Rheological Properties of Lamellae-Forming Diblock Copolymers
Rheological Properties of Lamellae-Forming Diblock Copolymers
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片层形成二嵌段共聚物的流变性质
DOI：
10.1002/adts.202100097
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
and Hiroshi Morita
中科院分区：
文献类型：
--
作者：
Yoshinori Tomiyoshi;Toshihiro Kawakatsu;Takeshi Aoyagi;and Hiroshi Morita
本文研究了无缠结和弱缠结两嵌段共聚物熔体在有限振幅振荡剪切流和定常剪切流作用下形成的微相分离层状结构的流变特性。为了模拟这样的系统，采用耗散粒子动力学(DPD)模拟来再现层状结构，其中多链滑移弹簧模型与DPD模拟相结合来模拟纠缠效应。通过施加振荡剪切流，该模型使我们能够测量三种不同(平行、垂直和横向)层片方向相对于流动方向的存储和损耗模数。这些取向表现出独特的流变行为，特别是横向取向表现出一种特殊的行为，这是由于片层界面的有限膨胀，这与以往的研究不同。在定常剪切流动中，计算了平行和垂直方向的定常剪切粘度。在这种情况下，层状结构域的取向和层状界面附近键的局部取向和伸展影响了稳定的剪切粘度。纠缠的空间分布对稳态剪切粘度的影响也不同于先前的另一项研究。
The present study investigates rheological properties of microphase‐separated lamellar structures formed by unentangled and weakly entangled diblock copolymer melts under a finite amplitude oscillatory shear flow and a steady shear flow. To simulate such a system, dissipative particle dynamics (DPD) simulation is employed to reproduce the lamellar structures, where a multi‐chain slip‐spring model is combined with DPD simulation to mimic entanglement effects. By imposing an oscillatory shear flow, this model enables us to measure storage and loss moduli for three different (parallel, perpendicular, and transverse) lamellar orientations with respect to the flow direction. These orientations display distinctive rheological behaviors, and especially the transverse orientation exhibits a peculiar behavior owing to a finite expansion of the lamellar interfaces, which differs from a previous study. In a steady shear flow, steady shear viscosities of parallel and perpendicular orientations are evaluated. In this case, the orientations of lamellar domains and the local orientation and stretching of bonds near the lamellar interfaces affect the steady shear viscosities. A spatial distribution of entanglements also affects the steady shear viscosities differently from another previous study.