Increased amine surface density of an aminosilylated molecular layer through hyperbranching

Abstract

An aminosilylated substrate was treated with aziridine to prepare hyperbranched polymers on solid supports. It is observed that the primary amine on the substrate is able to initiate the ring-opening polymerization of aziridine. Measuring the thickness of the film and absolute density of the primary amine functionality shows that a very highly branched poly(ethyleneimine) is formed since the primary amine functional group on the very top surface increased dramatically from 3.6 amines/nm(2) to 66-78 amines/nm(2). Atomic force microcopy shows that the polymerization is rather regular laterally and that the morphology of surface has not changed significantly after the polymerization.