title: Interactions and stress relaxation in monolayers of soft nanoparticles at fluid-fluid interfaces.
abstract: 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.
authors: Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom.
authors: Valeria
authors: V
authors: Garbin
authors: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors: Ian
authors: I
authors: Jenkins
authors: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors: Talid
authors: T
authors: Sinno
authors: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors: John C
authors: JC
authors: Crocker
authors: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors: Kathleen J
authors: KJ
authors: Stebe