Stabilization of oil-in-water emulsions with graphene oxide and cobalt oxide nanosheets and preparation of armored polymer particles

Liquid‐phase exfoliation method to access cobalt oxide nanosheets in pH‐neutral solutions

“…As CONs can be obtained by further exfoliation of the centrifuged powder by the simple addition of deionized water to the powder slurry and are not mentioned in the exfoliation studies of LCO. 21,[23][24][25][26][27][28][29][30][31][32][33][34][35] Upon addition of deionized water, indications of exfoliation are immediately observed, as supported by the presence of a dark solution that survives low-speed centrifugation. The behavior can be explained by an influx of water molecules into the interstices of the TMA-swelled layered cobalt oxide structure.…”

“…Most commonly exfoliated from lithium cobalt oxide (LCO) 21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36] (with many reports coming from our research group [23][24][25]28,29,34,36 ), CONs have been implemented in Liion batteries, thermoelectric devices, armored polymer particles, and layer-by-layer films. 21,23,27,30,31 CONs have also been synthesized through bottom-up techniques, but are not the focus of this work. 13,37 Interestingly, 2D CoO 2 has experimentally measured and theoretically predicted superconductivity and magnetic properties.…”

Polymer particles armored with cobalt oxide nanosheets for the catalytic degradation of bisphenol A

“…41 In a similar vein to the use of salt-flocculated LAPONITE® clay nanosheets, 42 our groups recently demonstrated that oil-in-water emulsions can be stabilized by a combination of CONs and GO nanosheets when flocculated with salt. 19 In this previous work, the CONs were difficult to fully disperse in water (they were 0.8 nm thick and ∼1 μm in diameter) and could not stabilize emulsions alone, as flocculation led to precipitation; this necessitated the use of GO nanosheets as co-surfactant. 19 Recent advances in soft-chemical exfoliation of LCO gives access to CONs that are fully dispersible in water.…”

“…19 In this previous work, the CONs were difficult to fully disperse in water (they were 0.8 nm thick and ∼1 μm in diameter) and could not stabilize emulsions alone, as flocculation led to precipitation; this necessitated the use of GO nanosheets as co-surfactant. 19 Recent advances in soft-chemical exfoliation of LCO gives access to CONs that are fully dispersible in water. 43 Sonication aided in the exfoliation process and led to nanosheets with thickness of 2–4 nm and lateral widths of >150 nm.…”

“…[7][8][9][10][11][12][13][14][15][16][17] We have also recently demonstrated that transition metal carbide (MXene) and transition metal oxide (cobalt oxide) nanosheets can stabilize oil-in-water emulsions, if first flocculated by simple inorganic salt such as NaCl. 18,19 Compared to GO, these inorganic 2D surfactants are expected to not only provide kinetic stability to the emulsion, but to also impart favorable performance properties to any composite structures formed. Pickering emulsions stabilized by 2D particles have also gained increased popularity for use as templates to access composite structures, leveraging the confinement of reagents.…”