Using molecular dynamics (MD) simulations and density functional theory (DFT) calculations, we systematically study the effective pair potential between two particles induced by unconnected monomers and by polymers at various polymer concentrations (above the overlap), particle sizes, and polymer–particle interactions. In the case of athermal interactions, we verify that the entropic depletion forces between two nanoparticles inside a solvent of unconnected monomers oscillate in accordance with the radial distribution of monomers around one nanoparticle, and that the strength of polymer-induced entropic depletion forces rises linearly with the increase of nanoparticle size. These results are quite consistent with previously obtained experimental and theoretical results. When introducing attractive interactions between nanoparticles and polymers, the adsorption of polymer segments on the surface of each nanoparticle induces repulsive forces between the nanoparticles which can eliminate the depletion attractions. Enhancing the attraction between monomers and nanoparticles leads to the formation of thin polymer-layers on the surfaces of nanoparticles. As a consequence, the depletion attraction reappears at a somewhat increased particle distance. The observed phenomena become increasingly pronounced at higher polymer concentrations. Throughout this work we systematically compare computer simulation results with predictions from density functional theory and show that the data obtained with both approaches are quite consistent with each other.

中文翻译：

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由单个单体和聚合物链诱导的纳米粒子之间的有效对电位

使用分子动力学（MD）模拟和密度泛函理论（DFT）计算，我们系统地研究了未连接的单体和聚合物在各种聚合物浓度（重叠以上），颗粒尺寸和聚合物-颗粒所诱导的两个颗粒之间的有效对电势。互动。在非热相互作用的情况下，我们验证未连接单体的溶剂内部的两个纳米粒子之间的熵耗尽力会根据单体在一个纳米粒子周围的径向分布而振荡，并且聚合物引起的熵耗尽力的强度随纳米颗粒尺寸的增加。这些结果与先前获得的实验和理论结果非常一致。当引入纳米粒子和聚合物之间有吸引力的相互作用时，聚合物链段在每个纳米颗粒表面上的吸附会在纳米颗粒之间产生排斥力，从而可以消除耗尽吸引力。增强单体和纳米颗粒之间的吸引力会导致在纳米颗粒表面形成薄的聚合物层。结果，耗尽引力以稍微增加的颗粒距离重新出现。在较高的聚合物浓度下，观察到的现象变得越来越明显。在整个工作中，我们系统地将计算机模拟结果与密度泛函理论的预测进行比较，并表明通过两种方法获得的数据彼此之间非常一致。