Abstract
The structural properties of generation 4 (G4) poly(amidoamine) starburst dendrimers
(PAMAM) with an ethylenediamine ne (EDA) central core in D O 2 solutions have been studied by small
angle neutron scattering. Upon the addition of DCl , SANS patterns show a pronounced inter-particle
2
correlation peaks due to the strong repulsion introduced by the protonation of the amino groups of the
dendrimers. By solving the Ornstein-Zernike integral equation (OZ) with hypernetted chain closure
(HNC), the dendrimer-dendrimer er structure factor S(Q) is determined and used to fit the experimental
data. Quantitative information such as the effective charge per dendrimer and its conformational change
at different conditions can be obtained. The results obtained show clear evidence that significant
counterion association occurs, strongly mediating the inter-dendrimer interaction. The influence of
interplay between counterions and molecular protonation of dendrimers has strong effect on the
dendrimer conformation and effective interaction.
