19 research outputs found
Ionic Liquids in Multiphase Systems
Ionic liquids (ILs) can be used to replace one or more phases in conventional oil/water emulsions including Pickering emulsionsâsurfactant-free emulsions which utilize nano- or micron-sized particles to stabilize the immiscible liquid-liquid interface. Due to the extreme tunability of both the ILs and particles used, the study of IL-based Pickering emulsions yields novel emulsion morphologies and insights into the ionic liquid-liquid-particle interactions present. This work discusses extensive experimental work on IL-based Pickering emulsions and IL/liquid interfaces, emphasizing unique phenomenaâsuch as âbridgingâ between emulsion droplets and spontaneous particle transport across the interfaceânever observed in more conventional Pickering emulsions. Molecular dynamics (MD) simulations of particles at the IL/liquid interface are also discussed, and fundamental insights from these simulations are used to enhance understanding of the unique interface behavior revealed by experiment
The One-Step Pickering Emulsion Polymerization Route for Synthesizing Organic-Inorganic Nanocomposite Particles
Polystyrene-silica core-shell nanocomposite particles are successfully prepared via one-step Pickering emulsion polymerization. Possible mechanisms of Pickering emulsion polymerization are addressed in the synthesis of polystyrene-silica nanocomposite particles using 2,2-azobis(2-methyl-N-(2-hydroxyethyl)propionamide (VA-086) and potassium persulfate (KPS) as the initiator. Motivated by potential applications of âsmartâ composite particles in controlled drug delivery, the one-step Pickering emulsion polymerization route is further applied to synthesize polystyrene/poly(N-isopropylacrylamide) (PNIPAAm)-silica core-shell nanoparticles with N-isopropylacrylamide incorporated into the core as a co-monomer. The polystyrene/PNIPAAm-silica composite nanoparticles are temperature sensitive and can be taken up by human prostate cancer (PC3-PSMA) cells
Molecular Dynamics Studies on the Adaptability of an Ionic Liquid in the Extraction of Solid Nanoparticles
Recently, a number of publications have suggested that
ionic liquids
(ILs) can absorb solid particles. This development may have implications
in fields like
oil sand processing, oil spill beach cleanup, and water treatment.
In this Article, we provide a computational investigation of this
phenomenon via molecular dynamics simulations. Two particle surface
chemistries were investigated: (1) hydrocarbon-saturated and (2) silanol-saturated,
representing hydrophobic and hydrophilic particles, respectively.
Employing 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]Â[PF<sub>6</sub>]) as a model IL, these nanoparticles were allowed to equilibrate
at the IL/water and IL/hexane interfaces to observe the interfacial
self-assembled structures. At the IL/water interface, the hydrocarbon-based
nanoparticles were nearly completely absorbed by the IL, while the
silica nanoparticles maintained equal volume in both phases. At the
IL/hexane interface, the hydrocarbon nanoparticles maintained minimal
interactions with the IL, whereas the silica nanoparticles were nearly
completely absorbed by it. Studies of these two types of nanoparticles
immersed in the bulk IL indicate that the surface chemistry has a
great effect on the corresponding IL liquid structure. These effects
include layering of the ions, hydrogen bonding, and irreversible absorption
of some ions to the silica nanoparticle surface. We quantify these
effects with respect to each nanoparticle. The results suggest that
ILs likely exhibit this absorption capability because they can form
solvation layers with reduced dynamics around the nanoparticles
Multipetal-Structured and Dumbbell-Structured GoldâPolymer Composite Particles with Self-Modulated Catalytic Activity
A simple
synthesis route for goldâpolymer composite particles
with controlled structure (multipetal structure and dumbbell structure)
is developed. It is intriguing to observe that by controlling the
reaction time and size of gold nanoparticles (AuNPs), tetrapetal-,
tripetal-, and dumbbell-structured goldâpolystyrene composite
are obtained via seeded polymerization. The average number of petals
on a single AuNP increases with the AuNP diameter. These particles
show potential applications as building blocks for advanced ordered
and hierarchical supracolloidal materials. Further, with the incorporation
of polyÂ(<i>N</i>-isopropylacrylamide) (PNIPAm), âsmartâ
thermoresponsive dumbbell-structured goldâPNIPAm/polystyrene
composite particles are formed. Significant size variation is validated
for particles with 83 and 91 wt % PNIPAm content around lower critical
solution temperature (LCST), which results in self-modulated catalytic
activity