Size‐Controlled Nanoparticle Clusters of Narrow Size‐Polydispersity Formed Using Multiple Particle Types Through Competitive Stabilizer Desorption to a Liquid–Liquid Interface

Abstract

A novel colloidal approach is presented for preparing fully dispersed nanoparticle (NP) assemblies (clusters) of narrow size‐polydispersity over a wide range of sizes through irreversible depletion of stabilizing ligands onto a liquid–liquid interface. Unusually, the relative monodispersity of the assemblies continuously improves throughout the process. A detailed kinetics study into the assembly of iron oxide NP clusters shows that the assembly rate decreases with NP concentration, pinpointing the role of the interface in size focusing. A new protocol for identifying initial conditions that enable controlled assembly is described, which allows extension of the approach to multiple NP types, opening up a general route to colloidally processed materials. The process uses cheap materials, it is reproducible, robust, and scaleable, and it allows for selection of both particle and cluster size. In the case of assemblies of magnetic iron oxide NPs, these advantages enable tuning of the magnetic properties of the assemblies for applications such as magnetically targetable MRI‐trackable agents in biomedicine.

Spatiotemporally Resolved Heat Dissipation in 3D Patterned Magnetically Responsive Hydrogels

“…[11] Nanocomposite materials which combine the tunable properties of nanoparticles with chemically defined polymer scaffolds represent a powerful means to improve controllability and alter the physicochemical properties of microenvironments in situ. [12] Suspension of magnetic nanoparticles (MNPs) has been developed for biomedical applications as contrast agents for MRI and for cancer ablation, [13][14][15][16][17] with the latter exploiting strong heating on exposure to alternating magnetic fields (AMF) arising due to their superparamagnetic properties (rapidly fluctuating moments). MNP polymer nanocomposites can in principle respond to applied AMF to induce structural changes and to program functional responses such as stimulating time-dependent deformation or release of cargo on Multifunctional nanocomposites that exhibit well-defined physical properties and encode spatiotemporally controlled responses are emerging as components for advanced responsive systems, for example, in soft robotics or drug delivery.…”

N‐Heterocyclic Carbene‐Stabilized Ultrasmall Gold Nanoclusters in a Metal‐Organic Framework for Photocatalytic CO2Reduction

“…However, owing to the high surface energy, Au‐NCs are often thermodynamically unstable and tend to migrate and coalesce, especially upon light irradiation or at elevated reaction temperature [3] . The structural aggregation will lead to a significant loss in catalytic activity and selectivity [4] …”

“…[3] The structural aggregation will lead to a significant loss in catalytic activity and selectivity. [4] Controlling the size and uniform dispersion of Au-NCs in a solid-state porous matrix is a major target in their heterogeneous catalysis. [5] As compared with traditional porous solids (e.g.…”

A Versatile Route to Assemble Semiconductor Nanoparticles into Functional Aerogels by Means of Trivalent Cations

“…In other words, novel nanoparticle‐based superstructures should combine the properties of the building blocks and the emerging new features that can be achieved solely based on the self‐assembly of the nanocrystals. This challenging task has called numerous assembly procedures into being: triggering the responsive ligand shell, [ 11,12 ] cross‐linking, [ 13,14 ] ligand desorption, [ 15 ] solvent exchange, [ 16 ] controlled solvent evaporation, [ 17 ] applying templates, [ 18 ] or using the cryoaerogelation method. [ 19,20 ]…”