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Surfactant-Polymer Interactions q
Nagarajan, R. Thermodynamics of Surfactant-Polymer
Interactions in Dilute Aqueous Solutions. Chemical
Physics Letters 76, 282-286 (1980). q
Nagarajan, R.; Harold, M. P.
Surfactant-Polymer Interactions in Tertiary Oil Recovery. In SOLUTION
BEHAVIOR OF SURFACTANTS - THEORETICAL AND APPLIED ASPECTS, Mittal, K. L.; Fendler, E. J., (Eds.), Plenum Press, New York (1982)
p.1391-1413. q
Nagarajan, R.; Kalpakci,
B. Viscometric Investigation of Complexes Between Polyethyleneoxide and Surfactant Micelles. In
MICRODOMAINS IN POLYMER SOLUTIONS, Dubin, P. L.,
(Ed.), Plenum Press (1985) p.368-381. q
Nagarajan, R. Thermodynamics of
Non-ionic Polymer-Micelle Association. Colloids
and Surfaces 13, 1-17 (1985). q
Nagarajan, R. Thermodynamics of
Micelles, Mixed Micelles and Solubilization: The Role of Interfacial
Interactions. Advances in Colloid and Interface Science 26, 205-264
(1986). q
Nagarajan, R. Association of Nonionic
Polymers With Micelles, Bilayers and Microemulsions.
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of Chemical Physics 90, 1980-1994 (1989). q
Nagarajan, R. Polymer-Induced Structural
Transitions in Microemulsions. Langmuir
9, 369-375 (1993). q
Nagarajan,
R. Polymer-Surfactant Interactions. In “New
Horizons: Detergents for the New Millennium Conference Invited Papers”,
sponsored by American Oil Chemists Society and Consumer Specialty Products
Association, Related Graduate
Student Thesis Ø
Sheu, Ji-zen (Ph.D. 83)
"Thermodynamics of Phase Separation in Aqueous Polymer -Surfactant
Electrolyte Solutions"
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Schematic of a Nonionic Polymer–Micelle Association
Structure The polymer segments partially penetrate and wrap around
the polar head group region of the surfactant micelles. A single polymer
molecule can associate with one or more surfactant micelles. We assume that the polymer segments shield the hydrophobic
domain of the aggregate from having contact with water by an area apol per surfactant molecule. This gives rise to
three competing contributions to the free energy of aggregation. Firstly, a decrease in the hydrophobic surface area of the
aggregate exposed to water occurs. This decreases the positive free energy of
formation of the aggregate-water interface and thus favors the formation of
polymer‑bound aggregates. Secondly, steric repulsions arise between the polymer segments
and the surfactant head groups at the aggregate surface. This increases the positive
free energy of head group repulsions and thus disfavors the formation of the
polymer‑bound aggregates. Finally, the contact area apol
of the polymer molecule is removed from water and transferred to the surface
of the aggregate which is concentrated in the surfactant head groups. This alters the free energy of the polymer
and can favor or disfavor the formation of the polymer‑bound micelles
depending upon the type of interactions between the polymer segments and the
interfacial region rich in head groups. |
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Prediction of Nonionic
Polymer-Induced Structural Transitions In SDS + Pentanol
+ Cyclohexane Microemulsion System The continuous lines correspond to the polymer-free
microemulsion system while the dotted lines show the consequence of the
addition of a nonionic polymer. Points marked I through V show simple
addition of polymer can cause phase transitions as well as microstructural
variations in microemulsion systems. (I) an O/W droplet microemulsion remains an O/W droplet system
but the amount of oil solubilized and the radius of the droplet are both
reduced; (II) a bicontinuous microemulsion transforms into an O/W
droplet microemulsion; (III) a W/O droplet microemulsion inverts to an O/W droplet
microemulsion with the droplet radius either decreasing in size (IIIA) or
increasing in size (IIIB); (IV) a W/O droplet
microemulsion transforms into a bicontinuous microemulsion; (V) a W/O droplet microemulsion
remains a W/O system but the droplet radius and the amount of water
solubilized are both increased. We also predict that the addition of polymers cannot lead to
the following types of transitions: (VI) an O/W droplet microemulsion cannot invert to a W/O
droplet microemulsion; (VII) an O/W droplet microemulsion cannot transform into a
bicontinuous microemulsion; (VIII) a bicontinuous microemulsion
cannot transform into a W/O droplet microemulsion. |
