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To stabilize and transport them through complex systems, nanoparticles are often encapsulated in polymeric nanocarriers, which are tailored to specific environments. For example, a hydrophilic polymer capsule maintains circulation and stability of nanoparticles in aqueous environments. A more highly-designed nanocarrier might have a hydrophobic core and a hydrophilic shell to allow transport of hydrophobic nanoparticles and pharmaceuticals through physiological media. Polydimethylsiloxane, PDMS, is a hydrophobic material in a liquidlike state at room temperature. The preparation of stable, aqueous dispersions of PDMS droplets in water is problematic due to the intense mismatch in surface energies between PDMS and water. The present work describes the encapsulation of hydrophobic metal- and metal oxide nanoparticles within PDMS nanodroplets using flash nanoprecipitation. The PDMS is terminated by amino groups and the nanodroplet is capped with a layer of poly(styrene sulfonate), forming a glassy outer shell. The hydrophobic nanoparticles nucleate PDMS droplet formation, decreasing the droplet size. The resulting nanocomposite nanodroplets are stable in aqueous salt solutions without the use of surfactants. The hierarchical structuring, elucidated with small angle x-ray scattering, offers a new platform for the isolation and transport of hydrophobic molecules and nanoparticles through aqueous systems. 

N-heterocyclic carbenes (NHCs) have attracted tremendous attention over the past decade, as it is expected to form strong coordination to transition metal complexes and surfaces. Here, we investigate the interactions between colloidal gold nanoparticles (AuNPs), or luminescent quantum dots (QDs) and a multidentate NHC-based polymer ligand. The ligand design relies on the nucleophilic addition reaction between several NHC anchoring groups, short polyethylene glycol (PEG) blocks, and a polymer chain. We find that such NHC-decorated ligands rapidly coordinate onto both sets of nanocrystals, which is attributed to the inherent σ-donating nature (soft Lewis base) of NHC groups combined with the soft Lewis acidic character of nanocrystal surfaces. We combine NMR spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy and dynamic light scattering to characterize the NHCstabilized nanocrystals and gain insights into the nature of the binding interactions. In particular, we find that the newly coated nanocrystals exhibit long-term colloidal stability over a broad range of conditions with no sign of degradation or aggregation build up, while preserving their photophysical properties, for at least one year of storage.