1Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ, USA
2Chemistry Department, Virginia Military Institute, Lexington, VA, USA
3Department of Chemistry, University of Utah, Salt Lake City UT, USA
Journal of Polymer and Biopolymer Physics Chemistry.
2018,
Vol. 6 No. 1, 26-30
DOI: 10.12691/jpbpc-6-1-3
Copyright © 2018 Science and Education PublishingCite this paper: James E. Hanson, Sibel Alkan, Hershel Lackey, Judith B. Cain. PFG-NMR Studies of Linear and Dendritic Polymers.
Journal of Polymer and Biopolymer Physics Chemistry. 2018; 6(1):26-30. doi: 10.12691/jpbpc-6-1-3.
Correspondence to: James E. Hanson, Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ, USA. Email:
james.hanson@shu.eduAbstract
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 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.
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