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Interfacial Properties of Extended‐Surfactant‐Based Microemulsions and Related Macroemulsions
Author(s) -
Witthayapanya Anuradee,
Phan Tri Thanh,
Heitmann Todd C.,
Harwell Jeffrey H.,
Sabatini David A.
Publication year - 2010
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-009-1151-5
Subject(s) - pulmonary surfactant , microemulsion , chemistry , surface tension , hydrocarbon , coalescence (physics) , chemical engineering , kinetics , polypropylene , membrane , polymer chemistry , thermodynamics , organic chemistry , biochemistry , physics , quantum mechanics , astrobiology , engineering
Extended surfactants containing an intermediate‐polarity spacer, such as polypropylene oxide, in between the hydrophilic head and the hydrocarbon tail are known to result in superior solubilization and low interfacial tension, though they exhibit slow kinetics. The present work seeks to evaluate both equilibrium and kinetic aspects of extended‐surfactant‐based micro‐ and macroemulsions. The interfacial morphology of the extended surfactant membrane, i.e., characteristic length ( ξ ) and interfacial rigidity ( E r ) at optimum middle‐phase microemulsion conditions, was characterized using the net‐average curvature model. The results showed that extended surfactants resulted in a relatively rigid interfacial membrane compared with conventional surfactants having similar hydrocarbon chain length. In addition, both ξ and E r parameters increased with the length of the polypropylene oxide spacer. Increasing E r values correlated to the slow coalescence rates of extended surfactant emulsified systems. Two alternative approaches (the addition of combined linkers and co‐surfactant) are shown to overcome the slow kinetics of coalescence while maintaining desirable high solubilization and low interfacial tension.