Assembly Of Polyelectrolyte Multilayers Research Articles

Layer-by-Layer Assembly of Polyelectrolyte Multilayers on Thermoresponsive P(NiPAM-co-MAA) Microgel: Effect of Ionic Strength and Molecular Weight

The layer-by-layer assembly of polyelectrolyte multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium styrenesulfonate) (PSS) on soft and porous thermoresponsive poly(N-isopropylacrylamide-co-methacrylic acid) (P(NiPAM-co-MAA)) microgel was studied by dynamic light scattering and electrophoretic measurements. Polyelectrolyte multilayers were prepared from solutions of polyelectrolytes in different salt concentrations of sodium chloride and from polycations of different molecular weights in order to analyze the influence of the ionic strength and the polyelectrolyte chain length, respectively, on the properties of the polyelectrolyte-coated microgels. We show that the latter retain their thermoresponsive property and that the swelling and deswelling processes are nearly reversible. There is an “odd−even” effect of the hydrodynamic radius of the coated microgel depending on the type of polyelectrolytes in the outermost layer: PSS-terminated microgels are more swollen and more temperature-sensitive than PDADMAC-terminated microgels. Upon assembly of a strong polyelectrolyte shell around the pH-responsive microgel core, the ensemble is no longer pH-responsive. The core−shell microgel shows a clear increase of the size with increasing salt concentration from which the layer (shell) is being deposited, although no strong dependence of the size on the polycation molecular weight has been found. The electrophoretic mobility results reveal charge reversal after each layer deposition and the magnitude of which decreases with increasing number of layers as well as with increasing salt concentration in the depositing polyelectrolyte solutions.

Hydrophobic surfaces of spin-assisted layer-by-layer assembled polyelectrolyte multilayers doped with copper nanoparticles and modified by fluoroalkylsilane

Polyelectrolyte multilayers (PEMs) fabricated by spin-assisted layer-by-layer assembly technique were used as nanoreactors for in situ synthesis of Cu nanoparticles, allowing generation of Cu nanoparticles doped composite, denoted as Cu-nanoparticles PEMs. Thus chemical reaction within the PEMs was initiated by a series of reaction cycles in which Cu 2+ was absorbed into the polymer-coated silicon substrate and reduced in NaBH 4 solution. The surface of Cu-nanoparticles PEMs was modified by heptadecafluorodecyl-trimethoxysilane (FAS-17) with low surface energy, generating a hydrophobic film. The adhesion and nano-friction behavior of the hydrophobic film was investigated using an atomic force microscope, while its macro-tribological behavior sliding against stainless steel under dry- and distilled-water-lubricated conditions was investigated using a UMT-2 test rig. It was found that Cu-nanoparticles PEMs modified with FAS-17 has a lower friction and higher adhesion than that without modification. Moreover, the hydrophobic film possesses lower friction coefficient under water-lubrication and higher friction coefficient under dry-sliding than the hydrophilic film under the same conditions, which could be mainly due to the difference in the surface energy. The titled hydrophobic films with low adhesion and friction would have potential application in micro/nano-electro-mechanical systems.

Amine-Rich Polyelectrolyte Multilayer Nanoreactors for in Situ Gold Nanoparticle Synthesis

In situ synthesis of inorganic clusters in polyelectrolyte multilayers (PEMs) has typically relied on free carboxylic acid groups as the binding sites, limiting the scheme to the loading of cationic precursor reagents. The use of amine groups for similar purposes has not been demonstrated because of the challenge of incorporating free amine groups that are not paired with the oppositely charged groups residing on the polyanion of the PEM. In this paper, we use specific PEM assembly conditions to produce ultrathin conformal films of PAH/PAA (poly(allylamine hydrochloride)/poly(acrylic acid)) and PAH/PSS (poly(styrene sulfonate)) that upon suitable postassembly treatment undergo substantial molecular rearrangements that generate free amine groups in the films. These PEMs are capable of binding anionic precursors including complexes widely used for the synthesis of gold nanoparticles. On the basis of our understanding of the gold binding mechanisms, we demonstrate systematic control over the size and spatial distribution of gold nanoparticles in the films by changing the PEM assembly and postassembly treatment conditions.

Magnetic Nanoparticle–Polyelectrolyte Interaction: A Layered Approach for Biomedical Applications

This study describes the surface modification of magnetic nanoparticles using two different approaches. The first approach consists of an in situ modification of the surface during the precipitation of the magnetic nanoparticles while the second approach consists of a post-modification of the surface after the formation of the magnetic nanoparticles. In the latter case, we adopted the Layer-by-Layer assembly of polyelectrolyte multilayers of poly(diallyl-dimethylammonium) chloride and poly(styrenesulfonate) to build a polymeric shell around the magnetic nanoparticle core, thereby intentionally conferring to this hybrid core-shell the same charge as the charge of the polyelectrolyte deposited in the last layer. Electrophoretic measurements reveal charge reversal indicating successful Layer-by-Layer deposition while magnetization studies show that the superparamagnetic behavior is not much affected by the presence of polyelectrolytes on the modified magnetic nanoparticles. Fourier transform infrared and thermogravimetry analysis results underline that the various polyelectrolytes employed, in both the methodologies adopted, were successfully bound to the nanoparticles.

Self-Assembly of S-Layer-Enveloped Cytochrome c Polyelectrolyte Multilayers

We report a study of the electrostatic layer-by-layer self-assembly of electroactive polyelectrolyte multilayers incorporating the redox protein cytochrome c (cyt c) combined with recrystallization of the bacterial cell wall surface layer from Bacillus sphaericus CCM 2177 SbpA (S-layer). The polyelectrolyte multilayer assembly was prepared on flat gold electrodes with a nanometer-scale roughness that allowed monitoring of the film formation throughout all the assembly stages by atomic force microscopy measurements in liquid with respect to topography and forces. The deposition of alternating layers of sulfonated polyaniline and cyt c was carried out by adsorption from the corresponding solutions on a cyt c monolayer electrode. The electroactivity of cyt c within the assembly was confirmed by cyclic voltammetry. We showed that the surface properties of the electrode terminating layer change after each adsorption step accordingly. We also found that S-layer recrystallization on the top of the multilayer film was feasible while electroactivity of cyt c within a polyelectrolyte matrix was partially maintained. This approach offers a new strategy to design a biocompatible and permselective outer envelope of a polyelectrolyte multilayer, promising sensor applications.

Polyelectrolyte Multilayer Assembly as a Function of pH and Ionic Strength Using the Polysaccharides Chitosan and Heparin

The goal of this work is to explore the effects of solution ionic strength and pH on polyelectrolyte multilayer (PEM) assembly, using biologically derived polysaccharides as the polyelectrolytes. We used the layer-by-layer (LBL) technique to assemble PEM of the polysaccharides heparin (a strong polyanion) and chitosan (a weak polycation) and characterized the sensitivity of the PEM composition and layer thickness to changes in processing parameters. Fourier-transform surface plasmon resonance (FT-SPR) and spectroscopic ellipsometry provided in situ and ex situ measurements of the PEM thickness, respectively. Vibrational spectroscopy and X-ray photoelectron spectroscopy (XPS) provided details of the chemistry (i.e., composition, electrostatic interactions) of the PEM. We found that when PEM were assembled from 0.2 M buffer, the PEM thickness could be increased from less than 2 nm per bilayer to greater than 4 nm per bilayer by changing the solution pH; higher and lower ionic strength buffer solutions resulted in narrower ranges of accessible thickness. Molar composition of the PEM was not very sensitive to solution pH or ionic strength, but pH did affect the interactions between the sulfonates in heparin and amines in chitosan when PEM were assembled from 0.2 M buffer. Changes in the PEM thickness with pH and ionic strength can be interpreted through descriptions of the charge density and conformation of the polyelectrolyte chains in solution.

Intact Pattern Transfer of Conductive Exfoliated Graphite Nanoplatelet Composite Films to Polyelectrolyte Multilayer Platforms

Layer-by-layer (LBL) assembly of polyelectrolyte multilayers (PEM) has become a ubiquitous process for creating functional ultrathin films. Introduced by Decher, the simple deposition of two oppositely charged polyions can be performed on many types of surfaces giving them new functionality based on the type of polyelectrolytes utilized. Incorporating new functional materials such as nanoparticles, proteins, or medicine (therapeutic chemicals) to alter film properties has lead to changes in mechanical, surface wetting, antireflective, and luminescent properties and resulted in applications as biosensors or in drug delivery. Exfoliated graphite has been incorporated into PEM and other polymer composite films for its unique mechanical, thermal and electrical properties, which are comparable to carbon nanotubes. Multilayer graphite, large stacks of sp hybridized graphene sheets bound together by weak van der Waals interactions, is an ideal starting material because it is inexpensive and available in large quantities. To take advantage of these properties, oxidized graphite has been incorporated into PEM. Oxidized graphite is created by the acid treatment of graphite, which exfoliates the multilayered graphene sheets into platelets of only a few graphene layers thick, creates a negative charge so that they are stable in aqueous solutions, and renders the graphite nonconductive. LBL assembly with a positively charged polyelectrolyte allows for the formation of PEM. To make conductive films, the oxidized graphite must be reduced back to graphite, which is not cost-effective and can change the film morphology. To our knowledge no one has performed LBL assembly using exfoliated graphite that was not oxidized. Mass production of these films for electronic devices requires a patterned film on the substrate surface. Patterning a single layer of graphite does not result in a large enough surface coverage to surpass the

Photopatterned Nanoporosity in Polyelectrolyte Multilayer Films

We report on spatial control of nanoporosity in polyelectrolyte multilayer (PEM) films using photopatterning and its effects on film optical and adsorption properties. Multilayers assembled from poly(acrylic acid-ran-vinylbenzyl acrylate) (PAArVBA), a photo-cross-linking polymer, and poly(allylamine hydrochloric acid) (PAH) were patterned using ultraviolet light followed by immersion in low pH and then neutral pH solutions to induce nanoporosity in unexposed regions. Model charged small molecules rhodamine B, fluorescein, and propidium iodide and the model protein albumin exhibit increased adsorption to nanoporous regions of patterned PEM films as shown by fluorescence microscopy and radiolabeling experiments. Films assembled with alternating stacks of PAH/poly(sodium-4-styrene sulfonate) (SPS), which do not become nanoporous, and stacks of PAH/PAArVBA were patterned to create nanoporous capillary channels. Interdigitated channels demonstrated simultaneous, separate wicking of dimethyl sulfoxide-solvated fluorescein and rhodamine B. In addition, these heterostack structures exhibited patternable Bragg reflectivity of greater than 25% due to refractive index differences between the nanoporous and nonporous stacks. Finally, the PEM assembly process coupled with photo-cross-linking was used to create films with two separate stacked reflective patterns with a doubling in reflectivity where patterns overlapped. The combined adsorptive and reflective properties of these films hold promise for applications in diagnostic arrays and therapeutics delivery.

Pulsed field gradient NMR study of phenol binding and exchange in dispersions of hollow polyelectrolyte capsules

The distribution and exchange dynamics of phenol molecules in colloidal dispersions of submicron hollow polymeric capsules is investigated by pulsed field gradient NMR (PFG-NMR). The capsules are prepared by layer-by-layer assembly of polyelectrolyte multilayers on silica particles, followed by dissolution of the silica core. In capsule dispersion, (1)H PFG echo decays of phenol are single exponentials, implying fast exchange of phenol between a free site and a capsule-bound site. However, apparent diffusion coefficients extracted from the echo decays depend on the diffusion time, which is typically not the case for the fast exchange limit. We attribute this to a particular regime, where apparent diffusion coefficients are observed, which arise from the signal of free phenol only but are influenced by exchange with molecules bound to the capsule, which exhibit a very fast spin relaxation. Indeed, relaxation rates of phenol are strongly enhanced in the presence of capsules, indicating binding to the capsule wall rather than encapsulation in the interior. We present a quantitative analysis in terms of a combined diffusion-relaxation model, where exchange times can be determined from diffusion and spin relaxation experiments even in this particular regime, where the bound site acts as a relaxation sink. The result of the analysis yields exchange times between free phenol and phenol bound to the capsule wall, which are on the order of 30 ms and thus slower than the diffusion controlled limit. From bound and free fractions an adsorption isotherm of phenol to the capsule wall is extracted. The binding mechanism and the exchange mechanism are discussed. The introduction of the global analysis of diffusion as well as relaxation echo decays presented here is of large relevance for adsorption dynamics in colloidal systems or other systems, where the standard diffusion echo decay analysis is complicated by rapidly relaxing boundary conditions.

Basic Law Controlling the Growth Regime of Layer-by-Layer Assembled Polyelectrolyte Multilayers

A mathematical expression describing the growth regime of multilayers formed layer by layer and the correlation between the nature of the growth process and the distribution of the charges in the polyelectrolyte deposited on the surface of the film is reported. Two typical polyelectrolyte pairs were chosen such that one of them causes the film to grow linearly while the other causes the film to grow exponentially. The growth processes were monitored by UV-Vis spectrophotometry and the experimental data was analyzed. The influence of the polyelectrolyte and NaCl concentration on the fabrication of PAH/ PSS and PDDA/PSS films is discussed by analyzing the change of model parameters.

Direct Evidence of Layer-by-Layer Assembly of Polyelectrolyte Multilayers on Soft and Porous Temperature-Sensitive PNiPAM Microgel Using Fluorescence Correlation Spectroscopy

We describe the layer-by-layer assembly of polyelectrolyte multilayers on soft and porous temperature-sensitive poly(N-isopropylacrylamide) (PNiPAM) microgel. Microgels are not hard and rigid but rather are soft and porous particles, and polyelectrolytes not only interdigitate with each other during multilayer formation but also with the microgel. Because of this difference, there could be concerns about the feasibility of the layer-by-layer technique on these systems. The argument is that the layer being deposited is stripping the underlying layer instead of anchoring to the latter, and common methods of characterizing film growth on particles such as zeta-potentials will still show "successful" charge reversal. To address this issue, we used two differently labeled polyelectrolytes during the deposition. Because of the small size of the microgel (400 nm) studied, we cannot distinguish between polyelectrolytes adsorbed on or in the microgel. However, with fluorescence correlation spectroscopy, we can clearly distinguish between free labeled polyelectrolytes and those that are bound to the microgel. Dual-color correlation confirms the presence of both polyelectrolytes bound to the same particle while fluorescence imaging (on a dry sample) provides the visual proof.

A QCM Study of the Immobilization of β-Galactosidase on Polyelectrolyte Surfaces: Effect of the Terminal Polyion on Enzymatic Surface Activity

This work describes the immobilization of beta-galactosidase onto polyelectrolyte multilayer assemblies of the polyanion poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) and the polycation poly(ethylenimine) (PEI) constructed by electrostatic self-assembly (ESA). A single layer of beta-galactosidase was deposited over a precursor film comprising up to five bilayers of the PEI/PAZO polyelectrolyte pair. The enzyme was deposited on both the polycationic (PEI) and the polyanionic (PAZO) surfaces. Quartz crystal microbalance with dissipation monitoring (QCM-D), single-wavelength ellipsometry, and UV-visible absorption spectroscopy revealed differences in both the amount of beta-galactosidase incorporated in each of the multilayer assemblies and the resulting enzyme packing density in the films. The enzymatic films were immersed in a reaction solution containing o-nitrophenyl-beta-d-galactopyranoside (ONPG), and absorbance measurements were used to monitor the concentration of o-nitrophenyl (ONP), the product of the beta-galactosidase catalyzed by hydrolysis of ONPG. Although our data indicate that comparable amounts of beta-galactosidase are incorporated onto both surfaces, enzymatic activity is substantially inhibited when the beta-galactosidase is immobilized on the polyanionic surface compared to the enzyme on the polycationic surface. The difference in catalytic activities reflects the different abilities of the two polyelectrolytes to screen the protein's active site from the substrate environment. In both assemblies, the protein interpenetrated the PEI/PAZO multilayer, disrupting the J-aggregated state of the PAZO chromophores. This work demonstrates that the charge, conformation, and composition of underlying polyelectrolyte cushions have a significant effect on the structure and function of an immobilized protein within functional nanoassemblies.

Polymer-surfactant complexation in polyelectrolyte multilayer assemblies.

Layer-by-layer self-assembly can be used to incorporate amphiphilic molecules into multilayered polyelectrolyte architectures. This review examines equilibrium LbL assemblies constructed by direct adsorption from aqueous solution. LbL systems have not only provided fundamental insight into the nature of polyion-surfactant complexation, but have also yielded functional materials with useful surface, optical, and electronic properties.

Assembly of polyelectrolyte multilayers on nylon fibers

AbstractNon‐woven nylon fibers were investigated as a new type of substrate for the deposition of polyelectrolyte multilayers (PEM) thin films. PEM assembled from cationic poly(diallyldimethylammonium chloride) PDADMAC, and anionic Scarlet dye (λmax absorbance = 510 nm) were deposited directly on Nylon fibers and characterized using a reflectometer spectrophotometer. Evidences of the film assembly are presented as well as a study of the factors controlling the growth of the PDAMAC/dye PEM film on the fiber. The relation between the sorption coefficient (K) and the scattering (S) extracted from the reflectance data is commonly used to represent the dye fixation or the dye content of a given textile fiber. The increase in K/S value at 510 nm was correlated with the dye deposition and was found to increase linearly with the number of layers. The effect of increasing number of layers, ionic strength of the solutions, concentration of chemicals, and dipping time on the film growth was investigated. Our results show that while increase in dye and PDADMAC concentrations from 0 to 1 mM enhance the deposition process, further increase in PDADMAC concentration to 50 mM led to a decrease in K/S value. The optimum salt concentration for the PDAMAC/dye film growth was found to be 0.5M and dipping times as short as 15 s were found to be sufficient for the deposition of the PEM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3286–3290, 2006

PH-Induced Hysteretic Gating of Track-Etched Polycarbonate Membranes: Swelling/Deswelling Behavior of Polyelectrolyte Multilayers in Confined Geometry

pH-induced hysteretic gating of track-etched polycarbonate membranes (TEPC) has been achieved by depositing layer-by-layer assembled polyelectrolyte multilayers comprising poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) at a high pH condition (pH > 9.0). Scanning electron microscopy and transmission electron microscopy showed that the average bilayer thickness of multilayers was greater within the cylindrical pores of track-etched polycarbonate membranes compared to the multilayers on planar substrates (e.g., Si wafers and the face of TEPC membranes). Swelling/deswelling properties of multilayers and gating properties of the multilayer-modified TEPC membranes were studied by measuring the flux of pH-adjusted deionized water. Large discontinuous changes in the transmembrane flux were observed, indicating that the multilayers within the cylindrical pores of TEPC membranes exhibit the discontinuous swelling/deswelling behavior observed previously for planar systems. The degree of swelling as estimated by simple models, however, showed that (PAH/PSS) multilayers in the confined geometry swelled to smaller extents compared to the same multilayers on planar substrates under the same conditions. Multilayer-modified membranes showed reversible gating properties as the pH condition of feed solution was alternated between pH 2.5 and 10.5. In situ atomic force microscopy (AFM) was used to visualize the closing of the pores as a function of time. The hysteretic gating property of the multilayer-modified TEPC membrane was utilized to achieve either a "closed" or "open" state at one pH condition depending on the pretreatment history, thereby enabling either the retention or passage of high-molecular weight polymers by varying the membrane pretreatment condition.

Probing the Stability of Biocompatible Sodium Hyaluronate/Chitosan Nanocoatings Against Changes in Salinity and pH

The stability of polyelectrolyte multilayer assemblies was investigated with emphasis on the effects of solution ionic strength, pH, and polymer molecular weight on the film thickness and surface topography. The multilayers consisting of two polysaccharides, the polyanion sodium hyaluronate (HA) and the polycation chitosan (CH) were studied using surface plasmon resonance (SPR) spectroscopy, impedance quartz crystal microbalance (QCM), and atomic force microscopy (AFM). SPR/QCM experiments show that coatings consisting of four HA/CH bilayers assembled at pH 4.5 in the presence of 0.15 M NaCl are stable in NaCl solutions of concentration less than 0.8 M. These multilayers are stable when placed in contact with aqueous solutions ranging in pH from 3.5 to 9. The molecular weight of the polysaccharides has only a marginal effect on the stability of the films in the range explored here (HA: Mn = 360,000 or 31,000 g/mol; CH: Mn = 160,000 or 30,000 g/mol). AFM imaging reveals that different mechanisms may account for the multilayers stability versus salt and pH treatments. While increasing the ionic strength induces reorganization of the surface topography from isolated spherical islets to elongated worm-like features, changes in pH have no appreciable effects on the coating topography prior to complete disintegration.

Photo-cross-linkable Polyelectrolyte Multilayers for 2-D and 3-D Patterning

We report the synthesis of poly(acrylic acid-ran-vinylbenzyl acrylate) (PAArVBA), a photo-cross-linkable weak polyelectrolyte, and its incorporation into polyelectrolyte multilayer (PEM) films. PEM films assembled from PAArVBA and poly(allylamine hydrochloride) (PAH) are found to exhibit similar thickness trends with assembly pH as those previously reported for poly(acrylic acid) (PAA)/PAH multilayers. Swelling properties of the as-built and photo-cross-linked films are studied by in situ ellipsometry. Two-dimensional masking techniques are used to pattern regions of high and low swelling, as confirmed by atomic force microscopy (AFM), and to provide spatial control over the low-pH-induced microporosity transition exhibited by PAH/PAA PEMs. Films containing alternating blocks of PAH/PAArVBA bilayers and PAH/PAA bilayers were assembled, laterally photopatterned, and exposed to low-pH solution to generate nanoporosity leading to patterned Bragg reflectors, thereby demonstrating three-dimensional control over film structure in these weak PEM assemblies.

Consecutively spin-assembled layered nanoarchitectures of poly(sodium 4-styrene sulfonate) and poly(allylamine hydrochloride)

The recently established spin-coating electrostatic self-assembly (SCESA) technique has been shown to facilitate not only the rapid fabrication of polyelectrolyte multilayer assemblies, but also allow each layer to be easily controlled on a monomolecular scale by minimizing the film thickness across a substrate surface. In this paper, the influence of polyelectrolyte concentration on the amount and thickness of spin-deposited polymer films has been examined for a multilayer system of poly(allyamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS), when the washing steps employed for removing weakly bound polyelectrolytes on a resultant film on a substrate are excluded from the standard fabrication procedure of the SCESA method. The thickness of the spin-deposited PAH/PSS bilayer increased linearly for the PSS concentrations in the range from 1 to 10 mM with PAH constant at 1 mM, which demonstrates the uniform deposition of each layer material onto the thin film. The thickness of PAH/PSS bilayers increased from 1.43 ± 0.06 to 3.37 ± 0.08 nm as the PSS concentration increased from 1 to 10 mM, while the PAH concentration was kept constant at 1 mM. The multilayer films were found to be stable in a good solvent (H 2O) for at least 30 h, without any noticeable loss of the adsorbed layer component of the polyelectrolyte. This improvement to the SCESA method (exclusion of washing steps) provides a convenient way to create multilayer heterostructures with the thickness of each layer being easily adjusted.

Polypeptide Multilayer Films

Research on polypeptide multilayer films, coatings, and microcapsules is located at the intersection of several disciplines: synthetic polymer chemistry and physics, biomaterials science, and nanoscale engineering. The past few years have witnessed considerable growth in each of these areas. Unexplored territory has been found at the borders, and new possibilities for technology development are taking form from technological advances in polypeptide production, sequencing of the human genome, and the nature of peptides themselves. Most envisioned applications of polypeptide multilayers have a biomedical bent. Prospects seem no less positive, however, in fields ranging from food technology to environmental science. This review of the present state of polypeptide multilayer film research covers key points of polypeptides as materials, means of polymer production and film preparation, film characterization methods, focal points of current research in basic science, and the outlook for a few specific applications. In addition, it discusses how the study of polypeptide multilayer films could help to clarify the physical basis of assembly and stability of polyelectrolyte multilayers, and mention is made of similarities to protein folding studies.

Self-assembled multilayer films based on functionalized poly(thiophene)s

We study the layer-by-layer assembly and properties of polyelectrolyte multilayers containing cationic and anionic polythiophene derivatives, poly-2-(3-thienyloxy)propyltriethylammonium chloride (PTPA), poly(thiophene-3-acetic acid) (PTAA), and poly(sodium-2-(4-methyl-3-thiehyloxy)ethane sulfonate) (P-SMTE). These polymers were synthesized by chemical oxidation with FeCl 3 and soluble in aqueous media. Two types of multilayers have been prepared by sequential adsorption of polyanions and polycations on charged surfaces: PTPA/PTAA and PTPA/P-SMTE. The linear relationship of the UV-vis adsorption spectra and QCM observed in these multilayer systems indicated that each layer was successfully deposited to form layer-by-layer films. FT-IR results also revealed that the multilayer structure was formed by electrostatic interaction.