Preparation of monodisperse silica spheres and determination of their densification behaviour

Abstract

Monodisperse silica spheres in the 50-520 nm size range were prepared by using the Stober process. Diffusive growth has been determined from Nielsen chronomal analysis for the 520 and 310 nm monodisperse silica spheres. The densification behaviour and evolution of the microstructure of the sphere compacts indicated an inverse dependence of shrinkage rate on the sphere size due to viscous sintering. The increase in sphere size from 50 to 500 nm shifted the densification temperature from $ 1120 1C to 1240 1C. The amorphous nature of the spheres was conserved up to 1200 1C where cristobalite crystal nucleation started and complete transformation to cristobalite phase has been observed upon heat treatment at 1300 1C. The activation energies for viscous sintering according to the Frenkel and Mackenzie/Shuttleworth models were calculated as 125 and 335 kJ/mol, respectively. These substantially low activation energies can be attributed to the presence of a significant level of silanol groups.

Improvement of Water Resistance of Hemp Woody Substrates through Deposition of Functionalized Silica Hydrophobic Coating, While Retaining Excellent Moisture Buffering Properties

“…After, this, the Z-average value plateaued at this value without further major fluctuation (in the range of an uncertainty of 3 nm due to the measuring technique). This phenomenon concurs with the findings of Topuz et al (2015), although they analysed particles of greater diameters (310 nm and 520 nm), and with Bogush and Zukoski IV (1991) for 390 nm, 410 nm, and 550 nm particles. The similarity for different sizes of particles would suggest that this model is valid across a range of size.…”

Kinetics of Alkoxysilanes and Organoalkoxysilanes Polymerization: A Review

“…In addition to the previous techniques, many other instruments, such as XPS [45,47], small angel X-ray spectroscopy (SAXS) [42], calorimetry [30,40], conductivity [2,36,43,50], colorimetry [32,33,40], transmission electron microscopy (TEM) [43,51], atomic absorption spectrometry (AAS) [43], titration [51], micro-pycnometry [51], ICP-AES [33], and dynamic light scattering (DLS) [95,96], were used to investigate the polymerization kinetics of silanes and its products. Lindberg’s group introduced a new method to follow the hydrolysis and condensation of octyl triethoxysialne over the surface of a water droplet in an octane solvent by surface tension [25].…”

Silica Nanoparticles as a Potential Carrier for Doxycycline Hyclate

“…As mentioned before, there is a variety fit as the shape and size of the silica nanoparticles created. This variety is identified with the difference in the nucleation and growth rate of the produced silica nanoparticles with each technique of preparation utilized [24]. Concerning, particles size growth is influenced by the rate of hydrolysis and buildup response brought about by the concentration of hydroxyl gathering.…”