactants were dependent on the polypropylene oxide chain length and also on the nature of the alkyl chains. The nonionic surfactants were evaluated at different concentrations as corrosion inhibitors against the corrosion of Al 6061 aluminum in 2 M HCl solution. The corrosion inhibition tendencies of the surfactants were completely dependent on the fatty acid ratio in the jatropha oil and also on the polypropylene oxide chain length. The corrosion inhibition efficiencies of the surfactants were correlated to their chemical structure and their surface activities.     

Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Synthesis,Characterization and Surface Properties of Amidosulfobetaine Surfactants Bearing Odd-Number Hydrophobic Tail

Three amidosulfobetaine surfactants were synthesized namely: 3-(N-pentadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2a); 3-(N-heptadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2b), and 3-(N-nonadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2c). These surfactants were prepared by direct amidation of commercially available fatty acids with 3-(dimethylamino)-1-propylamine and subsequent reaction with 1,3-propanesultone to obtain quaternary ammonium salts. The synthesized surfactants were characterized by IR, NMR and mass spectrometry. Thermogravimetric analysis (TGA) results showed that the synthesized surfactants have excellent thermal stability with no major thermal degradation below 300 °C. The critical micelle concentration (CMC) values of the surfactants 2a and 2b were found to be 2.2 × 10^?4 and 1.04 × 10^?4 mol/L, and the corresponding surface tension (γ_CMC) values were 33.14 and 34.89 mN m^?1, respectively. The surfactants exhibit excellent surface properties, which are comparable with conventional surfactants. The intrinsic viscosity of surfactant (2b) was studied at various temperatures and concentrations of multi-component brine solution. The plot of natural logarithm of relative viscosity versus surfactant concentration obtained from Higiro et al. model best fit the surfactant behavior. Due to good salt resistance, excellent surface properties and thermal stability, the synthesized surfactant has potential to be used in various oil field applications such as enhanced oil recovery, fracturing, acid diversion, and well stimulation.     

Synthesis and Surface Properties of Anionic Gemini Surfactants having N-acylamide and Carboxylate Groups

A straightforward synthetic strategy to an anionic gemini surfactant having both N-acylamide and carboxylate groups in a molecule has been demonstrated. The surface properties of the anionic gemini surfactant, such as CMC (critical micelle concentration), C₂₀ (the concentration required to reduce the surface tension of the solvent by 20 mN/m), γ _CMC (the surface tension at the CMC), ∏ _CMC (the surface pressure at the CMC), Γ _max (the maximum surface excess concentration at the air/aqueous solution interface), A _min (the minimum area per surfactant molecule at the air/water interface), and the CMC/C₂₀ ratio (a measure of the tendency to form micelles relative to adsorbtion at the air/water interface), have been studied. The influence of the different concentrations of NaCl on the surface properties of the gemini surfactant has been discussed. The results have shown that the CMC values decreased with an increase in the concentration of NaCl indicating that the Na⁺ preferentially adsorbs onto the surface of the charged aggregate and facilitates the aggregate growth by suppressing the main impediment of electrostatic repulsion among head groups. Additionally, the values of Γ _max are always higher in salt solutions as compared to those in pure water due to their salting out effect. The larger pC₂₀ value indicates that the surfactant adsorbs more efficiently at the air/water interface and reduces surface tension more efficiently. In addition, the geminis in water show little or no break in their specific conductance versus surfactant molar concentration plots. This is attributable to protonation of the carboxylate group and strong Na⁺ release during micellization.     

聚醚改性有机硅表面活性剂的合成与性能

以含氢硅油与端烯丙基聚醚为原料,在氯铂酸的催化作用下,经硅氢加成反应合成了聚醚改性有机硅乳化剂。通过正交实验测定反应的转化率,探讨了反应时间、反应物比例、催化剂用量以及反应温度对反应的影响,并得出较适宜的反应条件为：反应时间为7h,n（Si—H）：n（C=C）--1：1,催化剂用量为20μg/g,反应温度为130℃,在该条件下,含氢硅油中Si—H的转化率达96％。由此制备的表面活性剂能有效降低表面张力,具有优良的乳化性能。初步讨论了含氢硅油与聚醚反应生成的共聚物的阴离子化反应,合成了硫酸盐型阴离子表面活性剂,由于结构的差异,产物HLB值有所增加。     

Synthesis and Surface Properties of Novel Gemini Imidazolium Surfactants

Five new Gemini imidazolium surfactants were synthesized from imidazole and 1-bromoalkane (C₈, C₁₀, C₁₂, C₁₄, C₁₆) to get 1-alkylimidazole, which was further reacted with 1,3-dichloropropan-2-ol to form the surfactant molecule, 1,1′-(propane-1,3-diyl-2-ol) bis(3-alkyl-1H-imidazol-3-ium) chloride. The structures of the five new surfactants and intermediates were characterized by ¹H-NMR, ¹³C-NMR and IR spectra. Thermal properties of the five new surfactants were studied with thermogravimetric analysis and differential scanning calorimetry, the five new surfactants showed a transition from a crystalline phase to a thermotropic liquid–crystalline phase at around ca. 100 °C, which transformed to an isotropic liquid phase at around ca. 165 °C. The five new surfactants critical micelle concentrations (CMC) in the aqueous solutions were determined by surface tension and electrical conductivity methods. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γ _CMC), adsorption efficiency  (pC ₂₀), and effectiveness of surface tension reduction (π_CMC). In addition, with application of the Gibbs adsorption isotherm, maximum surface excess concentration (Γ_max) and minimum surface area/molecule (A_min) at the air–water interface were obtained. The parameters β (degree of counterion binding to micelles), ΔG _ads ^θ (Gibbs free energy of adsorption), and ΔG _mic ^θ (Gibbs free energy change of micellization) were also derived. The results indicated that the five new Gemini surfactants exhibited very low CMC and a good efficiency in lowering the surface tension of water. The foamability and foam stability of the five new surfactants were also examined at different CMC.     

Synthesis, Surface Active Properties of Novel Gemini Surfactants with Amide Groups and Rigid Spacers

A series of novel cationic gemini surfactants, bis-(N-(3-alkylamido-propyl)-N,N-dimethyl)-p-phenylenediammonium dichloride, were synthesized. The structures of the gemini surfactants were characterized by IR, ¹H NMR and ¹³C NMR. The Krafft temperatures of surfactants were determined through conductivity, the surface active properties in aqueous solution were studied at various temperatures by surface tension and conductivity. The thermodynamic functions of micellization process of the surfactants were also calculated by conductivity. The Krafft temperatures of the surfactants were 12, 13 and 28 °C. The values of CMC and Γ _max decreased with increasing the length of hydrophobic chains, but the values of CMC and α increased with increasing temperature. The process of micellization is a spontaneous, exothermic and entropy-driven process.     

Synthesis, Characterization, Biodegradation and Evaluation of the Surface Active Properties of Nonionic Surfactants Derived from Jatropha Oil

Four nonionic surface active agents were synthesized using the fatty acids obtained from the hydrolysis of Jatropha oil. The fatty acids obtained contained different fatty acids including: palmitic, stearic, oleic, linoleic and linolenic acids in different proportions. The chemical structures of the obtained surfactants were characterized using elemental analysis and FTIR spectroscopy. The surface activities of the different surfactants were determined using surface and interfacial tension measurements. The surfactants showed good surface and interfacial activities, which are dependent on their chemical structures. Thermodynamic parameters of adsorption and micellization confirmed these results. The biodegradation tests in river water showed that the surfactants are readily biodegradable, and reached the European standards after 24 days. Surfactants containing longer nonionic chains formed stable emulsions with paraffin oil, while shorter chains exhibit a lower emulsion stability performance.     

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.     

有机硅表面活性剂的合成及性能表征

用含氢硅油、烯丙基聚醚为原料,铂为催化剂制备有机硅表面活性剂(S);考察了各反应条件对合成S的影响;并使用红外光谱、接触角测定仪等对其进行表征;将S作为乳化剂应用在苯丙乳液中。实验结果表明,在原料配比为1∶1,80℃下反应5 h,催化剂用量6×10-6时,合成的产率最高为95.23%;用S作为乳化剂合成的苯丙乳液随着S用量的增加,乳液聚合单体转化率和乳液稳定性先增加后稳定、乳液粒子平均粒径、乳胶膜吸水率先降低后变化趋于平缓。     

Synthesis and Properties of Quaternary Ammonium Gemini Surfactants with Hydroxyethyl at Head Groups

A series of cationic gemini surfactants C_mH_{2m + 1}N⁺(CH₂CH₂OH)₂ (CH₂)_s N⁺(CH₂CH₂OH)₂C_mH_{2m + 1} 2Br⁻, referred to as m-s-m (OH) (m = 8,10,12, s = 3,4), were prepared by quaternization of dihydroxyethyl tertiary amines with dibromoalkane. The dihydroxyethyl tertiary amines were synthesized by nucleophilic substitution of diethanolamine with bromoalkane. The characterization of the m-s-m (OH) surfactants was performed using ¹H NMR and MS. The surface activities and aggregation behavior in aqueous solution of the m-s-m (OH) surfactants were studied using surface tension measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The surface tension and critical micellar concentration of these surfactants in aqueous solution decreased dramatically due to the introduction of hydroxyethyl at the head group. The micelles and/or vesicles formed in the aqueous solution of m-s-m (OH) surfactants were strongly dependent upon the lengths of spacer chains and carbon chains. The number of vesicles increases and that of micelles decreases when the lengths of spacer chains and carbon chains increase.     

2-Ethylhexanol Derivatives as Nonionic Surfactants: Synthesis and Properties

The synthesis and basic properties of 2‐ethylhexanol based innovative nonionic surfactants are described in this paper. 2‐Ethylhexanol as an available and relatively inexpensive raw material was used as the hydrophobe source modified by propoxylation and followed by polyethoxylation. As the result, six series of 2‐ethylhexyl alcohol polyalkoxylates (EHP_mE_n) were obtained with three steps of propoxylation, each followed by polyethoxylation and two series only with polyethoxylation (EHE_n). Two different catalysts were used, a dimetalcyanide and KOH. Values of average conversion rates and chemical content of the obtained products (GC, TG and GPC techniques) were compared. The influence of the applied catalyst and polyaddition degree on the homologue distribution, reactant conversion and amount of byproducts is discussed. The basic physicochemical parameters including refractive index, solubility in polar media, foaming properties and wettability were investigated and compared. Furthermore, surface activity parameters, i.e. surface tension (γ_CMC) and critical micelle concentrations were determined. Results are compared to C_12–14 alcohol ethoxylates (LaE_n). Accordingly, it was found that the studied 2‐ethylhexyl alcohol based compounds are effective, low foaming nonionic surfactants.     

Synthesis and Properties of New Cleavable Cationic Surfactants Containing Carbonate Groups

A novel series of cleavable alkyltrimethylammonium surfactants with different hydrocarbon chain lengths (C8–16) were synthesized. A carbonate break site inserted between the polar head and the hydrocarbon chain makes these compounds hydrolyzable. The reagents used are renewable, (bio)degradable, or reusable. The hydrolysis of these cleavable surfactants will lead to the generation of fatty alcohols and choline, which is an essential biological nutrient. The surface activities in aqueous solution of the synthesized carbonates fulfill the requirement of being good surfactants. In addition, the cleavable compounds containing n-decyl and n-dodecyl chains showed similar or higher antimicrobial activities when compared to a non-cleavable analog.     

Synthesis and Properties of Dissymmetric Gemini Surfactants

A series of novel dissymmetric gemini surfactants, [C _m H_2m+1COOC₂H₄(CH₃)₂N(CH₂)₃N(CH₃)₂C₂H₄OOCC _n H_2n+1]Br₂ was synthesized and symbolized as m-s–n. The Krafft temperatures and surface tension curves of the dissymmetric gemini surfactants were measured using an electrical conductivity method and a drop volume method. The low Krafft temperatures indicate very good solubility of these esterquat gemini surfactants. With the increasing numbers of carbon atoms in the hydrophobic alkyl chain, the critical micelle concentration (CMC) and the minimum surface area (A _min) decrease, and the efficiency of surface tension reduction (pc₂₀) increases. With the same numbers of carbon atoms in the hydrophobic alkyl chain, the dissymmetric gemini surfactant has a lower CMC and a smaller A _min than the corresponding symmetric gemini surfactant due to the enhanced hydrophobic interactions.     

Synthesis and Properties of Dicephalic Cationic Surfactants Containing a Quaternary Ammonium and a Guanidine Group

Novel dicephalic surfactants containing a quaternary ammonium and a guanidine group were synthesized, and the effect of the alkyl chain length on micellization and antimicrobial activity were investigated. Surface tension and conductivity were applied to study the self-aggregation of the amphiphilic molecule in aqueous solution. The results indicated that these compounds reduce the surface tension to a level of 30–36 mN/m at the air/water interface and that there is a characteristic chain length dependence of the micellization process of surfactants. The antimicrobial activity was evaluated against Gram-negative, Gram-positive bacteria and fungi, indicating strong antibacterial activity against tested strains.     

Surface and Biocidal Properties of Gemini Cationic Surfactants Based on Propoxylated 1,6-Diaminohexane and Alkyl Bromides

Two new classes of gemini cationic surfactants—hexanediyl-1,6-bis[(isopropylol) alkylammonium] dibromide {in the abbreviation form: C_nC₆C_n[iPr-OH] and C_nC₆C_n[iPr-OH]₂; alkyl: C_nH_{2n + 1} with n = 9, 10, 12 and 14}—have been synthesized by interaction of alkyl bromides with N,N′-di-(isopropylol)-1,6-diaminohexane and N,N,N′,N′-tetra-(isopropylol)-1,6-diaminohexane. The surface tension, electrical conductivity, and dynamic light scattering (DLS) techniques were used to investigate the aggregation properties of the gemini cationic surfactants in aqueous solution. The formation of critical aggregates at two concentrations in an aqueous solution from obtained gemini cationic surfactants were determined via the tensiometric method. Thus, these gemini cationic surfactants start to form aggregates at concentrations well below their critical micelle concentrations (CMC). The surface properties and the binding degree (β) of the opposite ion were tested against the length of the surfactant hydrocarbon chain and the number of the isopropylol groups in the head group. By applying the DLS technique, it was explored that how the number of isopropylol groups in gemini cationic surfactants with C₁₂H₂₅ chain affects the sizes of micelles at concentrations greater than CMC. It was discovered that the obtained gemini cationic surfactants have a biocidal character.     

Novel Nonionic Polyurethane Surfactants and Ag Nanohybrids: Influence of Nonionic Polymeric Chains

Five novel nonionic surfactants were prepared by the reaction of polyethylene glycol of different molecular weights with toluene diisocyanate. The obtained polyurethane polymers were reacted with oleic acid to obtain the nonionic polyurethane surfactants. The structures of the synthesized compounds were determined by using: Fourier Transform Infrared Spectroscopy (FTIR) and their average molecular weights by means of GC analysis. Silver nanohybrids of the nonionic polyurethane surfactants were prepared via physical combination by chemically prepared silver nanoparticles. The silver nanohybrids were determined using: UV, TEM, and DLS spectroscopy. The influence of the nonionic chain length (polyethylene glycol chains) on the surface activity of the synthesized nonionic polyurethane oleate surface active agents and their silver nanohybrids was studied. The results of surface activity of the nonionic polyurethanes oleate and their nanohybrids showed an increase in the critical micelle concentration by decreasing the polyethylene glycol chain lengths. The nanohybrids were also more surface active. Longer polyethylene glycol chains provide good protection for the formed silver nanoparticles than the shorter chains.     

The Effects of the Organic Groups Attached at the Silicone Atoms of the Organosilane-Based Gemini Nonionic Surfactants on Their Surface Activities

A novel trisiloxane gemini nonionic surfactant was synthesized by the reaction of 3-(diethoxy(methyl)silyl)propan-1-amine with hexamethyldisiloxane to get 3-(trisiloxane)propan-1-amine, which was further reacted with glutaroyl dichloride to form the surfactant molecule, N ¹,N ⁵-bis(3-(trisiloxane)propyl)glutaramide (3). Some related compounds were also prepared, including N ¹,N ⁵-bis (3-(trimethoxysilyl)propyl) glutaramide (1), and N ¹,N ⁵-bis(3-(diethoxy(methyl)silyl)propyl)glutaramide (2). All prepared compounds were analyzed by IR, ¹H-NMR and ¹³C-NMR to confirm their structures. Their interfacial activities, including surface tension and wetting ability, were measured. These surface activities were compared each other and a discussion was carried out on how the organic groups attached on the silicone atoms affect their surface tension and wetting ability. To explain the superior surface activities of the molecules 3, a hypothesis was proposed about a cyclic hydrophobic core area that could be formed by the two hydrophobic chains and the linker of the gemini molecule due to the dispersion force (Van der Waals force) between the two trisiloxane moieties, which close the hydrophobic cycle inside the molecule.     

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.