Styrene Sulfonate Sodium Salt Research Articles

Degradable Poly(styrene sulfonate) Polyanions for Biomedical and Electrochemical Applications

AbstractThe synthesis of poly(styrene sulfonate) with hydrolysable ester groups in the main chain is reported. The material is obtained by free radical copolymerization of either styrene sulfonate sodium salt (SSNa) or styrene sulfonate alkyl esters (SSA) with the cyclic ketene acetal 2‐methylen‐1,3,6‐trioxocane (MTC). As for other systems made from cyclic ketene acetals, the reactions are difficult to control and give copolymers with high polydispersity index. MTC homopolymer is obtained as a side product in both cases. Thermal cleavage of the alkyl protective groups of the poly(styrene sulfonate alkyl esters) to obtain the target polystyrene sulfonate anions remains incomplete. Thus, direct synthesis of the polyanion from SSNa and MTC is the more efficient process, especially since the poly(SSNa‐co‐MTC) copolymer can be easily separated from MTC homopolymer. 1H‐NMR analytics indicates MTC repeat unit contents of 2–11%, depending on the initial SSNa to MTC ratio. The MTC ester groups of the copolymers are hydrolyzed in aqueous conditions, with and without enzyme, and a marked decrease in the molar mass is observed after hydrolysis. This confirms that these copolymers have the designed intended break points in the main chain, and could become a part of fully degradable electroactive polymer systems.

PDADMAC/PSS Oligoelectrolyte Multilayers: Internal Structure and Hydration Properties at Early Growth Stages from Atomistic Simulations.

We analyze the internal structure and hydration properties of poly(diallyl dimethyl ammonium chloride)/poly(styrene sulfonate sodium salt) oligoelectrolyte multilayers at early stages of their layer-by-layer growth process. Our study is based on large-scale molecular dynamics simulations with atomistic resolution that we presented recently [Sánchez et al., Soft Matter 2019, 15, 9437], in which we produced the first four deposition cycles of a multilayer obtained by alternate exposure of a flat silica substrate to aqueous electrolyte solutions of such polymers at 0.1M of NaCl. In contrast to any previous work, here we perform a local structural analysis that allows us to determine the dependence of the multilayer properties on the distance to the substrate. We prove that the large accumulation of water and ions next to the substrate observed in previous overall measurements actually decreases the degree of intrinsic charge compensation, but this remains as the main mechanism within the interface region. We show that the range of influence of the substrate reaches approximately 3 nm, whereas the structure of the outer region is rather independent from the position. This detailed characterization is essential for the development of accurate mesoscale models able to reach length and time scales of technological interest.

Fiber optic SPR sensor for human Immunoglobulin G measurement based on the MMF-NCF-MMF structure

Abstract A sensitive, simple fiber optic surface plasmon resonance (SPR) sensor based on the MMF-NCF-MMF structure is proposed in this work. The structure of the sensing part is constructed by a section of noncore fiber (NCF) sandwiched between two multimode fibers (MMF). Gold film with a thickness of 50 nm was uniformly sputtered on the outside surface of the NCF. SPR phenomenon was stimulated and experimentally verified when light propagates at the interface between the dielectric and the gold layers. The length of the NCF section was optimized by experiments and determined to be 12 mm. The refractive index (RI) sensitivity of the SPR sensor is 3475.1 nm/RIU in the RI range of 1.343–1.373. For the realization of human Immunoglobulin G detection, the surface of this SPR sensor needs to be biomodified. A simple process of polyelectrolyte self-assembled multilayers (PSAMs) deposition cycled four times utilizing diallyldimethyl ammonium chloride (PDDA) and styrenesulfonate sodium salt (PSS). And we choose goat anti-human immunoglobulin G-human immunoglobulin G as a bioconjugated pair to examine the bio-sensing effectiveness of this SPR sensor, the maximum sensitivity of Immunoglobulin G (IgG) detection and the limit of detection (LOD) is calculated to be 57.06 nm/(mg/ml) and 1.75 μg/ml, respectively. The proposed sensor is simple, easy to fabricate, low loss, cost-effective and can be used in numerous chemical and biological analyses.

In situ preparation of magnetic Fe3O4.Cu2O.Fe3O4/cryogel nanocomposite powder via a reduction–coprecipitation method as adsorbent for methylene blue water pollutant

AbstractMagnetic nanocomposites have attracted great attention as adsorbents for the removal of water pollutants, which respond to an external magnet that is used to remove both pollutants and composite nanomaterial traces from water. They are environmentally friendly and effective adsorbents for water treatment. In this respect, a simple in situ preparation method was used to prepare cryogel powder composite based on Fe3O4.Cu2O.Fe3O4 nanomaterials. The ionic cryogel based on 2‐acrylamido‐2‐methylpropane sulfonate sodium salt and styrene sulfonate sodium salt was prepared by crosslinking polymerization at low temperature. The new magnetic nanoparticles based on Fe3O4.Cu2O.Fe3O4 were successfully prepared inside the cryogel networks by a simple reduction–coprecipitation method based on reaction of Fe3+ with sodium sulfite and Cu2+ in the presence of hydroxylamine and ammonia solution. The thermal stability, accurate Fe3O4.Cu2O.Fe3O4 content, magnetic properties, crystal lattice structure, particle sizes and morphology of the prepared cryogel composite were evaluated. The optimum conditions such as pH, contact time, adsorbate concentrations, adsorption equilibrium and adsorption kinetics were investigated to determine the efficiency of the prepared composite as an adsorbent to remove toxic methylene blue (MB) pollutant from aqueous solution. The data for MB adsorption confirmed the high ability of the prepared composite to remove more than 4.696 mmol L−1 of MB from water during 6 min. The regeneration and reuse experiments showed excellent data for the synthesized new dye as an effective adsorbent for water treatment. © 2018 Society of Chemical Industry

Fundamental properties, self-assembling behavior, and their temperature and salt responsivity of ionic amphiphilic diblock copolymer having poly(N-isopropylacrylamide) in aqueous solution

Molecular properties and self-assembling behavior of thermo-responsive ionic diblock copolymers, poly(N-isopropylacrylamide)-b-poly(styrenesulfonate sodium salt) (PNIPAm-b-PSSNa), which were precisely synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, were systematically studied as a function of temperature and added salt concentrations. Cloud point with elevation aqueous solution temperature was found at 35~40 °C for all the block copolymers studied which have a different block length and block ratio. Cloud point decreased with increasing added salt concentration, which was identified to be the critical micelle temperature (CMT) since micelle formation was confirmed at a higher temperature. The critical micelle concentration (cmc) at 50 °C could be determined by the static light scattering technique and cmc was found to increase with increasing added salt concentration. This is behavior typical of “non-surface active” polymers although it does not obey the famous Corin-Harkins law for ionic surfactants. However, the surface tension of the solution decreased with increasing polymer concentration and the adsorption of block copolymer molecules at the water surface was directly confirmed by X-ray reflectivity and foam formation observation. Micelle size was found to increase with increasing polymer concentration by dynamic light scattering. Vesicle-like particles were found by transmission electron microscopy (TEM) observation for some block copolymers. PNIPAm-b-PSSNa behaves as an amphiphilic block copolymer at 50 °C and has a non-surface active nature since it has an ionic block. However, the discrepancy between the non-surface active nature of cmc behavior and surface active nature of adsorption is quite mysterious, and this might be peculiar to PNIPAm-containing block copolymers since similar behavior was not observed in other ionic amphiphilic block copolymers having a conventional hydrophobic block.

Label-free fiber optic biosensor based on thin-core modal interferometer

A label-free, cost-effective fiber optic biosensor (FOB) using electrostatic self-assembly (ESA) technology is presented and experimentally demonstrated. The FOB was constructed by sandwiching a thin-core single-mode fiber (TCSMF) between two single-mode fibers (SMFs). Firstly, we simulated the refractive index (RI) sensitivity of this fiber structure, and validated it using different concentrations of glycerol solutions. Then the diallyldimethyl ammonium chloride (PDDA) and styrenesulfonate sodium salt (PSS) were employed as polyelectrolyte self-assembled multilayers (PSAMs) deposition for surface functionalization of the fiber. We selected biotin–streptavidin as a bioconjugate pair for testing the effectiveness of the biosensor, and achieved a streptavidin detection limit of 0.02nM. The specificity was further verified by a comparison experiment conducted using bovine serum albumin (BSA) and gelatin. These results demonstrate the feasibility of this sensor for use in biological and chemical applications.

Polystyrene–graphene oxide (GO) nanocomposite synthesized by interfacial interactions between RAFT modified GO and core–shell polymeric nanoparticles

Here we report simple and robust one-pot method for the preparation of polystyrene (PS)/graphene oxide (GO) nanocomposite using reversible addition fragmentation chain transfer (RAFT) modified GO in surfactant free emulsion polymerization (SFEP). The results suggested that ionic comonomer, styrene sulfonate sodium salt (SS-Na), concentration plays vital role in forming PS/GO nanocomposite. X-ray and electron diffraction studies suggest that there is no recombination of GO sheets when moderate SS-Na concentration is used, resulting complete exfoliation of GO sheets in the PS/GO nanocomposite. The formation of core–shell particles in which PS is the core and polystyrene sulfonate sodium salt (PSS–Na) is the shell, and the specific interactions between functional groups of GO and PSS–Na are attributed as the driving forces for the PS/GO nanocomposite formation.

Layer-by-Layer Formation of Oligoelectrolyte Multilayers: A Combined Experimental and Computational Study

For the first time, the combination of experimental preparation and results of fully atomistic simulations of an oligoelectrolyte multilayer (OEM) made of poly(diallyl dimethyl ammonium chloride)/poly(styrene sulfonate sodium salt) (PDADMAC/PSS) is presented. The layer-by-layer growth was carried out by dipping silica substrates in oligoelectrolyte solutions and was modeled by means of atomistic molecular dynamics simulations with a protocol that mimics the experimental procedure up to the assembly of four layers. Measurements of OEM thickness, surface roughness and amount of adsorbed oligoelectrolyte chains obtained from both approaches are compared. A good agreement between simulated and experimental results was found, with some deviations due to intrinsic limitations of both methods. However, the combination of information extracted from simulations to support the analysis of experimental data can overcome such restrictions and improve the interpretation of experimental results. On the other hand, processes dominated by slower kinetics, such as the destabilization of adsorbed layers upon equilibration with the surrounding environment, are out of reach for the simulation modeling approach, but they can be investigated by monitoring in situ the oligoelectrolyte adsorption during the assembly process. This demonstrates how the synergistic use of simulation and experiments improves the knowledge of OEM properties down to the molecular scale.

Magnetic Resonance Imaging for Monitoring of Magnetic Polyelectrolyte Capsule In Vivo Delivery

Layer-by-layer (LbL) assembled polyelectrolyte capsules have been widely studied as promising delivery systems due to their well-controlled architectures. Although their potential applications in vitro have been widely investigated, at present, it is still a challenging task to track their real-time delivery in vivo, where and how they would be located following their administration. In this work, the noninvasive magnetic resonance imaging (MRI) technique was applied to monitor the delivery of polyelectrolyte capsules in vivo, incorporating magnetite nanoparticles as imaging components. First, MRI scan was performed over 6 h after sample administration at the magnetic field of 3.0 T; magnetic capsules, both poly(allylamine hydrochloride)/poly(styrenesulfonate sodium salt)-based and poly-l-arginine hydrochloride/dextran sulfate (Parg/DS)-based, were detected mostly in the liver region, where the transverse relaxation time (T2) was shortened and hypointense images were visualized, demonstrating a contrast-enhanced MRI effect between liver and adjacent tissue. A continuous MRI scan found that the contrast-enhanced MRI effect can last up to 30 h; in the mean time, the Parg/DS-based capsules with smaller diameter were found to have a pronounced clearance effect, which resulted in a weakened MRI effect in the liver. No obvious toxicity was found in animal studies, and all mice survived after MRI scans. Histology study provided evidences to support the MRI results, and also revealed the destination of these magnetic capsules over 30 h after administration.

Optical Response of Fiber-Optic Fabry-Perot Refractive-Index Tip Sensor Coated With Polyelectrolyte Multilayer Ultra-Thin Films

The polyelectrolyte multilayer (PEM) thin film-coated Fabry-Perot (F-P) optical fiber tip sensors had been developed for in situ refractive index (RI) measurement. Using the simple layer-by-layer (LBL) approach, the sensor surfaces had been successfully coated with PEM thin films of poly(diallyldimethyl- ammonium choloride)/poly(styrenesulfonate sodium salt) (PDDA/PSS) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> (n is number of bilayers). Their optical response to the changes of external RI had been investigated and evaluated. The results demonstrated that after coated with PEM thin films, the inflection point of as-formed F-P tip sensor would shift from 1.457 to 1.4623 but its RI sensitivity was slightly reduced from 39 dB/RI to 25 dB/RI. In addition, their fringe contrast exhibited the unique temperature-independent performance. Therefore, owing to these special optical properties, simple operation and easy miniaturization, these novel PEM thin film coated F-P tip sensors have great potential in the detection and sensing of chemical and biological molecules, even at elevated temperature.

S-doped micro/mesoporous carbon–graphene composites as efficient supercapacitors in alkaline media

Composites of polymer (styrene-sulfonate sodium salt) derived carbon with highly oxidized graphite oxide were synthesized and tested as supercapacitors. The materials were characterized using adsorption of nitrogen, SEM/EDX, elemental analysis, thermal analysis-mass spectroscopy and potentiometric titration. The electrochemical performance was evaluated using cyclic voltammetry, galvanostatic charge–discharge techniques and impedance spectroscopy in 6 M KOH. Addition of the graphene phase increases DC conductivity, volume of small micropores, and sizes of mesopores. These changes enhance the capacitance. Sulfur species located in small micropores affect the charge of the carbon surface and decrease its affinity to adsorb water. This results in a specific electrosorption of electrolyte ions and thus in highly efficient space utilization. Sulfones and sulfoxides located in the larger pores (mesopores) contribute to a pseudocapacitive effect. On the materials tested ∼110 F g−1 was measured in spite of the small surface area (about 600 m2 g−1). This leads to a high volumetric capacitance of up to 65 F cm−3 (without a special densification).

Layer-by-Layer Surface Modification of Fruits with Edible Nano-Coatings

A new method for the surface modification of the surface of fruits based on the Layer-by-Layer (LbL) deposition of polyelectrolyte multilayers (PEM) is presented. Mangoes fruits were coated by sequential dipping in solutions of either Poly(diallyldimethylammonium chloride), (PDADMAC) or Poly(styrene sulfonate sodium salt) (PSS). After the deposition of only few polyelectrolyte layers, the skin of the fruits was changed from hydrophobic to hydrophilic as shown by contact angles measurements decreasing from 90 to 10. Fourier transform infrared spectroscopy (FTIR) was used to confirm the deposition of the PEM coating on the fruit which was then used as a matrix to load curcumin as model compound. Ultraviolet Visible (UV-Vis) spectroscopy was used to evaluate the amount of a curcumin loaded on the fruit surface as a function of the thickness of the film by indirect leaching in ethanol. This coating method provides a new approach to dope active compound on the fruit surface such as anti-oxidant, fragrance, color and other nutriment which could increase the market value of fruits.

Layer‐by‐Layer Self‐Assembled Metal‐Ion‐ (Ag‐, Co‐, Ni‐, and Pd‐) Doped TiO2 Nanoparticles: Synthesis, Characterisation, and Visible Light Degradation of Rhodamine B

Metal‐ion‐ (Ag, Co, Ni and Pd) doped titania nanocatalysts were successfully deposited on glass slides by layer‐by‐layer (LbL) self‐assembly technique using a poly(styrene sulfonate sodium salt) (PSS) and poly(allylamine hydrochloride) (PAH) polyelectrolyte system. Solid diffuse reflectance (SDR) studies showed a linear increase in absorbance at 416 nm with increase in the number of m‐TiO2 thin films. The LbL assembled thin films were tested for their photocatalytic activity through the degradation of Rhodamine B under visible‐light illumination. From the scanning electron microscope (SEM), the thin films had a porous morphology and the atomic force microscope (AFM) studies showed “rough” surfaces. The porous and rough surface morphology resulted in high surface areas hence the high photocatalytic degradation (up to 97% over a 6.5 h irradiation period) using visible‐light observed. Increasing the number of multilayers deposited on the glass slides resulted in increased film thickness and an increased rate of photodegradation due to increase in the availability of more nanocatalysts (more sites for photodegradation). The LbL assembled thin films had strong adhesion properties which made them highly stable thus displaying the same efficiencies after five (5) reusability cycles.

End‐group characterization of poly(styrene sulfonate sodium salt) by activated electron photo‐detachment dissociation

Tandem mass spectrometry of poly(styrene sulfonate sodium salt) (PSS) was performed after activated electron photo-detachment dissociation (activated EPD). In this technique, doubly charged PSS oligomers were first produced in negative mode electrospray ionization, then oxidized into radical anions upon electron photo-detachment using a 220 nm laser wavelength, and further activated by collision. In contrast to the collision-induced dissociation (CID) of negatively charged PSS oligomers, which does not provide informative data with regard to the end-groups, activated-EPD is shown here to promote radical-induced dissociation reactions thanks to the oxidation of a sulfonate group upon laser irradiation. Major product ions generated after backbone bond cleavages contained one or the other chain terminations and could be accounted for by two main mechanisms. Moreover, each of the proposed dissociation reactions was shown to generate two distinct fragments, depending on the location of the oxidized monomer near one or the other chain terminal moieties. As a result, a combination of these two fragments allowed a straightforward mass characterization of each end-group.

Preparation of core-shell and hollow fibers using layer by layer (LbL) self-assembly of polyelectrolytes on electrospun submicrometer-scale silica fibers

Herein, fabrication of hollow fibers made of polyelectrolyte multilayers is reported. Silica submicrometer-scale fibers were fabricated by electrospinning and layer by layer deposition of polyelectrolytes were performed to coat silica fibers with polyelectrolyte multilayers, which were prepared by consecutive deposition of poly(ethyleneimine) and poly(styrene sulfonate sodium salt)/sodium dodecyl sulfate onto the surface of the silica fibers. In order to obtain hollow fibers, the core removal was carried out by introducing the core-shell fibers to a hydrofluoric acid solution. The hollow fibers were stable in hydrofluoric acid solution and displayed pH-dependent structural changes. SEM microscopy indicated the formation of the glass fibers and the fibers coated with polyelectrolyte multilayers (Silica—polyelectrolyte multilayers (PEM) fibers). The diameter of the core-shell fibers was increased after layer-by-layer coating. ATR-FTIR was performed for characterization of the glass fibers before and after layer-by-layer coating as well as after selective core removal. IR spectrum of the Silica-PEM fibers indicates C-H stretching modes of saturated hydrocarbons, confirming multilayers formation. Core removal was also confirmed by IR spectroscopy as Si-O-Si band disappears for the IR spectrum of the fibers after core-removal.

Mass spectrometry analysis of poly(styrene sulfonate sodium salt), a polyanionic electrolyte

Electrospray ionization (ESI) of poly(styrene sulfonate sodium salt) (PSS) with a molar mass of 1100 Da (weight average) efficiently produces distributions of [M + Na] + cations in positive mode and [M–Na] −as well as [M–2Na] 2−anions in negative mode. From these distributions, repeat unit, end groups, and defects in the poly(electrolyte) can readily be determined by quadrupole ion trap mass spectrometry (QiT MS). During MS analysis, sodium/proton exchanges in the SO 3Na substituents of the [M–Na] −ions take place, with the number of exchanges observed being equal to the number of sulfonate groups present in the analyzed oligomer. Such exchanges are less pronounced for the oligomers with 2− charges and absent in the sodium-cationized oligomers (1+ charge). Collisionally activated dissociation (CAD) of the sodiated cations proceeds via charge-remote homolytic C–C bond cleavages in the polymer backbone, ultimately leading to fragments that contain both or neither of the end groups. The same chemistry is observed for the anions if they have not exchanged sodium ions for protons. In sharp contrast, precursor ions that contain SO 3H (sulfonic acid) groups due to Na/H exchange dissociate mainly by charge-catalyzed SO 3 losses. The number of SO 3 units lost is identical to the number of sulfonic acid pendants in the oligomer. The CAD results suggest that PSS may degrade to polystyrene under acidic conditions.

LbL Fabricated Poly(Styrene Sulfonate)/TiO2Multilayer Thin Films for Environmental Applications

Fabrication of multilayer ultrathin composite films composed of nanosized titanium dioxide particles (P25, Degussa) and polyelectrolytes (PELs), such as poly(allyl amine hydrochloride) (PAH) and poly(styrene sulfonate sodium salt) (PSS), on glass substrates using the layer-by-layer (LbL) assembly technique and its potential application for the photodegradation of rhodamine B under ultraviolet (UV) irradiation has been reported. The polyelectrolytes and TiO(2) were deposited on glass substrates at pH 2.5 and the growth of the multilayers was studied using UV/vis spectrophotometer. Thickness measurements of the films showed a linear increase in film thickness with increase in number of bilayers. The surface microstructure of the thin films was characterized by field emission scanning electron microscope. The ability of the catalysts immobilized by this technique was compared with TiO(2) films prepared by drop casting and spin coating methods. Comparison has been made in terms of film stability and photodegradation of rhodamine B. Process variables such as the effect of surface area of the multilayers, number of bilayers, and initial dye concentration on photodegradation of rhodamine B were studied. Degradation efficiency increased with increase in number of catalysts (total surface area) and bilayers. Kinetics analysis indicated that the photodegradation rates follow first order kinetics. Under maximum loading of TiO(2), with five catalyst slides having 20 bilayers of polyelectrolyte/TiO(2) on each, 100 mL of 10 mg/L dye solution could be degraded completely in 4 h. The same slides could be reused with the same efficiency for several cycles. This study demonstrates that nanoparticles can be used in wastewater treatment using a simple immobilization technique. This makes the process an attractive option for scale up.

Frozen Cyclohexane-in-Water Emulsion as a Sacrificial Template for the Synthesis of Multilayered Polyelectrolyte Microcapsules

This paper reports the application of frozen cyclohexane-in-water emulsions as sacrificial templates for the fabrication of hollow microcapsules through layer-by-layer assembly of polyelectrolytes, poly(styrenesulfonate sodium salt), and poly(allylamine hydrochloride). Extraction of the cyclohexane phase from frozen emulsions stabilized with 11 polyelectrolyte layers by compatibilization with 30% v/v ethanol leads to the formation of water-filled microcapsules while preserving the spherical geometry. The majority of microcapsules (>90%) are prepared with intact polyelectrolyte membranes as measured by their deformation induced by osmotic pressure. This work provides a new route for the synthesis of hollow multilayered microcapsules under mild operating conditions.

Photoresponsive layer-by-layer ultrathin films prepared from a hyperbranched azobenzene-containing polymeric diazonium salt

In this work, a hyperbranched diazonium salt (HB-DAS), prepared through azo-coupling reaction of an AB 2 monomer ( N, N-bis[2-(4-aminobenzoyloxy)ethyl]aniline), was used to prepare self-assembled multilayers and ultrathin films. Multilayer films were fabricated by dipping substrates in HB-DAS and other polyelectrolyte solutions alternately in a layer-by-layer (LBL) manner. It was somewhat surprising to observe that HB-DAS forms multilayer films with either a polyanion (poly(styrenesulfonate sodium salt), PSS) or a polycation (poly(diallyldimethylammonium chloride), PDAC) through alternate deposition in the solutions. Ultrathin films were formed in a sequential growth manner by dipping the substrates in the HB-DAS solution, washing with deionized water and drying repeatedly. In all the processes, the absorbance and thickness of the thin films linearly increase as the number of the dipping cycle increases. HB-DAS/PSS multilayer possesses an obviously larger bilayer thickness and lower density compared with the other two counterparts. The drying step after each deposition is necessary for the HB-DAS ultrathin film growth through the repeated dip-coating of HB-DAS. The multilayer and ultrathin films prepared by the above methods all show high resistance to erosion by organic solvents. The multilayers and ultrathin films exhibit photoinduced dichroism upon the irradiation of a polarized Ar + laser beam.

Fabrication of Novel Layer-by-Layer Assembly Films Composed of Poly(lactic acid) and Polylysine through Cation−Dipole Interactions

Novel layer-by-layer (LbL) assembly films composed of poly( L-lysine) (PLL) and poly( D-lactic acid) (PDLA) were prepared by the alternate immersion of a gold substrate into an aqueous PLL solution and an acetonitrile solution of PDLA. The formation of the LbL assembly film was confirmed by quartz crystal microbalance (QCM) analysis, atomic force microscopy observation, and attenuated total reflection Fourier transform infrared spectroscopy measurement. The driving force responsible for the LbL assembly was determined by investigating the formation behavior of the LbL assembly under various conditions. The formation of the LbL assembly was not affected either by the stereochemistry of polylysine and poly(lactic acid) or by the addition of urea, which is known to inhibit hydrogen bonding interaction between polymers, into the aqueous PLL solution. The LbL assembly was also formed by the combination of PDLA and polycations other than polylysine, such as poly(diallyldimethylammonium chloride). On the other hand, the combination of PDLA and any polyanions such as poly(styrene sulfonate sodium salt) produced little corresponding LbL assembly. The increase in positive charge on the amino nitrogen atom of PLL enhanced the LbL assembly. These results suggest that the LbL assembly film composed of PLL and PDLA was fabricated by cation-dipole interactions between the positive charge on the amino nitrogen atom of PLL and the lone pairs of the carbonyl oxygen atom of PDLA.