Exploring the 3D Conformation of Hard-Core Soft-Shell Particles Adsorbed at a Fluid Interface

The encapsulation of a rigid core within a soft polymeric shell allows obtainingcomposite colloidal particles that retain functional properties, e.g., optical ormechanical. At the same time, it favors their adsorption at fluid interfaceswith a tunable interaction potential to realize tailored two-dimensional (2D)materials. Although they have already been employed for 2D assembly, theconformation of single particles, which is essential to define the monolayerproperties, has been largely inferred via indirect or ex situ techniques. Here,by means of in situ atomic force microscopy experiments, the authorsuncover the interfacial morphology of hard-core soft-shell microgels,integrating the data with numerical simulations to elucidate the role of thecore properties, of the shell thicknesses, and that of the grafting density. Theyidentify that the hard core can influence the conformation of the polymershells. In particular, for the case of small shell thickness, low grafting density,or poor core affinity for water, the core protrudes more into the organic phase,and the authors observe a decrease in-plane stretching of the network at theinterface. By rationalizing their general wetting behavior, such compositeparticles can be designed to exhibit specific inter-particle interactions ofimportance both for the stabilization of interfaces and for the fabrication of 2Dmaterials with tailored functional properties