Adsorption of Polyelectrolytes onto Charged Surfaces 63leads to the increase of the area available for the deposition of polyelectrolyte
chains in the successive deposition cycles and consequently the adsorbed
amount can increase with N [217]. Therefore, the differences on the growth
mechanism can be mainly explained on the bases of the specific conformation
of the polymer chains [26, 31, 217].
The mechanism considering the interdiffusion as the main driving force
for the appearance of the non-linear growth is based on the existence of a
Donnan potential along the polymer matrix that is associated with the excess
of charge due to the adsorption of the layers. This allows the interdiffusion of
at least one of the polyelectrolyte forming the multilayer until the equilibration
of the aforementioned potential happens [218, 219]. Thus, the potential
can lead to an increase of the adsorbed amount on the successive deposition
cycles, leading to the supra-linear growth. Figure 12 illustrates the
interdiffusion phenomenom.
Reprinted with permission from Reference [219]. Copyright (2004) American
Chemical Society.
Figure 12. Cartoon representing the the interdiffusion phenomena during the LbL self
assembly of non-linear growth multilayers.