Chemical Engineering Journal, Vol.343, 561-571, 2018
Ionic liquids-infused slippery surfaces for condensation and hot water repellency
Functional surfaces that enable both hot water repellency and effective condensation have attracted great interest in both academic research and practical applications. Two kinds of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids (ILs) with different chain lengths ([C(n)mIm][PF6], n = 4 ([BmIm][PF6]), n = 8 ([OmIm][PF6])) are respectively infused into the porous surface constructed by nanocone arrays of (Ni, Co)-(CO3)(0.5)(OH)(0.11)H2O (NiCo-NCA), aiming to produce slippery surfaces (SSs) with stable non-wetting performance. Before the ILs infusion, the NiCo-NCA surface is functionalized by low surface energy material for conferring superhydrophobicity. The superhydrophobicity of the modified NiCo-NCA becomes ineffective after the heat treatment up to about 240 degrees C due to the formation of cracks on the surface. However, the slippery surfaces can be maintained in the ILs-infused samples followed by the same heat treatment due to the self-healing ability and thermal stability of the infused fluids. Moreover, hot water droplets are repellent on the ILs-infused SSs while pinned on the superhydrophobic surface. The nucleation process of condensing water droplets is easier on the ILs-infused SSs than that on the superhydrophobic surface. The sliding speed of the condensed water and the hot water droplets on the [OmIm][PF6]-infused SS are slower than those on the [BmIm][PF6]-infused SS due to the higher viscosity of [OmIm][PF6]. As well, the ILs-infused SSs can endure physical damage and impacting droplet. The ILs-infused SSs shows promise potential applications in hot liquid self-cleaning and high efficiency droplet manipulation.
Keywords:Ionic liquids;Hydrophobic;High temperature resistance;Mechanical stability;Slippery surfaces