Analysis of Dimer Impurity in Polyamidoamine Dendrimer Solutions by Small-angle Neutron Scattering

Dimer impurity in the solution of a generation five (G5) polyamidoamine (PAMAM) dendrimer has been investigated by small-angle neutron scattering (SANS). The existence of dimer impurity in dendrimer solution was evidenced by indirect Fourier transform (IFT) analysis of the SANS data, in which the maximum dimension of particles in solution was found to be about twice the diameter of G5 dendrimer. We then developed an analytical model which accounts for the scattering contribution from both dendrimer monomer and dimer. The experimental data were well fitted by using the established model. The results showed that the amount of dimer impurities is significant for the measured three batches of G5 PAMAM dendrimers.