We have prepared oil emulsions for various applications. Because these are in nano range, optical microscopy is not enough to provide the morphological insight of these emulsions. So how should we prepare our samples for TEM, SEM or AFM imaging or which microscopy may provide us the better insight?
To observe the emulsion "as it is" the best procedure would be cryo-SEM,
Fast freezing under pressure, to freeze avoiding crystallization, freeze fracture, conductive coating, transfer to the SEM cryo stage and observation.
For that you need special equipment:
High pressure freezing instrument
cryo transfer device
cryo -fracture-coating cryo machine
Cryo stage with all its attachments in the SEM
You mean, synthesis of nano-materials by oil in water emulsion(micro emulsion method). In that case you can go through SEM when gel starts forming.And when nano-material is obtained in dry state, you can go through any technique for morphological characterization.
No, its oil emulsion which can not come in dry state. And Mr. Anmol, I want to check the morphology of my sample.
If you want to check morphology just use SEM. Dilute your emulsion with water and coat the drop onto the sample stub. Prior to imaging, a thin layer of gold sputtering should be done to prevent surface charging in the electron
Oil emulsions can be subjected directly under TEM by just spreading in its grid.To get a good image, emulsion should be of good stability .
For AFM, thin smear 1:5(oil emulsion: Milli Q water) ratio of sample in a clean glass slide and allow it to dry for 24 h(shall be extended upto 48 h based on its dryness)
For SEM, dissolve emulsion in 60% ethanol at 1:1(1 ml) ratio and gently mix it for 10 min. mix 1 ml of this sample with 1 ml of 70% ethanol and mix it for 10 min. continue this process till 100% ethanol. take the sample and thins smear it in clean glass slide.Allow it to dry under room temperature and gold sputter just before analyzing under SEM.
For the answer of Amol Ganjare, dilution of emulsion with water will not give good result for all the emulsion
To observe the emulsion "as it is" the best procedure would be cryo-SEM,
Fast freezing under pressure, to freeze avoiding crystallization, freeze fracture, conductive coating, transfer to the SEM cryo stage and observation.
For that you need special equipment:
High pressure freezing instrument
cryo transfer device
cryo -fracture-coating cryo machine
Cryo stage with all its attachments in the SEM
For most of the techniques you will not see the liquid phase unless you do a cryo tem. Since is a emulsion, probably it aggregates easier so it is better to shake before using some apparatus to disperse the oil phase as a shaker then prepare the samples with few drops, I already have done this for AFM and I could see just the oil phase since the water alredy evaporated. You can not see liquid phase in AFM, SEM and TEM. If you need more help on the preparation of the samples, let me know, regards.
Has anyone advice if cryo-SEM isn't an option please? We have a peltier cool stage and want to view an oil/water mix at ~ minus 5 degrees C
Thanks
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology