Geometric Stability and Elastic Response of a Supported Nanoparticle Film

Abstract

The mechanical response to compression of a self-assembled gold nanoparticle monolayer and trilayer at the air-liquid interface is examined. Analysis of the film's buckling morphology under compression reveals an anomalously low bending rigidity for both the monolayer and the trilayer, in contrast with continuum elastic plates. We attribute this to the spherical geometry of the nanoparticles and poor coupling between layers, respectively. The elastic energy of the trilayers is first delocalized in wrinkles and then localized into folds, as predicted by linear and nonlinear elastic theory for an inextensible thin film supported on a fluid.

Forced Desorption of Nanoparticles from an Oil–Water Interface

“…Experiments have revealed a solid-like behavior [14][15][16][17][18][19][20][21][22] and in some instances, particle expulsion into one of the fluid phases [23][24][25] . This range of behavior is reminiscent of that of spread monolayers of lipids under strong compression: condensed monolayers exhibit solid-like response and collapse by folding, while monolayers that remain liquid expel material in the fluid subphase 26 .…”

Incommensurate phases of a supported nanoparticle film subjected to uniaxial compression

“…As the solvent droplet evaporates, the film condenses into solid monolayer domains separated by regions of open air-water interface (11,28). The monolayer is then compressed uniaxially in the plane of the interface in the x-direction by two moving barriers, while confined in the in-plane y-direction by the borders of the trough (see Fig.…”

“…The film is free to buckle out-of-plane in the z-direction into the subphase or superphase. Details about the experimental setup and apparatus have previously been published (11). Upon compression, the film buckles, forming localized trilayer regions surrounded by a monolayer (11,28).…”

“…In this report, we examine a different, 2D pattern observed on a self-assembled solid monolayer of gold nanoparticles that is in a metastable state. Under uniaxial compression, the film buckles into localized areas of trilayer coexisting with the monolayer, forming a complex "hash" network across the surface of the film (11). We examine the global arrangement of the buckled hash network on the surface, using statistical mechanical arguments.…”

“…In the experiments reported here, a nanoparticle film is formed by spreading a solution of 6-nm (11,28) Au nanoparticles ligated with dodecanethiol at the air-water interface in a Langmuir trough. As the solvent droplet evaporates, the film condenses into solid monolayer domains separated by regions of open air-water interface (11,28).…”