Abstract:

Four dispersion systems were prepared by surface modification of SiO₂ aerogel （AG） with four different nonionic surfactants, including fatty acid methyl ester ethoxylate （FMEE）, fatty alcohol polyoxyethylene ether （AEO₉）, alkyl polyglycoside （APG08-10）, and nonylphenol polyoxyethylene ether （NP-10）. The dispersity was evaluated by sedimentation volume ratio, Zeta potential, average particle size, FT-IR and TEM. The adsorption modes for different surfactants on the surface of AG and their effects on dispersing performance were analyzed. The results showed that the best dispersion of AG system was achieved at mass fractions of FMEE, AEO₉, APG08-10 and NP-10 of 0.04%, 0.10%, 0.04% and 0.06%, respectively. The order of dispersity of surfactant-modified AG was NP-10 > AEO₉ > FMEE > APG08-10. NP-10 attracted AG particles through hydrophobic interaction and van der Waals force, with its benzene ring adsorbing vertically onto the AG particle surface via π-π stacking. The strong steric hindrance of the long polyoxyethylene （EO） chain in the liquid phase prevented adsorptive agglomeration among AG particles and thus ensured the stability of the dispersion.

Key words: SiO₂ aerogel, non-ionic surfactant, dispersion, agglomerate