Diffusion Properties of PAMAM Dendrimers in Methanol

The diffusion properties and, as a consequence, the hydrodynamic radius, R_h, of dendrimers are of great importance for both theoretical studies and practical applications. In addition, the comparison of R_h values from simulations and experiments serves to verify the accuracy of the simulations. In this work, the translational mobility of polyamidoamine (PAMAM) dendrimers in methanol solution is investigated using molecular dynamics simulations. It is shown that the classical correction method related to the simulation cell sizes for R_h obtained from translational mobility gives underestimated values for different dendrimer generations. The approximation of the hydrodynamic radius using a linear fit to an infinitely diluted solution gives R_h close to experimental data for PAMAM dendrimers in methanol but requires simulation for multiple cell sizes. In contrast to this approach, the calculation from rotational diffusion allows R_h to be estimated using a single cell and yields values close to the experimental ones without any correction.