Neil Brons

Relationship between fundamental interfacial properties and foaming in linear and branched sulfate, ethoxysulfate, and ethoxylate surfactants

Abstract The effect of hydrocarbon chain branching on the foaming performance of a variety of sulfate, ethoxysulfate, and ethoxylate surfactants was determined by the Ross—Miles test. Data from static and dynamic surface tension experiments were used to obtain a structure—property—performance correlation. Initial foam heights correlated with π (CMC), the effectiveness of surface tension reduction, while foam instability correlated with R 1 2 , the rate of surface tension reduction at the air—water interface. Hydrocarbon chain branching resulted in increased π (CMC) and R 1 2 . Consequently, surfactants wherein the hydrocarbon chain is branched exhibited high initial foam heights and low foam stability.

Relationships between dynamic contact angle and dynamic surface tension properties for linear and branched ethoxylate, ethoxysulfate, and sulfate surfactants

Abstract The process of dynamic wetting of Teflon and its modification by linear and branched ethoxylates, ethoxysulfates, and sulfates has been examined via measurement of dynamic contact angles. A linear correlation between advancing dynamic contact angle and the air-liquid meso-equilibrium dynamic surface tension was observed. A value of 21 mN/m was obtained for the critical meso-equilibrium surface tension for complete dynamic wetting of Teflon. Surfactants that tend to meso-equilibrate quickly at the air-liquid interface are more effective in reducing the dynamic contact angle than those that equilibrate slowly. Branched hydrophobe surfactants exhibit better effectiveness in modifying dynamic wetting of Teflon than linear hydrophobe surfactants.

Effect of hydrocarbon chain branching on interfacial properties of monodisperse ethoxylated alcohol surfactants

Abstract Surfactant properties at the air-water, decane-water, and Teflon-water interfaces are strongly influenced by branching of the hydrocarbon chain of an ethoxylate surfactant. Although chain branching reduces chain length, branched ethoxylates exhibit properties intermediate between those of linear surfactants of the same carbon number and linear surfactants of the same chain length. Steric factors that disfavor micellization in bulk result in enhancement of adsorption properties at interfaces. Compared to linear ethoxylates, branched ethoxylates with the same number of oxyethylene groups exhibit a higher critical micelle concentration and are more effective in reducing the surface tension at the air-water interface by occupying a larger area per molecule. Better dynamic air-water interfacial properties result from branching the hydrophobe as branched ethoxylates attain meso-equilibrium faster and the surface tension at meso-equilibrium is lower than the corresponding linear hydrophobe surfactant. At the decane-water interface the effect of branching on critical aggregation concentration and effectiveness in interfacial tension reduction depends on the nature of branching. The water wettability of a hydrophobic Teflon surface is enhanced by branched hydrocarbon chain ethoxylates.

Influence of ethoxylate distribution on interfacial properties of linear and branched ethoxylate surfactants

The influence of ethoxylate distribution on interfacial properties of linear and branched hydrophobe C12 and C13 alcohols is examined at the air-water, decane-water, and Teflon-water interfaces. In the polydisperse ethoxylates, the presence of unreacted alcohol and broad ethoxylate distribution causes interfacial properties to change significantly at the decane-water interface and moderately at the Teflon-water and air-water interfaces. The linear hydrophobe ethoxylate is more sensitive to the presence of unreacted alcohol and broad ethoxylate distribution than the branched hydrophobe ethoxylate.