Pezzutti Aldo D, Gómez Leopoldo R, Vega Daniel A
Instituto de Física del Sur (IFISUR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional del Sur, Av. LN Alem 1253, 8000 Bahía Blanca, Argentina.
Soft Matter. 2015 Apr 14;11(14):2866-73. doi: 10.1039/c5sm00071h.
In this work we study equilibrium and non-equilibrium structures of smectic block copolymer thin films deposited on a topographically patterned substrate. A Brazovskii free energy model is employed to analyze the coupling between the smectic texture and the local mean curvature of the substrate. The substrate's curvature produces out-of-plane deformations of the block copolymer such that equilibrium textures are modified and dictated by the underlying geometry. For weak curvatures it is shown that the free energy of the block copolymer film follows a Helfrich form, scaling with the square of the mean curvature, with a bending constant dependent on the local pattern orientation. On substrates of varying mean curvature simulations show that topological defects are rapidly expelled from regions with large curvature. These results compare well with available experimental data of poly(styrene)-co-poly(ethylene-alt-propylene) smectic thin films.
在这项工作中，我们研究了沉积在具有地形图案的衬底上的近晶嵌段共聚物薄膜的平衡和非平衡结构。采用Brazovskii自由能模型来分析近晶织构与衬底局部平均曲率之间的耦合。衬底的曲率会导致嵌段共聚物产生面外变形，从而使平衡织构发生改变，并由底层几何形状决定。对于弱曲率情况，研究表明嵌段共聚物薄膜的自由能遵循Helfrich形式，与平均曲率的平方成比例，其弯曲常数取决于局部图案取向。在具有不同平均曲率的衬底上进行的模拟表明，拓扑缺陷会迅速从大曲率区域排出。这些结果与聚（苯乙烯）-共-聚（乙烯-交替-丙烯）近晶薄膜的现有实验数据吻合良好。
