Surface Modification Of Aerogels Research Articles

Hexafluoroisopropyl alcohol as a new solvent for aerogels preparation

Fluorinated alcohols are claimed to be promising solvents for supercritical drying. A number of metal oxide aerogels (both monoliths and powders) including silica, alumina and zirconia were prepared using hexafluoroisopropyl alcohol. It is shown that the specific surface area of all the aerogels dried in hexafluoroisopropyl alcohol is twice that of the aerogels prepared in ethanol. Surface modification of aerogels with fluorinated organic species is shown to take place upon supercritical drying.

Ambient pressure dried SiO 2 aerogel film on GaAs for application to interlayer dielectrics

The interfacial layer between ambient pressure dried SiO 2 aerogel film and GaAs has been examined with emphasis on varying the concentration of aerogel modification agent, trimethylchlorosilane (TMCS) in n-hexane solution. Through surface modification of aerogel, HCl was formed from the reaction between TMCS and OH bonds of silica aerogel surface, and the GaAs surface could be influenced according to the TMCS concentration in surface modifying solution. When mol concentration of TMCS is 0.066%, the GaAs interface with aerogel was roughly etched from the reflection of surface microstructure of aerogel. However, when the aerogel was modified with 0.05 mol.% of TMCS, uniform shape of the GaAs interface could be obtained and the resultant electrical property, especially leakage current density, showed almost the same behavior when the aerogel was applied to Si system.

Investigation on the interface formation of ambient-pressure-dried SiO 2 aerogel film deposited on GaAs

The interfacial state between ambient-pressure-dried aerogel and GaAs has been examined with specific emphasis on the solvent of modification. Trimethylchlorosilane (TMCS), being widely used to modify aerogel, was shown to be inadaptable due to its constitutional chlorine, which formed HCl and then etched GaAs oxides on GaAs surface. The interface of GaAs with aerogel was roughly etched from the reflection of surface microstructure of aerogel. Therefore, surface modification of aerogel with TMCS induced a great damage to interfacial GaAs surface, resulted in the change of surface characteristics of GaAs, and finally induced cracks and a collapse of aerogel fractal structure. On the contrary, hexamethyldisilazane, another modifying agent for aerogel surface, represented a relatively good interfacial state, while aerogel could be successfully formed on GaAs substrate.