Primitive chain network model for block copolymers
Primitive chain network model for block copolymers
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DOI：
10.1016/j.jnoncrysol.2006.01.144
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发表时间：
2006-11
影响因子：
3.5
通讯作者：
Yuichi Masubuchi;G. Ianniruberto;F. Greco;G. Marrucci
中科院分区：
文献类型：
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作者：
Yuichi Masubuchi;G. Ianniruberto;F. Greco;G. Marrucci
提出了纠缠态嵌段共聚物的粗粒度分子模拟作为原始链网络模型的扩展。聚合物被表示为连续缠结之间的一系列片段，后者被建模为与其他链的滑动连接。每个滑环仅连接两条链，即，纠缠被视为“二元”。由此产生的 3D 结构是一个原始链网络，这使得我们的模型不同于其他滑动链接单链模型，其中与其他链的链接是“虚拟”的。我们的模拟的 3D 性质使其与传统的分子动力学模拟相似，但粒度要粗得多。由于聚合物的 3D 空间分配，可以定义单体密度场，并且可以考虑由于单体的不同化学性质而导致的相互作用，类似于密度场计算。聚合物运动通过滑动连接的 3D 运动和单体沿原始链的 1D 传输来描述，而网络拓扑重排则由于链端的钩挂和脱钩过程而发生。每个动力学方程都考虑了沿链的弹力、密度梯度产生的场力以及热随机力。在本文中，对原始链网络模型进行了修改（i）在网络重排过程中以考虑共聚物中的不同化学成分，以及（ii）在涉及嵌段之间的边界时动力学方程的一些细节。我们报告了二嵌段共聚物的结果，其中为简单起见，除了相互作用之外，两种单体的所有相关性质都是相同的。模拟以较低的计算成本合理地再现了良好缠结共聚物的微相形成过程和相图。
A coarse-grained molecular simulation for block copolymers in the entangled state is proposed as an extension of the primitive chain network model. Polymers are represented as a sequence of segments between consecutive entanglements, the latter being modeled as sliplinks with other chains. Each sliplink connects two chains only, i.e., entanglements are taken as ‘binary’. The resulting 3D structure is a network of primitive chains, which makes our model different from other sliplink single-chain models, where the link to other chains is ‘virtual’. The 3D nature of our simulation makes it similar to, though considerably more coarse grained than, conventional molecular dynamics simulations. Because of the 3D space assignment of the polymers, monomeric density fields can be defined, and interactions due to different chemistry of the monomers can be accounted for, similarly to density field calculations. Polymer motion is described both by the 3D motion of sliplinks, and by the 1D transport of monomers along the primitive chain, while network topological rearrangement occurs due to chain-end hooking and unhooking processes. Each kinetic equation accounts for elastic forces along the chains, field forces arising from density gradients, and thermal random forces. In this paper, the primitive chain network model was modified (i) in the procedure of network rearrangement to account for the different chemistries in the copolymer, and (ii) in some details of the kinetic equations whenever the boundary between blocks is involved. We report results for diblock copolymers where for simplicity all relevant properties of the two monomers are the same, except for the interactions. Simulations reasonably reproduce the micro-phase formation process and the phase diagram for well entangled copolymers with a low calculation cost.