J. Engelking et H. Menzel, Adsorption of anionic polyelectrolytes to dioctadecyldimethylammonium bromide monolayers, EUR PHY J E, 5(1), 2001, pp. 87-96
Monolayers of dioctadecyldimethylammonium bromide (DODA) at the air/water i
nterface were used as model for charged surfaces to study the adsorption of
anionic polyelectrolytes. After spreading on a pure water surface the mono
layers were compressed and subsequently transferred onto a polyelectrolyte
solution employing the Fromherz technique. The polyelectrolyte adsorption w
as monitored by recording the changes in surface pressure at constant area.
For poly(styrene sulfonate) and carboxymethylcellulose the plot of the sur
face pressure as function of time gave curves which indicate a direct corre
lation between the adsorbed amount and surface pressure as well as a solely
diffusion controlled process. In the case of rigid rod-like poly(p-phenyle
ne sulfonate)s the situation is more complicated. Plotting the surface pres
sure as function of time results in a curve with sigmoidal shape, character
ized by an induction period. the induction period can be explained by a dom
ain formation, which can be treated like a crystallization process. Employi
ng the Avrami expression developed for polymer crystallization, the change
in the surface pressure upon adsorption of rigid rod-like poly(p-phenylene
sulfonate)s can be described.