Roles of methyl orange in preparation of emulsions stabilized by layered double hydroxide particles

The roles of a fluorescent dye, methyl orange (MO) in the emulsions stabilized by layered double hydroxide (LDH) particles have been investigated in detail. The hydrophilic LDH particles are rendered partially hydrophobic by the in situ surface modification with MO, leading to the enhanced stability of emulsions. The variation of contact angle, zeta potential and emulsion stability demonstrates the amphiphile-like behaviors of MO. Exploiting the fluorescence of MO, we have shown in situ microscopic images of MO-modified particle adsorption onto droplet surface using confocal fluorescence microscopy. Furthermore, the adsorption of MO-modified LDH on liquid droplet surface has also been exploited to produce hollow colloidosomes, the morphology of which has been observed with SEM.