Solvent‐Independent Molecular Weight Determination of Polymers Based on a Truly Universal Calibration

Abstract

Diffusion-ordered NMR spectroscopy (DOSY) allows for accurate molecular weight calibration and determination that can be corrected for solvent influences. Polystyrene and poly(ethylene glycol) standards have been used to calibrate DOSY diffusion data for a variety of solvents, showing a high correlation of data when the bulk viscosity of the solvent is accounted for following the Stokes-Einstein equation. In this way, a type of universal calibration is introduced that allows for determinations of average molecular weight that are at least as accurate as those of traditional size-exclusion chromatography (SEC), if not better. Further, we demonstrate that DOSY calibrations can be used between laboratories, hence removing the need for individual calibration of setups as currently done.

Responsive polyprodrug for anticancer nanocarriers

“…S3, ESI †) were observed at 2.92, 4.15, 3.00, and 4.32 ppm, respectively. The weight-average molecular weight of the polymer was evaluated by diffusion-ordered spectroscopy nuclear magnetic resonance (DOSY-NMR spectroscopy) to be ∼10 300 g mol −1 , according to technique recently reported by Junkers and coworkers 62 and with poly(ethylene glycol) as standard in DMSO-d 6 (Fig. S4, ESI †).…”

A fast and efficient way of obtaining the average molecular weight of block copolymers via DOSY

“…Furthermore, we have shown that even if standard calibration is applied to a very different type of polymer, a reasonable molecular weight estimate is obtained with an accuracy that at the very least rivals that of standard universal calibration SEC. 7 Most importantly, however, we have demonstrated that DOSY calibration is truly universal in the sense that no individual calibration of instruments is required. One calibration obtained in one lab is in principle applicable worldwide in a very broad molecular weight range from oligomers to millions of Da.…”

“…4–6 Diffusion-ordered spectroscopy (DOSY) has emerged as a promising technique for determining the molecular weight of polymers. 7,8 Based on many previous studies, we have demonstrated that DOSY is an accurate method for assessing the average molecular weights of polymers, competing favourably with standard SEC. Furthermore, we have shown that even if standard calibration is applied to a very different type of polymer, a reasonable molecular weight estimate is obtained with an accuracy that at the very least rivals that of standard universal calibration SEC.…”

“…A detailed description of DOSY and a practical guide to performing DOSY for molecular weight determination are given in our previous work. 7 Yet, so far, we only discussed the application of DOSY to linear homopolymers. Due to the rise of techniques such as controlled polymerization methods, polymer chemists have nowadays gained access to complex polymers in an abundant and easily accessible way.…”

On the Precise Determination of Molar Mass and Dispersity in Controlled Chain-Growth Polymerization: A Distribution Function-Based Strategy

“…Various methods have been developed to determine the molar mass such as size exclusion chromatography (SEC), , viscometry, and diffusion ordered nuclear magnetic resonance spectroscopy, − among which SEC is the most prominent technique at present . Generally, the SEC system is equipped with a concentration-sensitive refractive index detector (SEC-RI).…”