Polymeric surfactants for enhanced oil recovery. IV—Thermodynamic properties of ethoxylated alkylphenol formaldehyde polymeric surfactants

Abstract

Abstract The thermodynamic properties of some low molecular weight ethoxylated alkylphenol formaldehyde polymeric surfactants have been investigated. Surface tension as a function of concentration of the surfactants in aqueous solutions was measured at 28, 38, 48 and 58°C, using the spinning drop technique. From these measurements, the minimum area per molecule at the aqueous solution/air interface ( A min ) was determined. The thermodynamic parameters of micellization (Δ G mic , Δ H mic , Δ S mic ) and of adsorption (Δ G ad , Δ H ad , Δ S ad ) for these polymeric nonionics were calculated. Micellization is more sensitive to ethylene oxide chain length while adsorption is more dependent on the length of the alkyl chain.