Hydration and Ordering of Lamellar Block Copolymer Films under Controlled Water Vapor

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• 作者：Yohei Kamata ; Andrew J. Parnell ; Philipp Gutfreund ; Maximilian W. A. Skoda ; Andrew J. C. Dennison ; Robert Barker ; Shaomin Mai ; Jonathan R. Howse ; Anthony J. Ryan ; Naoya Torikai ; Masami Kawaguchi ; Richard A. L. Jones
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：December 23, 2014
• 年：2014
• 卷：47
• 期：24
• 页码：8682-8690
• 全文大小：592K
• ISSN：1520-5835

文摘

Amphiphilic block copolymers within a range of volume fraction spontaneously form vesicles in aqueous solution, where a water core is enclosed by a polymer bilayer. Thin-film rehydration is a method used to produce vesicles routinely; a thin film is immersed in water, the film swells, and vesicles are formed which bleb off from the film surface. We have studied the early stages of hydration for PEO鈥揚BO block copolymer thin films under controlled water vapor conditions to understand this formation mechanism and so enable more efficient ways to encapsulate molecules using this method. Neutron and X-ray measurements show that the initial film exhibits weakly ordered structure with isotropic parallel and vertical orientation; the films initially swell and maintain the same orientation. At a critical point the layer swells rapidly and makes highly ordered lamellae structure at the same time. The lamellae are almost exclusively oriented parallel to the substrate and swell with increasing water absorption.