Synthesis, aggregation behavior and interfacial activity of branched alkylbenzenesulfonate gemini surfactants

Impacts of Low Atmospheric Pressure on Properties of Cement Concrete in Plateau Areas: A Literature Review

Low atmospheric pressure (LAP) can enormously affect properties of cement concrete in plateau areas. There are fewer studies and attendances on this issue than those of cement concrete in normal atmospheric pressure (AP), because of the limitations of both environmental conditions and instruments. In order to improve properties of cement concrete under LAP, influences of LAP on properties of cement concrete were reviewed in this work. The influence rules and mechanism on properties of cement concrete were summarized. The corresponding mechanism and techniques were put forward for enhancing the properties of cement concrete. The results of researchers show that LAP can significantly reduce the air entraining ability of the air entraining agent (AEA). Air content in concrete linearly decreases with the decrease of AP when other conditions are constant. If the initial air content is high, the decrease rate of air content increases with the decrease of AP. When the initial air content in cement concretes is similar, the greater the slump of cement concrete, the stronger its resistance to the decrease of air content caused by the decrease of AP. In addition, the condition of the bubble characteristics of hardened cement concrete under LAP is worse than that under normal AP. Therefore, the change of concrete properties under LAP is mainly attributed to these bubble characteristics, such as air content, bubble spacing coefficient, bubble radius and bubble specific surface area. In this work, nano-silica (negative charges) with cationic oligomeric surfactants is recommended as a new type of AEA to optimize the bubble characteristics under LAP in plateau areas.

Surface and Interfacial Properties of Mono and Didodecyl Diphenyl Ether Disulfonates

In this paper, monododecyl diphenyl ether disulfonate (C12-MADS) and didodecyl diphenyl ether disulfonate (C12-DADS) are Friedel-Craft reaction product of 1-dodecene and diphenyl oxide using sulfated zirconium as a catalyst, followed by sulfonation with fuming sulfuric acid in 1,2-dichloroethane and neutralization with aqueous sodium hydroxide solution. The relationship between the structures of the surfactants C12-DADS, C12-MADS and linear alkylbenzene sulfonate (C12-LAS) and their surface and interfacial properties was studied by measuring equilibrium surface tensions, dynamic surface tensions and dynamic interfacial tensions (IFT). The results show that the surface and interfacial activity of C12-MADS is better than that of C12-DADS and C12-LAS. The gemini surfactant C12-DADS shows most unfavorable surface and interfacial activity due to the fact that the cross-linked hydrophobic carbon chains decreases the number of exposed methyl in molecule. The dynamic surface tensions results show that the diffusion coefficients values of C12-MADS and C12-DADS are lower than that of C12-LAS, and the adsorption process of surfactants at air/water interface is a mixed diffusion-kinetic adsorption mechanism. The data of dynamic ITF between aqueous surfactants solutions and dodecane indicate that the NaCl and CaCl2 concentration has a weak effect on the stable value of dynamic IFT for C12-DADS. With increasing the NaCl and CaCl2 concentration, the stable values of dynamic ITF for the three surfactants mostly passes through a minimum at an optimum concentration, and the C12-MADS and C12-LAS can reduce the IFT to the 10−2 mN/m order of magnitude.

Synthesis, surface activities, and aggregation behavior of phenyl-containing carboxybetaine surfactants

A novel series of carboxybetaine surfactants were synthesized for the first time and their physicochemical properties were systematically investigated.

Advances in the synthesis, molecular architectures and potential applications of gemini surfactants

Gemini surfactants have been the subject of intensive scrutiny by virtue of their unique combination of physical and chemical properties and being used in ordinary household objects to multifarious industrial processes. In this review, we summarize the recent developments of gemini surfactants, highlighting the classification of gemini surfactants based on the variation in headgroup polarity, flexibility/rigidity of spacer, hydrophobic alkyl chain and counterion along with potential applications of gemini surfactants, depicting the truly remarkable journey of gemini surfactants that has just come of age. We have focused on those objectives which will act as suitable candidates to take the field forward. The preceding information will permit us to estimate the effect of structural variation on the aggregation behavior of gemini surfactants for nanoscience and biological applications like antimicrobial, anti-fungal agent, better gene and drug delivery agent with low cytotoxicity and biodegradability, which makes them more advantageous for a number of technological processes and hence reduces the impact of these gemini surfactants on the environment.

Study on the Properties of Mixed Micelles of Disodium Salt of 3-({2-[(2-Carboxy-ethyl)-dodecanoyl-amino]-ethyl}-dodecanoyl-amino)-propionic Acid in Solution Systems

This study focuses on the properties of mixed micelles of di-sodium salt of 3-({2-[(2-Carboxy-ethyl)-dodecanoyl-amino]-ethyl}-dodecanoyl-amino)-propionic acid (symbolized as DLMC) in solution systems (DLMC/DTAB and DLMC/AEO6). The micro-polarity of the mixed micelles was determined by the fluorospectrophotometer. When the concentration is above CMC, the micellar micro-polarity and the aggregation number (Nm) of the mixed micelles were measured by a steady state fluorescence quenching method. The average hydrodynamic radius (Rh) of the mixed micelles was studied by means of dynamic light scattering. The results show that the micro-polarity of micelle nucleus decreases obviously with increasing concentration. The aggregation number of DLMC mixed systems is smaller than that of single surfactants. The difference of the proportion of the two surfactants has little effect on the aggregation number of mixed systems. It is easy to generate molecular aggregates with lower curvature from DLMC than the corresponding monomeric surfactant (DTAB), and DLMC can generate huge linear micelles at low concentrations when mixed with other surfactants.

Interface Activity and Thermodynamic Properties of Cardanol Polyoxyethylene Ether Carboxylates

A series of saturated cardanol polyoxyethylene ether carboxylates was synthesized using renewable saturated cardanol originating from Cashew Nut Shell Liquid as raw material. The structures were characterized by hydrogen nuclear magnetic resonance spectroscopy. The studies of their surface activity and interface activity were carried out to analyze the influence of the chemical structures of the series of cardanol surfactants on the adsorption and micellization. Results showed that saturated cardanol polyoxyethylene ether carboxylates had a good surface activity and interface activity, and the interface activities of the Gemini cardanol surfactants were better than those of the corresponding monomer cardanol surfactants. The critical micelle concentrations (CMC) of all investigated cardanol surfactants, obtained from surface tension measurements, were low in the order of 10−5 mol/L. The CMCs decreased and the oil-water interface tension for the same cardanol surfactants increased with the increase of the oxyethylene number. The process of micellization became easier with increasing the oxyethylene number. The ΔG θ m values of the Gemini cardanol surfactants were more negative than those of the corresponding monomer cardanol surfactants. The micellization for all cardanol surfactants was a spontaneous process and exhibited enthalpy-entropy compensation. The micellization of all the cardanol surfactants was entropy-driven.

Mesomorphism of a new series of catanionic 4-(1-pentylheptyl)benzenesulfonates

The effect of cationic chemical structure on the mesophase behavior, and self-assembly of catanionic compounds is studied through a systematic structure variation of six cationic surfactants with anionic sodium 4-(1-pentylheptyl)benzenesulfonate surfactant. A series of cationic surfactants are selected with an increasing number of n-dodecyl chains on the same ammonium headgroup (from one to three), and with an increasing number of ammonium headgroups (from two to four). Thermal and phase behavior of the synthesized products were examined by thermogravimetry, polarizing microscopy, differential scanning calorimetry, powder and grazing incidence X-ray diffraction, and molecular simulation. The compounds are complexes of high thermal stability. Most of the thermotropic mesophases are smectic, although the hexagonal mesophase is also observed. Introduction of the third dodecyl chain into the cationic part leads to pronounced lower melting temperatures and eradicates mesomorphism, while the addition of a fourth ammonium headgroup leads to a catanionic benzenesulfonate that decomposes simultaneously under melting. Melting and crystallization temperatures show nonlinear dependence on the total number of alkyl chains, and on the number of headgroups in the molecule. Molecular dynamics simulation of the smectic phase points to separated hydrophilic and hydrophobic layers, favoring head-to-head packing of antiparallel molecules. On the other hand, there are two ion pairs in the column cross-section of the hexagonal LC phase of didodecyldimethylammonium-4-(1-pentylheptyl)benzenesulfonate.

Cost Effective Procedures for Extremely Efficient Synthesis of Environmental Friendly Surfactants

Für die Synthese von Tensiden mit bestimmten Eigenschaften werden verschiedene Vorgehensweisen der Synthese ausgearbeitet. In der gegenwärtigen Arbeit werden einige kostengünstige Vorgehensweisen mit reduzierter Anzahl an Reaktionsschritten zur äußerst effizienten Synthese biologisch abbaubarer und umweltfreundlicher Tenside diskutiert. Die in diesen Methoden verwendeten Ausgangsmaterialien stammen aus ökonomisch günstigen Quellen wie Monosacchariden, Harzsäuren, Fettsäuren etc. Kosten entstehen dann nur noch aufgrund des Einsatzes von Lösemitteln und Spezialreagenzien. Obwohl viele Naturprodukte bereits jetzt schon erhältlich sind, sind nur einige wenige für die Umsetzung zu Tensiden geeignet. Die Diskussion über die Herstellung von verschiedenen Tensiden für gängige Produkte ergibt sich aus der Tatsache, dass kein gutes Universaltensid für jede potentielle Anwendung erhältlich ist.