Adsorption and aggregation behavior of aliphatic alcohol polyoxyethylene ether phosphate with different ethylene oxide addition numbers

Self-assembly mechanism, physicochemical analyses and application performance investigations of branched alkyl glycosides with alcohol ether carboxylic acids of varied epoxide numbers

Green surfactants, specifically alkyl glycosides and fatty alcohol ether carboxylic acids, are known for their biocompatibility, multiresponsiveness, and versatile applications, garnering significant attention in the realms of green and colloid chemistry. This study systematically investigated the mechanism underlying micelle formation within aqueous solutions comprising alcohol ether carboxylic acids featuring diverse EO group chain quantities (AEC-nH, where n equals 5, 7, and 9) and branched alkyl glycosides (IG). The elucidation of these mechanisms sheds light on their prospective application properties. It was observed that the self-assembly of micelles in these hybrid systems is predominantly influenced by hydrogen bonding, electrostatic interactions, and hydrophobic forces. The spherical-rod morphology of the micelles responds to the varying numbers of EO group chains, with an increased number of EO leading to the formation of rod-like micelles, which exhibit relative instability, while a decreased number of EO results in the formation of spherical micelles with relative stability. Additionally, by means of kinetic analysis, it was determined that the micelle formation process of the three hybrid systems is driven by enthalpy, and a mixed diffusion-kinetics adsorption mechanism is involved in the adsorption process. These findings significantly impact their application properties. This report stands as the first exploration of the synergistic mechanisms and application performance of two types of green surfactants in aqueous solutions, considering the influence of different numbers of EO group chains. Not only does it provide fundamental insights into their properties, but it also offers novel perspectives on the applications of green surface activation.

Effect of Different Ethylene Oxide Addition Numbers on the Performance of Polyoxyethylene Tallow Amine as a Pesticide Emulsifier

Surfactant reduces the surface tension of liquids, resulting in improved emulsion stability, and there is great interest in pesticide additives. Ethoxylate is often used as a pesticide emulsifier. However, the degree of ethoxylation and the existence of dioxane byproducts can significantly affect the performance of emulsifiers. Here, a series of polyoxyethylene tallow amines with the addition of different numbers of ethylene oxide (EO) were synthesized and characterized. Their physical and chemical performances were measured. The ability of POEA as a surfactant to reduce water surface tension and the surface adsorption of molecules were assessed based on the static and dynamic surface tensions. The results show that the surfactant molecules preferentially form a saturated adsorption layer in solution, and the mixed-diffusion-kinetics mechanism dominates the adsorption process. With the increase of the EO addition number, the emulsifying property of POEA increases, while the wetting property gradually decreases and the contact angle increases. These results can provide a basis for the selection of pesticide additives. At the same time, the mechanism of removing dioxane by ethoxylate is described, and a simple and low-consumption method is put forward to reduce the dioxane content. It provides a new idea for the removal of dioxane.

Effect of Oxyethylene Groups of Fatty Alcohol Polyoxyethylene Ether Sodium Sulfates on Equilibrium and Dynamic Surface Tension in Relation to Wetting Properties

The effect of hydrophilic chain of surfactants fatty alcohol polyoxyethylene ether sodium sulphates (AEnS, n = 2, 3, 7) on surface properties and wetting properties was investigated by the measurement of equilibrium surface tension, dynamic surface tension and dynamic contact angle. The fatty alcohol polyoxyethylene ether sodium sulphates with different head group sizes were used. From the results of equilibrium surface tension measurements, we could obtain the critical micellisation concentration, adsorption efficiency, maximum surface excess concentration and Langmuir equilibrium adsorption constant at air/liquid interface. The dynamic surface tension results showed that the adsorption of aqueous solutions at the air/liquid interface follows a mixed-diffusion kinetic adsorption mechanism. In conclusion, for both studied surfactant, the longer the oxyethylene chains, the higher the maximum rate of surface tension reduction, the higher the diffusivity and wetting properties in terms of contact angle.

Interfacial and Emulsion Characteristics of Oil-Water Systems in the Presence of Polymeric Lignin Surfactant

It is hypothesized that polymeric lignin surfactants have different affinities for stabilizing oil-water emulsions and that the emulsifying performance of these surfactants is highly affected by their adsorption performance at the oil-water interface. To validate this hypothesis, the adsorption performance of sulfethylated lignin (SEKL) surfactant at different oil-water interfaces was examined by assessing the contact angle, dynamic interfacial tension, and surface loading (Γ). Moreover, the interfacial adsorption kinetics of SEKL was comprehensively assessed in different oil-water systems to reveal the mechanisms of the SEKL adsorption at the interface. Also, the impacts of SEKL concentration and ionic strength on the performance of SEKL as an effective emulsifier for the emulsions were assessed. Furthermore, the droplet size and instability index of the emulsions were systematically correlated with the adsorption performance of SEKL at the interface of oil and water. For the first time, by implementing a modified Ward Toradai diffusion model, two distinct early stages of the adsorption of SEKL at the oil interface were identified. Interestingly, the second stage was the determining stage of adsorption with the diffusion-controlled mechanism when polymers reconfigured at the oil-water interface. Salt screening facilitated the clustering of SEKL upon charge repulsion elimination, which removed the energy barrier in the first stage of adsorption (ΔE_p→0 = 0), but it introduced a steric barrier upon the reconfiguration of polymers at the oil interfaces in the second stage of adsorption. In addition to the kinetics of adsorption, satisfactory correlations were observed between surface pressure (Δγ = γ_∞ - γ₀), surface loading (Γ) of polymers, and contact angle at oil interfaces on one hand and the oil droplet size and emulsion stability on the other hand.

An efficient organosilane-modified polycarboxylate dispersant with excellent dispersing performance and superior wettability for tebuconazole suspension concentrate

The dispersion stability and wettability of suspension concentrates are beneficial for improvement of the utilization rate of pesticides.