Adsorption of Polyelectrolytes onto Charged Surfaces 57those used for the classical methodologies used to fabricate flat multilayers;
some methodological modifications are needed on the LbL method associated
with the specific characteristics of the template used. Figure 7 schematized the
conventional methodology used for the deposition of polyelectrolyte onto
colloidal particles; some modifications are needed when vesicles [197-199] or
emulsions [200] are used as templates.
The coating of colloidal particles requires a first step in which the first
component is mixed with the suspension of colloidal particles and after a
certain time the excess of polyelectrolyte is remove by centrifugation [201] or
ultrafiltration [202]. Afterwards, the particles are redispersed in the solvent;
the cleaning step is repeated several times to ensure that the excess of material
is removed, thus avoiding the formation of bulk interpolyelectrolyte complex
during the second adsorption cycle. Once the cleaning step is finished, the
addition of the second layer is performed, following a similar procedure to that
used for the adsorption of the first layer. The adsorption-cleaning step are
repeated several times to obtain the desired number of layers [193, 194]. Most
of the applications of multilayers onto colloidal particles are related with the
delivery of active compounds.
Reproduced from Reference [196] with permission from The Royal Society of
Chemistry.
Figure 7. Sketch of the fabrication process of LbL multilayers onto charged particles.