We are studying organic micelles suspended in water or diesel and want to get images of them to see what they look like (an actual image, rather than size characteristics from something like a DLS). At a minimum, we want to see the micelles after formation, but it would be nice to observe their formation as well. Unfortunately, they are very susceptible to temperature changes so any low-temperature applications likely won't work. I know TEM is an option for this. Is anyone aware of any other options?
Zach Haber
The concentration and approximate size is really important. It's also very important if your continuous phase is water or diesel. These are totally different and need totally different approaches.
TEM via freeze-fracture isn't likely to work, IMHO. I'd look at cryo-EM - the freezing is so rapid that structural changes are not likely to happen. One thing worth considering is improving the contrast with an appropriately soluble dye. For water in diesel I may try a 1% methylene blue in alcohol and add a few drops to say 500 mL of the diesel.
Hi Zach Haber, I would give cryo-TEM a go, especially for the micelles in water this should work. Most plungers allow you to control the temperature before plunging and as Alan F Rawle mentions, the freezing is really fast, so you may capture the micelles before temperature changes become an issue. Comparison with DLS will allow you to control if any changes in size have occured. I have never tried cryo-TEM with diesel, but you could try it. It is fine with some organic solvents, but unfortunately not with all.
Zach Haber
If you mean surfactant micelles, then they are formed in water through hydrophobic interaction (combined by the intermolecular interaction of water with each other). In hydrocarbon solvents through the dipole-dipole interaction of hydrophilic groups. Temperature greatly affects hydrophobic interaction and crystallization; therefore, it is not correct to study cryoTEM. Better to use SAXS or SANS methods. DLS method gives original results. For comparison, see the article
Article Structure of Micelles of Sodium Dodecyl Sulphate in Water: a...
The question states 'want to get images of them to see what they look like (an actual image, rather than size characteristics from something like a DLS)'... I've not seen pictures (just graphic plots and tables) from DLS or SAXS.
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