Lyophobic slippery surfaces on smooth/hierarchical structured substrates and investigations of their dynamic liquid repellency

Slippery surfaces were prepared by infusing lubricant into smooth or hierarchical-structured superhydrophobic surfaces (SHS) to compare different surface-free energies. The surfaces obtained showed good repellency towards liquids with various values of surface tension/molecular polarity/viscosity, including hexane, tetradecane, water, ethylene glycol and viscous engine oil. The lyophobicity could be realized on a relatively smooth surface, indicating that the first principle of preparing a lyophobic slippery surface is to perform a low surface-free energy modification. The dynamic liquid repellency was also studied: the sliding speeds of different liquids on lubricant infused SHS showed a negative correlation to their kinematic viscosity values, and a higher surface roughness was favorable for dynamic wettability, whereas for the smooth slippery surface, the travelling speeds showed randomness.