The effect of gold nanoparticles on the spreading of triple line

The work reports a unique phenomenon of gold nanoparticles on the formation of gas bubbles. The well-defined gold nanofluids prevent the spreading of triple line during bubble formation, i.e. the triple line is pinned somewhere around the middle of the tube wall during the rapid bubble formation stage whereas it spreads to the outer edge of the tube for pure liquid. Compared with pure liquid, adding nanoparticles raises bubble frequency and reduces departure bubble volume. Different to other observations of bubble dynamics in nanofluids under evaporation or boiling conditions, which are caused by the surface modification due to particle sedimentation, this work reveals an inherent feature of enhanced pinning of triple lines for well-defined nanofluids, which bears extensive implications to a number of nanoparticle-associated interfacial phenomena.