AFM studies of monolayers of hydrophobically-modified poly(propylene imine) dendrimers.

摘要

A series of hydrophobically-modified dendrimers were prepared by using the second generation poly(propylene imine) dendrimer and fatty acid chlorides. The modified dendrimers were characterized by 1H and 13C NMR spectra. The dendrimers were also studied by Langmuir technique and AFM. Surface pressure-area isotherms and atomic force microscopy (AFM) measurements showed that the C12-fatty acid modified amphiphilic dendrimers formed stable monolayers of smooth and homogenous surface with roughness 0.5 nm. High resolution AFM images showed a tetragonal motif with spacing of between 0.4 and 0.5 nm, indicating crystalline two dimensional packing of the alkyl chains on a mica surface. The C18-fatty acid modified dendrimers formed relatively stable films and showed island structures at surface pressure of 10 mN/m, and the monolayers were collapsed at surface pressure of 25 mN/m.