I read papers calculating based on weigh loss difference by TGA before and after surface modification. However, I found another paper (doi:10.1016/j.eurpolymj.2006.10.021) can calculate based on TGA only after surface modification. In this case they require few more values such as density and the radius of the nanoparticle.
[The equation is also given as the Image]
No of molecules per nm2 = [Weight loss * density of NP * radius of NP * 6.022^23] / [Molecular weight of surfactant (1-Weight loss) * 3*10^21]
Given that
Weight loss = 32.7 %
density of MNP = 5.1 g/ml
nanoparticle size (probably diameter)= 9 nm
Molecular weight of surfactant = 282.47 g/mol
The result they showed is 6.3 molcules per nm2
Is it true?
Dear Abu,
Ligand densities on NC surfaces typically fall in the range of a couple of ligands per nm2 surface (roughly 3 on average). While the order of magnitude of your calculation seems correct, 6.3 ligands/nm2 is likely an overestimation of the actual number (TGA will show both bound and free ligands). If your dispersions are stable, you could verify your results through quantitative NMR.
https://pubs.acs.org/doi/full/10.1021/cm303361s?casa_token=pFkOBa3iOBUAAAAA%3AUdmBkCTklEs1HjXyMi8T0drs4JAF_-8kjUPLkilsLXoIp-wr37NwqAcanrYOurBglIZ3-2DAB1L4aeU8iQ
Dear Pieter Schiettecatte ,
Thank you very much for your valuable comment with another possible way to calculate bound molecules. My nanoparticle is also QD, so its useful. Did you see the equation? I put the values on that paper. But, I cant not match to the final value 6.3 with the given values.
Kind regards!
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