This is not really my area so I may be totally wrong here but I always
thought the hydrophilicity of SiO2 was down to silanol groups on the
surface. At high temperatures I thought the surface becomes dehydrated to
form pure SiO which is naturally hydrophobic (I think?). Keeping it stable
over time may just be a matter of heating it back up again or keeping it in
a dry atmosphere.


On Tue, Nov 17, 2009 at 10:06, Miyakawa, Natsuki
wrote:

> Dear all,
>
> Does anyone of you know some methods to turn the surface of thermally
> oxidized Si hydrophobic (say contact angle > 70°)? The hydrophobisity should
> be long-term stable (> years @ room temperature), thermally stable (> 1h @
> 800-900°C), and chemically stable (esp. under alkaline conditions).
>
>
> Thank you!
>
> Natsuki