Structural Characteristics of Amphiphilic Cyclic and Linear Block Copolymer Micelles in Aqueous Solutions

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• 作者：Kyuyoung Heo ; Young Yong Kim ; Yu Kitazawa ; Mihee Kim ; Kyeong Sik Jin ; Takuya Yamamoto ; Moonhor Ree
• 刊名：ACS Macro Letters
• 出版年：2014
• 出版时间：March 18, 2014
• 年：2014
• 卷：3
• 期：3
• 页码：233-239
• 全文大小：402K
• 年卷期：v.3,no.3(March 18, 2014)
• ISSN：2161-1653

文摘

The structural characteristics of aqueous micelles composed of amphiphilic cyclic poly(n-butyl acrylate-b-ethylene oxide) (cyclic PBA-b-PEO) or a linear analogue (i.e., linear poly(n-butyl acrylate-b-ethylene oxide-b-n-butyl acrylate) (linear PBA-b-PEO-b-PBA)) were examined for the first time using synchrotron X-ray scattering techniques and quantitative data analysis. The scattering data were analyzed using a variety of methodologies in a comprehensive complementary manner. These analyses provided details of the structural information about the micelles. Both micelles were found to consist of a core and a fuzzy shell; however, the cyclic block copolymer had a strong tendency to form micelles with core and shell parts that were more compact and dense than the corresponding parts of the linear block copolymer micelles. The PBA block of the cyclic copolymer was found to form a hydrophobic core with a density that exceeded the density of the homopolymer in the bulk state. The structural differences originated primarily from the topological difference between the cyclic and linear block copolymers. The elimination of the chain end groups (which introduced entropy and increased the excess excluded volume) from the amphiphilic block copolymer yielded more stable dense micelles in solution.