[T1] Powder Production

[15P-T1-03] Wettability of Hydrophobic Silica Nanoparticles in Hexane/Ethanol Mixture Characterized by a Time-Domain Nuclear Magnetic Resonance (TD-NMR)

*A. Kato¹, A. Teramae¹, J. Ikeda^{3, 1}, P. K. Kimani¹, C. Takai-Yamashita^{1, 2} (1.Gifu University, Japan, 2.Tohoku University, Japan, 3.Mageleka Japan Co,. Ltd., Japan)

Keywords:Time-domain nuclear magnetic resonance, Surface modification, Silica, Wettability, Modification ratio

Wettability between hydrophobic silica nanoparticles and organic solvents as a dispersing medium has been characterized with change in the relaxation time (T₂) obtained by a time-domain nuclear magnetic resonance (TD-NMR). The modification ratio was controlled with different chain lengths modifiers (as C3, C6, C12). For ethanol, the longer chain length and higher modification ratio showed the higher wettability while for hexane, vice versa even though a quite poor wettability appeared in whole conditions. We hypothesize that the ethanol molecules could be attracted to residual silanol groups among long-chain groups. Then the wettability of the partially hydrophobic silica nanoparticles with ethanol/hexane mixture has been investigated. Ranging from 60 to 80 vol% of hexane, T₂ of the C12-modified silica nanoparticles quickly decreased. When the residual silanol was additionally modified with C3, the corresponding decrease has been disappeared. The TD-NMR is effective to detect the surface wettability change of the partially hydrophobic nanoparticles.