In characterization of the samples with GPC, is it possible to determine the molecular weight of dendrimer samples with GPC columns calibrated with PS samples (If the columns were calibrated with PS samples with low PDI values.)?
. Calculation of molecular weight of the non-linear dendrimers with GPC columns calibrated with linear PS samples seems to be somewhat strange.
Dear Tanveer Shah, this chapter reviews properties of dendrimers including the MW weight determination by GPC compared to a known polymer MW. My Regards
https://doi.org/10.1016/B978-0-12-816504-1.00004-1
Thank you so much bro... i will go through this...actually this is not my field of expertise.. i would be glad if you can share your views about this question specifically...thanks
Linear PS samples aren't the best standards for dendrimers, but if they are all you have..... If you have access to a light scattering detector you don't have to worry about calibration.
You can also use some other techniques to get the MW. Here is a paper where we compared linear and dendritic polymers by diffusion NMR.
- DOI: 10.12691/jpbpc-6-1-3
Article PFG-NMR Studies of Linear and Dendritic Polymers
James E Hanson ,Thank you so much for very convincing answer. i really appreciate your time.. i would be very grateful if you can elaborate your answer specifically about some experimental correctness which we can make for linear PS standards to estimate the molecular weight. thanks in advance
Hawker compared equivalent linear and dendritic polymer.
J. Am. Chem. Soc. 1997, 119, 9903-9904
What you can see is that the hydrodynamic radius of linear polymers follows a predictable power law function with MW or polymerization number N: R = N^0.57 This radius then impacts the GPC retention time - smaller radius = longer retention time.
The hydrodynamic radius of dendritic structures is less predictable - it can be modelled with either a power law or logarithmic law, depending on structure and solvent.
Since you don't know how the radius of the dendritic structure will scale with MW, it is hard to give a standard answer on how you can calibrate GPC columns with linear structures.
James E Hanson , Thank you so much, indeed it is a great help...i really appreciate your valuable time.
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