56 Sara Llamas, Laura Fernández-Peña, Ana Mateos-Maroto et al.
ab
Adapted from Referenvce [183] with permission from The Royal Society of
Chemistry.
Figure 6. Sketch of the alternative methodologies to the dipping for the fabrication of
PEMs onto macroscopic substrates. (a) Spin-Assisted Assembly. (b) Spray-Assisted
Assembly.
The spray-assisted deposition of LbL multilayers is based in the alternate
spraying of oppositely charged polyelectrolytes onto the substrate, including
intermediate rinsing steps [192]. The compositional, morphological and
chemical uniformity of the films obtained by spraying is better than those
obtained by the dipping [192]. During the spraying of the layer a simultaneous
adsorption and drainage of the liquid occurs, being the spraying generally
performed in a perpendicular direction to the surface, thus the draining of the
solution by gravity is favoured and consequently the excess of polyelectrolyte
solution is quickly removed. The control of the characteristics of the polymer
solution and the spraying conditions is critical for the accurate fabrication of
films following this methodology [184, 185].
The above discussion has been referred so far to the fabrication of
polyelectrolyte multilayers onto macroscopic flat substrates. However, most
of the recent applications of the LbL method are based on the deposition
of polyelectrolyte multilayers onto colloidal templates including colloidal
particles, liposomes/vesicles or emulsions [193-196]. Despite the physico-
chemical bases governing the deposition onto these templates are similar to