Towards the universal use of DOSY as a molar mass characterization tool: temperature dependence investigations and a software tool to process diffusion coefficients

Abstract

Two aspects of molar mass determination via diffusion ordered spectroscopy (DOSY) are described in this work. Firstly, we investigated in how far the temperature of measurement affects the outcome of...

Real-Time Determination of Molecular Weight: Use of MaDDOSY (Mass Determination Diffusion Ordered Spectroscopy) to Monitor the Progress of Polymerization Reactions

“…This results in the higher temperatures used in the MaDDOSY calibration no longer holding true, and as such, the calibration should be used with caution. The effects of this can be somewhat mitigated due to the viscosity correction, provided the viscosity at the given temperature is known and convection correction is accounted for . For the reaction studied here, conducted at 70 °C, the viscosity of dioxane was determined experimentally.…”

“…The measured diffusion constant can be correlated with the molecular weight of the macromolecule, and indeed, this has been shown in previous works , and further developed into a universal calibration within our groups …”

“…This viscosity of course may not be the true viscosity for the DOSY measurement, as some degree of cooling will have occurred in the tubing; however, it remains a good approximation. Further work is aiming to create a temperature-corrected calibration, and its use would be more appropriate in the future . The M wt increased linearly as a function of time, Figure , and once again, we see an agreement between the values calculated through MaDDOSY and those obtained by conventional, offline, GPC analysis, in all cases with the GPC values being within the uncertainty of the MaDDOSY values.…”

Polymer conformation determination by NMR spectroscopy: comparative diffusion ordered 1H-NMR spectroscopy of poly(2-ethyl-2-oxazoline)s and poly(ethylene glycol) in D2O

“…As a point of comparison, Silva et al have recently reported using the dstebpgp3s pulse sequence to expand the usable temperature window of the measurement. 28…”

“…21 DOSY has already been shown as excellent tool for analysing the molecular weights of polymers. 22–29 It is non-invasive and requires extremely small amounts of material. It can even be performed on benchtop spectrometers to give rapid and convenient measurements.…”