Partitioning behavior of an acid-cleavable, 1,3-dioxolane alkyl ethoxylate, surfactant in single and binary surfactant mixtures for 2- and 3-phase microemulsion systems according to ethoxylate head group size

• Published in: Journal of colloid and interface science 2010-12, Vol.352 (2), p.424-435
• Main Authors: Rio, Javier Gomez del, Hayes, Douglas G., Urban, Volker S.
• Format: Article
• Language: English
• Subjects: Acids - chemistry; Aerosol-OT; AFFINITY; ALCOHOLS; Alkyl ethoxylate surfactants; Alkyl glucoside surfactant; BASIC BIOLOGICAL SCIENCES; BINARY MIXTURES; Binary systems; Chemistry; Cleavable surfactants; Colloidal state and disperse state; Dioxolanes - chemistry; DISTRIBUTION; Emulsions - chemistry; Emulsions. Microemulsions. Foams; Ethylene Glycols - chemistry; Exact sciences and technology; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; General and physical chemistry; HPLC analysis of surfactants; Hydrogen-Ion Concentration; MATHEMATICAL MODELS; MICROEMULSIONS; MIXTURES; NEUTRONS; Nonionic surfactants; Octanes - chemistry; Optimization; Particle Size; Partition coefficients; Partitioning; PHASE DIAGRAMS; Phases; Physical and chemical studies. Granulometry. Electrokinetic phenomena; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; PROTEINS; PURIFICATION; SCATTERING; SENSITIVITY; Small-angle neutron scattering; Surface Properties; Surface-Active Agents - chemical synthesis; Surface-Active Agents - chemistry; SURFACTANTS; Thermodynamic model; THERMODYNAMICS; Water - chemistry
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2010.08.076

Partition coefficients for a 1,3-dioxolane alkyl ethoxylate surfactant in 2- and 3-phase microemulsion systems as a function of the ethoxylate size ( n): experimental data and thermodynamic model (curves). [Display omitted] ► Aerosol-OT and cyclic ketal alkyl ethoxylate form temperature-insensitive microemulsions. ► HLB temperature for alkyl ethoxylate microemulsions predicted using partition coefficient data. ► Partitioning of cyclic ketal alkyl ethoxylates strongly affected by ethoxylate size. ► Tail region of cyclic ketal alkyl ethoxylates more polar than the that of fatty alcohol ethoxylates. ► Microemulsions in Winsor-III bottom phases formed by cyclic ketal alkyl ethoxylates (SANS). Partition coefficients for a pH-degradable 1,3-dioxolane alkyl ethoxylate surfactant, 4-CH 3O (CH 2CH 2O) 5.6-CH 2, 2,2-(CH 2) 12CH 3, 2-(CH 2) CH 3, 1,3-dioxolane or “cyclic ketal” surfactant, CK-2,13-E 5.6,ave, between isooctane- and water-rich phases of 2- and 3-phase microemulsion systems ( K n ) were determined as functions of the ethoxylate size, n, and temperature for the neat surfactant and its binary surfactant mixtures, to understand the partitioning of alkyl ethoxylates possessing a broad distribution of ethoxylate size and to determine conditions required for formation of 3-phase microemulsion systems at an optimal temperature where phase separation occurs rapidly, important for protein purification via proteins’ selective partitioning to the middle phase, driven by affinity to the second surfactant of the binary mixture. A semi-empirical thermodynamic mathematical model described the partitioning data well, provided optimal temperature values consistent with phase diagrams and theory, and demonstrated that the tail region of CK-2,13-E 5.6,ave is more polar than the hydrophobes of fatty alcohol ethoxylates. The addition of Aerosol-OT (AOT) removed the temperature sensitivity of CK-2,13-E 5.6,aves partitioning, producing 3-phase microemulsion systems between 20 °C and 40 °C. Analysis of the bottom phases of the 2- and 3-phase microemulsion systems formed by CK-2,13-E 5.6,ave via small-angle neutron scattering demonstrated the presence of spherical, monodisperse oil-in-water microemulsions.