46 Sara Llamas, Laura Fernández-Peña, Ana Mateos-Maroto et al.
Adapted with permission from reference [22]. Copyright (2011) American Chemical
Society.
Figure 3. Dependence of the adsorbed amount of polymer (Γ) on the charge density of
the surface for JR400 and PEG. The molecular formulas of the polymers are included
inside the plot. The lines are guides for the eyes.
3.3. Nature of the Surface
The charge density of the surface is a critical parameter on the adsorption
of polymers onto solid surfaces due to the different interactions that can be
established between polymer and surface [22, 96]. It is expected that the
adsorption of polyelectrolytes onto oppositely charged surfaces occurs until
reaching the neutralization of the charge of the surface. However,
experimental and theoretical studies have showed that the adsorption occurs
until a certain degree of overcompensation of the bare surface charge occurs
[96-98]. In most of the cases, a certain overcompensation of the surface is
found [35, 61, 62, 97]. One of the most critical apects that determines the
maximum adsorption onto the surface is the local environment associated with
the presence of loops and tails [54]. In addition, it can be expected that under
specific conditions the interactions from non-electrostatic origin, e.g.,
hydrogen bond and van der Waals, can play an important role in the polymer –