I have polymeric nanoparticles with a hydrophobic core and a water soluble corona, in the TEM images I see defined spheres but they are almost embedded in a continuous film/membrane. Do interparticle brush interactions dry as films?
All will depend on your typeand clealiness of yoru solvent, the type of support you use for imaging and the observation mode you use (TEM BF, TEM DF, STEM ADF or STEM HA-ADF) so you really need to be more specific.
If it is core shell nanoparticles you will have a well defined core with distinct shell visible in high resolution images obtained by HRSEM or HRTEM. However, how meticulously the synthetic process is followed so as to obtained well defined growth of the nanoparticles.
I disagree, Shrikaant: this may be the case only if the support is perfectly even and flat and/or if the material in the core is much heavier than the material in the shell. If polymer particles are small and dispersed onto a holey carbon film, or if both core and shell are different organic carbon or carbohydrate modifications, there often is little contrast in HREM even though the resolution is near-atomic.
If I understood you correctly, you have to prove a corona (and not a dense layer/shell) on a core. But if densities of the both polymers are close it is difficult to resolve these components on TEM images. You can try a known technique of staining the samples with e.g. phosphotungstic acid prior to placing onto the TEM grids.
Thomas Walther my nanoparticles were in water and vacuum dried (not freeze dried) onto a grid and used TEM BF.
Alexander Pud you are right, I have a corona and not a dense layer/shell. I am not aware of the brush density and want to see how dense the corona is really. My cores are crosslinked, but since the core polymer is a different one than the corona it is hard to know what the density of the core would be with the crosslinking. I do see a defined black core, the problem I am facing is that my corona doesn't appear as a crinkly outer layer, I see a blanket film in which I see the black spots (cores or perhaps core and a shrunken corona?). I see a size change from the cores on DLS, with almost identical PDI but unable to see the structure of these grown particles. I will look into staining. Thank you very much for your response and recommendation
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