Hypothesis: Dispersion or aggregation of ceramic nanoparticles in suspension is mainly influenced by their surface properties. The preparation of hydrophobic/hydrophilic nanoparticles was studied by synthesizing for the first time fluorinated Janus particles via a Pickering emulsion method.
Experiments: Fluorinated silica Janus particles were synthesized with a "grafting to" method using silica/wax emulsions. The parameters investigated to control the emulsion were (i) the SiO2 particles/wax ratio, (ii) the cetyltrimethylammonium bromide (CTAB)/SiO2 ratio and (iii) the ionic strength, i.e. NaCl concentration. Prior to grafting with fluorinated molecules, the partially wax-embedded silica particles were functionalized with an aminosilane. Fourier Transformed Infrared and Nuclear Magnetic Resonance spectroscopies, thermogravimetric and zeta potential analyzes were conducted to characterize the fluorinated Janus particles.
Findings: Silica quantity has an influence on the silica nanoparticles distribution at the surface of the wax solid droplets. CTAB amount controls the size and shape of silica/wax solid droplets, whereas the ionic strength in the range 0-6.22 g L(-1) does not influence the silica/wax emulsion. Aminosilane functionalization was successfully employed on partially wax-embedded silica particles, followed by a grafting step with a carboxylic acid fluorinated compound.
Keywords: Fluorinated particles; Janus particles; Pickering emulsion; Silica particles.
Copyright © 2015 Elsevier Inc. All rights reserved.