Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA 01003, USA.
Small. 2013 Mar 11;9(5):779-84. doi: 10.1002/smll.201201950. Epub 2012 Nov 23.
The self-assembly of cylinder-forming block copolymer (BCP) microdomains confined within chemical stripe patterns of widths incommensurate with the natural period of the copolymers, L0 , is studied. It is shown that this incommensurability causes changes in both the shapes of the microdomains and their spatial period. Specifically, a transition from n to n + 1 rows of microdomains is observed when the stripe width is about n ± 1/2 L0 . When the stripe's width is comparable to L0 , ellipticity of microdomains can be induced with an aspect ratio up to 2.2. Free energy models are applied to describe the energetic origin of such behavior. Although our observations qualitatively resemble results in sphere-forming BCPs confined in topographical trenches, the quantitative difference is noteworthy and technologically important for the design of nanostructures with programmable shapes.
本文研究了受限于化学条纹图案中的柱状形成嵌段共聚物 (BCP) 微域的自组装，这些条纹图案的宽度与共聚物的自然周期 L0 不成整数倍。结果表明，这种非整数倍导致微域的形状和空间周期都发生了变化。具体来说，当条纹宽度约为 n ± 1/2 L0 时，观察到从 n 到 n + 1 行微域的转变。当条纹宽度与 L0 相当时，可以诱导微域的椭圆度，其纵横比可达 2.2。应用自由能模型来描述这种行为的能量起源。尽管我们的观察结果在定性上类似于在形貌沟槽中受限的形成球体的 BCP 的结果相似，但定量差异值得注意，对于设计具有可编程形状的纳米结构具有重要的技术意义。
