Properties of single dendrimer molecules studied by atomic force microscopy

Well-separated, individual polyphenylene dendrimer molecules have been prep ared by spin coating on a mica surface, and subsequently imaged by nonconta ct atomic force microscopy (NCAFM). The observed height is in good agreemen t with the size of a single dendrimer molecule, as calculated by molecular dynamics simulation. By using pulsed force mode (PFM) AFM, stiffness and ad hesion properties of individual polyphenylene dendrimers have been studied. They could be related to the molecular structure and the chemical nature o f the outer surface of the dendrimers and the thin film of water adsorbed o n mica when imaged under ambient conditions. Finally, by changing the conce ntration of the spin-coating solution, two different kinds of aggregates ha ve been characterized.