Effect of nanoparticles on vapour-liquid surface tension of water: A molecular dynamics study

We study the effect of nanoparticles on the vapour-liquid surface tension of TIP4P/2005 water model using molecular dynamic simulations. The interactions of nanoparticles with water and volume percentage of nanoparticles are varied. It is found that the surface tension increases with increasing hydrophilicity and decreases with increasing hydrophobicity, as the nanoparticle volume percentage is increased. However, the surface tension values do not increase at higher volume fraction, both for hydrophilic and hydrophobic interactions. We also present the effect of temperature on the surface tension of water with nanoparticles. It is found that surface tension of water with hydrophobic nanoparticles reduces substantially faster with increasing temperature compared to that containing hydrophilic nanoparticles. The behaviour is well supported by the interfacial width data.