[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^2,3, P. K. Kimani¹, C. Takai-Yamashita^1,2 (1.Gifu University, Japan, 2.Tohoku University, Japan)

Keywords:TD-NMR, surface modification, silica, affinity, modification ratio

Using TD-NMR, the affinity of partially hydrophobic silica nanoparticles for ethanol and hexane was examined. The silica surfaces were modified with C3, C6, and C12 chains, with modification ratios controlled. Longer chains and higher modification ratios increased ethanol affinity. Conversely, hexane affinity was generally poor, but improved with shorter chains and lower modification ratios. It was hypothesized that ethanol is attracted to residual silanol groups among long-chain functional groups. This was tested in ethanol/hexane mixtures. In 60-80% hexane, the relaxation time of C12-modified silica (1.4/nm²) quickly decreased, but this effect disappeared when residual silanol was further modified with C3. TD-NMR effectively detects changes in surface affinity of partially hydrophobic nanoparticles, even with the same hydrophobicity.