SURFACE-ADSORPTION OF MODEL DENDRIMERS

Lattice model dendrimers interacting with an adsorbing planar surface are studied by computer simulation, where G is the number of generatio ns of the dendrimer and A is the interaction strength. With increasing A, dendrimers are observed to spread out and flatten down on the surf ace, as expected. In certain regions of G-A space, two competing confi gurational states, S-2 and S-3, are observed. In S-3 all three dendron s are adsorbed on the plane. In S-2 two dendrons are adsorbed, while t he third sits up and away from the surface. G-A space divides into fiv e separate regions: a desorption region where A is too weak to maintai n adsorption, a weak adsorption region in which the dendrimer tends to maintain contact but with only weak perturbation of its shape, a regi on in which S-2 and S-3 compete because they have comparable free ener gies and are separated by a modest free energy barrier, a region in wh ich S-3 dominates because it has lower free energy, and finally a regi on in which S-2 and S-3 both have high stabilities because they are se parated by a large free energy barrier. Copyright (C) 1996 Elsevier Sc ience Ltd.