The effect of ionic strength on electrical properties of polyelectrolyte multilayers on colloidal particles

Abstract

The effect of ionic strength on the electrical properties of poly(styrene sulfonate)/poly(allylamine) (PSS/PAH) multilayer film was investigated using electric light scattering and electrophoresis. A multilayer film was created by sequential adsorption of fully charged polymers from solutions containing 10 (- 1) M NaCl and its properties were compared to those of a PSS/PAH film prepared in the absence of salt. All measurements were carried out after rinsing the films with an aqueous solution of HCl to adjust the pH to 4.6. We found that the electrical polarizability of the film coated particles and its frequency of relaxation increase when the film was constructed in the presence of salt. The increase in the electrical polarizability value is due to the screening-enhanced adsorption. We hypothesize that the increase in the relaxation frequency of the electrical polarizability is a consequence of the adsorption of the polymer chains in more coiled conformations. This restricts the movement of small ions to shorter distances than in the film prepared without salt. In both cases, the small ions are located near the film surface, which indicates the key role of the last deposited polymer for the behavior of the entire PSS/PAH film.

Adsorption Characteristics of Lignosulfonates in Salt-Free and Salt-Added Aqueous Solutions

“…SL with different M w has a different adsorpion amount, but this difference only appears when the SL dipping solution possess a certain ionic strength. Although the layer-by-layer self-assembly mechanism and the influence of ion strength on this self-assembly have been widely investigated for linear or branched charged polymers, − the adsorption mechanism of SL on PDAC and its salt effect seem to have a different rule regarding the specific microgel structure of SL in aqueous solutions.…”

“…Actually, the effect of salt on the solution and adsorption behaviors of polyelectrolyte is very complex. − The main difficulties for understanding the solution behaviors are related to the long-range character of Coulomb interactions and to the nonlinear character of charge-screening of polyions . Here, NaCl is added into the SL polyanion to screen the Coulomb interactions.…”

Smart and green interfaces: From single bubbles/drops to industrial environmental and biomedical applications

“…Mixtures of polyelectrolyte chains and oppositely charged colloidal objects are of fundamental importance for biology and medicine and present great interest for applications in the field of water treatment, food technology, cosmetics, ceramics, etc. Recently, electro-optics was applied for studying multilayer films on non-spherical colloidal particles at high concentration of low molecular salt [4,5,6]. …”

“…In parallel, new technological issues appear (such as smart or biomimetic interfaces) that call for fundamental backing and technologies to control them. One of the reasons for the rich M A N U S C R I P T ACCEPTED MANUSCRIPT 4 literature during the last decade on analyzing applications based on first principles is the vast increase in computational power and the development of sophisticated numerical methods. These tools render possible quantitative analysis that was not accessible before.…”