Kłos J, Sommer J-U
Leibniz Institute For Polymer Research Dresden e. V., 01069 Dresden, Germany.
J Chem Phys. 2007 Nov 7;127(17):174901. doi: 10.1063/1.2794330.
Combining scaling arguments and Monte Carlo simulations using the bond fluctuation method we have studied concentration effects for the adsorption of symmetric AB-random copolymers at selective, symmetric interfaces. For the scaling analysis we consider a hierarchy of two length scales given by the excess (adsorption) blobs and by two dimensional thermal blobs in the semidilute surface regime. When both length scales match, a densely packed array of adsorption blobs is formed (saturation). We show that for random copolymer adsorption the interface concentration can be further increased (oversaturation) due to reorganization of excess blobs. Crossing over this threshold results in a qualitative change in the behavior of the adsorption layer which involves a change in the average shape of the adsorbed chains towards a hairpinlike form. We have analyzed the distribution of loops and tails of adsorbed chains in the various concentration regimes as well as the chain order parameter, concentration profiles, and the exchange rate of individual chains. We emphasized the role of saturation scaling which dominates the behavior of static and dynamic quantities at higher surface concentration.
结合标度论证和使用键涨落方法的蒙特卡罗模拟，我们研究了对称AB-无规共聚物在选择性对称界面上吸附的浓度效应。对于标度分析，我们考虑了由过量（吸附）团簇和半稀溶液表面区域中的二维热团簇给出的两个长度尺度层次结构。当两个长度尺度匹配时，会形成紧密堆积的吸附团簇阵列（饱和）。我们表明，对于无规共聚物吸附，由于过量团簇的重组，界面浓度可以进一步增加（过饱和）。越过这个阈值会导致吸附层行为的定性变化，这涉及吸附链的平均形状向发夹状形式的变化。我们分析了各种浓度区域中吸附链的环和尾的分布以及链序参数、浓度分布和单个链的交换率。我们强调了饱和标度的作用，它在较高表面浓度下主导静态和动态量的行为。
