KINETICS AND MULTILAYERING IN THE ADSORPTION OF POLYELECTROLYTES TO ACHARGED SURFACE

The kinetics of radiolabeled poly(styrene sulfonate) adsorbing at a po sitively-charged surface were determined using a surface-charged plast ic scintillator as substrate. In situ measurements indicate diffusion- limited adsorption with the final adsorbance dependent on the solution concentration of polyelectrolyte. An absence of self-exchange of unla beled for labeled polymer suggests a thermodynamically irreversible pr ocess, at least for highly-charged polymers on highly-charged surfaces in the weak screening limit. Charge compensation of sulfonate was det ermined by displacement of labeled calcium (Ca-45(2+)) probe ions. Com pensation is complete for surface sites and only partial for interior sulfonates. The use of radiometric techniques facilitates studies of p olyelectrolyte multilayer formation.