eng Science and Education Publishing Journal of Polymer and Biopolymer Physics Chemistry 2373-3411 2018-10-10 6 1 26 30 10.12691/jpbpc-6-1-3 JPBPC2018613 article James E. Hanson james.hanson@shu.edu 1 Sibel Alkan 1 Hershel Lackey 2 3 Judith B. Cain 3 Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ, USA Chemistry Department, Virginia Military Institute, Lexington, VA, USA 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. http://pubs.sciepub.com/jpbpc/6/1/3/jpbpc-6-1-3.pdf dendrimers pulsed field gradient NMR diffusion coefficients scaling law hydrodynamic radii