I am searching for a suitable preparation technique to investigate water soluble polymers using transmission electron microscopy. Any liquid contact would change the structure.
Does anyone have experience working with these kind of samples and can recommend the most suitable preparation technique?
I think Fib-lift out should work but are there other possibilities like ion thinning or is it possible to coat the TEM grid with a polymer in a suitable thickness?
Due to the water(/DMSO) used on diamond knives, ultra-thin sectioning should not be possible.
Best regards and thanks in advance
Thilo
You may want to use other than water liquid for filling a boat of a diamond knife. I had experience with propylene glycol when I needed to keep a specimen away from water. Just do not use aggressive solvents which can soften a glue used in a knife fabrication.
If nothing else works I'd imagine that plunge freezing followed by cryo-FIB thinning and cryo TEM could work... but there are not many places where you can have this done, and I supposed it'd be expensive.
Martin Schauflinger , why cryo? If the sample is dry and solid, room temperature FIB lamella milling and lift-out should be Ok. Just coat it with something conductive (e.g. 10 nm of gold using a sputter) and use a pretty low ion current to prevent bleaching. Such equipment and high-skilled operators can be found in EM facilities working for material science, but it will be definitely difficult and expensive...
I also thought of alternative solvents, but most likely any solvent in contact with the sample could have a potential impact. But it might be worth a try. How did you get rid of the propylene glycol stuck to the thin sections?
Ion Beam techniques bear the risk of sample damage, but with gentle settings i think it might be possible to thin the sample appropriately.
If nothing would work at all, i still could investigate a knife polished surface using FE-SEM.
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