Influence of Hydrophobic Polystyrene Blocks on the Rehydration of Polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene Films Investigated by in Situ Neutron Reflectivity

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• 作者：Qi Zhong ; Ezzeldin Metwalli ; Monika Rawolle ; Gunar Kaune ; Achille M. Bivigou-Koumba ; André Laschewsky ; Christine M. Papadakis ; Robert Cubitt ; Jiping Wang ; Peter Müller-Buschbaum
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：January 12, 2016
• 年：2016
• 卷：49
• 期：1
• 页码：317-326
• 全文大小：536K
• ISSN：1520-5835

文摘

The rehydration of thermoresponsive polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene (PS-b-PMDEGA-b-PS) films forming a lamellar microphase-separated structure is investigated by in situ neutron reflectivity in a D₂O vapor atmosphere. The rehydration of collapsed PS-b-PMDEGA-b-PS films is realized by a temperature change from 45 to 23 °C and comprises (1) condensation and absorption of D₂O, (2) evaporation of D₂O, and (3) reswelling of the film due to internal rearrangement. The hydrophobic PS layers hinder the absorption of condensed D₂O, and a redistribution of embedded D₂O between the hydrophobic PS layers and the hydrophilic PMDEGA layers is observed. In contrast, the rehydration of semiswollen PS-b-PMDEGA-b-PS films (temperature change from 35 to 23 °C) shows two prominent differences: A thicker D₂O layer condenses on the surface, causing a more enhanced evaporation of D₂O. The rehydrated films differ in film thickness and volume fraction of D₂O, which is due to the different thermal protocols, although the final temperature is identical.