Non-agglomerated dry silica nanoparticles

• Published in: Powder technology 2004-02, Vol.140 (1), p.40-48
• Main Authors: Mueller, Roger, Kammler, Hendrik K., Pratsinis, Sotiris E., Vital, Andri, Beaucage, Gregory, Burtscher, Peter
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; Chemical engineering; Degree of agglomeration; Exact sciences and technology; Flame aerosol reactor; Miscellaneous; Nanocomposites; Reactors; Sintering, pelletization, granulation; Solid-solid systems
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2004.01.004

Silica nanoparticles for polymer nanocomposites are made by oxidation of hexamethyldisiloxane (HMDSO) in methane/oxygen diffusion flames. The flame temperature is measured by in-situ Fourier transform infrared (FTIR) spectroscopy while the degree of agglomeration of the product powder is quantitatively determined by ultra small angle X-ray scattering (USAXS) and is confirmed by transmission electron microscopy (TEM). Precisely controlled, non-agglomerated silica particles having an average primary particle diameter of 18–85 nm, as determined by N 2 adsorption and TEM, are made at low silica production rates of 9 g/h or at low O 2 flow rates at silica production rates of 17 g/h, while smaller and highly agglomerated particles are made at high O 2 flow rates at silica production rates of 17 g/h. The differences in morphology result from the completion of gas-to-particle conversion and from the onset of steep cooling in the flames that determines the duration of full coalescence. Nanocomposites with dimethylacrylate polymers are made using non-agglomerated silica particles and compared to the ones made with commercially available silicas.