Abstract
Sequential adsorption of polyelectrolytes on nanoparticles is a popular method to obtain thin films after deposition. However, the effect of polyelectrolyte multilayer formation on the colloidal stability of the nanoparticles has not been studied in detail. In the present work, layered double hydroxides (LDH) were synthesized and interaction with oppositely and like-charged polyelectrolytes was investigated. Electrophoretic and light scattering measurements revealed that colloidal stability of LDH can be tuned by adsorption of poly(styrene sulfonate) (PSS) on the oppositely charged LDH surface in appropriate doses and thus, unstable or stable dispersions can be designed. Negatively charged LDH of adsorbed PSS monolayer was obtained and a poly(diallyldimethyl ammonium chloride) (PDADMAC) second layer was systematically built on the particles. The obtained polyelectrolyte bilayer provided high colloidal stability for the LDH-PSS-PDADMAC dispersions due to the presence of repulsive interparticle forces of electrostatic and steric origin. The results provide crucial quantitative information on designing highly stable particle-polyelectrolyte systems for the preparation of thin films or immobilization of guest substances between the layers for delivery processes.
Highlights
Self-assembled multilayers have been in the focus of many research groups due to their widespread applications in electrochemical devices, sensors, membranes, smart coatings and biotechnological procedures [1]
The sheet-like layered double hydroxides (LDH) particles composed of magnesium(II) and aluminium(III) layer forming metal ions and chloride intercalated anions were prepared by the flash co-precipitation method followed by hydrothermal treatment to narrow the particle size distribution
The present study reports a systematic assessment of the colloidal stability of positively charged LDH particles in the presence of poly(styrene sulfonate) (PSS) and poly(diallyldimethyl ammonium chloride) (PDADMAC) polyelectrolytes of negative and positive charges, respectively
Summary
Self-assembled multilayers have been in the focus of many research groups due to their widespread applications in electrochemical devices, sensors, membranes, smart coatings and biotechnological procedures [1]. Different substrates were applied as base for the multilayer formation including both planar surfaces [10] and colloidal particles [11]. In the latter case, once polyelectrolytes are applied as building blocks, the choice of the appropriate dose is critical, since polyelectrolyte adsorption on oppositely charged particles may lead to charge neutralization and unstable particle dispersions containing large aggregates, which are insufficient for further applications [12,13,14]. LDH films were prepared in a hydrothermal process and modified with PSS to achieve higher drug loading ability [31]. An LDH-PSS-based nanocontainer was synthesized to deliver corrosion inhibitors, which were either embedded in the polyelectrolyte layer or intercalated within the interlayer space of LDH [32]
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