Janus liquid marbles containing both oil and water stabilised by silica or sericite particles

The preparation of Janus liquid marbles containing both oil and water is reported. The marbles were prepared by coalescing an oil liquid marble with a water liquid marble mechanically on a powdered bed of omniphobic solid particles, followed by further rolling on the particle bed so as to increase the particle coating and prevent disintegration upon removal. The coalescence of the marbles involves the rarification of the particle layers around the interacting marbles followed by the fusion of their liquid cores. Upon further rolling, the marbles exhibited four characteristic shapes depending on the oil to water ratio and the stabilising solid particles. Janus marbles containing equal volumes of oil and water and stabilised by fluorinated clay particles were ‘egg-like’ in shape with the water portion remaining almost spherical compared with the oil portion. The marbles elongate and change to a ‘tadpole-like’ shape as the volume fraction of oil increases, leaving the shape of the water portion which forms the head of the tadpole intact (quasi-spherical). On the contrary, increasing the volume fraction of water did not affect the marble shape. When stabilised by fluorinated fumed silica particles, a quasi-spherical shape forms at equal oil and water volumes, but an increase in either oil or water fraction changes the shape to a puddle. The stability of the Janus marbles to evaporation depends on the vapour pressure of the encapsulated liquids, with those of higher vapour pressure evaporating faster as in the case of liquid marbles containing only one liquid. Lastly, by coalescing a cyclohexane marble containing sebacoyl chloride with a water marble containing hexamethylene diamine, resulting in the formation of Nylon 6–10 at the interface, the possibility of performing chemical reactions in the Janus oil-water liquid marbles was illustrated.