Cylindrical inclusions in a copolymer membrane.
Cylindrical inclusions in a copolymer membrane.
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DOI：
10.1021/jp063951t
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发表时间：
2006-12
期刊：
影响因子：
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通讯作者：
Qiyi Zhang;Yuqiang Ma
中科院分区：
文献类型：
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作者：
Qiyi Zhang;Yuqiang Ma
利用自洽场理论(SCFT)研究了两个平行的柱状夹杂物之间的膜相互作用。棒状夹杂物位于双层的内部，由两层单层包裹。它们可能表现出两种基本类型的行为之一，包括将两个单分子层捏在一起并向外膨胀。对于不同的参数，我们计算了变形膜的密度分布、相关的相互作用自由能以及高分子链的构象熵。这两类相互作用势的相似性是质的特征。能量势垒将吸引区域与排斥区域分开；在排斥区域之前有一大段距离的弱吸引。它们之间的区别在于棒周围接触环境的不同，在于在夹持结构中短距离出现了一个小势垒。特别强调了相互作用势的紧密能量分析和熵分析。结果表明，化学势能提供了一种定性的趋势，并粗略地控制了相互作用势的基本形状；溶胀结构中的两亲性熵和夹点结构中的溶剂熵与相应的化学势能相结合，分别导致了中等距离的排斥势垒和较大距离的弱吸引。考虑了包裹体疏水性对相互作用势的影响。具体地说，在中等疏水性的体系中，可以出现收缩和膨胀结构，并且可以相互转化。
The membrane-mediated interaction between two parallel, cylindrical inclusions is investigated by using the self-consistent field theory (SCFT). The rodlike inclusions are located within the interior of the bilayer and are enveloped by two monolayers. They may exhibit one of the two basic types of behaviors involving pinching two monolayers together and swelling them outward. For different parameters, we calculate the density profile of the deformation membrane, the associated interaction free energy, as well as the conformational entropy of polymer chains. The similarity of the two types of interaction potentials is the qualitative characteristics. An energy barrier separates an attractive from a repulsive region; the repulsive region is preceded by a weak attraction at a large distance. The difference between them, which is due to the different contact environments around the rods, lies in the appearance of a small barrier at a short distance in the pinching structure. Particular emphasis is put on the closely energetic and entropic analyses of the interaction potential. We show that the chemical potential energy has provided a qualitative trend and roughly dominated the basic shape of the interaction potential; the amphiphile entropy in the swelling structure and the solvent entropy in the pinching structure, combined with the corresponding chemical potential energy, are responsible for the repulsive barrier at an intermediate distance and for the weak attraction at a large distance, respectively. The influence of inclusion hydrophobicity on the interaction potential is taken into account. In particular, the pinching and swelling structures can appear and can transform into each other in a system at intermediate hydrophobicity.