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arXiv 1503.03262cond-mat.softcond-mat.stat-mechphysics.chem-ph
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一对纳米粒子之间的有效相互作用

Effective interactions between a pair of nanoparticles

Alexandr Malijevský

摘要:

我们研究了两个纳米粒子(或胶体)浸泡在溶剂中表现出两相分离之间的有效相互作用。利用非局域密度泛函理论,我们确定了当溶剂是近体两相共存的纳米粒子的分离的有效电位的依赖性。如果将优先吸附相$α$的相同纳米颗粒插入相$β$中,则在其表面形成优选相$α$的厚润湿层。在纳米颗粒的某些特定分离$h_b$处,润湿层连接以形成单个桥,并且诱导的有效电势对于所有距离$h<h_b$都变得强烈吸引。对于大于临界半径$R_c$的纳米颗粒的所有半径,桥接是一级毛细管冷凝状转变,对于温度$T/T_c\approx0.9$,其值估计为大约$R_c\approx20σ$,其中$σ$是溶剂(方孔)颗粒的尺寸。对于半径$R<R_c$,桥接过程是连续的。如果相同的颗粒插入优选相$α$中,则它们之间的唯一有效相互作用由短程耗尽电位引起。如果纳米颗粒具有相反的吸附偏好,则仅在其中一个纳米颗粒周围形成单个润湿层,并且有效相互作用在两相中是强烈排斥的。由第二颗粒的存在引起的润湿膜的破坏引起的排斥在低密度状态下更大并且稍微更长。

英文摘要:

We investigate the effective interactions between two nanoparticles (or colloids) immersed in a solvent exhibiting two-phase separation. Using a non-local density functional theory, we determine the dependence of the effective potential on the separation of the nanoparticles when the solvent is near bulk two-phase coexistence. If identical nanoparticles preferentially adsorbing phase $α$ are inserted into phase $β$, thick wetting layers of the preferable phase $α$ develop at their surfaces. At some particular separation $h_b$ of the nanoparticles, the wetting layers connect to form a single bridge, and the induced effective potential becomes strongly attractive for all distances $h<h_b$. The bridging is a first order capillary condensation like transition for all radii of the nanoparticles greater than the critical radius $R_c$, the value of which was estimated to be approximately $R_c\approx20σ$ for a temperature $T/T_c\approx0.9$, where $σ$ is the size of the solvent (square-well) particles. For radii $R<R_c$ the process of bridging is continuous. If the same particles are inserted into the preferable phase $α$, the only effective interaction between them is induced by the short-ranged depletion potential. If the nanoparticles have opposite adsorption preferences, only a single wetting layer forms around one of the nanoparticles and the effective interaction is strongly repulsive in both phases. The repulsion, induced by a disruption of the wetting film by the presence of the second particle, is larger and slightly longer-ranged in a low density state.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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