Synthesis and surface chemistry study of a new amphiphilic PAMAM dendrimer

A new disk-shaped amphiphilic dendrimer has been synthesized by attaching sixty-four 12-hydroxy-dodecanoic acid chains to a fourth generation poly(amido amine) (PAMAM) dendrimer core. Surface pressure and surface potential-area isotherm measurements have shown that the dendrimer forms a stable monolayer at the air/water interface with limiting molecular area of 160 angstrom²/molecule. This small area relative to the huge size of the dendrimer suggests that the dendrimer molecules form an edge-on disk-shaped structure at the air/water interface. The topography of the dendrimer monolayer was observed by Brewster angle microscopy (BAM) at air/water interface as well as by environmental scanning electron microscopy (ESEM) as a Langmuir-Blodgett film. The striplike monolayer domains observed from BAM images correspond to the monolayer topography as observed from ESEM images.