a) b - École Polytechnique de Montréal

A relationship between macropore sizes and mass deposition of layers is found. Approximate
average macropore sizes for samples A, B, C and D after annealing are 300μm, 500μm, 100μm,
and 150μm respectively (see Figure 5-5). Figure 5-7 represents the maximum mass deposition
for each sample: sample A attains 1.6% after deposition of 31 PSS/PANI layers and 0.82% after
deposition of 32 layers. Sample (B) attains 2% and 1.16% after deposition of 31 and 32 layers.
Samples C and D attain about 0.8% for 31 layers and 0.5% for 32 layers. These results confirm
that larger pore sizes facilitates the penetration of solution and thicker layers constructs
5.1.1. Diffuse Network Structure of PSS/PANI
Lavalle et al.(Lavalle, et al., 2002), using molecular labeling, observed a diffusion of a portion of
polyelectrolytes in and out of the film in a nonlinear manner leading to exponential growth. This
was observed when one of the polyelectrolytes used was weak as in the current work with PANI.
Schlenoff et al.(Dubas & Schlenoff, 2001b; Schlenoff & Dubas, 2001) have reported that the
surface charge, propagated and inverted by sequential adsorption steps, is overneutralized
(overcompensated) at each step. In that work, the multilayer/solution interface, the charge of the
last-added polymer compensates the previous one by a factor φ. The opposite polymer charges
are in exact stoichiometric ratio for φ=1 yielding a steady-state thickness increment vs layer
number. The overcompensation factor, phi, can be defined for multilayers when the charge factor
has a value higher than 1. Overcompensation leads to excess charge density from the last-added
polyelectrolyte, but only at the surface is φ “unrestricted” by bulk effects. At increasing length, l,
from the interface into the multilayer, the level of overcompensation decreases in an exponential
fashion demonstrating an overcompensation gradient(Schlenoff & Dubas, 2001).
The diffusion of a portion of polyelectrolytes in and out of the film in a nonlinear manner leading
to exponential growth was proposed as a model for overcompensation(Lavalle, et al., 2002). In
this mechanism, the first population was constituted of chains directly interacting with the
surface of the multilayer, which are responsible for linearly growing films. The second
population was constituted of free chains that diffuse into the multilayer over its whole surface
and are responsible for exponential growth. In this study, when a substrate is brought into contact
with a charged PSS solution, many free PSS chains paired with hydrated counter-ions in the
solution diffuse throughout the film in the x, y, and z directions due to electrostatic interactions.
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