In Situ Tracking of Microstructure Spacing and Ordered Domain Compression during the Drying of Solution-Cast Block Copolymer Films Using Small-Angle X-ray Scattering

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• 作者：Michael J. Heinzer ; Sangil Han ; John A. Pople ; Donald G. Baird ; Stephen M. Martin
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：April 24, 2012
• 年：2012
• 卷：45
• 期：8
• 页码：3480-3486
• 全文大小：292K
• 年卷期：v.45,no.8(April 24, 2012)
• ISSN：1520-5835

文摘

Changes in the spacing of hexagonally packed cylinders in a poly(styrene-b-butadiene) copolymer film during the continual extraction of toluene under different solvent removal conditions were studied by in situ small-angle X-ray scattering (SAXS) measurements. As the solvent is removed from the film, the structure spacing increases due to increasing segregation power and then decreases as the polymer chains become kinetically trapped while microdomains continue to deswell. The structure spacing in the vertical film direction decreases more drastically due to compression of the domains as the film thickness decreases. The degree of compression increased with increased polymer concentration because of an increase in the chain relaxation time. Increasing the drying temperature resulted in more severe domain compression, which is ascribed to faster solvent removal. Removing solvent in the presence of a sweep gas further increased the domain compression as a result of the formation of a skin at the film surface. When the solvent removal rate was decreased and skinning was avoided by saturating the sample chamber with the casting solvent, domain compression was impeded.