The structure factor of a wormlike chain and the random-phase-approximation solution for the spinodal line of a diblock copolymer melt.
The structure factor of a wormlike chain and the random-phase-approximation solution for the spinodal line of a diblock copolymer melt.
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DOI：
10.1039/c4sm00374h
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发表时间：
2014-07
期刊：
影响因子：
3.4
通讯作者：
Xinghua Zhang;Ying Jiang;B. Miao;Yunlin Chen;Dadong Yan;Jeff Z. Y. Chen
中科院分区：
文献类型：
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作者：
Xinghua Zhang;Ying Jiang;B. Miao;Yunlin Chen;Dadong Yan;Jeff Z. Y. Chen
本文提出了一种直接处理绿色函数形式解的计算蠕虫链模型结构因子的简便有效的数值方法。一个精确的数值表示的蠕虫状链模型的结构因子，然后获得，任意链刚度。一方面，在柔性极限下，数值结果恢复了高斯链结构因子的德拜函数，并进一步预言了高斯模型无法捕捉的大k行为;另一方面，在刚性极限下，数值结果恢复了刚性杆结构因子的纽介堡函数.基于计算得到的结构因子，采用无规相近似方法研究了不对称蠕虫状嵌段共聚物有序-无序转变的物理性质，特别是计算了无序相的旋节线.对于对称的二嵌段共聚物微相分离的情况下，本计算再现的相边界先前确定的自洽场理论，并产生整个图片跨越从柔性链的限制刚性链的限制。
An efficient and convenient numerical approach to calculate the structure factor of a wormlike chain model is proposed by directly dealing with a formal solution of the Green's function. A precise numerical representation of the structure factor of the wormlike chain model is then obtained, for arbitrary chain rigidity. On one hand, in the flexible limit, the numerical results recover the well-known Debye function of the structure factor of a Gaussian chain and furthermore predict the correct large-k behavior that a Gaussian model fails to capture; on the other hand, in the rigid limit, the numerical results recover the well-known Neugebauer function of the structure factor of a rigid rod. Based on the calculated structure factor, the random phase approximation is employed to study the physical properties of the order-disorder transition for asymmetric wormlike diblock copolymers; particularly, the spinodal line of the disordered phase is calculated. For the case of symmetric diblock copolymer microphase separation, the present calculation reproduces the phase boundary previously determined by self-consistent field theories and yields the entire picture crossing over from the flexible-chain limit to the rigid-chain limit.