Lightly crosslinked poly(4-vinylpyridine)-silica nanocomposite microgel particles are used to prepare either oil-in-water or water-in-oil "Pickering" emulsions at around pH 8-9. Rapid demulsification occurs below pH 3, since the addition of acid leads to the protonation of 4-vinylpyridine residues which, in turn, impart hydrophilic character to the nanocomposite particles, hence promoting their desorption from the droplet interface (see Figure).