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 of Triazole-Based Nonionic Surfactants for Nanostructured Drug Delivery: Investigation of Their Physicochemical and Biological Aspects

Synthesis of novel nonionic surfactants has attracted attention of synthetic chemists due to the issues of the currently used commercial surfactants. The synthesis of three biocompatible triazole-based nonionic surfactants is reported for nanovesicular drug loading. The surfactants were synthesized in a three-step reaction and characterized using ¹HNMR and mass spectroscopy techniques. They were investigated for their critical micelle concentration (CMC) using a UV–Visible spectrophotometer. Their biocompatibility was investigated against cell culture and in blood. All the synthesized nonionic surfactants were further explored for their nanovesicular drug loading using clarithromycin as a model hydrophobic drug. Nonionic surfactants revealed lower CMC in 35–45 μM and were less hemolytic and cytotoxic. They were capable of self-assembling in nanosize niosomal vesicles encapsulating increased amounts of drug. The results suggest the synthesized nonionic surfactants as biocompatible nanotechnology-based drug-delivery vehicles.     

Highly efficient supported AlCl3-based cationic catalysts to produce polyα-olefin oil base stocks

The main aim of this research is to decrease the amount of AlCl₃ content that is very corrosive and hazardous in the catalytic system, required for the α-olefin oligomerization without substantial change of final oil features. This was successfully achieved by supporting AlCl₃ on different carriers. More precisely, a series of supported bimetallic catalysts was synthesized by immobilization of AlCl₃ and TiCl₄ onto Al₂O₃, SiO₂, and mixed supports, that is, Al₂O₃/FeCl₃ and SiO₂/FeCl₃. It was found that silica and alumina-based catalysts had higher catalytic activities compared to support free AlCl₃; however, this enhancement for silica-based supports was more significant. According to gel permeation chromatography (GPC) results, the use of single supports, that is, Al₂O₃ and SiO₂, increased oligomer's molecular weight, while the application of mixed supports resulted in the decrease of molecular weight of the oligomers. Viscosity characteristics of the synthesized oligomers have also been studied at two different temperatures of 40 and 100°C (KV⁴⁰ and KV¹⁰⁰). The viscosity index (VI) values, derived from KV⁴⁰ and KV¹⁰⁰, of the prepared oligomers were in the range of 126–145. The molecular weight and termination mechanisms of the oligomers were studied by ¹H-NMR spectroscopy. The obtained results disclosed that the employed reaction conditions led to the production of oligomer chains with various structures including vinylidene (Vd), and di and three-substituted vinylene (2Vn, 3Vn) structures.     

适用于“一步酸溶法”生产氧化铝工艺中稀释料浆的高分子絮凝剂的合成

为达到"一步酸溶法"生产氧化铝工艺中稀释料浆在高温、高酸度工况下进行固液高效分离的目的,以丙烯酰胺(AM)与阳离子(DMDAAC)为共聚单体,通过水溶液聚合法合成了阳离子聚丙烯酰胺(CPAM)絮凝剂。以转化率和相对分子质量为目标,通过单因素分析法确定了最优的合成工艺条件,即反应温度30℃,单体总质量分数为30%,阳离子度5%,K2S2O8和NaHSO3质量分数均为0.005%,2,2′-偶氮二(2-脒基丙烷盐酸盐)(V50)质量分数为0.0025%,乙二胺四乙酸(EDTA)质量分数为0.05%的条件下,反应时间为6 h,获得相对分子质量为1.2×107溶解性能较好的阳离子型聚丙烯酰胺(CPAM)。     

Study of the Antioxidative Properties of Several Amino Acid-Type Surfactants and their Synergistic Effect in Mixed Micelle

Cysteine and methionine, two sulfur-containing amino acids (AA), were introduced in their surfactant forms as potential antioxidants. The antioxidative (AOX) properties of lauroyl methionine (C12-Met) and lauroyl cysteine (C12-Cys) was investigated by means of the oxygen radical absorbance capacity assay. Both the surfactants exhibited excellent AOX behavior at the premicellar state and micellar medium. The AOX behavior was found to be comparable for both the surfactants at their premicellar states. However, in micellar medium, C12-Met showed better AOX property than C12-Cys. The AOX power of the surfactants was compared with other previously developed AA-type surfactants. The order of the AOX power was found to be: C12-tryptophan > C12-tyrosine ≈ C12-methionine ≈ C12-cysteine > C12-histidine at the premicellar state and C12-tryptophan > C12-tyrosine > C12-methionine > C12-cysteine > C12-histidine at the micellar state. C12-Cys displayed lower AOX property in micellar medium due to its dimer formation tendency. Based on the HPLC and UPLC-Q-TOF-MS analysis, the dimer formation of C12-Cys was found to be accelerated due to the micellar environment and results into negative synergistic effect on other aromatic AA-type surfactants. However, the presence of C12-His in the micellar solution of C12-Cys resulted no synergistic effect due to stronger H-bonding between the surfactants and resulting less dimer formation.     

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.     

Excellent Mechanical and Transparency Properties of Cationic Waterborne Polyurethane Films Modified by Boehmite Sol

The strategies for nanosol from metal alkoxide have enabled production of ultratransparent and mechanically robust polymer nanocomposites at extremely high loading. Herein, a simple approach to fabricate high‐performance polyurethane‐based nanocomposites via unmodified boehmite nanoparticles is reported. Evaluating their physical properties, the uniform dispersion of boehmite in the matrix caused nanocomposites retains ultrahigh transparency. Hydrogen bonding and intermolecular entanglement between boehmite and polyurethane brings about the mechanical properties of the nanocomposites material enhanced, i.e., strength, stiffness, and toughness. Optimized strength, stiffness, and toughness of Boehmite/Cationic waterborne polyurethane at 40 wt% (BNC40) are up to 58.1 MPa, 1096.7 MPa, 249.5 MJ m^?3, respectively. Furthermore, the feasibility and mechanism of polymer strengthening and toughening by inorganic rigid nanoparticles is explored from the aspects of crystallinity and micromorphology.     

节能减排的颜料印染与助剂(一)

颜料印染对当前印染行业节能减排,降低能耗很有意义,但要做到对纤维没有亲和力的颜料印染,必需制备润湿性、分散性良好的超细颜料粒子。重点阐述利用各种表面活性剂和助剂制备出一种包覆阴离子的超细粒子的稳定分散液,包括各种润湿剂、分散剂、黏合剂和纤维阳离子改性剂,还概述了相关基础理论。     

Interfacial energy for solutions of nanoparticles,surfactants, and electrolytes

The addition of surfactants to modify the surface property of nanoparticles (NPs) from hydrophilic to hydrophobic also enhances their interfacial properties. Several approaches were previously proposed to calculate the surface tension/interfacial tension (IFT) for different systems in the presence of NPs, surfactants, and electrolytes. However, most of these approaches are indirect and require several measured parameters. Therefore, a mathematical model is developed here to calculate the surface tension/IFT for these systems. The developed model takes into account the cohesive energy due to the interaction of the surfactant CH₂ groups, the electric double layer effect due to the interaction among the ions of NPs, surfactants, and electrolytes, and the dipole–dipole interaction of NPs and electrolytes. The developed model is compared and validated with the laboratory experimental data in literature. The results reveal further understanding of the mechanisms involved in stabilization of oil/water emulsion in the presence of NPs, surfactants, and electrolytes.