A two-step silica sol-gel process investigated with static and dynamic light-scattering measurements

1989 ◽  
Vol 109 (2-3) ◽  
pp. 153-163 ◽  
Author(s):  
A.H. Boonstra ◽  
T.P.M. Meeuwsen ◽  
J.M.E. Baken ◽  
G.V.A. Aben
1994 ◽  
Vol 9 (8) ◽  
pp. 2102-2108 ◽  
Author(s):  
E. Haro-Poniatowski ◽  
R. Rodríguez-Talavera ◽  
Heredia M. de la Cruz ◽  
O. Cano-Corona ◽  
R. Arroyo-Murillo

Sols of titania were obtained by the sol-gel method and their size profile was followed by dynamical light scattering. In the early stages of the reaction an unstable behavior was detected. After this unstable regime the particle size reaches a steady state where the sols have a constant size while increasing in number. Once the sol concentration reaches its overlap value, the gelation regime takes place. For samples prepared in this way Raman spectra and x-ray diffractometry were used to characterize the kinetics of crystallization of the material.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2442 ◽  
Author(s):  
Hui Liu ◽  
Jianfeng Wang ◽  
Jiachen Wang ◽  
Suping Cui

In this study, Multiwalled carbon nanotubes (MWCNTs) were oxidized by a mixture of sulfuric acid and nitric acid (V:V = 3:1) at 70 °C for 1, 2, and 4 h, respectively. The oxidized MWCNTs were characterized by N2 adsorption, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), and Raman spectroscopy to determine the oxidation degree. The dispersion of the MWCNTs was investigated by UV-vis-NIR, SEM, and dynamic light scattering measurements. Results show that sulfonitric treatment increased the surface area and total pore volume and reduced the average pore diameter of MWCNTs. The treatment promoted the formation of oxidized species on the surface MWCNTs, as identified by FT-IR, TGA, and X-ray photoelectron spectroscopy measurements, and more oxygen-containing functional groups were generated when treatment time was extended. Moreover, a general relationship between oxidation degree and dispersibility of MWCNTs in water was established. UV-vis-NIR and dynamic light scattering measurements and SEM images revealed that MWCNTs with higher oxidation degree showed better dispersibility in water.


1991 ◽  
Vol 24 (26) ◽  
pp. 6839-6842 ◽  
Author(s):  
Liqi Fang ◽  
Wyn Brown ◽  
Cestmir Konak

Sign in / Sign up

Export Citation Format

Share Document