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arXiv 0810.2049cond-mat.softcond-mat.stat-mech
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疏水区与亲水区平板间的疏水相互作用和去湿

Hydrophobic Interactions and Dewetting between Plates with Hydrophobic and Hydrophilic Domains

Lan Hua, Ronen Zangi, B. J. Berne

摘要:

我们研究的分子动力学模拟的润湿/去湿过渡和板之间的距离,包含疏水性和亲水性颗粒的自由能的依赖关系。我们发现,去湿和疏水相互作用的强度是非常敏感的疏水和亲水域的分布。特别是,我们发现,板的特点是由一个大的域的疏水性网站诱导去湿过渡和有吸引力的溶剂诱导的相互作用。另一方面,疏水性和亲水性颗粒在板上的均匀分布防止去湿转变,并产生排斥性溶剂诱导的相互作用。我们还提出了一种Janus接口,其中一个板由疏水颗粒和其他亲水颗粒,显示板间间隙保持湿润,直到空间的限制,在小的分离喷射水分子的结果。结果表明,Cassie方程不能用于预测非均质平板的接触角临界脱湿距离。这些结果表明,具有强的大长度尺度疏水性的纳米级表面之间的疏水相互作用可以是高度合作的,因此他们反对在这些情况下不同表面域之间的疏水相互作用的加和性。这些发现与某些蛋白质-蛋白质相互作用有关,其中通常假设加和性。

英文摘要:

We study by molecular dynamics simulations the wetting/dewetting transition and the dependence of the free energy on distance between plates that contain both hydrophobic and hydrophilic particles. We show that dewetting and strength of hydrophobic interaction is very sensitive to the distribution of hydrophobic and hydrophilic domains. In particular, we find that plates characterized by a large domain of hydrophobic sites induce a dewetting transition and an attractive solvent-induced interaction. On the other hand, a homogeneous distribution of the hydrophobic and hydrophilic particles on the plates prevents the dewetting transition and produces a repulsive solvent-induced interaction. We also present results for a kind of Janus interface in which one plate consists of hydrophobic particles and the other of hydrophilic particles showing that the inter-plate gap remains wet until steric constraints at small separations eject the water molecules. Our results indicate that the Cassie equation, for the contact angle of a heterogeneous plate, can not be used to predict the critical distance of dewetting. These results indicate that hydrophobic interactions between nanoscale surfaces with strong large length-scale hydrophobicity can be highly cooperative and thus they argue against additivity of the hydrophobic interactions between different surface domains in these cases. These findings are pertinent to certain protein-protein interactions where additivity is commonly assumed.

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