We have studied assembly at air-water and liquid-liquid interfaces with an emphasis on systems containing both surfactants and nanoparticles. Anionic surfactants, sodium dodecyl sulfate (SDS) and non-ionic surfactants, Triton X-100 and tetraethylene glycol alkyl ethers (C(8)E(4), C(12)E(4) and C(14)E(4)), effectively decrease the surface tension of air-water interfaces. The inclusion of negatively charged hydrophilic silica nanoparticles (diameters of approximately 13 nm) increases the efficiency of the SDS molecules but does not alter the performance of the non-ionic surfactants. The former is likely due to the repulsive Coulomb interactions between the SDS molecules and nanoparticles which promote the surfactant adsorption at air-water interfaces. For systems involving trichloroethylene (TCE)-water interfaces, the SDS and Triton X-100 surfactants effectively decrease the interfacial tensions and the nanoparticle effects are similar compared to those involving air-water interfaces. Interestingly, the C(12)E(4) and C(14)E(4) molecules, with or without the presence of nanoparticles, fail to decrease the TCE-water interfacial tensions. Our molecular dynamics simulations have suggested that the tetraethylene glycol alkyl ether molecules tend to disperse in the TCE phase rather than adsorb at the TCE-water interfaces.

Precise control of interlayer spacing and functionality is crucial in two-dimensional material based membrane separation technology. Here we show anion intercalation in protonated graphite phase carbon nitride (GCN) that tunes the interlayer spacing and functions of GCN-based membranes for selective permeation in aqueous/organic solutions. Sulfate anion intercalation leads to a crystalline and amphipathic membrane with an accessible interlayer spacing at ~10.8 Å, which allows high solvent permeability and sieves out the solutes with sizes larger than the spacing. We further extend the concept and illustrate the example of GCN-based chiral membrane via incorporating (1R)-(-)-10-camphorsulfonic anion into protonated GCN layers. The membrane exhibits a molecular weight cutoff around 150 among various enantiomers and highly enantioselective permeation towards limonene racemate with an enantiomeric excess value of 89%. This work paves a feasible way to achieve water purification and chiral separation technologies using decorated laminated membranes.

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 “smart” 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.

No abstract