Structural and thermodynamic properties of interfaces between coexisting phases in polymer blends: a Monte Carlo simulation
Structural and thermodynamic properties of interfaces between coexisting phases in polymer blends: a Monte Carlo simulation
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聚合物共混物中共存相之间界面的结构和热力学性质：蒙特卡罗模拟
DOI：
10.1039/ft9959102369
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
W. Oed
中科院分区：
文献类型：
--
作者：
M. Müller;K. Binder;W. Oed
采用大规模Monte Carlo方法研究了部分不相容二元对称高分子混合物中富A相和富B相的界面。使用简单立方晶格上的键涨落模型，占据晶格位置的体积分数= 0.5，链长NA=NB=N= 32，假设有效单体之间的相互作用IµAA=IµBB=-IµAB=-Iµ，相互作用范围为√6晶格间距。所研究的温度范围为0.144 < T/Tc < 0.759，涵盖了从低温下的强偏析区到临界温度Tc附近的弱偏析区的整个范围（后者已经从以前的工作中的有限尺寸标度分析中非常准确地估计）。的界面亥姆霍兹能量和界面宽度，w，温度依赖性，它表明，前者是兼容的与当前的理论，而w超过理论预测的约两个因素。将平行于界面的线性尺寸L从L= 64变化到L= 512，我们可以表明，由于毛细波引起的浓度分布的加宽不能解释这种差异（注意，我们的系统的大尺寸，高达约100 μ m）。16 × 106格点，需要使用大规模并行CRAY-T3 D系统）。我们提出的证据为丰富的链端和“自由体积”在界面处，并表明，链界面附近的取向和轻微收缩的强隔离限制。我们认为，“有效的”Flory-Huggins χ参数减少界面附近的这些影响。
A large-scale Monte Carlo investigation of the interface between the A-rich and B-rich phase of a partially incompatible binary (AB) symmetric polymer mixture is presented. The bond fluctuation model on the simple cubic lattice at a volume fraction ϕ= 0.5 of occupied lattice sites and chain lengths NA=NB=N= 32 is used, assuming an interaction IµAA=IµBB=–IµAB=–Iµ between effective monomers, with an interaction range of √6 lattice spacings. The temperature range studied, 0.144 < T/Tc < 0.759, encompasses the whole range from the strongly segregated regime at low temperatures to the weak segregation regime near the critical temperature Tc(the latter has already been estimated very accurately from a finite-size scaling analysis in previous work). The temperature dependence of both interfacial Helmholtz energy and interfacial width, w, are presented, and it is shown that the former is compatible with current theory, while w exceeds the theoretical predictions by about a factor of two. Varying the linear dimension L parallel to the interface from L= 64 to L= 512 we can show that broadening of the concentration profile due to capillary waves cannot explain this discrepancy (note that the large size of our systems, up to ca. 16 × 106 lattice sites, needed the use of a massively parallel CRAY-T3D system). We present evidence for the enrichment of chain ends and of ‘free volume’ at the interface and show that chains near the interface are oriented and slightly contracted in the strong segregation limit. We suggest that the ‘effective’ Flory–Huggins χ parameter is reduced near the interface by these effects.