Surface Of Hybrid Films Research Articles

Bismuth-magnesium-oxide-based graphene oxide hybrid film for liquid crystal device application

Hybrid films containing bismuth magnesium oxide (BiMgO) and graphene oxide (GO) are investigated in this study. Solution-processed brush coating is used to fabricate the hybrid films, with the graphene oxide weight ratios adjusted to 0, 5, and 15%. The hybrid films show more stable and higher optical transmittances than the pure BiMgO film. A directional micro/nanogroove structure is observed on the hybrid film surface, which is derived from the shear stress during the brush-coating process; this anisotropic structure is used as a uniform liquid crystal (LC) alignment layer. Uniform and homogeneous LC alignment is then demonstrated via polarized optical microscopy and pretilt angle analyses, along with perfect light-control performance. Enhanced LC polar anchoring energy and hysteresis-free characteristics are observed for the brush-coated hybrid film as the GO-doping concentration is increased. Based on this perspective, the BiMgO-based GO hybrid film achieved via brush coating has potential for applications in next-generation LC systems.

In situ growth of TiO2 and its immobilization on PVDF films for the adsorption and photocatalytic degradation of dye

Organic pollutants, such as dyes, contaminated water bodies seriously. Suitable materials and efficient technologies for degrading pollutants needed to be explored to protect the environment and human health. In this investigation, PVDF(PAA-g-β-CD)@TiO2 hybrid film was prepared by a combination of “in situ hydrothermal-vapor induction” under mild conditions. The distribution, particle size, and interaction with the film surface for TiO2 were investigated by XRD, XPS, SEM, and EDS. The TiO2 nanoparticles were firmly immobilized and uniformly distributed on the hybrid film surface. Poly (acrylic acid) (PAA) and β-cyclodextrin (β-CD) on the film matrix were connected by the chemical bond, which provided stable nucleation and growth sites for TiO2 while inhibiting photogenerated electron-hole recombination and significantly enhancing the adsorption ability. Furthermore, the multiple interaction forces (hydrogen bonding, coordination, and hydrophilic-hydrophilic interactions) between the film matrix and the TiO2 were evaluated by simulated geometries and theoretical calculations. The multiple interactions reduced the band gap (Eg) while endowing the hybrid photocatalytic film with excellent degradation efficacy (η), stability, and recycling properties. Finally, the η of methylene blue (MB) reached 97.34 % within 120 min and remained above 90 % even after 8 reuses. It was believed that PVDF(PAA-g-β-CD)@TiO2 film provided an approach for the mild preparation of polymer/TiO2 hybrid film with high catalytic activity and optimization of photocatalytic properties.

Achievement of Unidirectional Aluminum Tin Oxide/UV-Curable Polymer Hybrid Film via UV Nanoimprinting Lithography for Uniform Liquid Crystal Alignment

A uniform unidirectional nanostructure composed of aluminum tin oxide and ultraviolet (UV)-curable polymer is introduced herein. The nanostructure was produced by UV-nanoimprint lithography (UV-NIL), and the fabricated hybrid film was used as a uniform liquid crystal (LC) alignment layer. Atomic force microscopy and line profile analysis were performed to confirm a well-ordered nanostructure with 760 nm periodicity and 30 nm height. X-ray photoelectron spectroscopy analysis was also conducted to examine the chemical modifications to the hybrid film surface during UV exposure. Optical transmittance investigation of the nanopatterned hybrid film revealed its compatibility for LC device application. Stable, uniform, and homogeneous LC alignment on the hybrid film was confirmed by polarized optical microscopy observance and analysis of LC pretilt angle. The unidirectional structure on the film surface enabled uniform LC orientation along with surface anisotropy property. Hence, we expect that the proposed UV-NIL process can be applied to fabricate high-resolution unidirectional nanostructures with various inorganic/organic hybrid materials and that these nanostructures have high potential for next-generation LC systems.

Solution-based CdS thin film transistors with low temperature-processed Al2O3-GPTMS-PMMA as hybrid dielectric gate

Herein, we report the low-temperature fabrication process and the electrical response of n-type cadmium sulfide (CdS)-based thin-film transistors (TFTs) with an Al2O3-GPTMS-polymethylmethacrylate (PMMA) hybrid dielectric gate. The TFTs with bottom-gate structure were assembled on ITO (indium-tin-oxide)-coated glass substrates employing solution processes for the deposition of both the dielectric gate and semiconductor layers. The hybrid dielectric layers were deposited by the sol-gel process and subsequently annealed at 150 °C. The FTIR and XPS analysis of the hybrid films demonstrated a proper link between Al2O3 and PMMA through the cross-linking agent 3-glycidoxy(propyltrimethoxysilane) silane (GPTMS). The surface characteristics were obtained by contact angle and atomic force microscope studies, the results show that the surface of hybrid films displays a hydrophobic behavior with a smooth surface. The CdS active layer was deposited on the hybrid dielectric gate at room temperature by a simple photochemical bath deposition using a 313 nm UV lamp. The CdS-TFTs showed outstanding electrical performance with a low threshold voltage of 1.3 V, I ON /I OFF of 104, subthreshold swing of 440 mV dec−1, and remarkable high mobility value of 64.4 cm2 V−1 s−1. Ultimately, the feature of these completely solution-based CdS TFTs is the maximum processing temperature of 150 °C, and the findings of this study are very promising for potential low-cost solution-processed TFTs.

Perfluorinated compounds are not necessary: pegylated organosilanes can endow good water sliding/removal properties

From a viewpoint of reducing the burden on both human health and the environment, alternative surface modification techniques for preparing highly water-repellent surfaces without the use of environmentally damaging perfluorocarbons are highly desirable. Among them, the development of hydrophilic surfaces showing superior water sliding/removal properties has been scarcely reported. In this study, we have successfully demonstrated the fabrication of smooth, transparent, and hydrophilic pegylated organosilanes (PEGn-Si, CH3O-(C2H4O)n-C3H6-Si(OCH3)3 where n = 3, 6–9, 9–12)-derived hybrid films showing excellent water sliding/removal properties using a simple sol-gel reaction of PEGn-Si and tetraethoxysilane (TEOS, Si(OC2H5)4). The final static/dynamic surface wetting properties of the samples were found to be significantly influenced by both the PEG chain length and their mixing ratios. The use of PEGn-Si with the longest PEG chain (n = 9–12) was found to be effective for improving water sliding/removal properties. Small volume water droplets (5 μL) on the PEG9−12-Si/TEOS hybrid film (static water contact angle (CA) of ∼40°) at a 90°-inclined surface could slide at an average speed of 3.4 mm/sec without pinning and tailing, which was about twice as fast as that on the PEG6−9-Si/TEOS hybrid film surface (1.5 mm/sec, static water CA of ∼40°), in spite of having similar static hydrophilic nature.

Electrochemical Deposition of γ-MnO2 on Ag/rGO Hybrid Films as Flexible Electrode Materials for Asymmetric Supercapacitor

The flexible electrodes are the essential components for fabricating modern flexible supercapacitors. In this study, a composite hybrid film integrated with silver nanoparticles (Ag NPs), reduced graphene oxide (rGO) and γ-MnO2 nanorods as a flexible electrode has been developed by the electrochemical deposition method. The substrate (rGO) of the electrode not only provides mechanical stability but also ensures fast electron transfer during charge–discharge. The Ag NPs distributed in electrode provide the electronic channel to enhance the electric conductivity. The γ-MnO2 electroplated on the surface of hybrid films further improved the electrochemical performance of them. The resultant γ-MnO2/Ag/rGO hybrid films exhibit a high specific capacitance of 1090.3 F g−1 at current density of 0.3 A g−1. The asymmetric supercapacitor (ASC) devices were further fabricated by γ-MnO2/Ag/rGO films as anode and AC/rGO films as cathode electrodes within a wide operating voltage of 0–1.7 V. The energy density of obtained ASC devices was 71.8 Wh kg−1 at a power density of 279.4 W kg−1.

Synthesis of nano‐TiO2/fluorinated polyacrylate core‐shell latex and its application in fabric finishing

Nano‐TiO2/fluorinated polyacrylate hybrid latex was prepared by soap‐free emulsion polymerization using reactive emulsifier. With the increase of modified nano‐TiO2 content, the monomer conversion gradually decreased while the gel rate slowly increased accordingly. The transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses indicated that the core‐shell latex particles were uniform with narrow size distribution. In addition, the hybrid film formed from nano‐TiO2/fluorinated polyacrylate latex presented higher thermal stability, mechanical and UV‐shielding performance than the film formed from fluorinated polyacrylate latex. Scanning electron microscopy (SEM) and water contact angles (WCA) analyses confirmed that the surface of hybrid film was slightly rough and hydrophobic. Furthermore, the energy dispersive X‐ray (EDX) analysis revealed that the organic fluorine segment had the tendency to migrate to the film‐air interface. At last, the results of the antibacterial activity and WCA showed that the cotton fabric treated with nano‐TiO2/fluorinated polyacrylate hybrid latex possessed good antibacterial property and remarkable water repellency. POLYM. COMPOS., 39:4467–4476, 2018. © 2017 Society of Plastics Engineers

Synergistic enhancement of electrical and mechanical properties of polypyrrole thin films by hybridization of SiO2 with vapor phase polymerization

This paper reports the fabrication of conductive polypyrrole (PPy)-SiO2 hybrid thin films having a flat surface (surface roughness value < 10 nm) through vapor phase polymerization (VPP) of pyrrole and tetraethyl orthosilicate (TEOS) on a ferric p-toluenesulfonate-coated substrate. Substantial improvement in the physicochemical and electrical properties of the hybrid film, compared to those of the pristine PPy film, could be achieved by simultaneous VPP of pyrrole and TEOS. The SiO2 proportion in the hybrid films, as investigated by X-ray photoelectron spectroscopy, strongly depended on the content of TEOS in the monomer mixture. Formation of a homogeneous interpenetrating network of PPy and silica was indicated by the enhancement of conductivity, atomic force microscopy images, and roughness value of the hybrid film surface. Moreover, a micropatterned PPy-SiO2 hybrid film could be fabricated by micromolding in capillaries combined with the simultaneous VPP method. Excellent electromechanical stability of PPy-SiO2 hybrid film was confirmed by the post-bending resistance change. Significant electrical degradation of PPy-SiO2 hybrid film was not observed even 11% strain in the compressive condition.

Phosphonate appended porphyrins as versatile chemosensors for selective detection of trinitrotoluene.

Fluorescent molecular probes based on phosphonate-functionalized porphyrin derivatives have been designed for selective detection of nitroaromatics. It is shown that molecular recognition is based on cooperative hydrogen bonding and π-π stacking interactions with electron-deficient molecules (nitroaromatic compounds, NACs), displaying superior detection toward trinitrotoluene (TNT). The P═O functional groups decrease the lowest unoccupied molecular orbital (LUMO) energy level of the porphyrins and, consequently, facilitate the electron inoculation to TNT through a photoinduced electron transfer (PET) process. The hydroxyl groups of the phosphonates and pyrrole -NH protons are further engaged in donor-acceptor interactions with TNT by strong intermolecular hydrogen bonding interactions (as evidenced by single crystal X-ray, NMR, and density functional theory (DFT)) showing turn off fluorescence behavior. The nonplanarity of the porphyrins induced by protonation at the central core of the porphyrin H4TPPA(2+) undergoes additional interactions, furnishing an anomalous increase in the selectivity of TNT at nanomolar levels in solution (limit of detection, LOD ∼ 5 nM). Porphyrin-doped hybrid PMMA [poly(methyl methacrylate)] polymer films demonstrate the reversibility of the fluorescence behavior and exhibit high photostability. The formation of discrete molecular aggregates on the surface of hybrid films and efficient diffusion of TNT vapors (10 ppb) displayed high selectivity in the solid state. The hybrid films are further used to demonstrate the detection of NACs in the aqueous medium, ultimately providing a platform for a practical strategy and implementation for the detection of toxic NACs.

The influence of SiO2 doping on the microstructure and photochromic behavior of phosphomolybdic acid/polyvinyl pyrrolidone hybrid films

New hybrid films were synthesized by SiO2 doping into phosphomolybdic acid (PMoA)/polyvinyl pyrrolidone (PVPd) composite system, and the effect of SiO2 doping on microstructure and photochromic properties was studied via atomic force microscope (AFM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectra (UV–vis) and X-ray photoelectron spectroscopy (XPS). The hybrid film surface with dome projection changed rough from smooth after SiO2 doping. The vibrational spectra of FT-IR verified that component of the heteropolyacids and the polymer did not changed, the vibration bands were expanded and had shifted by a few cm−1, and changed interaction between the acid and the polymer after SiO2 doping. The hybrid film exhibited a good photochromic property, which changed from colorless to blue under UV irradiation. The color change intensity of SiO2/PMoA/PVPd film was 1.48 times stronger than that of PMoA/PVPd under the same condition. XPS results indicated that the amount of PMoA in photo-reductive reaction was increased after SiO2 doping.

Atomic oxygen resistance of polyimide/silicon hybrid thin films with different compositions and architectures

Silicon (Si)-containing polyimides (PIs) with superior atomic oxygen (AO) resistance are promising materials for space applications. Here, in this study, we present the synthesis and characterization of eight Si-containing PI thin films and evaluate their AO durability. The resulting PI films exhibited high thermal stability and preferable AO resistance but showed slightly reduced mechanical performance relative to pristine PI. The highest optical transparency at 550 nm was observed for PI/octaaminopropylsilsesquioxane, while the lowest value was observed for PI/silica (SiO2) hybrids. X-Ray photoelectron spectroscopic study suggested that the topmost surface of PI was degraded at the early stage and an SiO2 inert protective layer was finally formed on the surface of hybrid films after AO exposure. It is found that Si-containing units of higher oxidation states and with higher Si/O molar ratio are favorable to improve the AO resistance. Dispersion of Si at molecular level contributes to improving anti-AO property as well as optical transparency of the prepared films. The characterization of scanning electron microscopy indicated a continuous SiO2 protective layer was crucial to prevent AO from eroding the bulk matrix.

Why Can Organic Liquids Move Easily on Smooth Alkyl-Terminated Surfaces?

The dynamic dewettability of a smooth alkyl-terminated sol-gel hybrid film surface against 17 probe liquids (polar and nonpolar, with high and low surface tensions) was systematically investigated using contact angle (CA) hysteresis and substrate tilt angle (TA) measurements, in terms of their physicochemical properties such as surface tension, molecular weight/volume, dielectric constant, density, and viscosity. We found that the dynamic dewettability of the hybrid film markedly depended not on the surface tensions but on the dielectric constants of the probe liquids, displaying lower resistance to liquid drop movement with decreasing dielectric constant (ε < 30). Interfacial analysis using the sum-frequency generation (SFG) technique confirmed that the conformation of surface-tethered alkyl chains was markedly altered before and after contact with the different types of probe liquids. When probe liquids with low dielectric constants were in contact with our surface, CH3 groups were preferentially exposed at the solid/liquid interface, leading to a reduction in surface energy. Because of such local changes in surface energy at the three-phase contact line of the probe liquid, the contact line can move continuously from low-surface-energy (solid/liquid) areas to surrounding high-surface-energy (solid/air) areas without pinning. Consequently, the organic probe liquids with low dielectric constants can move easily and roll off when tilted only slightly, independent of the magnitude of CAs, without relying on conventional surface roughening and perfluorination.

Surface and mechanical properties of hydrophobic silica contained hybrid films of waterborne polyurethane and fluorinated polymethacrylate

The surface and mechanical properties of hybrid films of waterborne polyurethane (WPU) and fluorinated polymethacrylate (FPMA), and high-hydrophobic silica (SiO2) contained hybrid films of FPMA/WPU were investigated. X-ray photoelectron spectroscopy confirmed that the surfaces of hybrid films exhibited notable fluorine enrichment. Scanning electron microscopy observation demonstrated that micro-scale rough structures consisted of sub-micro papillae and micro-scale wrinkles formed on the surfaces of FPMA/WPU. This was attributed to the enhanced phase separation of WPU and the incompatibility of low-surface-energy FPMA and WPU. Colloidal SiO2 was modified by polydimethylsiloxane and the modified SiO2 was reactive and high-hydrophobic. After the addition of reactive SiO2, the rough structures became micro-scale striped wrinkles studded with nano- and sub-micro papillae formed by the high-hydrophobic SiO2. The combination of the fluorine enrichment and the rough structures accounted for the high hydrophobic FPMA/WPU film and superhydrophobic SiO2/FPMA/WPU film.

Biomimetic Films of BLMs Based on Conductive Hybrid Films of Au NPs and Cellulose

A new type of biomimetic films of bilayer lipid membrane (BLM) supported by conductive hybrid film of Au nanoparticles (Au NPs) and cellulose is developed. The facile preparation method of the conductive hybrid films and the relevant micro conducting mechanism under electrochemical redox environment are revealed. The regenerated cellulose film is prepared from the cellulose/N-methylmorpholine N-oxide monohydrate solution. After the cellulose film is regenerated by deionized water, Au NPs in the colloid react with the newborn cellulose film. Rectangular pieces of dry hybrid films with one ends clamped with copper foil are used as electrodes. The lipid solution of phospholipid and cholesterol with a ratio of 3:1 is brushed onto the surface of dry hybrid films. There are only reducing currents in the cyclic voltammetry responses of biomimetic films under the aqueous electrolyte solution of 0.1 mol/L KCl, 1 mmol/L K3[Fe (CN)6] and 1 mmol/L K4[Fe (CN)6]. It means that the anions of [Fe (CN)6]4- are almost impossible to be oxidized into [Fe (CN)6]3- by the positively charged surfaces of Au NPs under voltages below 0.3 V.

Glucose Biosensor Based on Pt Nanoparticles/Graphene Chitosan Bionanocomposites

In this paper, we fabricated a bionanocomposite film of glucose oxidase/Pt nanoparticles/graphene-chitosan (GOD/PtNPs/GR-Chit) for glucose sensing. The hybrid bionanocomposites modified GCE were characterized by scanning electron microscopy (SEM), cyclic voltammetry, and amperometric i-t curve. It was found that the PtNPs were uniformly deposited on the surface of GR-Chit hybrid film. The resultant PtNPs/GR-Chit/GCE exhibited a high electrochemical catalytic ability to hydrogen peroxide (H2O2), due to the electrocatalytic synergy of GR and PtNPs. The redox behavior of the GOD/PtNPs/GR-Chit/GCE is a surface-controlled process. Finally, we obtained the amperometric response of the GOD/PtNPs/GR-Chit/GCE toward different concentration of glucose, and also achieved a sensitive glucose oxidase biosensor with a detection limit of 4.6μM glucose.

Hybrid composites of xanthan and magnetic nanoparticles for cellular uptake

We describe a fast and simple method to prepare composite films of magnetite nanoparticles and xanthan networks. The particles are distributed close to hybrid film surface, generating a coercivity of 27 ± 2 Oe at 300 K. The proliferation of fibroblast cells on the hybrid composites was successful, particularly when an external magnetic field was applied.

Release of Ceria Nanoparticles Grafted on Hybrid Organic–Inorganic Films for Biomedical Application

The controlled release of nanoparticles from a hybrid organic-inorganic surface allows for developing several applications based on a slow delivery of oxygen scavengers into specific environments. We have successfully grafted ceria nanoparticles on a hybrid film surface and tested their release in a buffer solution; the tests have shown that the particles are continuously delivered within a time scale of hours. The hybrid film has been synthesized using 3-glycidoxypropyltrimethoxysilane as precursor alkoxide; the synthesis has been performed in highly basic conditions to control the polycondensation reactions of both organic and inorganic networks via controlled aging of the solution. Only films prepared from aged solutions are able to graft ceria nanoparticles on their surface. The ceria nanoparticles have been characterized by X-ray diffraction, transmission electron microscopy and UV-vis spectroscopy, the hybrid films have been analyzed by Fourier transform infrared spectroscopy, atomic force microscopy and Raman spectroscopy. Raman imaging has been used for the release test. The hybrid film-ceria nanoparticles system fulfils the requirements of optical transparency and stability in buffer solutions which are necessary for biomedical applications.

Evaluation of conduction mechanism and electronic parameters for Au/organic–inorganic CuCl hybrid film/ITO structures

Hybrid materials are capable of combing organic and inorganic compounds into a nano-composite with unique characteristics. An example of such organic–inorganic CuCl hybrid films is studied here using a combination of organic polysilsesquioxane and inorganic CuCl; γ-CuCl is an ionic I–VII compound semiconductor material with the zincblende structure at room temperature. It has excellent ultraviolet (UV) emission properties at room temperature and is a promising candidate material for optoelectronic applications. The CuCl hybrid films were deposited on indium tin oxide (ITO)-coated glass by simple spin-coating techniques. Au/CuCl hybrid film/ITO structures were fabricated, and field-dependent electrical studies were carried out at room temperature in the range 2.5 × 105–3.5 × 106 V m−1. We confirm that the organic–inorganic CuCl film structure behaves as an effective single semiconducting medium, possessing bandstructure and other related properties. For electric field magnitudes up to 1.25 × 106 V m−1, an ohmic conduction mechanism was observed, and for field magnitudes >1.5 × 106 V m−1, Schottky emission conduction prevails in these structures. The electronic parameters were evaluated and an effective barrier height, ideality factor and series resistance were found to be 0.84 ± 0.05 eV, 1.12 ± 0.08 and 50 ± 2 MΩ, respectively, whereas the effective barrier height obtained from the C–V measurement was 1.05 ± 0.05 eV. This value is somewhat higher than the value obtained from the I–V measurement. This difference is likely caused by the presence of a thin intervening insulating layer between the hybrid film surface and the Schottky metal. The density distribution of the interface states decreases with an increase of the energy of the interface states. This organic–inorganic CuCl hybrid film behaves as an effective single semiconductor material structure, and a schematic energy-level diagram for the device is proposed.

Electrocatalytic oxidation of GMP on an ITO electrode modified by the photodeposition of Pd nanoparticles onto a monolayer TiO2 nanosheets/[Ru(phen)2(dC18bpy)]2+ hybrid film

An indium tin oxide (ITO) electrode coated with monolayer TiO2/[Ru(phen)2(dC18bpy)]2+ (phen = 1,10-phenanthroline, dC18bpy = 4,4′-dioctadecyl-2,2′-bipyridyl) hybrid film (denoted as ITO/TiO2-Ru) has been prepared using the modified Langmuir-Blodgett (LB) method, and the electrocatalytic oxidation of mononucleotide of guanosine 5′-monophosphate (GMP) on an ITO/TiO2-Ru electrode after Pd-photodeposition (denoted as ITO/TiO2-Ru/Pd) has been studied. Atomic force microscopy reveals that the single-layered hybrid film of TiO2 nanosheets/[Ru(phen)2(dC18bpy)]2+ is closely packed at a surface pressure of 25 mN m−1 and has a thickness of (3.20 ± 0.5) nm. X-ray photoelectron spectra show the formation of Pd nanoparticles on the surface of hybrid film with radii of 20–200 nm by the reduction of [Pd(NH3)4]2+ under light irradiation. When it is applied to oxidize GMP, a larger catalytic oxidative current is achieved on the ITO/TiO2-Ru/Pd electrode at the external potential above 700 mV (vs. Ag|AgCl|KCl) in comparison with the naked ITO electrode and ITO/TiO2-Ru electrode. Such a result indicates that the Pd nanoparticles are able to hamper the combination of electron hole pairs and reduce the counterwork of insulating long alkyl chains of amphiphilic Ru(II) complexes, and thus develops the electron transfer efficiency and produces the enhanced redox current.

Fabrication and High Electrocatalytic Activity of Three-Dimensional Porous Nanosheet Pt/Boron-Doped Diamond Hybrid Film

A three-dimensional (3-D) Pt nanosheet perpendicular to boron-doped diamond (BDD) hybrid film surface was prepared by the double template method, with a hydrogen bubble template and subsequent metallic Zn template to control the morphology of the Pt catalyst on the BDD surface. The porous Zn nanostructured template on oxygen-terminated BDD was first synthesized by electrodeposition with a concomitant hydrogen bubble as a dynamic template. Then a porous Pt nanostructure was obtained by immersing the Zn nanostructure in H2PtCl6 aqueous solution for a typical displacement reaction. Field emission scanning electron microscopy (FESEM) revealed that the morphology of the Zn template obtained was a 3-D porous nanosheet structure perpendicular to the BDD thin film surface, and Pt kept the morphology of the Zn template after the displacement reaction. Energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) revealed that the Pt nanosheet obtained was the classical face-centered cubic (fcc) pattern. Cyclic ...