Natural Science Forum / Physics / Optics / November 2004

Hi Martina,

I would suggest cryoultramicrotomy as a good way to approach the problem.  This
way, you could observe the nanocomposite material in a "close-to-native" state.

I've used this technique to visualize silica-rubber nanocomposites, and it
works quite well.

The technique requires an ultramicrotome that's equipped with a cryosectioning
system.  It works very similar to regular frozen sectioning, except the
temperatures are much lower (down to about -186 degrees C if necessary) and the
sections are thin enough (60-100 nm) so that you can mount them on a grid and
observe them in the TEM.

Some trial-and-error would be needed to identify the proper sectioning
temperature for the resin, and the sections may tend to collapse on the grid
after they're brought to room temperature, but there are some things you can do
minimize these problems.

Please contact me off-list if you would like additional information.  I can
recommend some people to talk to.

Good luck and best regards,

Robert (Bob) Chiovetti, Ph.D.
<rchiovetti@aol.com>

Hi,
The idea about cryo electron microscopy sounds like a good one. It
depends what you want to find out about the resin...
You COULD try AFM. You don't get sample heating with this. I would
suggest tapping/noncontact mode, but if your expoy resin is already
quite tacky before cure, it's likely even in this mode the probe will
stick to your sample. It MIGHT work though, if the sample is not too
sticky. It is possible to see some very soft polymer surfaces(even
liquids) with great care. IF you can get a cryo electron microscope,
that'd be best, though.
Pete.