Mechanics of Interfacial Composite Materials

TL;DR

This paper investigates the mechanical behavior of particle-covered interfaces, revealing their solid-like properties, plastic and elastic responses, and the potential for their use as composite materials with unique properties.

Contribution

It provides a combined experimental and theoretical analysis of the mechanical properties and stress responses of interfacial composite materials, highlighting their solid-like behavior and potential applications.

Findings

Inhomogeneous stresses cause plastic deformation.

Homogeneous stresses induce elastic response.

Particle rearrangements under shear lead to plasticity.

Abstract

Recent experiments and simulations have demonstrated that particle-covered interfaces can exist in stable non-spherical shapes as a result of the steric jamming of the interfacially trapped particles, which confers the interface with solid-like properties. We provide an experimental and theoretical characterization of the mechanical properties of these armored objects, with attention given to the two-dimensional granular state of the interface. Small inhomogeneous stresses produce a plastic response while homogeneous stresses produce a weak elastic response. Shear-driven particle-scale rearrangements explain the basic threshold needed to obtain the near-perfect plastic deformation that is observed. Furthermore, the inhomogeneous stress state of the interface is exhibited experimentally by using surfactants to destabilize the particles on the surface. Since the interfacially trapped particles retain their individual characteristics, armored interfaces can be recognized as a kind of composite material with distinct chemical, structural and mechanical properties.