Abstract
Droplets partially submersed in an immiscible liquid pool attract each other. We experimentally study the interaction of floating droplets containing aqueous solution of a volatile liquid. A droplet affects its neighbors by generating a vapor gradient to the surrounding and responds by evaporating asymmetrically over its exposed cap. We show that the induced asymmetric temperature distribution causes a surface tension gradient driving the droplet. We highlight that the attracting motion always consists of an accelerating and a decelerating stages. We finally provide a theoretical model that quantitatively captures the interactive forces between droplets and predicts essential features of the attracting motion.