Molecular fluctuations in the packing of polymeric liquid crystals
Molecular fluctuations in the packing of polymeric liquid crystals
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DOI：
10.1021/ma00210a023
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发表时间：
1990-04
期刊：
影响因子：
5.5
通讯作者：
R. Podgornik;V. Parsegian
中科院分区：
文献类型：
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作者：
R. Podgornik;V. Parsegian
最近对DNA聚电解质间力的测量表明，在相互作用粒子的晶格中，分子间力与分子无序之间存在直接的、连续的耦合。在广泛的条件下，组装功受分子构型熵的控制，而分子构型熵又受来自相邻分子的排斥力的限制。这种观察到的熵力衰减速度的一半是从一个静电双层或平行分子之间的水合力的衰减长度预测。它不能用具有有效硬壁半径的柔性分子的传统模型来拟合。在本文中，我们建立了一个高斯随机行走聚合物的统计力学模型，该模型被其邻居的有效“管”包围，该模型可以通过严格的形式类比来求解有界二维量子化振子的问题。基本衰变长度的加倍自然出现。人们也可以提取出分子运动受到限制的潜在的直接分子间力.
Recent measurements of forces between DNA polyelectrolytes have shown a direct and con-tinuous coupling between intermolecular forces and molecular disorder in lattices of interacting particles. Over a wide range of conditions the work of assembly is dominated by the configurational entropy of mol-ecules restricted by repulsiveforces from their neighbors. This observed entropic force decays half as fast as what is predicted from thedecay lengths for an electrostatic double layer or hydration forces between parallel molecules. It cannot be fit by the traditional model of flexible molecules with an effective hard wall radius. In this paper we develop a statistical mechanical model of a Gaussian randomly walking poly-mer surrounded by an effective “tube” of its neighbors, a model that can be solved in strict formal analogy to the problem of a bounded two-dimensional quantized oscillator. The doublingof the underlying expo-nential decay length emerges naturally. One may also extractthe underlying direct intermolecular force through which molecular motion is restricted.