Compression of hard core–soft shell nanoparticles at liquid–liquid interfaces: influence of the shell thickness

Abstract

Soft hydrogel particles show a rich structural and mechanical behaviour compared to hard particles, both in bulk and when confined in two dimensions at a fluid interface. Moreover, encapsulation into hydrogel shells makes it possible to transfer the tunability of soft steric interactions to hard nanoparticle cores, which bear interest for applications, e.g. in terms of optical, magnetic and reinforcement properties. In this work, we investigate the microstructures formed by hard core-soft shell particles at liquid-liquid interfaces upon compression. We produced model particles with the same silica core and systematically varied the shell-to-core ratio by synthesising shells with three different thicknesses. These particles were spread at an oil-water interface in a Langmuir-Blodgett trough and continuously transferred onto a solid support during compression. The transferred microstructures were analysed by atomic force and scanning electron microscopy. Quantitative image analysis provided information on the particle packing density, the inter-particle distance, and the degree of order of the monolayers. We discovered several essential differences compared to purely soft hydrogel particles, which shed light on the role played by the hard cores in the assembly and compression of these composite monolayers.

Dynamics and Wetting Behavior of Core–Shell Soft Particles at a Fluid–Fluid Interface

“…We synthesized three different batches of fluorescent silica particles, which are denoted as Core1 (C1), Core2 (C2), and Core3 (C3) in Table 1, following a recently published protocol. 5 Prior to the Stöber synthesis of the silica particles, we functionalized the RITC dye. A ten-fold excess of APS was added dropwise to a 10 mM ethanolic RITC solution to ensure covalent binding to the dye molecule.…”

“…The functionalization of silica particles using MPS was performed as described in reference. 5 The final concentration of the different silica seed stock dispersions and the radius of the silica cores obtained from SEM images are also reported in Table 1. Since the core radius of C2 is nearly the same as that of C3, we will refer to both batches as particles with core radius of 176 nm in Section 3.…”

“…1b). [4][5][6] Experimentally, it has been found that the extent of deformation in the plane of the interface depends on the cross-linking density of the poly-mer network, i.e., its elasticity. 4 Moreover, a recent numerical work by Mehrabin et al showed…”

Short- and long-range contributions to equilibrium and transport properties of solid electrolytes

“…The right-hand side of equation (3.11) can be considered in a diagram representation [42]. In order to derive equations determining the mean potentials, we use the condition 13) which means that all the diagrams containing at least one free node are taken into account. In this case, the free energy functionals for the initial and the reference systems, therefore, coincide for the same distributions of the number of particles over the volume of the system.…”

Exactly solvable model for self-assembly of hard core–soft shell particles at interfaces

“…Our results agree with experimental observations. Hybrid hard-core soft-shell particles (HCSS) consisting of solid cores encapsulated in a cross-linked hydrogel network can self-assemble into ordered patterns on air-water or oilwater interfaces [1][2][3][4][5][6][7]. Highly ordered arrays of particles with cores having desired properties can find applications in various fields, e.g.…”