Dipartimento di Chimica e Biologia, Università di Salerno, Via Giovanni Paolo II, 132, I-84084, Fisciano, SA, Italy.
Nanoscale. 2018 Nov 29;10(46):21656-21670. doi: 10.1039/c8nr05135f.
We perform a systematic application of the hybrid particle-field molecular dynamics technique [Milano, et al., J. Chem. Phys., 2009, 130, 214106] to study interfacial properties and potential of mean force (PMF) for separating nanoparticles (NPs) in a melt. Specifically, we consider Silica NPs bare or grafted with Polystyrene chains, aiming to shed light on the interactions among free and grafted chains affecting the dispersion of NPs in the nanocomposite. The proposed hybrid models show good performances in catching the local structure of the chains, and in particular their density profiles, documenting the existence of the "wet-brush-to-dry-brush" transition. By using these models, the PMF between pairs of ungrafted and grafted NPs in Polystyrene matrix are calculated. Moreover, we estimate the three-particle contribution to the total PMF and its role in regulating the phase separation on the nanometer scale. In particular, the multi-particle contribution to the PMF is able to give an explanation of the complex experimental morphologies observed at low grafting densities. More in general, we propose this approach and the models utilized here for a molecular understanding of specific systems and the impact of the chemical nature of the systems on the composite final properties.
我们采用混合粒子-场分子动力学技术[Milano 等人，J. Chem. Phys.，2009，130，214106]对熔融状态下分离纳米颗粒（NPs）的界面性质和平均势（PMF）进行了系统研究。具体来说，我们研究了无支链和支链化二氧化硅 NPs，旨在揭示影响纳米复合材料中 NPs 分散的游离链和支链之间的相互作用。所提出的混合模型在捕捉链的局部结构方面表现良好，特别是它们的密度分布，证明了“湿刷-干刷”转变的存在。利用这些模型，我们计算了聚苯乙烯基质中无支链和支链化 NPs 之间的 PMF。此外，我们还估计了三粒子对总 PMF 的贡献及其在调节纳米尺度相分离中的作用。特别是，PMF 的多粒子贡献能够解释在低接枝密度下观察到的复杂实验形态。更一般地说，我们提出了这种方法和这里使用的模型，用于对特定体系的分子理解以及体系的化学性质对复合材料最终性能的影响。
