Nonbulk Complex Structures in Thin Films of Symmetric Block Copolymers on Chemically Nanopatterned Surfaces

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• 作者：Guoliang Liu ; Fran莽ois Detcheverry ; Abelardo Ram铆rez-Hern谩ndez ; Hiroshi Yoshida ; Yasuhiko Tada ; Juan J. de Pablo ; Paul F. Nealey
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：May 8, 2012
• 年：2012
• 卷：45
• 期：9
• 页码：3986-3992
• 全文大小：420K
• 年卷期：v.45,no.9(May 8, 2012)
• ISSN：1520-5835

文摘

Thin films of symmetric polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) with a bulk lamellar period of L_o were equilibrated on chemically nanopatterned surfaces that had alternating PS and PMMA preferential wetting stripes. The chemical patterns had a period of L_S, and the width of the PMMA wetting stripes was W. We identified a set of four morphologies, two of which are fully three-dimensional. On chemical patterns with L_S = 2L_o, as W/L₀ increased from 0 to 1, block copolymers formed morphologies including bulk-like structures, nominally, parallel lamellae and vertical lamellae, and two bulk-deviate complex morphologies. On chemical patterns with W/L₀ = 0.5, as the commensurability factor, 未 = L_S/L₀, increased from 0.87 to 3.05, block copolymers formed complex three-dimensional structures. At the substrate, the block copolymer had a wetting layer reflecting the chemical pattern. At the free surface, the block copolymer formed lamellar-like structures with period L₀ along the direction of the underlying chemically patterned stripes when 未 was close to an integer, and fingerprint-like structures when 未 was not close to an integer. Morphologies obtained by numerical simulations of a coarse grained model of block copolymers compare favorably with our experimental results and help explain the origin of the observed behavior.