Brownian dynamics simulations of hydrophobic dendrimer adsorption

The adsorption of an isolated hydrophobic dendrimer onto a flat surface is studied in this work using Brownian dynamics simulations. The dendrimer is modelled as a freely jointed bead-rod chain. Bead–bead and bead–surface hydrophobic interactions along with excluded-volume interactions are accounted for using a Lennard-Jones potential. Adsorption behaviour is studied as a function of the strength of hydrophobic interactions, dendrimer generation and distribution of hydrophobic groups within the dendrimer. The adsorbed dendrimer adopts a disk-like conformation by compressing in the direction normal to the surface and expanding in the direction parallel to the surface. As the strength of hydrophobicity decreases, the adsorbed dendrimer expands in the normal direction and contracts in the parallel direction. Eventually, at a very low level of hydrophobicity, the dendrimer desorbs and adopts a sphere-like conformation. Bead density profiles show that the adsorbed hydrophobic dendrimer forms a two-layer struct...