Characteristics of Model Polyelectrolyte Multilayer Films Containing Laponite Clay Nanoparticles

Abstract

Polyelectrolyte films structure formed by the "layer-by-layer" (LbL) technique can be enriched by addition of charged nanoparticles like carbon nanotubes and silver or hydroxyapatite nanoparticles, which can improve properties of the polyelectrolyte films or modify their functionality. In our paper we examined the formation and properties of model polyelectrolyte multilayers containing a synthetic layered silicate, Laponite. The Laponite nanoparticles were incorporated into multilayer films, which were formed from weak, branched polycation PEI and strong polyanion PSS. Since charge of PEI is pH-dependent, we build up multilayer films in two deposition conditions: pH = 6 when PEI was strongly charged and pH = 10.5 when charge density of PEI was low. Thicknesses of the films constructed with various numbers of Laponite layers were measured by single wavelength ellipsometry. We also determined the differences in permeability for selected electroactive molecules using cyclic voltamperometry. Properties of the films containing clay nanoparticles were compared with model polyelectrolyte multilayer films PEI/PSS formed at the same conditions. We found that Laponite nanoparticles strongly influenced PEI/PSS multilayer film properties. Replacement of PSS by Laponite eliminated the oscillations of the film thickness in the case when PEI was weakly charged. PSS layer adsorbed on top of PEI/Laponite bilayers increased the thickness of multilayer films and improved their barrier properties so synergistic effects between these properties for polyelectrolytes and Laponite nanoparticles could be observed.

Transfer of electroactive agents of different molecular size through the polyelectrolyte membranes

“…3-5. The results of voltammetry experiments demonstrate that deposition of polyelectrolyte films on a gold electrode surface leads to a decrease in the current of reduction for all electroactive probes in comparison with one on the bare electrode (black curve), with the exception of NQS at the 2 and 3 layer thick films. Such phenomenon was already observed in our previous work [47] and ascribed to the accumulation of the electroactive probe molecules in the polyelectrolyte layer. One can observe correlation between the number of layers in the film, i.e.…”

Comparison of permeability of poly(allylamine hydrochloride)/and poly(diallyldimethylammonium chloride)/poly(4-styrenesulfonate) multilayer films: Linear vs. exponential growth

“…They found that, by deposition of different number of polyelectrolyte layers on an electrode it is possible to tune blocking degree of the electrode surface [45]. Similar studies of the permeability and mechanical properties of multilayers composed from polyelectrolytes and montmorillonite clay were investigated by Ball et al [46] and Elzbieciak et al [47]. The differences in permeability of linearly and exponentially growing polyelectrolyte films were discussed by Michel et al [48], but without quantifying them.…”

“…The simplicity of fabrication makes polyelectrolyte films also potent candidates as materials for photovoltaic [8] and fuel cells [9]. Since the only precondition for the formation of multilayers is the presence of charge, films can be built at any surface from variety of nanocomponents, such as: polyelectrolytes, metallic, oxide or polymer nanoparticles, delaminated clay platelets [10]. Polyion coatings have been investigated on macroscopic surfaces such as metals, silicon wafers, glass or mica as well as on colloidal size objects [11] such as latex particles, metal colloids, CaCO 3 or emulsion droplets.…”

Chitosan‐Based Nanocoatings for Hypothermic Storage of Living Cells

“…The chitosan membrane has to be semipermeable to allow transmembrane exchange of nutritions and metabolites. The CV technique is widely used for determining permeability of ultrathin films . The permeability of CCh/ACh nanocoatings was studied using two compounds, which considerably differ in sizes, undergoing cyclic redox reactions in contact with electrode surface.…”