Showing papers on "Layer by layer published in 2009"

Layer-by-layer assembly of all carbon nanotube ultrathin films for electrochemical applications.

Abstract: All multiwall carbon nanotube (MWNT) thin films are created by layer-by-layer (LBL) assembly of surface functionalized MWNTs. Negatively and positively charged MWNTs were prepared by surface functionalization, allowing the incorporation of MWNTs into highly tunable thin films via the LBL technique. The pH dependent surface charge on the MWNTs gives this system the unique characteristics of LBL assembly of weak polyelectrolytes, controlling thickness and morphology with assembly pH conditions. We demonstrate that these MWNT thin films have randomly oriented interpenetrating network structure with well developed nanopores using AFM and SEM, which is an ideal structure of functional materials for various applications. In particular, electrochemical measurements of these all-MWNT thin film electrodes show high electronic conductivity in comparison with polymer composites with single wall nanotubes, and high capacitive behavior with precise control of capacity.

Layer‐by‐Layer Hydrogen‐Bonded Polymer Films: From Fundamentals to Applications

Abstract: Recent years have seen increasing interest in the construction of nanoscopically layered materials involving aqueous-based sequential assembly of polymers on solid substrates. In the booming research area of layer-by-layer (LbL) assembly of oppositely charged polymers, self-assembly driven by hydrogen bond formation emerges as a powerful technique. Hydrogen-bonded (HB) LbL materials open new opportunities for LbL films, which are more difficult to produce than their electrostatically assembled counterparts. Specifically, the new properties associated with HB assembly include: 1) the ease of producing films responsive to environmental pH at mild pH values, 2) numerous possibilities for converting HB films into single- or two-component ultrathin hydrogel materials, and 3) the inclusion of polymers with low glass transition temperatures (e.g., poly(ethylene oxide)) within ultrathin films. These properties can lead to new applications for HB LbL films, such as pH- and/or temperature-responsive drug delivery systems, materials with tunable mechanical properties, release films dissolvable under physiological conditions, and proton-exchange membranes for fuel cells. In this report, we discuss the recent developments in the synthesis of LbL materials based on HB assembly, the study of their structure–property relationships, and the prospective applications of HB LbL constructs in biotechnology and biomedicine.

Spraying asymmetry into functional membranes layer-by-layer.

Abstract: A process based on spray-assisted layer-by-layer deposition produces conformal coatings on individual fibres within the bulk porous substrate. Additional processing creates a sublayer with properties that differ from the substrate. The method is used to fabricate a material that acts as both a toxin barrier and a photocatalyst.

Layer‐By‐Layer Films as a Biomimetic Reservoir for rhBMP‐2 Delivery: Controlled Differentiation of Myoblasts to Osteoblasts

Abstract: Efficient delivery of growth or survival factors to cells is one of the most important long-term challenges of current cell-based tissue engineering strategies. The extracellular matrix acts as a reservoir for a number of growth factors through interactions with its components. In the matrix, growth factors are protected against circulating proteases and locally concentrated. Thus, the localized and long-lasting delivery of a matrix-bound recombinant human bone morphogenetic protein 2 (rhBMP-2) from a biomaterial surface would mimic in vivo conditions and increase BMP-2 efficiency by limiting its degradation. Herein, it is shown that crosslinked poly(L-lysine)/hyaluronan (HA) layer-by-layer films can serve as a reservoir for rhBMP-2 delivery to myoblasts and induce their differentiation into osteoblasts in a dose-dependent manner. The amount of rhBMP-2 loaded in the films is controlled by varying the deposition conditions and the film thickness. Its local concentration in the film is increased up to approximately 500-fold when compared to its initial solution concentration. Its adsorption on the films, as well as its diffusion within the films, is evidenced by microfluorimetry and confocal microscopy observations. A direct interaction of rhBMP-2 with HA is demonstrated by size-exclusion chromatography, which could be at the origin of the rhBMP-2 "trapping" in the film and of its low release from the films. The bioactivity of rhBMP-2-loaded films is due neither to film degradation nor to rhBMP-2 release. The rhBMP-2-containing films are extremely resistant and could sustain three successive culture sequences while remaining bioactive, thus confirming the important and protective effect of rhBMP-2 immobilization. These films may find applications in the local delivery of immobilized growth factors for tissue-engineered constructs and for metallic biomaterial surfaces, as they can be deposited on a wide range of substrates with different shapes, sizes, and composition.

One-step synthesis of silver nanoparticles/carbon nanotubes/chitosan film and its application in glucose biosensor

Abstract: One-step synthesis of silver nanoparticles/carbon nanotubes/chitosan film (Ag/CNT/Ch) was firstly proposed as a novel immobilization matrix for the enzymes to fabricate sensitive glucose biosensor. The biosensor was prepared by embedding horseradish peroxidase (HRP) and glucose oxidase (GOD) in Ag/CNT/Ch hybrid films based on layer by layer technique. The electron mediator, o-phenylenediamine (OPD), was also co-immobilized with HRP in the inner layer on the surface of an indium tin oxide (ITO) electrode. Hydrogen peroxide produced by the GOD catalytic oxidation of glucose was then detected by OPD in the presence of HRP. Under the optimized experimental conditions, the resulting biosensor could detect glucose in a linear range from 0.5 to 50 μM with a detection limit of 0.1 μM at a signal-to-noise ratio of 3. The sensitivity was calculated as 135.9 μA mM−1. The proposed biosensor offered sensitive amperometric responses to glucose based on the Ag/CNT/Ch films.

Ordered Poly(p-phenylene)/Layered Double Hydroxide Ultrathin Films with Blue Luminescence by Layer-by-Layer Assembly

Abstract: Lavender layers: A poly(p-phenylene) anionic derivate and exfoliated Mg-Al layered double hydroxide monolayers were assembled into ultrathin films with well-defined blue fluorescence (see picture; the numbers indicate the number of bilayers), long-range order, and high photostability. These films work as multiple quantum-well structures for valence electrons.

Low temperature thin film transistor process, device property, and device stability improvement

Abstract: A method and apparatus for forming a thin film transistor is provided. A gate dielectric layer is formed, which may be a bilayer, the first layer deposited at a low rate and the second deposited at a high rate. In some embodiments, the first dielectric layer is a silicon rich silicon nitride layer. An active layer is formed, which may also be a bilayer, the first active layer deposited at a low rate and the second at a high rate. The thin film transistors described herein have superior mobility and stability under stress.

Construction of highly ordered lamellar nanostructures through Langmuir-Blodgett deposition of molecularly thin titania nanosheets tens of micrometers wide and their excellent dielectric properties.

Abstract: Exfoliated unilamellar titania nanosheets of Ti(0.87)O(2) with a lateral size of 10-30 microm were deposited layer-by-layer onto various substrates by Langmuir-Blodgett procedure to produce a highly ordered lamellar nanofilms. The nanosheets dispersed in an aqueous suspension containing quaternary ammonium ions as a supporting electrolyte floated spontaneously at the air/liquid interface, and they were successfully transferred onto the substrate after surface compression. Neat tiling of the nanosheets could be realized at an optimized surface pressure. The film thus obtained was exposed to UV light to turn the substrate surface hydrophilic, which was helpful for stable repetition of monolayer deposition. Layer-by-layer growth was confirmed by UV-visible absorption spectra, which showed progressive enhancement of an absorption band due to the nanosheet. Cross-sectional transmission electron microscopy images visualized the ultrathin film homogeneously deposited on the substrate surface and a lamellar fringe of the layer-by-layer assembled nanosheets was clearly resolved at a higher magnification. X-ray diffraction data on the films showed sharp basal reflections up to the seventh order, and Williamson-Hall analysis of the pattern indicated that the film was coherent across the total thickness with respect to X-ray and that the lattice strain was extremely small. In addition, the first basal reflection was accompanied by small satellite peaks, which are accounted for by the Laue interference function. All these features clearly indicate the formation of a highly ordered lamellar nanostructure of the titania nanosheets comparable to artificial lattice films produced via modern vapor-phase deposition processes. The obtained films showed superior dielectric and insulating properties as a reflection of the highly organized film nanoarchitecture.

Covalent layer-by-layer assembled superhydrophobic organic-inorganic hybrid films.

Abstract: Using the concept of covalent layer-by-layer assembly (covalent LbL), used until now for the elaboration of films from polymers or dendrimers, we have constructed hybrid organic/inorganic surfaces by alternating different layers of amino-functionalized silica nanoparticles (295 nm diameter) and epoxy-functionalized smaller silica nanoparticles (20 nm diameter). The so-realized macromolecular edifice leads to a hierarchical integration of nanoscale textures. Then hydrophobization of the last layer of amino-functionalized silica particles was carried out by grafting a new designed highly fluorinated aldehyde, creating a monomolecular layer via the formation of an imine function. Five highly fluorinated surfaces were built, and their water-repellent abilities were directly correlated to the surface topologies (i.e., the number of layers of silica nanoparticles and their organization on the glass support). The hydrophobicity increased with the number of layers and stable highly water-repellent surfaces (stati...

Layer-by-Layer Films of Dual-Pore Carbon Capsules with Designable Selectivity of Gas Adsorption

Abstract: Stable, homogeneous ultrathin films of uniformly dimensioned dual-pore carbon capsules with mesoporous walls and macroscopic empty cores were fabricated using layer-by-layer methods based on electrostatic interaction between a polyelectrolyte and a surfactant coating of the carbon capsules. The resulting dual-porous carbon capsule films were investigated as a sensor substrate for vapors of different organic solvents. The carbon capsule films have much higher adsorption capacities than conventional electrolyte films and even than noncapsular mesoporous carbon films. The dual-pore carbon capsules have greater affinities for aromatic volatiles over their aliphatic counterparts, probably due to stronger pi-pi interactions. Additionally, the adsorption selectivity can be designed. Impregnation of additional recognition components into the carbon capsules permits further control over adsorption selectivity between aromatic and nonaromatic substances and between acids and bases in the prevailing atmosphere. Therefore, it is anticipated that the dual-pore carbon capsule films developed in this work will find application in sensing and separation applications because of their designable selectivity.

Layer-by-Layer Deposition of Polyelectrolyte−Polyelectrolyte Complexes for Multilayer Film Fabrication

Abstract: Positively charged poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) complexes (noted as PAH-PAA) with a molar excess of PAH were layer-by-layer (LbL) assembled with polyanion poly(sodium 4-styrenesulfonate) (PSS) to produce multilayer films. The film structure and deposition behavior of the PAH-PAA/PSS films were influenced by the structure of PAH-PAA complexes in solution. For the PAH-PAA complexes with a low ratio of PAA to PAH the PAH-PAA complexes have low-level cross-linking and are flexible. The resultant PAH-PAA/PSS films have a thin film thickness and smooth surface and exhibit a nonlinear deposition behavior where the amount of PAH-PAA complexes and PSS deposited in each deposition cycle are larger than in its previous cycle. The PAH-PAA complexes with a high ratio of PAA to PAH have high-level cross-linking and are rigid. The PAH-PAA/PSS films constructed from the rigid PAH-PAA complexes have a large film thickness and rough surface and exhibit a linear deposition behavior. Deposition of the PAH-PAA/PSS films was well characterized by quartz crystal microbalance, atomic force microscopy, and scanning electron microscopy. The thermally cross-linked PAH-PAA/PSS films can be released from substrate to form stable free-standing films by an ion-triggered exfoliation method. Meanwhile, positively charged PAH-PAA complexes can be LbL assembled with negatively charged PAH-PAA complexes with a molar excess of PAA to produce multilayer films. Use of polyelectrolyte-polyelectrolyte complexes as building blocks for LbL fabrication provides a facile way to tailor the structures of the resultant films by simply changing the structure of the complexes in solution.

The Preparation of Sugar Polymer-Coated Nanocapsules by the Layer-by-Layer Deposition on the Liposome

Abstract: We intended to combine the liposomal preparation and the layer-by-layer deposition to prepare a nanosized capsule. Chitosan (CHI) was deposited to form the cationic polymeric layer onto a negatively charged liposomal surface and further deposition was carried out using anionic polymers dextran sulfate (DXS) or deoxyribonucleic acid (DNA). ζ-Potentials of nanocapsules changed between positive and negative charges at each deposition. FE-TEM revealed that the liposome remained a spherical shape even after the layer-by-layer (LbL) deposition. The capsule wall showed a dramatic increase in stability against the surfactant Triton X-100 compared to a bare liposome, and the stability was controllable by the adsorption amount of the polymer. These suggest that the polymer multilayer was generated on the liposome surface by the layer-by-layer depositions of polysaccharides. The three kinds of chemical substances with different charges, 1-hydroxy pyrene-3,6,8-trisulfonic acid (HPTS), alendronate, and glucose, were e...

Grapheme-organic material layered assembling film and preparation method thereof

Abstract: The invention relates to a graphene-organic material layered assembly film and a preparation method thereof. The preparation method comprises: using a graphene material and an organic material as raw materials, utilizing interaction of static electricity, hydrogen bonds, coordinate bonds or charge transfer and the like between the graphene and the organic material, and superposing films layer by layer through the film preparation methods such as spin coating, spraying, dipping, lifting and pulling and the like to prepare the film, wherein the thickness of each layer of the film can be controlled between 10 nanometers and 2 millimeters according to requirement. The layered assembly film and the preparation method have the characteristics that multilayer film materials with different functions are prepared by utilizing unique electric, magnetic, mechanical and chemical properties of the grapheme, and can be used as biomaterials, conductive materials, electromagnetic shielding and wave absorbing materials, photovoltaic materials, electrode materials, film filtering and separating materials, and the like to be applied to chemistry and chemical industry, biology and precision instruments, and manufacture of micro electrons, machinery and aviation and aerospace devices according to the selected different organic materials.

Spin-assisted layer-by-layer assembly: variation of stratification as studied with neutron reflectivity.

Abstract: We apply neutron reflectivity to probe the internal structure of spin-assisted layer-by-layer (SA-LbL) films composed of electrostatically assembled polyelectrolytes. We find that the level of stratification and the degree of layer intermixing can be controlled by varying the type and concentration of salt during SA-LbL assembly. We observe well-defined layer structure in SA-LbL films when deposited from salt-free solutions. These films feature 2-nm-thick bilayers, which are approximately 3-fold thicker than those in conventional LbL films assembled under similar conditions. The addition of a 10 mM phosphate buffer promotes progressive layer interdiffusion with increasing distance from the substrate. However, adding 0.1 M NaCl to the phosphate buffer solution restores the layer stratification. We also find that SA-LbL films obtained from buffer solutions are more stratified as compared to the highly intermixed layers seen in conventional LbL films from buffer. Our results yield new insights into the mechanism of SA-LbL assembly and the final microstructure in comparison with traditional LbL assemblies.

Layer-by-layer deposition of polyelectrolytes. Dipping versus spraying.

Abstract: We studied the properties of polyelectrolyte multilayer films prepared using the technique of polyelectrolyte deposition from solution (dipping) or supplying the solutions to the surface by spraying. The quality of films obtained by those two techniques was compared to find out whether the well-established dipping procedure can be replaced with the spraying technique. Neutron and X-ray reflectometric studies were performed on the samples of interest. We found that multilayers prepared by dipping are thicker, denser and less rough than films having the same number of layers, i.e., having the same number of deposition cycles, obtained by spraying.

Layer by layer immobilized horseradish peroxidase on zinc oxide nanorods for biosensing.

Abstract: Using zinc powders as source material, ZnO nanorods (ZnONR) were fabricated on gold wire by a hydrothermal reaction without any other surfactant. The gold wire end was coated by a thin layer of Zn-Au alloy to improve the nucleation for growth of ZnO nanostructures and to further improve the performance of the biosensor, which was constructed by alternatively immobilizing poly(sodium 4-styrenesulfonate) (PSS) and horseradish peroxidase (HRP) on the ZnONR. Electrochemical measurement, ultraviolet-visible spectrum, zeta-potential, and scanning electron microscopic analysis demonstrated that PSS and HRP were stably adsorbed layer by layer on the ZnONR surface, and the HRP kept bioactivity for H(2)O(2) detection without an electron transfer mediator. The multilayered HRP sensors exhibited a wide linear range and low detection limit. The sensitivity of the biosensor increased with the immobilized HRP layers from the lowest value of 36.28 microA mM(-1) for a monolayer.

Preparation of Protamine–Titania Microcapsules Through Synergy Between Layer‐by‐Layer Assembly and Biomimetic Mineralization

Abstract: A novel approach combining layer-by-layer (LbL) assembly with biomimetic mineralization is proposed to prepare protamine-titiania hybrid microcapsules. More specifically, these microcapsules are fabricated by alternative deposition of positively charged protamine layers and negatively charged titania layers on the surface of CaCO 3 microparticles, followed by dissolution of the CaCO 3 microparticles using EDTA. During the deposition process, the protamine layer induces the hydrolysis and condensation of a titania precursor, to form the titania layer. Thereafter, the negatively charged titania layer allows a new cycle of deposition step of the protamine layer, which ensures a continuous LbL process. The morphology, structure, and chemical composition of the microcapsules are characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Moreover, these protamine-titania hybrid microcapsules are first employed as the carrier for the immobilization of yeast alcohol dehydrogenase (YADH), and the encapsulated YADH displays enhanced recycling stability. This approach may open a facile, general, and efficient way to prepare organic-inorganic hybrid materials with different compositions and shapes.

Structural color via layer-by-layer deposition: layered nanoparticle arrays with near-UV and visible reflectivity bands

Abstract: The same near-ultraviolet (NUV) (300–400 nm) light that facilitates photo-degradation in polymers is also a key component in animal communication, particularly in insects and birds. We developed a nature-inspired 1D photonic crystal structure that has simultaneous narrow stop bands in the NUV and visible wavelength range, resulting in a NUV reflector with tunable structural color in the visible region of the spectrum. The samples were prepared by high precision deposition of alternating stacks of SiO2 and more densely packed TiO2nanoparticlesvia aqueous layer-by-layer (LbL) deposition. Multilayer thin films with eleven stacks achieved up to 75% reflectance with a 50 nm bandwidth and 65% reflectance with a 100 nm bandwidth for structural colors centered at 500 nm and 690 nm, respectively. Despite UV absorbance of the TiO2nanoparticles and the supporting glass substrate, all samples exhibited a narrow NUV stop-band centered in the 300–400 nm range with a reflectance over 65%. Upon introduction of a defect mode, we also demonstrated the creation of a narrow reflectance dip associated with a localized state in the photonic band gap. Multilayer-based structural colors with NUV reflectivity can be used as pigments that can promote prevention of photo-degradation in coatings, in addition to bird and insect repelling functionality.

Vapour sensing with conductive polymer nanocomposites (CPC): Polycarbonate-carbon nanotubes transducers with hierarchical structure processed by spray layer by layer

Abstract: The development of conductive polymer nanocomposite (CPC) sensors for volatile organic compounds (VOC) detection has been carried out using a spray layer by layer (LbL) process. This technique was successfully used to hierarchically structure polycarbonate-multiwall carbon nanotubes (PC-CNT) solutions into a double percolated architecture as attested by atomic force microscopy (AFM) and optical microscopy (OM). PC-CNT vapour sensing behaviour was investigated as a function of CNT content, films thickness, vapour flow and vapours solubility parameter. The response ranking Ar(toluene) > Ar(methanol) > Ar(water) of PC-CNT was found to be coherent with κ12 Flory–Huggins interaction parameters provided that signals are normalised by analyte molecules number. Signals shape was interpreted to the light of Langmuir–Henry–Clustering (LHC) model and found to be proportional to vapour content.

Heterogeneous ultrathin films of poly(vinyl alcohol)/layered double hydroxide and montmorillonite nanosheets via layer-by-layer assembly.

Abstract: In this paper, Co−Al layered double hydroxide (LDH) and montmorillonite (MMT) have been exfoliated into charged single layers in the solvent of formamide and water, respectively. The structures of ...

Influence of pH on the structure of multilayer films composed of strong and weak polyelectrolytes.

Abstract: The sequential adsorption of oppositely charged polyelectrolytes called the "layer by layer" technique is a method for formation of ultrathin films with controlled thickness and interfacial properties. Composition of polyelectrolyte solutions, pH, and electrolyte concentration are important parameters governing formation of multilayer films. Since pH is the factor controlling charge of weak polyelectrolytes, the structure of multilayers should be sensitive to its value. In this paper we focused on formation of PE multilayer films composed from weak and strong polyelectrolytes. We used weak, branched polycation polyethyleneimine (PEI, 70 kDa) and strong polyanion poly-4-styrenesulfonate (PSS, 70 kDa) to form films by the layer-by-layer technique on the surface of silicon wafers under two deposition conditions: pH = 6 when PEI was strongly charged and pH = 10.5 when the charge density of PEI was low. Thicknesses of films were measured by single wavelength ellipsometry, and the results were confronted with ones concerning mass of the adsorbed films obtained by quartz crystal microbalance. We found that, depending on pH of the solutions, combination of weakly and strongly charged polyelectrolytes gave either linear or nonmonotonic increase of film thickness with a number of deposited PE layers. We observed a good correlation between multilayer film thickness and adsorbed mass. The atomic force microscopy images of surface topography of PEI/PSS films demonstrated large differences between films deposited at pH = 6 and 10.5. Additionally the cyclic voltamperometry was used to determine the differences in permeability of films formed at various pH conditions.

Method and apparatus for producing three-dimensional objects

Abstract: The invention concerns a method for producing three-dimensional objects (6) layer by layer using a powdery material (7) which can be solidified by irradiating it with a high-energy beam(4), said method comprising the steps of: applying a first layer of powdery material onto a working area (5); solidifying a part of said first layer by irradiating it with a high-energy beam; andapplying a second layer (8) of powdery material onto thefirst, partly solidified layer. The invention is characterized in that the method comprises the step of: determining a rate at which the temperature of the second layer (8) increases after application onto the first layer.The invention also concerns an apparatus configured to operate according tothe above method.

Adsorption kinetics and mechanical properties of ultrathin polyelectrolyte multilayers: liquid-supported versus solid-supported films.

Abstract: Multilayers of sodium salt of poly(4-styrene sulfonate) (PSS) and poly(diallyl dimethyl ammonium) chloride (PDADMAC) have been built layer by layer (LbL) both at the solid/aqueous interface (solid supported) and the air/aqueous interface (liquid supported). For the solid-supported multilayers, the adsorption kinetics and the complex shear modulus were measured using a dissipative quartz crystal microbalance and a null ellipsometer. A bubble tensiometer was used to measure the adsorption kinetics and the elasticity modulus of the liquid-supported multilayers. At the solid/aqueous interface, adsorption kinetics changes with the number of adsorbed layers. However, at the air/aqueous interface, PSS dynamics were the same for all adsorbed layers except the first. Conversely, the adsorption kinetics of PDADMAC at the air/water surface differed between those layers close to the interface and those far from it. Multilayers grow at the air/water interface by an intrinsic-charge-compensation process, whereas, for the same ionic strengths, solid-supported layers deposit by the extrinsic-charge-compensation process. No significant differences were found between the recoverable dilational storage modulus of the liquid-supported multilayers and the real part of the shear modulus of the solid-supported ones built at the same ionic strength. The values of the modulus are in the MPa range, which corresponds to gel-like films. This result is in agreement with the strong hydration degree of the LbL films calculated from ellipsometry measurements.

Layer-by-layer TiO2 films as efficient blocking layers in dye-sensitized solar cells

Abstract: Charge recombination at the conductor substrate/electrolyte interface has been prevented by using efficient blocking layers of TiO2 compact films in dye-sensitized solar cell photoanodes Compact blocking layers have been deposited before the mesoporous TiO2 film by the layer-by-layer technique using titania nanoparticles as cations and sodium sulfonated polystyrene, PSS, as a polyanion The TiO2/PSS blocking layer in a DSC prevents the physical contact of FTO and the electrolyte and leads to a 28% increase in the cell's overall conversion efficiency, from 57% to 73%

Epitaxial and layer-by-layer growth of EuO thin films on yttria-stabilized cubic zirconia (001) using MBE distillation

Abstract: We have succeeded in growing epitaxial and highly stoichiometric films of EuO on yttria-stabilized cubic zirconia (YSZ) (001). The use of the Eu-distillation process during the molecular beam epitaxy assisted growth enables the consistent achievement of stoichiometry. We have also succeeded in growing the films in a layer-by-layer fashion by fine tuning the Eu vs oxygen deposition rates. The initial stages of growth involve the limited supply of oxygen from the YSZ substrate, but the EuO stoichiometry can still be well maintained. The films grown were sufficiently smooth so that the capping with a thin layer of aluminum was leak tight and enabled ex situ experiments free from trivalent Eu species. The findings were used to obtain recipes for better epitaxial growth of EuO on MgO (001).

Centrifugal Deposition of Microgels for the Rapid Assembly of Nonfouling Thin Films

Abstract: Thin films assembled from microgel building blocks have been constructed using a simple, high-throughput, and reproducible centrifugation (or “active”) deposition technique. When compared to a common passive adsorption method (e.g., dip coating), microgels that are actively deposited onto a surface have smaller footprints and are more closely packed. Under both active and passive deposition conditions, the microgel footprint areas decrease during deposition. However, under active deposition, the microgel footprint appears to decrease continually and to a greater degree over the course of the deposition, forming a tightly packed, homogeneous film. Taking advantage of the rapid and uniform assembly of these films, we demonstrate the use of active deposition toward the fabrication of polyelectrolyte multilayers containing anionic microgels and a cationic linear polymer. Microgel multilayers successfully demonstrated effective blocking of the underlying substrate toward macrophage adhesion, which is a highly ...