Height and Width of Adsorbed Dendronized Polymers: Electron and Atomic Force Microscopy of Homologous Series

Abstract

The width, w, and height, h, of dendronized polymers (DPs) adsorbed onto mica and highly oriented pyrolitic graphite (HOPG) were characterized by atomic force microscopy (AFM) and electron microscopy (EM). The study utilized a homologous series of generations g = 1–5, hence enabling coadsorption and characterization under identical conditions and thus facilitating comparison. The w and h values, as acquired by AFM and EM on HOPG and mica are comparable and can be collapsed onto a single master curve by a constant horizontal shift of each set of points. This master curve exhibits the scaling behavior of a cylinder and supports the visual impression that DPs adsorb as weakly deformed cylinders. The h and w curves suggest a dendron density of ρ ≃ 1.35 to 1.45 g/cm 3 . Density measurements of solutions of the “attached-to monomer” suggest ρ ≃ 1.10 g/cm 3 . The corresponding estimates of the maximal generation of structurally perfect DP for this family is g max = 6 to 7 and close to the currently explored range of g = 1–5.