The lifetime of floating liquid marbles: the influence of particle size and effective surface tension

Abstract

In this study, we investigated the factors affecting the lifetime of liquid marbles placed on a glass surface and floating on water. It was found that the particle size, surface free energy and hydrophobicity of the encapsulating microparticles determine the effective surface tension and lifetime of a liquid marble floating on water. We formed liquid marbles using ultra-hydrophobic poly(perfluoroalkyl ethyl acrylate) powder with three different particle sizes (8 AE 1, 20 AE 2 and 60 AE 5 mm) and polytetrafluoroethylene powder (7 AE 2 mm). It was found that both the effective surface tension and lifetime of a floating liquid marble increased considerably with the decrease in the particle size of the ultra-hydrophobic poly(perfluoroalkyl ethyl acrylate) powder. We also determined that a floating liquid marble had a longer lifetime if the water contact angle of the polymer powder was high and its surface free energy was low by comparing the results of two different powders having very close average particle sizes but different hydrophobicities.

Deformation of a floating liquid marble

“…None of the liquid marble burst within minutes after proper placement on water, unlike previous reports. 17 The stability is most likely due to a difference in PTFE diameters as the powder used in the experiment is smaller than that of previous report, 1 mm compared to 7 mm. 43 because air is present between the liquid marble and the liquid carrier.…”

Interpretation of elasticity of liquid marbles

“…1, is the non-stick droplet encapsulated with micro-or nano-scaled solid particles [5][6][7]. Since liquid marbles were introduced in the pioneering works of Quèrè et al, they have been exposed to the intensive theoretical and experimental research [8][9][10][11][12][13]. An interest in liquid marbles arises from both their very unusual physical properties and their promising applications.…”

Measuring the Coefficient of Friction of a Small Floating Liquid Marble

“…A liquid marble is a liquid droplet coated with hydrophobic powder, which can roll on a solid surface12345 and float on a liquid surface due to its non-wetting coating678910111213141516. A liquid marble can be driven across a liquid surface using thermocapillarity1718.…”