Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films,ACS Nano

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Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films
ACS Nano ( IF 15.8 ) Pub Date : 2018-09-18 00:00:00 , DOI: 10.1021/acsnano.8b04202
Su-Mi Hur ₁ , Vikram Thapar _{1,

2} , Abelardo Ramírez-Hernández _{3,

4} , Paul F. Nealey _{2,

3} , Juan J. de Pablo _{2,

3}

Affiliation

Defects in highly ordered self-assembled block copolymers represent an important roadblock toward the adoption of these materials in a wide range of applications. This work examines the pathways for annihilation of defects in symmetric diblock copolymers in the context of directed assembly using patterned substrates. Past theoretical and computational studies of such systems have predicted minimum free energy pathways that are characteristic of an activated process. However, they have been limited to adjacent dislocations with opposite Burgers vectors. By relying on a combination of advanced sampling techniques and particle-based simulations, this work considers the long-range interaction between dislocation pairs, both on homogeneous and nanopatterned substrates. As illustrated here, these interactions are central to understanding the defect structures that are most commonly found in applications and in experimental studies of directed self-assembly. More specifically, it is shown that, for dislocation dipoles separated by several lamellae, multiple consecutive free energy barriers lead to effective kinetic barriers that are an order of magnitude larger than those originally reported in the literature for tightly bound dislocation pairs. It is also shown that annihilation pathways depend strongly on both the separation between dislocations and their relative position with respect to the substrate guiding stripes used to direct the assembly.

中文翻译：

层状嵌段共聚物薄膜定向组装中的缺陷An灭途径

高度有序的自组装嵌段共聚物的缺陷代表了在广泛应用中采用这些材料的重要障碍。这项工作在使用图案化基材进行定向组装的情况下，研究了消除对称双嵌段共聚物中缺陷的途径。此类系统的过去理论和计算研究已经预测了激活过程所特有的最小自由能途径。但是，它们仅限于具有相反Burgers向量的相邻位错。通过结合先进的采样技术和基于粒子的模拟，这项工作考虑了位错对之间的长距离相互作用，无论是在均质的还是纳米图案的衬底上。如此处所示，这些相互作用对于理解在定向自组装的应用和实验研究中最常见的缺陷结构至关重要。更具体地，显示出，对于由几个薄片隔开的位错偶极子，多个连续的自由能垒导致有效的动力学势垒，其比在文献中最初报道的紧密结合的位错对大一个数量级。还显示出an灭路径在很大程度上取决于位错之间的间隔及其相对于用于引导组件的基板引导条的相对位置。对于由数个薄片隔开的位错偶极子，多个连续的自由能垒导致有效的动力学势垒，其大小比文献中最初报道的紧密结合的位错对要大一个数量级。还显示出an灭路径在很大程度上取决于位错之间的间隔及其相对于用于引导组件的基板引导条的相对位置。对于由数个薄片隔开的位错偶极子，多个连续的自由能垒导致有效的动力学势垒，其大小比文献中最初报道的紧密结合的位错对要大一个数量级。还显示出an灭路径在很大程度上取决于位错之间的间隔及其相对于用于引导组件的基板引导条的相对位置。

更新日期：2018-09-18

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