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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

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

Monnery, B.D., Jerca, V.V., Hoogenboom, R., Swift, Thomas 30 July 2024 (has links)
Yes / Diffusion ordered 1H-NMR spectroscopy (DOSY) is a useful, non-destructive technique for analysing polymer hydrodynamic size and intrinsic/solution viscosity. However, to date there has been no investigation of DOSY under variable temperature conditions that allow trends in polymer conformation to be determined. Poly(2-ethyl-2-oxazoline) (P(EtOx)) is a hydrophilic polymer that has the potential to replace poly(ethylene glycol) (PEG) in biomedical applications. Applying DOSY to a series of narrow-distribution P(EtOx) revealed that the apparent hydrodynamic radii scaled with molecular weight as expected. By altering the temperature of the solution the trends in Flory-type exponents were determined, enabling the determination of the power laws related to the coil-globule conformation of linear polymers directly from NMR data. These measurements were complicated by the onset of convection currents at higher temperatures, which impose a limit to the effective measurement range of ca. 10–35 °C. It was revealed that P(EtOx) had a more expanded random coil conformation than PEG, and it trended towards θ conditions at the lower critical solution temperature. In comparison, PEG was approximately in θ-conditions at room-temperature. This shows the use, and limitations of DOSY in polymer conformation analysis, and applies it to P(EtOx), a polymer which has not been analysed in this manner before. / University of Ghent (Grant Number: RM1602-1695)

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