Controlling patterns by geometry in block copolymer thin films

自组装嵌段共聚物为制备纳米管提供了一个强大的框架，可用于各种应用，包括用于超净化的纳米孔膜、太阳能电池、纳米模板、有机光电子学和UV偏振器等。然而，自组装方法的一个常见问题是由于图案波动和缺陷而缺乏长程有序。已经提出了许多方法来产生具有明确取向顺序的图案，如剪切取向、电场取向、区和溶剂退火法或图形和化学外延法。在这里，我们探索另一个可能的排列因素，嵌段共聚物膜系统嵌入其中的几何形状。在之前的资助期间，我们已经证明了几何可以作为一个有效的引导场来诱导长程有序，并规定拓扑缺陷的分布和密度。在这个项目中，我们计划研究沉积在弯曲衬底上的自组装嵌段共聚聚合物薄膜的平衡和动力学性质。主要的挑战是开发一种有意义的理论，允许识别控制带有自组装图案的曲面薄膜的内在顺序的主导参数。这项拟议的研究涉及在广泛的长度和时间尺度上处理有序和缺陷动力学，从分子尺度到在实验可获得的几何场的作用下支配有序的介观动力学的那些尺度。将特别注意图案形态与局部对称性和几何之间的耦合。这些问题将通过实验和模拟相结合的努力来解决。

Self-assembling block copolymers provide a powerful framework for producing nanopatterns for a diversity of applications, including nanoporous membranes for ultra-purification, solar cells, nanotemplates, organic optoelectronics, and UV polarizers, and many others. However, one frequent problem with the self-assembly approach is lack of long-range order due to pattern undulations and defects. Numerous methods to produce patterns with well-defined orientational order have been proposed, such as shear alignment, alignment through electric fields, zone and solvent annealing, or grapho- and chemo-epitaxy. Here, we explore another possible aligning factor, the geometry in which the block copolymer film system is embedded. In the previous funding period, we have demonstrated that geometry can be an effective guiding field to induce long-range order and to prescribe the distribution and density of topological defects. In this project, we propose to study the equilibrium and kinetic properties of self-assembling block copolymer thin films deposited onto curved substrates. The central challenge is to develop a meaningful theory that allows identifying the leading parameters that control the intrinsic order in curved films carrying self-assembled patterns. The proposed study involves the treatment of ordering and defect dynamics on a wide range of length and time scales, spanning from molecular scales up to those that govern the mesoscopic kinetics of ordering under the action of experimentally accessible geometric fields. Special attention will be paid to the coupling between pattern morphologies and local symmetry and geometry. These problems will be tackled by a combined experimental and simulation effort.