The
adsorption kinetics and equilibrium of amphiphilic dendrimers
based on poly(amidoamine) modified with a dodecyl chain, G<i><sub>n</sub></i>QPAMC<sub>12</sub> (<i>n</i> represents
the generation number), with different generation numbers at a silica–water
interface have been investigated. The effect of molecular shape with
different charge characteristics on the adsorption kinetics, adsorption
isotherms, and the conformation of a self-assembled layer has been
elucidated. For the adsorption kinetics, two steps were observed including
the adsorption of individual molecules at concentrations below the
critical micelle concentration (cmc) and the predominant adsorption
of aggregates above the cmc. However, the adsorption
isotherm, as a function of the generation number, presented an exceptional
characteristic, in which a decrease in adsorption mass with different
levels occurred in a high generation of amphiphilic dendrimers, depending
on the balance of hydrophobic interaction and electrostatic repulsion.
Atomic force microscopy imaging showed that flattened films with pores
(spacing) of various shapes and roughness of 3–4 nm were formed,
of which the pores (spacing) decreased obviously as the generation
number increased. The addition of electrolyte (NaBr) has a great effect
on the film morphology formed by the G<sub>3</sub>QPAMC<sub>12</sub> dendrimer adsorbed at the silica–water interface, showing
that the film became closer with smaller pores with increased NaBr
concentration
