Molecular weight of PEG using NMR?

23 June 2023 1 1K Report

How can we detect the molecular weight of PEG in NMR? Is it possible to detect the number of monomers in that?

Thanks

it depends on the MW. If you can see the resonances of terminal units ( usually in polymers they have a slightly different Chemical shift) you can try to make the calculation of MW from the ratio of their integral with respect to that of the CH2 units of the polymer , Otherwise a DOSY 2D experiment may give an estimate of the molecular Diffusion from which you can derive the MW by the Stokers Einstein equation.

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