Aggregation Behavior of Polyisoprene鈥揚luronic Graft Copolymers in Selective Solvents

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• 作者：Shirin Alexander ; Terence Cosgrove ; Wiebe M. de Vos ; Thomas C. Castle ; Stuart W. Prescott
• 刊名：Langmuir
• 出版年：2014
• 出版时间：May 27, 2014
• 年：2014
• 卷：30
• 期：20
• 页码：5747-5754
• 全文大小：397K
• 年卷期：v.30,no.20(May 27, 2014)
• ISSN：1520-5827

文摘

Novel amphiphilic graft copolymers composed of a polyisoprene (PIP) backbone with Pluronic side chains, polyisoprene-g-Pluronic, have been synthesized using a 鈥済raft onto鈥?technique. Small-angle neutron scattering (SANS) has been used to characterize the conformation of the P123 and P103 Pluronic graft copolymers in selective solvents such as ethanol and hexane and in a nonselective solvent, tetrahydrofuran (THF). The results indicated that, in a selective solvent for the side chain Pluronics (e.g., ethanol), 鈥渃rew-cut鈥?micelles were formed with a large core of radius 120 脜; data were fitted with a core鈥搒hell model. In a good solvent for the backbone (e.g., hexane), 鈥渇lowerlike鈥?micelles were formed with a small inner radius of 64 脜. In the nonselective solvent, a swollen polymer coil was found, which was described using the Guinier鈥揇ebye model. As THF/ethanol and THF/hexane can be prepared in any ratio, it was possible to vary the solvent composition gradually in order to study the transition from swollen coil to micelle. When going from 100% THF to 100% ethanol, the transition to micellar behavior was observed at a ratio of 20:80 (v/v %) THF/ethanol for both grafted copolymers and 40:60 (v/v %) THF/hexane for grafted P123 copolymers.