DENSITY PROFILE OF TERMINALLY ANCHORED POLYMER-CHAINS - A MONTE-CARLO STUDY
DENSITY PROFILE OF TERMINALLY ANCHORED POLYMER-CHAINS - A MONTE-CARLO STUDY
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DOI：
10.1021/ma00209a023
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发表时间：
1990-04-02
期刊：
影响因子：
5.5
通讯作者：
TORAL, R
中科院分区：
文献类型：
--
作者：
CHAKRABARTI, A;TORAL, R
我们展示了对大量末端锚定或末端接枝在平面上的聚合物链系统进行详细蒙特卡罗模拟研究的结果。我们在三维晶格上研究了该系统的几个不同的表面覆盖度和链长值。我们还考虑了链长度的几种不同分布。对于单分散链，我们发现单体密度分布在接枝平面附近显示出耗尽层，这与现象学理论一致。在该耗尽层之外，密度分布可以用抛物线形式表示。该结果与最近的自洽场 (SCF) 计算一致，而不是与预测密度分布平稳区域的缩放参数一致。链端密度也与 SCF 计算结果一致；即，我们发现链的自由端不排除在接枝表面附近的区域之外。我们还研究了多分散性对链长的影响。在由两种长度为 N 和 2N 的聚合物组成的系统的情况下，我们发现存在一个区域，其中密度分布与链长为 N 的单分散情况的密度分布相匹配，这与最近的另一个自洽场计算一致。然而，该区域的宽度比理论预测的要窄。我们还考虑了链长的均匀分布，并将密度分布与通过对 SCF 形式中导出的方程进行积分而获得的函数形式进行了比较。蒙特卡罗数据与理论之间的一致性是显着的，除了接枝平面附近存在耗尽层之外。
We present results of a detailed Monte Carlo simulation study of a system of a large num-ber of polymerchains terminally anchored or end-grafted on a flat surface. We study this system on a three-dimensional lattice for several different values of the surface coverage andthe chain length. We also consider several different distributions forthe chain lengths. For monodisperse chains, we find that the monomer density profile shows a depletion layer near the grafting plane in agreement with phenomenological theories. Beyond this depletion layer, the density profile can be represented by a parabolic form. This result is in agreement with recent self-consistent-field (SCF) calculations rather than with the scaling arguments that predict a plateau region for the density profile. The chain-end density is also found to be con-sistent with the SCF calculations; ie, we find that the free ends of the chains are not excluded from regions near the grafting surface. We also study the effect of polydispersity in the chain lengths. In the case of a system consisting of two species of polymers of length N and 2N, we find that there is a region in which the density profile matches that of the monodisperse case with chain length N, in agreement with another recent self-consistent-field calculation. The width of this region, however, is narrower than that predicted by the theory. We have also considered a uniform distribution of chain lengthsand compared the density profile with the functional form obtainedby intergrating the equations derived in theSCF formalism. The agreement between the Monte Carlo data and the theory is remarkable except, again, for the presence of a depletion layer near the grafting plane.