Association and Surface Properties of Poly(ethylene oxide)−Poly(styrene oxide) Diblock Copolymers in Aqueous Solution

Mai, Shaomin, Booth, Colin, Kelarakis, Antonis, Havredaki, Vasiliki and Ryan, Anthony J. (2000) Association and Surface Properties of Poly(ethylene oxide)−Poly(styrene oxide) Diblock Copolymers in Aqueous Solution. Langmuir, 16 (4). pp. 1681-1688. ISSN 0743-7463

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Official URL: http://dx.doi.org/10.1021/la991004o

Abstract

The association and surface properties of three oxyethylene/oxyphenylethylene (ES) diblock copolymers
in aqueous solution have been studied. Copolymers E50S3.5, E50S5.1, and E51S6.5 were synthesized and
characterized by gel permeation chromatography and 13C NMR spectroscopy. Surface tensiometry was
used to determine critical micelle concentrations (cmc) at several temperatures, and thereby values of the
enthalpy of micellization (DmicHo). The values of cmc and ¢micHo were found to be low (e.g., 0.03 g dm-3
at 30 °C and 12 kJ mol-1 forE51S6.5), which is consistent with the high hydrophobicity of oxyphenylethylene
block. Dynamic and static light scattering were used to characterize the micelles in dilute solution, yielding
micellar association number, hydrodynamic and thermodynamic radius, and the related thermodynamic
expansion factor. At higher concentrations, solution of copolymersE50S5.1 andE51S6.5 formed hard isotropic
gels.
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