Micellization and Gelation of Diblock Copolymers of Ethylene Oxide and Styrene Oxide in Aqueous Solution

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• 作者：Michael Crothers ; David Attwood ; John H. Collett ; Zhuo Yang ; Colin Booth ; Pablo Taboada ; Victor Mosquera ; Ná ; gila M. P. S. Ricardo ; and Luigi G. A. Martini
• 刊名：Langmuir
• 出版年：2002
• 出版时间：October 29, 2002
• 年：2002
• 卷：18
• 期：22
• 页码：8685 - 8691
• 全文大小：120K
• 年卷期：v.18,no.22(October 29, 2002)
• ISSN：1520-5827

文摘

Four diblock copolymers of styrene oxide and ethylene oxide were prepared by oxyanionic polymerization: E₄₅S₁₀, S₁₅E₆₃, S₁₇E₆₅, and S₂₀E₆₇. Surface tension measurements were used to determine criticalmicelle concentrations of copolymer E₄₅S₁₀ in aqueous solution at several temperatures and thereby itsstandard enthalpy of micellization. A compilation of known results for copolymers with hydrophobic blocksformed from either styrene oxide or 1,2-butylene oxide shows a discontinuity at S₅ or B₁₀ in the block lengthdependence of the Gibbs energy of micellization which is assigned to lengthy hydrophobic blocks beingtightly coiled in the molecular state in water. Light scattering was used to determine micellar associationnumbers and radii, and scaling exponents were established for the dependence of these parameters onS-block length. Phase diagrams defining regions of hard and soft gel were determined by tube inversionand Couette rheometry.