Stability of Some Silicone Lubricating Interlayers in Liquid-Infused Coatings

One of the most actively developing research areas in materials science relevant to polyfunctional coatings is the creation of slippery liquid-infused porous surfaces (SLIPS) based on porous hydrophobic or hydrophilic materials filled with low-volatility viscous liquids (lubricants). In the present work, we have investigated the possibility of using two organosilicon liquids of different polarities, bis(trifluoromethylsulfonyl)imide dicationic ionic liquid and silicone oil, as lubricants for fabricating slippery coatings that reduce the adhesion of solid and liquid aqueous precipitations to aluminium oxide substrates. To calculate the stability of the films of such lubricants, we have employed the theory of van der Waals forces to study the refractive index dispersions and the dielectric properties of the liquids in the region of microwave relaxation. On the basis of experimentally obtained data, the dielectric permittivity spectra have been calculated as functions of imaginary frequency for the entire spectral range, as well as the contribution of the van der Waals forces to the stability of the disjoining pressure isotherms of the lubricant films on the hydrophobic and hydrophilic aluminium oxide substrates. The disjoining pressure isotherms obtained in this work have indicated that the ionic liquid used to prepare slippery coatings is a more durable lubricant than silicone oil, because its films retain their stability when the vapor phase is replaced by an aqueous medium over a wider range of thickness.