Interfacial Activity and Contact Angle of Homogeneous, Functionalized, and Janus Nanoparticles at the Water/Decane Interface

Abstract

Surface heterogeneity affects the behavior of nanoparticles at liquid interfaces. To gain a deeper understanding on the details of these phenomena, we have measured the interfacial activity and contact angle at water/decane interfaces for three different types of nanoparticles: homogeneous poly(methyl methacrylate) (PMMA), silica functionalized with a capping ligand containing a methacrylate terminal group, and Ag-based Janus colloids with two capping ligands of different hydrophobicity. The interfacial activity was analyzed by pendant drop tensiometry, and the contact angle was measured directly by freeze-fracture shadow-casting cryo-scanning electron microscopy. The silver Janus nanoparticles presented the highest interfacial activity, compared to the silica nanoparticles and the homogeneous PMMA nanoparticles. Additionally, increasing the bulk concentration of the PMMA and silica nanoparticles up to 100-fold compared to the Janus nanoparticles led to silica particles forming fractal-like structures at the interface, contrary to the PMMA particles that did not show any spontaneous adsorption.

Ionic hydration-induced evolution of decane–water interfacial tension

“…The density of the decane or water bulk phase in our simulations is consistent with the actual density. In addition, compared to the experimental and simulation values in previous studies, [46][47][48][49] our simulation values of IFT for the decane-water systems under different temperature or pressure conditions are acceptable (see the ESI, † Section 1.4).…”

Dynamics of network fluids

“…with permission from the Royal Society of Chemistry; (b) Functionalized silica particles at the interface of a water drop. Reproduced from Ref [57]…”

Interfacial Activity of Gold Nanoparticles Coated with a Polymeric Patchy Shell and the Role of Spreading Agents

“…Additionally, a change in the slope is visible in Figure 4 b, around A p = 10 4 nm 2 /particle, which has also been reported for silver JPs by Fernández-Rodríguez et al 16 In the present case, we do not have enough particles to obtain a close-packed monolayer, but it is likely that the change in slope is due to nanoparticles coming in contact by percolating domains in a fractal-like manner, as observed by several authors for JPs. 19 , 20 …”