Mapping Substrate Surface Field Propagation in Block Polymer Thin Films

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• 作者：Cameron K. Shelton ; Thomas H. Epps III
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：January 26, 2016
• 年：2016
• 卷：49
• 期：2
• 页码：574-580
• 全文大小：446K
• ISSN：1520-5835

文摘

We isolated the key substrate–polymer interactions responsible for the propagation of substrate surface field effects in block polymer (BP) thin films through a modified approach to the Owens and Wendt interfacial energy formalism. This modification captured the influence of long-range surface energy components on through-film nanostructure orientation in BP thin films, and it provides a framework for manipulating BP thin film behavior without the need for extensive parameter space exploration. Optical microscopy (OM) of gradient thickness films on chlorosilane-modified substrates provided a high-throughput approach for identifying the critical propagation depth of substrate–polymer interfacial energy effects. Atomic force microscopy (AFM) was combined with OM to verify changes in free surface nanostructure as a function of film thickness. Using a model poly(methyl methacrylate-b-n-butyl acrylate) BP thin films system, we mapped the critical propagation depth as a function of interfacial energy difference and found a nearly linear increase in propagation depth at low interfacial energy differences followed by the onset of a plateau at high interfacial energy differences. Our results connect seemingly disparate trends found in the substrate surface field propagation literature and demonstrate a more translatable approach for improving BP thin film through-film orientation via appropriate chemical tailoring of substrate surfaces.