Molecular weight determination of an azobenzene-derivatized poly(amic acid) by AFM

Abstract

In this paper we report the determination of the molecular weight of a poly(amic acid) with azobenzene-chromophore side groups (azo-PAA) employing atomic force microscopy (AFM). Visualization of an ensemble of single chains of the azo-PAA adsorbed on a flat polar solid substrate allows for direct measuring the length distribution of the polymer chains and thus calculating the molecular weight distribution of azo-PAA. The obtained results agreed well with measurements of the volume of individual chains adsorbed to non-polar surfaces where the molecules adsorb in the shape of globular structures.