Lamellar block copolymers: Diffusion and reduction of entanglement effects
Lamellar block copolymers: Diffusion and reduction of entanglement effects
复制标题
层状嵌段共聚物：扩散和减少缠结效应
DOI：
10.1209/epl/i1998-00262-4
复制
发表时间：
1998
期刊：
影响因子：
1.8
通讯作者：
K. Kremer
中科院分区：
文献类型：
--
作者：
M. Murat;G. Grest;K. Kremer
用分子动力学模拟方法研究了对称两嵌段共聚物链在宏观取向层状相中的运动。对于长度为N = 40（1.1Ne）和100（3 Ne）的二嵌段，其中Ne是均聚物熔体的缠结长度，平行于界面的扩散常数D ε几乎与χ无关，而垂直分量D ε随着χ（Flory-Huggins参数）的增加而被强烈抑制，这与基于Rouse模型的理论预测一致。对于更长的链（N高达400）的纠缠效应的强烈减少观察。我们认为，由于减少链重叠在层状相在这个中间制度的链运动是类似于一个椭球形的分子在近晶相。
Motion of symmetric diblock copolymer chains in the macroscopically oriented lamellar phase is studied by molecular-dynamics simulation. For diblocks of length N = 40 (1.1Ne) and 100 (3Ne), where Ne is the entanglement length of the homopolymer melt, the diffusion constant parallel to the interface D∥ is nearly independent of χ, while the perpendicular component D⊥ is strongly suppressed as χ, the Flory-Huggins parameter, is increased in agreement with theoretical predictions based on the Rouse model. For even longer chains (N up to 400) a strong reduction of entanglement effects is observed. We argue that due to the reduced chain overlap in the lamellar phase in this intermediate regime the chain motion is similar to an ellipsoidal molecule in a smectic phase.