Grafted polymers under the influence of external fields
Grafted polymers under the influence of external fields
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DOI：
10.1063/1.465641
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发表时间：
1993-11
影响因子：
4.4
通讯作者：
J. Marko;A. Johner;C. Marques
中科院分区：
文献类型：
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作者：
J. Marko;A. Johner;C. Marques
接枝聚合物“刷子”的结构可能会通过“外部场”的作用而发生深刻的改变——例如由于接枝表面的界面效应而导致的化学势的局部变化。我们讨论了暴露于任意外部电势的刷子的自洽平均场理论的强拉伸极限，在外部场将单体推向表面的情况下，出现了刷子高度的简单缩放定律。相反，排斥相互作用可能导致“禁区”或聚合物末端被排斥的区域，导致简单的缩放公式崩溃。我们精确地解决了总是出现排斥区的排斥方井中的刷子自洽理论。我们的结果描述了一种刷子，其中二元溶剂的一种组分的薄层润湿接枝表面，该二元溶剂对于聚合物来说是比本体混合物更差的溶剂。我们还讨论了热波动和链多分散性对结果的影响，并估计了各种界面现象对刷结构的影响。
The structure of grafted polymer ‘‘brushes’’ may be profoundly modified by the action of ‘‘external fields’’—local shifts in chemical potential due to, e.g., interfacial effects at the grafting surface. We discuss the strong‐stretching limit of the self‐consistent mean‐field theory for a brush exposed to an arbitrary external potential, a simple scaling law for the brush height arises in the case where the external field pushes monomers towards the surface. In contrast, repulsive interactions can lead to ‘‘exclusion zones’’ or regions from which polymer ends are repelled, leading to a breakdown of the simple scaling formula. We exactly solve the self‐consistent theory of the brush in a repulsive square well where an exclusion zone always appears. Our results describe a brush in the case where a thin layer of one component of a binary solvent that is a worse solvent for the polymer than is the bulk mixture wets the grafting surface. We also discuss the effects of thermal fluctuations and chain polydispersity on our results, and estimate the effects of various interfacial phenomena on the brush structure.