posted on 2019-02-05, 00:00authored byLiam R.
J. Scarratt, Liwen Zhu, Chiara Neto
Lubricant-infused
surfaces have attracted great attention recently
and are described as slippery liquid-infused porous surfaces (SLIPS).
Here, we measured the hydrodynamic drainage forces on SLIPS by colloid
probe atomic force microscopy (AFM) and quantified the effective slip
length over a nanothin silicone oil layer on hydrophobized [octadecyltrichlorosilane
(OTS)-coated] silicon wafers. The thickness of a stable silicone oil
film on OTS–Si under sucrose solution was determined to be
1.8 ± 1.3 nm and was found to induce an average effective slip
length of 29 ± 3 nm, very close to that of an uninfused OTS substrate.
These relatively low values of effective slip are confirmed by the
relatively large macroscopic roll-off angle values of water droplets
on the same substrates. Both nano- and macroscale results reflect
the immobilized nature of a silicone oil layer of thickness around
2 nm within an underlying monolayer. These results have important
implications in the design of drag-reducing coatings using lubricant
infusion.