Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom.
Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
Phys Rev Lett. 2015 Mar 13;114(10):108301. doi: 10.1103/PhysRevLett.114.108301. Epub 2015 Mar 9.
Nanoparticles with grafted layers of ligand molecules behave as soft colloids when they adsorb at fluid-fluid interfaces. The ligand brush can deform and reconfigure, adopting a lens-shaped configuration at the interface. This behavior strongly affects the interactions between soft nanoparticles at fluid-fluid interfaces, which have proven challenging to probe experimentally. We measure the surface pressure for a stable 2D interfacial suspension of nanoparticles grafted with ligands, and extract the interaction potential from these data by comparison to Brownian dynamics simulations. A soft repulsive potential with an exponential form accurately reproduces the measured surface pressure data. A more realistic interaction potential model is also fitted to the data to provide insights into the ligand configuration at the interface. The stress of the 2D interfacial suspension upon step compression exhibits a single relaxation time scale, which is also attributable to ligand reconfiguration.
当带有接枝配体分子层的纳米粒子吸附在流体-流体界面时，它们表现为软胶体。配体刷可以变形和重新配置，在界面上采用透镜状结构。这种行为强烈影响了流体-流体界面上软纳米粒子之间的相互作用，这在实验上很难探测到。我们测量了与配体接枝的纳米粒子稳定二维界面悬浮液的表面压力，并通过与布朗动力学模拟的比较，从这些数据中提取相互作用势。具有指数形式的软排斥势准确地再现了测量的表面压力数据。还拟合了更现实的相互作用势模型，以深入了解界面上的配体配置。二维界面悬浮液在阶跃压缩时的应力表现出单一的弛豫时间尺度，这也归因于配体的重新配置。
