Assembly Of Films Research Articles

Vortex-assisted layer-by-layer assembly of silver nanowire thin films for flexible and transparent conductive electrodes

Silver nanowires (AgNWs) have drawn much attention as potential candidates to replace conventional transparent conductive materials such as indium tin oxide (ITO). AgNWs have advantages over ITO with respect to cost and ease of fabrication, and can be used in flexible electrodes. However, the preparation of homogeneous films from the AgNW colloidal suspension is still a challenge mainly because of the coagulation and sedimentation of AgNWs in aqueous media. In this study, uniform transparent conductive films were prepared by using AgNWs paired with poly(allylamine hydrochloride) (PAH) via the vortex-assisted layer-by-layer (VA-LbL) assembly method. We introduced poly(allylamine hydrochloride) (PAH) to bind the AgNWs to the substrates via coordination bonding. Vortex agitation was also applied during the adsorption of AgNWs to achieve a uniform deposition on the substrate. We systematically examined other experimental conditions such as the concentration of AgNW solution and temperature of the heat treatment to correlate them to the transparency and the conductivity of the films. In addition, AgNW films were prepared on transparent and flexible substrates and these exhibited excellent durability against bending (1000 bending cycles).

Impact of surface wettability on S-layer recrystallization: a real-time characterization by QCM-D.

Quartz crystal microbalance with dissipation monitoring (QCM-D) has been employed to study the assembly and recrystallization kinetics of isolated SbpA bacterial surface proteins onto silicon dioxide substrates of different surface wettability. Surface modification by UV/ozone oxidation or by vapor deposition of 1H,1H,2H,2H-perfluorododecyltrichlorosilane yielded hydrophilic or hydrophobic samples, respectively. Time evolution of frequency and dissipation factors, either individually or combined as the so-called Df plots, showed a much faster formation of crystalline coatings for hydrophobic samples, characterized by a phase-transition peak at around the 70% of the total mass adsorbed. This behavior has been proven to mimic, both in terms of kinetics and film assembly steps, the recrystallization taking place on an underlying secondary cell-wall polymer (SCWP) as found in bacteria. Complementary atomic force microscopy (AFM) experiments corroborate these findings and reveal the impact on the final structure achieved.

DNA Fingerprints: Advances in their Forensic Analysis Using Nanotechnology

For deciphering the secrets of forensic science, nanotechnology has quite extensively been utilized. Generally, for identifying the fingerprints, a lot of combination of different materials and film assemblies have already been utilized. Since the mode of interaction between the nanoparticles and fingerprint marks, is still not clearly understood, fabricating the nanoparticle assemblies for their identification is quite challenging. Complete identification of fingerprint marks which are generally because of a combination of some kind of proteins and fatty acids, is still a difficult task and is only partially being done with the help of different techniques. Nanotechnology has already shown immense potential in many fields like medicine, molecular biology, genetics, material science etc. and it has also marked promising potential even in forensic analysis studies. This review aims to discuss the details of the process of fingerprint formation, their role in forensic analysis along with the latest advances in the field of nanotechnology for their identification. This information may enhance our understanding about the progress in the forensic analysis of fingerprints, which may further be utilized in solving the puzzle of various criminal cases.

Surface modification of PEN and PET substrates by plasma treatment and layer-by-layer assembly of polyelectrolyte multilayer thin films and their application in electroless deposition

Surface modification of PEN and PET substrates by plasma-treatment and LbL assembly of polyelectrolyte multilayers and subsequent electroless nickel deposition.

Ordered assembly of hybrid room-temperature phosphorescence thin films showing polarized emission and the sensing of VOCs.

Benefitting from the self-organization of organic phosphors into 2D galleries of clay nanosheets, we have developed a method for the ordered assembly of long-lived room-temperature phosphorescence (RTP) thin films through a layer-by-layer (LBL) process. The clay-based thin films present polarized RTP and serve as sensors for VOCs.

Development of target fabrication for laser-driven inertial confinement fusion at research center of laser fusion

As the basic conditions for laser inertial confinement fusion (ICF) research, the targets are required to be well specified and elaborately fabricated. Because of the characteristics of the targets, the research and fabrication process is a systematically tough task, which needs fundamental and deep insights into film deposition, mechanical machining, precise measurement and assembly, etc. As a result, knowledge of material science, physics, mechanical as well as electronics is a necessity for target researchers. In this paper, we give introductions to the state of art on target fabrication for ICF research at Research Center of Laser Fusion (RCLF) in China.

Integrated Flexible Thin Film Sensor Around Angiographic Catheter for Flow Detection

Integration of thin film inorganic sensors over curved surface requires flexibility of the thin film assembly along with the substrate for various applications. In the present study, a micro thin film flow sensor was fabricated over a soft biocompatible PDMS elastomer. A non-planar topology was used for proper orientation of the thin film buckles along the direction of bending along with pre-stretching of the elastomer to account for larger buckles. The resulting sensors demonstrated high flexibility by successfully wrapping around angiographic 2mm diameter catheter maintaining good electrical continuity. Preliminary flow sensing of a meanderline shaped micro thermal flow sensor was performed using a custom build flow setup for high and low pulsatile flow rates as well as detection of flow abnormalities due to blockage/stenosis formation. The sensors demonstrated significant response to varying degree of blockages at even low flow rates thereby indicating potential application of such sensor for in-vivo catheterial operations.

Templated assembly of metal nanoparticle films on polymer substrates

We report on directed self-assembly of ordered, vapor-deposited gallium nanoparticles on surface-relief-structured polymer substrates. Grating templates impose periodic order in one dimension, most effectively when the grating half-period is of the order of the mean unperturbed center-to-center particle spacing for a given mass-thickness of Ga. Self-organized order also emerges in the perpendicular direction as a consequence of the liquid-phase particles' nucleation, growth, and coalescence on the ridges of the grating pattern in relative isolation from the adjacent slots, and vice versa.

Light welding nanoparticles: from metal colloids to free-standing conductive metallic nanoparticle film

Bottom-up assembly of nanostructured thin films could offer an alternative low-cost approach to electronic thin films. However, such solution-processed thin films are often plagued by excessive inter-particle resistance and only exhibit limited current delivering capability. Here, we report a novel approach to fabricate highly conductive free-standing metallic thin film, accomplished by combining interfacial self-assembly of nanoparticles (NPs) and a light welding process. We found that light from a xenon lamp can weld adjacent Ag and Au NPs assembled at the water-air interface, forming a highly interconnected, free-standing metallic thin film structure with excellent electrical transport properties. With such a unique structure, the resultant thin metallic films show not only high flexibility and robustness, but also high conductivity comparable to bulk metallic thin films. Our studies offer a low-cost, room-temperature, and solution-processable approach to highly conductive metallic films. It can significantly impact solution-processable electronic and optoelectronic devices.

A Technical Study of DI Workflow in Hollywood

The DI (Digital Intermediate) is often defined as a digital replacement for a photochemical ‘intermediate’, a stage in processing in which a strip of film is used to reorganize and make changes to the original, source footage prior to output, and is regarded as widely applicable from Hollywood big budget film productions to Korean low budget Independent film productions. DI is often incorrectly understood as the digital assembly and color correction of films. Companies that set up their DI business in the early days of the technology primarily on the basis of colour correction have either left the business or have changed their approach. This technical study introduce ASC and PGA Camera Assessment Series for DI that was set up by American Society of Cinematographers and Producers Guild of America in 2009-2010. And also Image Interchange Framework(IIF) based on Academy of Motion Picture Arts and Sciences Regulations in 2011-2012 is discussed. This essay try to figure the Hollywood Standard DI Workflow out in recent years. This essay has been put together for those thinking of becoming involved in DI. It is based on the real world experiences of established DI post houses. This study discusses how practical technology issues about DI relate to making it a successful system.

Innovation in Layer-by-Layer Assembly.

Methods for depositing thin films are important in generating functional materials for diverse applications in a wide variety of fields. Over the last half-century, the layer-by-layer assembly of nanoscale films has received intense and growing interest. This has been fueled by innovation in the available materials and assembly technologies, as well as the film-characterization techniques. In this Review, we explore, discuss, and detail innovation in layer-by-layer assembly in terms of past and present developments, and we highlight how these might guide future advances. A particular focus is on conventional and early developments that have only recently regained interest in the layer-by-layer assembly field. We then review unconventional assemblies and approaches that have been gaining popularity, which include inorganic/organic hybrid materials, cells and tissues, and the use of stereocomplexation, patterning, and dip-pen lithography, to name a few. A relatively recent development is the use of layer-by-layer assembly materials and techniques to assemble films in a single continuous step. We name this "quasi"-layer-by-layer assembly and discuss the impacts and innovations surrounding this approach. Finally, the application of characterization methods to monitor and evaluate layer-by-layer assembly is discussed, as innovation in this area is often overlooked but is essential for development of the field. While we intend for this Review to be easily accessible and act as a guide to researchers new to layer-by-layer assembly, we also believe it will provide insight to current researchers in the field and help guide future developments and innovation.

Catalyst morphology matters for lithium–oxygen battery cathodes

The effectiveness of using catalyst nanoparticles to reduce the overpotential and energy efficiency of lithium–oxygen (or lithium–air) batteries (LOBs) is usually attributed to the inherent catalytic properties of individual nanoparticles. Here, we demonstrate that the morphology of the catalyst layer is equally important in maintaining integrity of the catalyst coating during product formation in LOBs. We demonstrate this by comparing the performance of smooth, conformal coated Mn2O3 catalyst nanoparticles prepared by electric field-assisted deposition, and more irregular coatings using conventional film assembly techniques both on three-dimensional mesh substrates. Smooth coatings lead to an improved overpotential of 50 mV during oxygen reduction and 130 mV during oxygen evolution in addition to a nearly 2X improvement in durability compared to the more irregular films. In situ electrochemical impedance spectroscopy combined with imaging studies elucidates a mechanism of morphology-directed deactivation of catalyst layers during charging and discharging that must be overcome at practical electrode scales to achieve cell-level performance targets in LOBs.

Carbonized Electrospun Nanofiber Sheets for Thermophones.

Thermoacoustic performance of thin freestanding sheets of carbonized poly(acrylonitrile) and polybenzimidazole nanofibers are studied as promising candidates for thermophones. We analyze thermodynamic properties of sheets using transport parameters of single nanofibers and their aligned and randomly electrospun thin film assemblies. The electrical and thermal conductivities, thermal diffusivity, heat capacity, and infrared blackbody radiation are investigated to extract the heat exchange coefficient and enhance the energy conversion efficiency. Spectral and power dependencies of sound pressure in air are compared with carbon nanotube sheets and theoretical prediction. Despite lower thermoacoustic performance compared to that of CNT sheets, the mechanical strength and cost-effective production technology of thermophones make them very attractive for large-size sound projectors. The advantages of carbonized electrospun polymer nanofiber sheets are in the low frequency domain (<1000 Hz), where the large thermal diffusion length diminishes the thermal inertia of thick (∼200 nm) nonbundled fibers and the high intrinsic thermal conductivity of fibers enhances the heat exchange coefficient. Applications of thermoacoustic projectors for loudspeakers, high power SONAR arrays, and sound cancellation are discussed.

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker.

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.

Resistive Switching Characteristics of Ta&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;5&lt;/SUB&gt; Thin Film and Maghemite Nanoparticles Assembly Hybrid Device

Resistive Switching Characteristics of Ta&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;5&lt;/SUB&gt; Thin Film and Maghemite Nanoparticles Assembly Hybrid Device

Regenerable polymer/ceramic hybrid nanofiltration membrane based on polyelectrolyte assembly by layer-by-layer technique

A new regenerable nanofiltration membrane based on LbL film assembly of PDADMAC/PSS on a ceramic support is presented. Using a constant flux coating method the large pores of the ceramic support with a diameter of about 100nm could be covered and closed with only 3 bilayers. The performance of the presented membrane is comparable to today's nanofiltration membranes. Remarkably, the stability is superior as the membranes withstand backwashing as well as low and high pH. The intrinsic contradiction of a stable but also regenerable membrane is addressed as well. The LbL film is deconstructed using high concentrated salt solution, ionic surfactants, and hypochlorite in succession. After deconstruction the film is rebuilt resulting in exactly the same properties as observed before film deconstruction. Due to the ability of regeneration the more stable but also more expensive ceramic support can be reused. The regeneration was conducted within the membrane housing demonstrating its practical viability for membrane assembly and regeneration within modules being potentially on-site in a membrane plant.

Surface‐directed molecular assembly of pentacene on aromatic organophosphonate self‐assembled monolayers explored by polarized Raman spectroscopy

Organophosphonate self-assembled monolayers (SAMPs) fabricated on SiO2 surfaces can influence crystallization of vapor-deposited pentacene and thus can affect device performance of pentacene-based organic thin film transistors. Polarized Raman spectroscopy is demonstrated to be an effective technique to determine the degree of anisotropy in pentacene thin films deposited on three structurally different, aromatic SAMPs grown on silicon oxide dielectrics. Vibrational characterization of pentacene molecules in these films reveals that the molecular orientation of adjacent crystalline grains is strongly correlated on the SAMP-modified dielectric surface, which results in enhanced interconnectivity between the crystallite domains, well beyond the size of a single grain. It is found that vibrational coupling interactions, relaxation energies, and grain size boundaries in pentacene thin films vary with the choice of SAMP. This information clearly shows that molecular assembly of pentacene thin films can be modulated by controlling the SAMP-modified dielectric surface, with potentially beneficial effects on the optimization of electron transfer rates. Copyright © 2016 John Wiley & Sons, Ltd.

Layer-by-Layer Assembly of Carbon Dots-Based Ultrathin Films with Enhanced Quantum Yield and Temperature Sensing Performance

Carbon dots (CDs), an rising kind of fluorescent carbon material, have been extensively studied due to their unique physicochemical properties, but the research on solid state devices and applications is rather lacking. Herein, we report the fabrication of fluorescent ultrathin films (UTFs) by embedding CDs into the 2D layered double hydroxides (LDHs) nanosheets through layer-by-layer assembly. The resulting UTFs present long-range ordered structure and improved luminescent properties compared with the CDs drop-casted films, including quantum yield (57.17% vs 3.04%) and fluorescence lifetime (14.47 ns vs 0.813 ns). This significant enhancement is due to the molecular level dispersion of CDs and the confinement of photoexcited electrons imposed by LDH nanosheets, which is confirmed by both experimental studies and density functional theoretical (DFT) calculations. Moreover, the UTFs display temperature-responsive photoluminescence (PL) and electrochemiluminescence (ECL) performances. Therefore, this work p...

Isomeric Effect Enabled Thermally Driven Self-Assembly of Hydroxystyrene-Based Block Copolymers.

We demonstrate through isomeric effect the modulation of thermal properties of poly(hydroxystyrene) (PHS)-based block copolymers (BCPs). A minimal structural change of substituting 3HS for 4HS in the BCP results in a drastic decrease in Tg, which in turn enables the thin film assembly of the BCP via thermal annealing. We synthesized a series of poly(3-hydroxystyrene-b-tert-butylstyrene) [P(3HS-b-tBuSt)] and poly(4-hydroxystyrene-b-tert-butylstyrene) [P(4HS-b-tBuSt)] BCPs by sequential anionic polymerization of protected 3HS/4HS monomer and tBuSt followed by deprotection. Measured Tg of P(3HS) was ∼20-30 °C lower than P(4HS) of comparable molecular weights. As a result, thermally driven self-assembly of P(3HS-b-tBuSt) BCPs in both bulk and thin film is demonstrated. For P(4HS-b-tBuSt) thermal annealing in thin-film at high temperatures results in poorly developed morphology due to cross-linking reaction of the 4HS block. The smallest periodicity observed for P(3HS-b-tBuSt) was 8.8 nm in lamellar and 11.5 nm in cylindrical morphologies. The functionality of the 3HS block was exploited to incorporate vapor phase metal oxide precursors to generate sub-10 nm alumina nanowires.

Patterned Liposome–Polymer Composite Coatings

AbstractEngineered biointerfaces are crucial for many biomedical applications involving the interaction of (bio)materials with cells and tissue. Providing cues to support cell adhesion/proliferation in the form of biomolecules and/or by providing spatially controlled adhesive patches are important aspects. We demonstrate the assembly of composite films consisting of negatively charged liposomes (Ln), poly(dopamine) or cholesterol‐modified poly(methacrylic acid) (PMAc) capping layers and (poly(l‐lysine)/PMAc)x terminating multilayers. We show that hepatocytes adhere to the assembled composite coatings. Their association with fluorescent lipids from the film varies depending on the capping layer and cell adhesion time. This association was suggested to be an energy‐dependent process. Further, the incorporation of paclitaxel (TX) into Ln reduces the number of hepatocytes adhering to films without terminating multilayers. An exemplary composite coating is patterned, and the subsequent site‐selective adhesion of hepatocytes is shown. For the first time, composite coatings to be used for substrate‐mediated drug delivery with control over the positioning of the adhering cells are shown.