Synthesis and surface chemistry study of a new amphiphilic PAMAM dendrimer

A new disk-shaped amphiphilic dendrimer has been synthesized by attaching s ixty-four 12-hydroxydodecanoic acid chains to a fourth generation poly(amid o amine) (PAMAM) dendrimer core. Surface pressure and surface potential-are a isotherm measurements have shown that the dendrimer forms a stable monola yer at the air/water interface with limiting molecular area of 160 Angstrom (2)/molecule. This small area relative to the huge size of the dendrimer su ggests that the dendrimer molecules form an edge-on disk-shaped structure a t the air/water interface. The topography of the dendrimer monolayer was ob served by Brewster angle microscopy (BAM) at air/water interface as well as by environmental scanning electron microscopy (ESEM) as a Langmuir-Blodget t film. The striplike monolayer domains observed from BAM images correspond to the monolayer topography as observed from ESEM images.