Scaling Behaviour of PAMAM Dendrimers Determined by Diffusion NMR

Abstract Summary: The hydrodynamic radius of PAMAM dendrimers as a function of molar mass is investigated by diffusion NMR. As a characteristic length, the hydrodynamic radius is calculated by Stokes‐Einstein equation. Poly(amidoamine) (PAMAM) dendrimers of generations 0 to 7 of two different terminal groups (NH2, COONa) have been investigated. This dependence of the hydrodynamic radius from molar mass is compared with a scaling model and statistical model. A scaling exponent of 3.7 has been found in both cases. The scaling exponent found exceeds the dimension of the embedding space, thus the possible growth of dendrimers of this structure is limited. Hydrodynamic radius of PAMAM‐NH2 □, PAMAM‐COONa ○ as a function of molar mass. magnified image Hydrodynamic radius of PAMAM‐NH2 □, PAMAM‐COONa ○ as a function of molar mass.