Article
PFG-NMR Studies of Linear and Dendritic Polymers
Journal of Polymer and Biopolymer Physics Chemistry
(2018)
Abstract
Diffusion coefficients were measured by pulsed-field gradient NMR for low molecular weight linear polystyrenes in THF and for a broader molecular weight range of linear polystyrenes in chloroform and for PAMAM dendrimers up to generation 4 in methanol. Radii were calculated from the measured diffusion coefficients using the Stokes-Einstein relationship. The linear polystyrenes displayed a relationship between radius and molecular weight that followed the expected power law. From simple theoretical considerations, the dendritic polymers were expected to follow a logarithmic relationship between radius and molecular weight. The PAMAM dendrimers gave reasonable fits to both a power law and a logarithmic relationship from generation 0 to generation 3 (the power law gave a slightly better fit), but displayed a turnover with generation 4, which gave a smaller Stokes radius than generation 3. These results were compared with earlier results from poly (aryl ether) monodendrons, where the relationship was ambiguous between a power law and a logarithmic relationship.
Keywords
- dendrimers,
- pulsed field gradient NMR,
- diffusion coefficients,
- scaling law,
- hydrodynamic radii
Disciplines
Publication Date
2018
DOI
10.12691/jpbpc-6-1-3
Citation Information
James E. Hanson, Sibel Alkan, Hershel Lackey and Judith B. Cain. "PFG-NMR Studies of Linear and Dendritic Polymers" Journal of Polymer and Biopolymer Physics Chemistry Vol. 6 Iss. 1 (2018) p. 26 - 30 Available at: http://works.bepress.com/dr_james_hanson/25/