Flow through oil nanothreads

摘要

Emulsion droplets with ultralow interfacial tensions can be pulled apart by a pair of optical traps into daughter droplets that remain connected by an oil thread of nanoscopic thickness. This thread is stabilized by the bending modulus of the oil-water interface, which opposes the necking that leads to break up into droplets in the Rayleigh-Plateau instability. Variation in the pressure exerted on the droplets by the optical traps leads to a flow of liquid between the droplets via the nanothread. The flow has two components: (i) Poiseuille flow within the thread, and (ii) transport of the entire thread from one droplet to the other, with interface being created on one droplet and destroyed on the other. For typical viscosities of the oil and water, the dominant contribution to flow arises from the transport of the whole thread with the flow internal to the thread making a minor contribution.