Seyyed Ghasem Masoudi - Department of chemical and petroleum engineering, Sharif university of technology, Tehran, Iran
Aliasghar Mohammadi - Department of chemical and petroleum engineering, Sharif university of technology, Tehran, Iran

In this study the surface of silica nanoparticles were coated with eiher propyl trimethoxy silane, as a hydrophobic agent, or polyethylene glycol methyl ether as a hydrophilic agent. Also, silica nanoparticles coated with both propyl and MPEG chains. Water surface tension in the presence of either of bare or surface-modified silica nanoparticles were measured at various temperatures. It was observed that the bare silica nanoparticle has little effect on the surface tension regardless of the temperature. The MPEGylated-silica nanoparticle reduces the surface tension more than the propyl-coated nanoparticle. Also, nanoparticles coated with both propyl and MPEG chains reduce the surface tension more than our other surface-modified nanoparticles. In spite of the general reduction of the surface tension with temperature in the presence of the nanoparticles, the surface tension increases beyond a temperature in the presence of nanoparticles coated with both propyl and MPEG chains.

silica nanoparticle, hydrophilic, hydrophobic, amphiphilic, temperature