Thanks a lot Edward,

I am really a newbie to nanomaterails. What you said is very valuable for me and
i am going to try what you suggest.

By the way, if it is not easy to disperse tio2 nanoparticles in oil, how about
disperse tio2 in polymer soliution, like vinyl terminated polydimethylsiloxanes?
Do you have experience in this area?


Regards,

Guangmin

> From: esebesta@tx.rr.com
> To: sonic_1217@hotmail.com; mems-talk@memsnet.org
> Subject: RE: [mems-talk] Dispersion of TiO2 nanopowders in oil
> Date: Fri, 20 Nov 2009 06:14:09 -0600
>
> Surfactants are designed to suspend hydrophobic materials into water
> solutions. I am not sure that any would work well to suspend a hydrophilic
> particle into an oil. Usually soaps have an organic tail with a short
> hydrophilic end.
>
> Also, I am not sure that the surfactant would disperse in a non-aqueous
> solution.
>
> The basic problem is that TiO2 is polar and you wish to disperse them into
> non-polar liquids. This material is very finely divided and has a high
> surface area and hence a very high work function for dispersal into a
> non-polar liquid. Also, the particles in contact with each other would have
> a lower work function.
>
> You need to treat the TiO2 powder such that it has a hydrophobic non-polar
> surface. Perhaps some carboxylic acid or such so the organic molecule is
> bound to the surface with its organic tail facing outward. Or mix the TiO2
> powder in water with the surfactant and then dry it.
>
> Another approach might be to disperse the TiO2 in water and then mix the
> water with acetone or ethanol. The composition won't be 100% acetone or
> ethanol though.
>
> Finally, some shearing mixing might be of use than just relying on
> Ultrasonic mixing.
>
> Ed