Nanostructured Composite Films Research Articles

Poly(vinyl chloride)/Nanocarbon Composites for Advanced Potentiometric Membrane Sensor Design.

Polymer nanocomposites filled with carbon nanoparticles (CNPs) are a hot topic in materials science. This article discusses the current research on the use of these materials as interfacial electron transfer films for solid contact potentiometric membrane sensors (SC-PMSs). The results of a comparative study of plasticized poly (vinyl chloride) (pPVC) matrices modified with single-walled carbon nanotubes (SWCNTs), fullerenes-C60, and their hybrid ensemble (SWCNTs-C60) are reported. The morphological characteristics and electrical conductivity of the prepared nanostructured composite films are reported. It was found that the specific electrical conductivity of the pPVC/SWCNTs-C60 polymer film was higher than that of pPVC filled with individual nanocomponents. The effectiveness of this composite material as an electron transfer film in a new potentiometric membrane sensor for detecting phenylpyruvic acid (in anionic form) was demonstrated. Screening for this metabolic product of phenylalanine in body fluids is of significant diagnostic interest in phenylketonuria (dementia), viral hepatitis, and alcoholism. The developed sensor showed a stable and fast Nernstian response for phenylpyruvate ions in aqueous solutions over the wide linear concentration range of 5 × 10-7-1 × 10-3 M, with a detection limit of 10-7.2 M.

Electrodeposition of Polyaniline on Tantalum: Redox Behavior, Morphology and Capacitive Properties

Polyaniline (PANI) is among the most widely studied conducting polymers due to its potential technological applications in various fields. Recently, PANI-based hybrid materials have played an important role in the development of energy storage and conversion systems. The aim of the present work is the investigation of the simultaneous electrochemical growth of PANI and Ta2O5 on the Ta substrate and the characterization of the morphology, redox behavior and pseudocapacitive properties of the resulting micro- or nanostructured composite thin films. A well-adherent conductive Ta2O5-PANI composite film was first formed using cyclic voltammetry on Ta that facilitates the on-top electrodeposition of single PANI via an autocatalytic mechanism. The electrochemical characterization of the Ta|Ta2O5-PANI|PANI electrodes reveals unique redox properties of PANI not shown previously upon using PANI electrodeposition on Ta. Scanning electron microscopy shows that the morphology of the electrodeposited films comprises nano- or microspheres that may develop into nano- or microrods when the polymerization proceeds. Preliminary evaluation of the capacitive properties of the Ta|Ta2O5-PANI|PANI electrode shows adequately high specific capacitance values as high as 1130 F g−1 (at 9.2 mA cm−2), depending on the electrochemical parameters, as well as adequate stability (~80% retention after 100 cycles), indicating their potential application as energy storage devices.

Porous Nanostructured Composite Film for Visible-to-Infrared Camouflage with Thermal Management.

Progressive advancement in modern detection technologies entails multispectral compatible camouflage. Previously, infrared camouflage materials, such as photonic crystals and metamaterials, have been developed, but improved multispectral compatibility, easy fabrication, and cost-effectiveness remain a challenge. Here, we report a nanostructured composite film based on oxalate-rich porous alumina (OPA) for visible-to-infrared compatible camouflage and simultaneous thermal management. The nanostructured composite film consists of a visible-transparent OPA layer, a composite layer of OPA/metal oxides, and an aluminum substrate. Each functional layer exhibits desirable reflection/emission properties for infrared and visible camouflage. Infrared camouflage is realized by the high reflection (low emission) of the metal substrate in both infrared-detected bands (3-5 and 8-14 μm). Meanwhile, radiative cooling arising from the intrinsic absorption of oxalate in the undetected band (5-8 μm) enhances surface heat dissipation. In addition, background-matching colors can be tuned by the metal oxides in the composite layer for visible camouflage, such as green for forest and brown for desert. This work provides a facile strategy to modulate multispectral absorption/emission properties with much flexibility and thus has great potential for energy conversion and stealth applications.

Characterization of nanostructured nickel cobalt oxide-polyvinyl alcohol composite films for supercapacitor application

In the present work, thin films of nickel cobalt oxide and polyvinyl alcohol nanocomposite (NCO-PVA) are prepared by chemical methods. The as-prepared NCO-PVA films have been structurally studied by X-ray diffraction and Fourier transform infrared spectroscopy. The morphology of the NCO-PVA films has been studied by Field emission scanning electron microscopy and High-resolution transmission electron microscopy. X-ray diffraction analysis has been used to study its crystallinity and phase. The optical properties of NCO-PVA nanocomposite films have also been studied. The surface area and pore size measurements have also been done. The UV-Vis spectrum analysis reveals that the films possess two direct band gaps (2.91 eV and 3.48 eV). The red shift of Photoluminescence emission has been observed for nanocomposite films with increasing excitation intensity. The AC electrical conductivity of NCO-PVA films has been studied as the high value of AC conductivity is essential for getting high power and high energy density in supercapacitors. Also, the high value of the dielectric constant of nanocomposite at small frequencies shows its supercapacitive nature. A short relaxation time (~6.37 ≤ 10−7 s) reveals a very small delay in molecular polarization along with changing the electric field, suggesting fewer energy losses. Electrochemical performance is checked by cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy measurements using 1 M Na2SO4neutral aqueous electrolytic solution. Also, the symmetric supercapacitor has been fabricated, using NCO-PVA films as the electrodes, which exhibits the specific capacitance value of50 F g−1and energy density of 18.9 W h kg−1. The results reveal that the prepared nanocomposite films have enough potential for supercapacitor device fabrication, especially the flexible supercapacitors.

Mechanically Strong Double-Layered Aramid Nanofibers/MWCNTs/PANI Film Electrode for Flexible Supercapacitor

As the key material for flexible electronics, free-standing supercapacitor electrodes have attracted great research interests in recent years. However, constructing the novel supercapacitor electrodes with excellent mechanical properties and high areal capacitance remains a challenge. This study demonstrates the fabrication of a highly flexible and mechanically robust supercapacitor electrode based on combination of aramid nanofibers (ANFs), multi-walled carbon nanotubes (MWCNTs), and polyaniline (PANI) in form of nanostructured composite film. The ANFs/MWCNTs/PANI film electrode obtained via vacuum-assisted layer-by-layer (VA-LBL) assembly technique achieves a tensile strength of 158.7 MPa and an areal specific capacitance of 497.3 mF cm−2 at a current density of 0.25 mA cm−2, showing an outstanding compatibility between high electrochemical performance and superior mechanical properties. In addition, the ANFs/MWCNTs/PANI film electrode exhibits an excellent cycle life with 89% capacitance retention after 3000 cycles. Synergistic effect from the strategic assembly of ANFs, MWCNTs and PANI in form of a single nanostructured platform makes this kind of free-standing electrode applicable for flexible and solid-state energy storage systems.

Microstructural and electrical properties of nanostructured lead zirconate titanate composite thick films processed for MEMS applications via hybrid sol–gel approach

An alternative chemical solution processing version of thick and crack free PZT films was developed. PZT films were equally deposited from pure sol and composite suspension on ITO-coated corning glass substrates by dip-coating process and were sintered at various temperatures. The PZT composite sol–gel suspension/slurry was optimized to dip-coating to form thick films with nearly constant thickness and limited cracking. The XRD spectra indicate that the 0–3 ceramic/ceramic composites films possess single-phase perovskite type. SEM micrographs of thick film cross-sections displayed composite structures with no observable boundary between layers. The optimized PZT layer revealed a capacitance resultant to a permitivity of Ɛr = 1282 and tang(δ) = 0.17 at 100 Hz. The remnant polarization, and coercive field for the same sample estimated from the ferroelectric P–E hysteresis loop were 30 μC cm−2, and 17 kV cm−1, respectively. The ferroelectric and dielectric constant values were equivalent to those reported for bulk material.

Inspection the corrosion prevention performance and dry/wet interfacial adhesion qualities of the melamine-cured polyester coating applied on the treated mild steel surface with a nanostructured composite cerium-neodymium film

The aim of this study is to investigate the influence of a cerium-neodymium (Ce-Nd) conversion coating on the corrosion protection performance and surface characteristics of a polyester/melamine coating (PMC) applied on the mild steel (MS) surface. The energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), and field emission scanning electron microscopy (FE-SEM) methods were exploited to examine the surface morphology and roughness of the deposited layers. Also, an X-ray photoelectron spectroscopy (XPS) analysis was carried out for the characterization of the deposited Ce-Nd film chemical composition. The influence of MS surface chemical treatment via Ce-Nd film on the PMC corrosion protection activity was surveyed through accelerated salt spray (SS) and electrochemical impedance spectroscopy (EIS) tests. The impact of Ce, Nd, and Ce-Nd conversion coatings on the adhesion properties of PMC was studied by the pull-off (PO) test in dry and wet conditions. Through the steel surface decoration with Ce-Nd oxide film the highest improvement in the work of adhesion (about 47.5 %) and surface free energy (about 42.7 %), compared to the untreated sample, were obtained. The results of the cathodic delamination (CD) test revealed a 69 % improvement of the PMC resistance against disbondment by employing the Ce-Nd conversion coating. Pull-off test results evidenced that the steel substrate modified by Ce-Nd film resulted in the maximum improvement (about 57 %) in dry adhesion strength and the lowest adhesion loss of about 20 % compared to the bare (untreated) sample. FE-SEM and AFM observations showed the uniform growth of the Ce and Nd layers and Ce-Nd complexes (with particle sizes almost less than 100 nm) on the substrate, coincidentally. EIS results evidenced 67 %, 43 %, and 77 % improvement in total resistance (Rt) of the epoxy coating with artificial defect on the steel surface with Ce, Nd and Ce-Nd treatments, respectively, confirming that the redox reactions have been limited in the Ce-Nd/PMC interface more than each of Ce and Nd treatments.It should be noted that the Ce-Nd is a novel non-toxic and environmentally friendly chemical treatment method for replacement of the conventional metals' surface pretreatment methods like phosphating and chromating with numerous advantages like excellent corrosion resistance as well as good adhesion to the metal surface and subsequent organic film. One major practical application of the developed coating can be in the automotive and gas/oil industries for the car body and pipe surface chemical treatment prior to the application of the organic coating.

High performance flexible solid-state asymmetric supercapacitor composed of a polyaniline/PEDOT/polyaniline/ultralarge reduced graphene oxide tetralayer film and a PEDOT/MoS2 composite film

A flexible solid-state asymmetric supercapacitor (ASC) was assembled with a polyaniline (PANi)/PEDOT/PANi/ultralarge reduced graphene oxide (UrGO) tetralayer film (denoted as PPPrG, used as the positive electrode) and a PEDOT/MoS2 film (denoted as PMo, used as the negative electrode) on a flexible polyethylene terephthalate (PET) substrate with polyvinyl alcohol/H2SO4 gel electrolyte. The PPPrG tetralayers were fabricated on PET via a layer-by-layer self-assembly method, whereas the PMo electrode was fabricated on PET using a drop-coating approach. The ASC exhibited a maximum energy density of 5.4 mW h/cm3 at a power density of 110 mW/cm3, demonstrating excellent electrochemical performance without performance loss despite various deformation states due to high conductivity and flexibility of the multilayer film electrodes, which act as both the active electrode and the current collector. The ASC retained an energy density of 4.0 mW h/cm3 at a power density of 265 mW/cm3 with an optimized cell voltage of 0.8 V. The excellent performance of this ASC was ascribed mainly to the conductivity of the multilayer film electrodes, which was improved by the combination of PANi, UrGO and PEDOT layers, which functioned as conducting networks in the nanostructured composite films. This flexible ASC system based on multilayer film electrodes with superior capacitive performance offers substantial promise for use in grid-scale energy storage devices integrated into portable and bio-implantable microelectronic devices.

Direct Electrodeposition Li-V-Mn-Ni-O Composite Films on Al Foils Toward Li Ion Battery Cathode Materials

Nowadays, Lithium-ion secondary batteries (LIBs) are considered as indispensable power sources in our daily life, because they are widely used in various mobile electronic products such as smart phones, portable computers, and recently, extended to electric vehicles (EVs). Commercial LIB comprises LiCoO2 cathode with maximum capacity of 140 mAh g−1. V2O5 has been widely investigated because of its high theoretical capacity of 294 m Ah g−1, low cost and abundant sources on the earth crust. However, problems, such as severe capacity fading and poor rate capability, prevent its use in commercial LIBs. So far, much effort has been done to improve the cycling stability of V2O5 by doping Ag, Cu, Zn, and Mn through sol-gel process, beam evaporation, hydrothermal reaction, etc. In this study, we proposed a novel hybrid electrodeposition to fabricate Li-V-Mn-Ni-O composite films directly on Al foils in ethanol-water bath containing V5+、Ni2+, Mn2+ ions as sulfate or chloride, with and without adding Li+ ions. Before electrodeposition, an electro-etching pretreatment was used to enhance the adhesion between the Al substrate and the electrodeposits. The microstructures, chemical composition, and crystalline structure of the anodized specimens before and after annealed were investigated FE-SEM (EDS), TEM (FIB), XRD, XPS, and GD-OES. Moreover, the cyclic voltammetric behaviors, electrochemical impedance, and charge-discharge performances of various nanostructured composite films on Al foils were investigated as binder-free cathode materials for Li ion secondary batteries.Figs. 1a-b show the representative surface FE-SEM images of as-deposited Li-V-Mn-Ni-O composite films on Al foils. The composite films coated uniformly on electro-etched Al foils irrespectively of the rough surface, composing of nano-flakes (Fig.1a) and nanoparticles (Fig.1b). According to EDS analysis, the compositions of V, Mn, and Ni components except for O were 69 at%–23 at%–8 at% and 45 at%–21 at%–34 at% for the nano-flake and nanoparticle regions respectively. The XPS analysis confirmed that the vanadium existed mainly as mixed V4+ and Mn5+ oxides, manganese as mixed Mn2+ and Mn4+ oxides, and nickel as metallic Ni and Ni2O3 for the composite films before and after heated at different temperatures. Moreover, it was found from GD-OES measurements that Li also included in the V-Mn-Ni-O composite films through a co-deposition process and/or a Li+ insertion/dis-insertion process. Fig. 1c shows the cyclic voltammograms (CVs) of Li-V-Mn-Ni-O composite films after being heated at 723 and 923 K for 2 h, as cathodes with Li-metal as the counter and reference electrodes, in the potential range 2.0–4.5 V vs. Li/Li+, at a slow scan rate of 0.1 mV s-1. Two main anodic peaks (Li-extraction) at around 3 and 4 V are noted for both specimens heated at 723 and 923 K, which can be ascribed to the Li extraction reactions from vanadium oxides and V-Mn-Ni-O compounds. Especially, the current density of 4-V peak increased with heating temperature, indicating the transformation and crystallization of V-Mn-Ni-O compounds from vanadium oxides. Furthermore, the composite films after being heated at different temperatures worked well as binder-free and conductor-free cathode materials for LIBs in galvanostatic charge/discharge tests, and the results will be reported on the meeting. Figure 1

Metal Oxide Nanocomposites: A Perspective from Strain, Defect, and Interface.

Vertically aligned nanocomposite thin films with ordered two phases, grown epitaxially on substrates, have attracted tremendous interest in the past decade. These unique nanostructured composite thin films with large vertical interfacial area, controllable vertical lattice strain, and defects provide an intriguing playground, allowing for the manipulation of a variety of functional properties of the materials via the interplay among strain, defect, and interface. This field has evolved from basic growth and characterization to functionality tuning as well as potential applications in energy conversion and information technology. Here, the remarkable progress achieved in vertically aligned nanocomposite thin films from a perspective of tuning functionalities through control of strain, defect, and interface is summarized.

Technology for Creation and Detailed Analysis of Polymer Composites with Uniform Distribution of Quantum Dots and Liquid Crystals

.

Enhanced Piezoelectric Response in Nanostructured Ni/PVDF Films

Poly(vinylidene fluoride) (PVDF) composites have recently emerged as excellent candidates to fabricate flexible and small piezoelectric generators for portable devices. Among various techniques used to nanostructure polarized PVDF, the track-etching represents a new route for manufacturing nanostructured composite thin films. The moderate influence of irradiation on the piezoelectric response of polarized PVDF makes possible the use of this technique. In this way, a nanostructured composite based on polarized thin PVDF films comprising embedded nickel nanowires (Ni NWs) was fabricated. The nanostructured PVDF/Ni NWs composites were tested under bending conditions using a homemade pressure cell. Due to the presence of NWs, an increase of five-fold the initial dielectric permittivity, in the low-frequency range, was observed. It suggested the presence of an interfacial polarization at the PVDF/Ni interface. With respect to the etched PVDF, the nanostructured PVDF/Ni NWs composites exhibited a non-negligible enhancement by 2.5 times the piezoelectric efficiency. This result was attributed to the increased Au/Ni NWs electrode surface.

High efficiency water splitting photoanodes composed of nano-structured anatase-rutile TiO2 heterojunctions by pulsed-pressure MOCVD

In this article, thin solid films are processed via pulsed-pressure metal organic chemical vapour deposition (PP-MOCVD) on FTO substrates over a range of processing times to produce a range of thicknesses and microstructures. The films are highly nanostructured anatase-rutile TiO2 composite films with unique single crystal dendrites. After annealing, carbon was removed, and materials showed improved water splitting activity; with IPCEs above 80% in the UV, photocurrents of ∼1.2mAcm−2 at 1.23VRHE at 1 sun irradiance and an extension of photoactivity into the visible range. The annealed material exhibits minimal recombination losses and IPCEs amongst the highest reported in the literature; attributed to the formation of a high surface area nanostructured material and synergetic interactions between the anatase and rutile phases.

Tunable simultaneously visible-light and near-infrared transmittance for VO2/SiO2 composite films to enhance thermochromic properties

The ordered nano-structure composite films based on VO2/SiO2 as the thermochromic “smart window” have been fabricated by combining the PS template and RTA process. The study showed that the ordered VO2/SiO2 composite films exhibited good thermochromic performance with the large solar modulation efficiency (ΔTsol) of 8.42% and high visible transmittance (Tlum) of 55.6%, which is superior to pure VO2 foils with ΔTsol of 3.03% and Tlum of 46.1%, due to simultaneous control of transmittance in visible and near infrared region for VO2/SiO2 composite films. Hence, it offers a novel method to boost remarkably thermochromic properties for the “smart window” based on VO2 film.

Transparent nanostructured cellulose acetate films based on the self assembly of PEO-b-PPO-b-PEO block copolymer

In this study fabrication and characterization of transparent nanostructured composite films based on cellulose triacetate (CTA) and poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (EPE) triblock copolymer were presented. The effect of the addition of EPE triblock copolymer on the thermal stability, morphology, and mechanical properties of cellulose triacetate films was investigated. The triblock EPE was chosen since PEO blocks interact favorably with CTA, whereas, PPO blocks remain immiscible which provokes a microphase separation. This allows to obtain EPE/CTA composite films with ordered microphase-separated structures where PPO spherical microdomains are well-dispersed in PEO/CTA matrix by simple solvent-evaporation process. During this process, PEO block chains selectively interact with CTA by strong interpolymer hydrogen-bonding while PPO block microseparated. The addition even 40wt% of EPE leads to nanostructured EPE/CTA composite. The cytotoxicity assay of CTA and EPE/CTA composite films confirm non-toxic character of designed transparent nanostructured composites based on sustainable matrices.

Reduced graphene oxide/Cu2O nanostructure composite films as an effective and stable hydrogen evolution photocathode for water splitting

An efficient photocathode consisting of reduced graphene oxide/Cu2O/Cu (rGO/Cu2O/Cu) has been successfully prepared in this work via a facile two step method, consisting of chemical oxidation of a copper foil in alkaline solution using (NH4)2S2O8 as the oxidizing agent, dipping the prepared samples in graphene oxide (GO) solution and calcination at vacuum to form a rGO layer onto Cu2O/Cu photocathode, which acts as a protective layer. The products were composed of a thin Cu2O layer topped with a thin rGO film as the protective coating. The chemical composition and rGO amount in the composite materials were easily controlled by changing the immersion time to enhance PEC performance. UV–Vis spectroscopy, Raman spectroscopy, XRD, SEM, TEM and FTIR spectroscopy were used in the optical and morphological characterization of the graphene oxide and prepared photocathodes. Distinct patches of GO film are formed on the Cu(OH)2 nanostructure surface, as shown by SEM results. Linear sweep voltammetry and chronoamperometry analysis have been applied in the photoelectrochemical characterizations in the dark and under illumination conditions. Photocurrent density provided by rGO/Cu2O/Cu photocathode − 2.54 mA cm− 2 is three times greater than that of bare Cu2O/Cu photocathode − 0.82 mA cm− 2 at 0 V vs. RHE under illumination. Low photostability of 42% is exhibited by bare Cu2O/Cu photocathode after 200 s irradiation whereas rGO/Cu2O/Cu photocathode shows approximately 98% of the initial photocurrent density. Therefore, a strategy has been developed in this work for the synthesis of this new photocathode using Cu2O/Cu as an effective photocathode for photoelectrochemical (PEC) water splitting.

A nanostructured cell-free photosynthetic biocomposite via molecularly controlled layer-by-layer assembly

Thylakoids, on which complete sets of photosynthetic membrane proteins are contained, behave as soft nanoparticles of a few tens nm sizes. Thus, we separated the thylakoid extracts from spinach chloroplasts and densely organized them in a film with either insulating polyethyleneimine (PEI) or conducting polyaniline (PANI) by molecularly controlled layer-by-layer (LBL) assembly. The resulting nanostructured composite films demonstrated photoelectrochemical activities with thylakoids whose stabilities were significantly improved on the charge balanced LBL multilayers compared to one on a randomly deposited film or in solution. The thylakoid LBL films continuously generated photochemical electrons for longer than 130h with the 2,6-dichlorophenolindophenol (DCPIP) mediated photosynthetic energy conversion cycle while photoactivities of thylakoid moiety slowly decreased in the open circuit potential measurements throughout which the photosynthetic redox cycles were incomplete. As the photofunctional groups of the thylakoid films originated from a biotic system and the photofuctional thylakoids were exceptionally well preserved on the charge-balanced artificial structures, the developed thylakoid LBL film have shown inherent biocompatibility upon PC12 neural cell attachment and differentiation tests, which are essential qualities for emerging human-friendly electronic applications such as disposable electronics, artificial retina, and implantable neural interfacing meditronics as well as cell-free photosynthetic production.

Investigation on multiferroic, optical and photoluminescence properties of CoFe2O4/(Pb1−xSrx)TiO3 nanostructured composite thin films

Multiferroic nanostructured composite thin films consisting of CoFe2O4 (CFO) and Pb1−xSrxTiO3 (PST; x = 0.1, 0.2, 0.3, 0.4 and 0.5) layers have been deposited on Pt/TiO2/SiO2/Si and quartz substrates by using metallo-organic decomposition process and spin coating. The effect of Sr content on the multiferroic and optical properties have been investigated. The phase purity such as spinel structure of CFO and perovskite structure of PST has been verified by X-ray diffraction. Cross-sectional scanning electron microscopy images revealed clear interface between CFO and PST layers without any noticeable diffusion. The multiferroic properties of CFO/PST composite films have been confirmed by magnetic and ferroelectric hysteresis loops with low leakage current density. The residual strain sensitivity of multiferroic and optical properties has been observed in the composite films. The decrease in saturation magnetization and saturation polarization with increase in Sr content has been observed which could be attributed to the decrease in residual strain of CFO/PST composite films. The magnetic phase transition temperature of the CFO/PST composite films is also reduced. The optical refractive index decreases with increase of amount of Sr content. The photoluminescence spectra of the CFO/PST composite films possess a blue shift which can be attributed to the Pb and oxygen vacancies as localized sensitizing centers. We show that the multiferroic and optical properties of the CFO/PST composite films are highly sensitive to the heterostructure strains which can be controlled by Sr content.

Synthesis of nanostructured amorphous carbon-copper composite films by plasma-enhanced chemical vapour deposition

Nanostructured amorphous carbon-copper composite films were formed by plasma-enhanced chemical vapour deposition. The formation was done on copper-silicon substrates at 25°C, 300°C, 520°C, and 700°C temperatures using an acetylene gas at 40–70Pa pressure. The heating of the CuSi substrate induced formation of Cu nanospheres with 50–500nm size depending on the substrate temperature. The microstructure and composition of nanostructured carbon-copper composite films were investigated. The SEM views showed formation of amorphous carbon films with the randomly distributed nanostructures. The oxygen concentration in the composite films decreased with the increased heating temperature. The surface roughness measurements indicated that the surface roughness values increased with the increase of the temperature. The increase of the substrate temperature stimulated to the graphitization, enhanced the fraction of sp2 CC sites and lead to the formation of the nanocrystaline graphite clusters in composite films. The nanohardness values of the formed nanostructured amorphous carbon-Cu films varied in the range of 0.2–3GPa.

Functionalized Antimicrobial Composite Thin Films Printing for Stainless Steel Implant Coatings.

In this work we try to address the large interest existing nowadays in the better understanding of the interaction between microbial biofilms and metallic implants. Our aimed was to identify a new preventive strategy to control drug release, biofilm formation and contamination of medical devices with microbes. The transfer and printing of novel bioactive glass-polymer-antibiotic composites by Matrix-Assisted Pulsed Laser Evaporation into uniform thin films onto 316 L stainless steel substrates of the type used in implants are reported. The targets were prepared by freezing in liquid nitrogen mixtures containing polymer and antibiotic reinforced with bioglass powder. The cryogenic targets were submitted to multipulse evaporation by irradiation with an UV KrF* (λ = 248 nm, τFWHM ≤ 25 ns) excimer laser source. The prepared structures were analyzed by infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and profilometry, before and after immersion in physiological fluids. The bioactivity and the release of the antibiotic have been evaluated. We showed that the incorporated antibiotic underwent a gradually dissolution in physiological fluids thus supporting a high local treatment efficiency. Electrochemical measurements including linear sweep voltammetry and impedance spectroscopy studies were carried out to investigate the corrosion resistance of the coatings in physiological environments. The in vitro biocompatibility assay using the MG63 mammalian cell line revealed that the obtained nanostructured composite films are non-cytotoxic. The antimicrobial effect of the coatings was tested against Staphylococcus aureus and Escherichia coli strains, usually present in implant-associated infections. An anti-biofilm activity was evidenced, stronger against E. coli than the S. aureus strain. The results proved that the applied method allows for the fabrication of implantable biomaterials which shield metal ion release and possess increased biocompatibility and resistance to microbial colonization and biofilm growth.