Effect of nanoparticles on the wetting of different solid surfaces

Abstract

The wetting of solids by liquid is gaining a lot of importance as it is connected to physical chemistry (wettability) to statistical physics (wetting transition) and long-range forces (van der Waals, double layer) to fluid dynamics. The present study mainly focused on the effect of nanoparticles on the wetting of different solid surfaces, as nanoparticles are gaining importance because of their wide applications in various field like pharmaceutical, biomedical and electronics. The effect of two different nanoparticles hydrophobic (sulfur) and hydrophilic (TiO2) on both the hydrophilic (glass) and hydrophobic (PTFE) surfaces have been studied. The sulfur nanoparticles were prepared by acid catalyzed precipitation reaction from sodium thiosulphate, whereas TiO2 is prepared by hydrolysis of trititanium (IV) butaoxide (TBOT). It is observed the use of nanoparticles enhanced the wetting process as compared to the base liquids without nanoparticles. The effect of reactant concentration on the particles size of both particles is initially studied and the results shows with increasing concentration the particles size increases in both the cases. Then the effect of particles size on the wetting of glass and PTFE surfaces were studied by measuring surface tension and contact angle. In the presence of the sulfur particles the wetting property of the both surfaces increases whereas, due to the presence of TiO2 particles the wetting property increases for PTFE surface but the wetting property decreases for the glass surface. The extent of measurement of wetting process was done by calculating work of adhesion, Hamaker constant, and wetting free energy for both the surfaces in the presence of both particles.