Shear-induced parallel and transverse alignments of cylinders in thin films of diblock copolymers†,Soft Matter

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Shear-induced parallel and transverse alignments of cylinders in thin films of diblock copolymers†
Soft Matter ( IF 2.9 ) Pub Date : 2018-07-03 00:00:00 , DOI: 10.1039/c8sm00833g
Yulong Chen _{1,

2,

3,

4} , Qian Xu _{1,

2,

3,

4} , Yangfu Jin _{1,

2,

3,

4} , Xin Qian _{1,

2,

3,

4} , Rui Ma _{1,

2,

3,

4} , Jun Liu _{4,

5,

6,

7} , Dexin Yang _{4,

8,

9,

10}

Affiliation

Coarse-grained Langevin dynamics simulations were performed to investigate the alignment behavior of monolayer films of cylinder-forming diblock copolymers under steady shear, a structure of significant importance for many technical applications such as nanopatterning. The influences of shear conditions, the interactions involved in the films, and the initial morphology of the cylinder-forming phase were examined. Our results showed that above a critical shear rate, the cylinders can align either along the shearing direction or transverse (log-rolling) to the shearing direction depending on the relative strength between the interchain attraction in the cylinders (ε_AA) and the surface attraction of the confining walls with the film (ε_BW). To understand the underlying mechanism, the microscopic properties of the films under shear were systematically investigated. It was found that at low ε_AA/ε_BW, the majority blocks of the diblock polymer that are adsorbed on the confining walls prefer to move synchronously with the walls, inducing the cylinder-forming blocks to align along the flow direction. When ε_AA/ε_BW is above a threshold value, a strong attraction between the cylinder-forming blocks restrains their movement during shear, leading to the log-rolling motions of the cylinders. To predict the threshold ε_AA/ε_BW, we developed an approach based on equilibrium thermodynamics data and found good agreement with our shear simulations.

中文翻译：

剪切诱导的二嵌段共聚物薄膜中圆柱体的平行和横向排列†

进行了粗粒度的Langevin动力学模拟，以研究在稳定剪切作用下圆柱形成的二嵌段共聚物的单层膜的排列行为，该结构对于许多技术应用（例如纳米图案）具有重要意义。考察了剪切条件，薄膜中的相互作用以及圆柱形成相的初始形态的影响。我们的研究结果表明，临界剪切速率的上方，所述汽缸可以沿剪切方向或横向（日志轧制），以根据所述链间的吸引力之间在气缸的相对强度（剪切方向对齐ε _AA）和表面的吸引力有膜的围壁（ε _BW）。为了理解其基本机理，系统地研究了在剪切作用下薄膜的微观性能。结果发现，在低的ε _AA / ε _BW，即吸附在围壁上的二嵌段聚合物的多数块倾向于与壁沿着流动方向同步移动，诱导所述气缸形成块对齐。当ε _AA / ε _BW是在阈值以上，所述气缸形成块之间有很强的吸引力剪切期间限制它们的运动，从而导致气缸的对数滚动运动。为了预测阈值ε _AA / ε _BW，我们根据平衡热力学数据开发了一种方法，并与我们的剪切模拟发现了很好的一致性。

更新日期：2018-07-03

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