Dielectric property study of poly(4-vinylphenol)-graphene oxide nanocomposite thin film

NASA Astrophysics Data System (ADS)

Roy, Dhrubojyoti

2018-05-01

Thin film capacitor device having a sandwich structure of indium tin oxide (ITO)-coated glass/polymer or polymer nanocomposite /silver has been fabricated and their dielectric and leakage current properties has been studied. The dielectric properties of the capacitors were characterized for frequencies ranging from 1 KHz to 1 MHz. 5 wt% Poly(4-vinylphenol)(PVPh)-Graphene (GO) nanocomposite exhibited an increase in dielectric constant to 5.6 and small rise in dielectric loss to around˜0.05 at 10 KHz w.r.t polymer. The DC conductivity measurements reveal rise of leakage current in nanocomposite.

Evolution of microstructure, strain and physical properties in oxide nanocomposite films

DOE PAGES

Chen, Aiping; Weigand, Marcus; Bi, Zhenxing; ...

2014-06-24

Using LSMO:ZnO nanocomposite films as a model system, we have researched the effect of film thickness on the physical properties of nanocomposites. It shows that strain, microstructure, as well as magnetoresistance strongly rely on film thickness. The magnetotransport properties have been fitted by a modified parallel connection channel model, which is in agreement with the microstructure evolution as a function of film thickness in nanocomposite films on sapphire substrates. The strain analysis indicates that the variation of physical properties in nanocomposite films on LAO is dominated by strain effect. These results confirm the critical role of film thickness on microstructures,more » strain states, and functionalities. Furthermore, it shows that one can use film thickness as a key parameter to design nanocomposites with optimum functionalities.« less

Biopolymer nanocomposite films reinforced with nanocellulose whiskers

Treesearch

Amit Saxena; Marcus Foston; Mohamad Kassaee; Thomas J. Elder; Arthur J. Ragauskas

2011-01-01

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating...

Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi

2014-07-01

Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemicalmore » approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene.« less

Mechanical and solubility properties of bio-nanocomposite film of semi refined kappa carrageenan/ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Saputri, Apriliana Eka; Praseptiangga, Danar; Rochima, Emma; Panatarani, Camellia; Joni, I. Made

2018-02-01

The aim of this present work is to develop semi refined kappa carrageenan based bio-nanocomposite film as an alternative to synthetic petroleum based food packaging materials. Among natural polymers, carrageenan is one of the most promising material, since it is a renewable bioresource. The ZnO nanoparticles (0.5%; 1.0%; 1.5% w/w carrageenan) was incorporated into carrageenan polymer to prepare bio-nanocomposite films, where ZnO acts as reinforcement for carrageenan matrix. The mechanical and solubility properties of the prepared films were investigated as a function of ZnO concentration. The results indicated that the addition of ZnO exhibits greater solubility compared to the neat film. The elongation at break is insignificantly different on the films with and without addition ZnO. The tensile strength of the film was highest for the sample with 0.5% ZnO. These mechanical and solubility properties suggest that bio-nanocomposite film of semi refined kappa carrageenan and nanoparticle ZnO can be effectively used as food packaging material.

Characteristics of Thermoplastic Potato Starch/Bentonite Nanocomposite Film

NASA Astrophysics Data System (ADS)

Zakaria, N. H.; Muhammad, N.; Abdullah, M. M. A. B.; Sandu, I. G.; Wan, C. L. Mei

2018-06-01

The aim of this study is to investigate the effect of bentonite towards thermoplastic potato starch nanocomposite films on the mechanical, microstructure and physical properties. The nanocomposite films were prepared using bentonite nano filler (0, 1, 5, 10, 15 and 20%) through solution casting technique. Obtained result indicate that, tensile strength increased significantly with increasing bentonite content and the highest tensile strength was recorded for nanocomposite film with 20% bentonite content. Meanwhile, elongation at break increased as the bentonite content increased from 0 to 15%, however significantly decreased at 20% bentonite content due to ductile structure and anti-plasticizing effect. Besides, good dispersion between bentonite nano filler and starch matrix with slightly remaining anglomerates was evident in scanning electron microscopy (SEM) image. Overall result shows that the addition of bentonite nano filler in potato starch film significantly influenced the properties of the films.

Large-Strain Transparent Magnetoactive Polymer Nanocomposites

NASA Technical Reports Server (NTRS)

Meador, Michael A.

2012-01-01

A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

Exchange-coupled hard magnetic Fe-Co/CoPt nanocomposite films fabricated by electro-infiltration

NASA Astrophysics Data System (ADS)

Wen, Xiao; Andrew, Jennifer S.; Arnold, David P.

2017-05-01

This paper introduces a potentially scalable electro-infiltration process to produce exchange-coupled hard magnetic nanocomposite thin films. Fe-Co/CoPt nanocomposite films are fabricated by deposition of CoFe2O4 nanoparticles onto Si substrate, followed by electroplating of CoPt. Samples are subsequently annealed under H2 to reduce the CoFe2O4 to magnetically soft Fe-Co and also induce L10 ordering in the CoPt. Resultant films exhibit 0.97 T saturation magnetization, 0.70 T remanent magnetization, 127 kA/m coercivity and 21.8 kJ/m3 maximum energy density. First order reversal curve (FORC) analysis and δM plot are used to prove the exchange coupling between soft and hard magnetic phases.

Silver/poly(vinyl alcohol) nanocomposite film prepared using water in oil microemulsion for antibacterial applications.

PubMed

Fatema, Ummul K; Rahman, M Muhibur; Islam, M Rakibul; Mollah, M Yousuf A; Susan, Md Abu Bin Hasan

2018-03-15

Water in oil microemulsion (w/o) is a simple preparative route for nanoparticles where water droplets (dispersed in continuous oil medium and stabilized by surfactants and cosurfactants) act as nanoreactors to carry out chemical reactions. If polymeric matrix is incorporated inside the core of the microemulsions, it should prevent the agglomeration of nanoparticles after separation from microemulsions. Thus polymer nanocomposite films prepared from w/o microemulsions are expected to give narrow and homogeneous size distribution of nanoparticles throughout the polymer host. Silver/poly(vinyl alcohol) (Ag/PVA) nanocomposite film was successfully prepared, for the first time, using Triton X-100 (TX-100)/1-butanol/cyclohexane/water microemulsion. Reduction of the metal salt was carried out in the core of w/o microemulsion droplets containing PVA polymeric matrix. After separation from the microemulsion, Ag/PVA nanocomposite film was then prepared by solution casting method. The antibacterial activity of the nanocomposites was tested against Gram-negative, Escherichia coli and Gram-positive, Staphylococcus aureus by agar diffusion method. Ag nanoparticles with an average diameter of 105 nm could be synthesized using PVA, whereas in the absence of PVA the nanoparticles agglomerated. The distribution of Ag nanoparticles on PVA surface of the nanocomposite film prepared using microemulsion was uniform, whereas the film prepared through in situ generation of Ag nanoparticles by chemical reduction process on PVA host showed non-uniform, coagulated, bunches of Ag nanoparticles. The film synthesized using microemulsion exhibited enhanced antibacterial efficacy compared to that prepared through in situ synthesis under the same test condition. Copyright © 2017 Elsevier Inc. All rights reserved.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole-Chitosan-Titanium Dioxide Nanocomposite Films.

PubMed

Al-Mokaram, Ali M A Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M; Mahmud, Habibun Nabi Muhammad Ekramul

2017-05-31

The performance of a modified electrode of nanocomposite films consisting of polypyrrole-chitosan-titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1-14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.

Multicolored Emission and Lasing in DCM-Adamantane Plasma Nanocomposite Optical Films.

PubMed

Alcaire, María; Cerdán, Luis; Zamarro, Fernando Lahoz; Aparicio, Francisco J; González, Juan Carlos; Ferrer, Francisco J; Borras, Ana; Espinós, Juan Pedro; Barranco, Angel

2017-03-15

We present a low-temperature versatile protocol for the fabrication of plasma nanocomposite thin films to act as tunable emitters and optical gain media. The films are obtained by the remote plasma-assisted deposition of a 4-(dicyano-methylene)-2-methyl-6-(4-dimethylamino-styryl)-4H-pyran (DCM) laser dye alongside adamantane. The experimental parameters that determine the concentration of the dye in the films and their optical properties, including light absorption, the refractive index, and luminescence, are evaluated. Amplified spontaneous emission experiments in the DCM/adamantane nanocomposite waveguides show the improvement of the copolymerized nanocomposites' properties compared to films that were deposited with DCM as the sole precursor. Moreover, one-dimensional distributed feed-back laser emission is demonstrated and characterized in some of the nanocomposite films that are studied. These results open new paths for the optimization of the optical and lasing properties of plasma nanocomposite polymers, which can be straightforwardly integrated as active components in optoelectronic devices.

Assessment of morphology and property of graphene oxide-hydroxypropylmethylcellulose nanocomposite films.

PubMed

Ghosh, Tapas Kumar; Gope, Shirshendu; Mondal, Dibyendu; Bhowmik, Biplab; Mollick, Md Masud Rahaman; Maity, Dipanwita; Roy, Indranil; Sarkar, Gunjan; Sadhukhan, Sourav; Rana, Dipak; Chakraborty, Mukut; Chattopadhyay, Dipankar

2014-05-01

Graphene oxide (GO) was synthesized by Hummer's method and characterized by using Fourier transform infrared spectroscopy and Raman spectroscopy. The as synthesized GO was used to make GO/hydroxypropylmethylcellulose (HPMC) nanocomposite films by the solution mixing method using different concentrations of GO. The nanocomposite films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and thermo-gravimetric analysis. Mechanical properties, water absorption property and water vapor transmission rate were also measured. XRD analysis showed the formation of exfoliated HPMC/GO nanocomposites films. The FESEM results revealed high interfacial adhesion between the GO and HPMC matrix. The tensile strength and Young's modulus of the nanocomposite films containing the highest weight percentage of GO increased sharply. The thermal stability of HPMC/GO nanocomposites was slightly better than pure HPMC. The water absorption and water vapor transmission rate of HPMC film was reduced with the addition of up to 1 wt% GO. Copyright © 2014 Elsevier B.V. All rights reserved.

Production and characterization of a new biodegradable fenugreek seed gum based active nanocomposite film reinforced with nanoclays.

PubMed

Memiş, Saliha; Tornuk, Fatih; Bozkurt, Fatih; Durak, M Zeki

2017-10-01

In the present work, fenugreek seed gum (FSG)/clay nanocomposite films were prepared with nanoclays (Na + montmorillonite [MMT], halloysite [HNT] and Nanomer ® I.44 P [NM]) at different amounts (0, 2.5, 5.0 and 7.5g clay/100g FSG) by solution casting method and characterized. Increasing amount of nanoclay significantly (P<0.05) improved oxygen barrier and thermal properties of the biodegradable films. Agar diffusion tests revealed that FSG based nanocomposite films exhibited strong antimicrobial properties against foodborne pathogens namely Listeria monocytogenes, Escherichia coli O157:H7, Staphylococcus aureus and Bacillus cereus independently of clay type and concentration. In the case of mechanical properties, nanoclay incorporation up to 5% provided higher (P<0.05) tensile strength (TS) properties while elongation at break (EB) values of the films significantly (P<0.05) decreased in the presence of clay in the film matrix. SEM micrographs showed that especially lower levels (up to 5%) of nanoclay reinforcements provided a homogeneous and smooth film structure. In conclusion, FSG based nanocomposite films reinforced with nanoclays up to 5% showed a precious potential to be used in antimicrobial food packaging applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Dielectric spectroscopy of Ag-starch nanocomposite films

NASA Astrophysics Data System (ADS)

Meena; Sharma, Annu

2018-04-01

In the present work Ag-starch nanocomposite films were fabricated via chemical reduction route. The formation of Ag nanoparticles was confirmed using transmission electron microscopy (TEM). Further the effect of varying concentration of Ag nanoparticles on the dielectric properties of starch has been studied. The frequency response of dielectric constant (ε‧), dielectric loss (ε″) and dissipation factor tan(δ) has been studied in the frequency range of 100 Hz to 1 MHz. Dielectric data was further analysed using Cole-Cole plots. The dielectric constant of starch was found to be 4.4 which decreased to 2.35 in Ag-starch nanocomposite film containing 0.50 wt% of Ag nanoparticles. Such nanocomposites with low dielectric constant have potential applications in microelectronic technologies.

Characterization of an Olive Flounder Bone Gelatin-Zinc Oxide Nanocomposite Film and Evaluation of Its Potential Application in Spinach Packaging.

PubMed

Beak, Songee; Kim, Hyeri; Song, Kyung Bin

2017-11-01

Olive flounder bone gelatin (OBG) was used for a film base material in this study. In addition, zinc oxide nanoparticles (ZnO) were incorporated into the OBG film to prepare a nanocomposite film and to impart antimicrobial activity to it. The tensile strength of the OBG film increased by 6.62 MPa, and water vapor permeability and water solubility decreased by 0.93 × 10 -9 g/m s Pa and 13.79%, respectively, by the addition of ZnO to the OBG film. In particular, the OBG-ZnO film exhibited antimicrobial activity against Listeria monocytogenes. To investigate the applicability of the OBG-ZnO packaging film, fresh spinach was wrapped in this film and stored for a week. The results indicated that the OBG-ZnO film showed antimicrobial activity against L. monocytogenes inoculated on spinach without affecting the quality of spinach, such as vitamin C content and color. Thus, the OBG-ZnO nanocomposite film can be applied as an efficient antimicrobial food packaging material. As a base material of edible films, gelatin was extracted from olive flounder bone, which is fish processing by-product. Olive flounder bone gelatin (OBG) nanocomposite films were prepared with zinc oxide nanoparticles (ZnO). For an application to antimicrobial packaging, spinach was wrapped with the OBG-ZnO nanocomposite film. © 2017 Institute of Food Technologists®.

The Development of Non-Enzymatic Glucose Biosensors Based on Electrochemically Prepared Polypyrrole–Chitosan–Titanium Dioxide Nanocomposite Films

PubMed Central

AL-Mokaram, Ali M. A. Abdul Amir; Yahya, Rosiyah; Abdi, Mahnaz M.; Mahmud, Habibun Nabi Muhammad Ekramul

2017-01-01

The performance of a modified electrode of nanocomposite films consisting of polypyrrole–chitosan–titanium dioxide (Ppy-CS-TiO2) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO2 nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO2 NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO2 in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1–14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO2 nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell. PMID:28561760

Biodegradable Nanocomposite Films Based on Sodium Alginate and Cellulose Nanofibrils

PubMed Central

Deepa, B.; Abraham, Eldho; Pothan, Laly A.; Cordeiro, Nereida; Faria, Marisa; Thomas, Sabu

2016-01-01

Biodegradable nanocomposite films were prepared by incorporation of cellulose nanofibrils (CNF) into alginate biopolymer using the solution casting method. The effects of CNF content (2.5, 5, 7.5, 10 and 15 wt %) on mechanical, biodegradability and swelling behavior of the nanocomposite films were determined. The results showed that the tensile modulus value of the nanocomposite films increased from 308 to 1403 MPa with increasing CNF content from 0% to 10%; however, it decreased with further increase of the filler content. Incorporation of CNF also significantly reduced the swelling percentage and water solubility of alginate-based films, with the lower values found for 10 wt % in CNF. Biodegradation studies of the films in soil confirmed that the biodegradation time of alginate/CNF films greatly depends on the CNF content. The results evidence that the stronger intermolecular interaction and molecular compatibility between alginate and CNF components was at 10 wt % in CNF alginate films. PMID:28787850

Fabrication of gelatin-TiO2 nanocomposite film and its structural, antibacterial and physical properties.

PubMed

He, Qingyan; Zhang, Yuchen; Cai, Xixi; Wang, Shaoyun

2016-03-01

Biodegradable fish skin gelatin-titanium dioxide (TiO2) nanocomposite films were fabricated and characterized as a function of incorporating amount of TiO2 nanoparticles (gelatin/TiO2 ratio of 30:1, 20:1 and 10:1). A uniform distribution of TiO2 nanoparticles into gelatin matrix was observed using atomic force microscopy (AFM) micrographs. The data of intrinsic fluorescence spectra, Fourier transform infrared spectra (FTIR) and X-ray diffraction confirmed the interaction between protein and nanoparticles through hydrogen bonding. The TiO2-incorporated gelatin nanocomposite films exhibited more effective antibacterial activity for Escherichia coli after irradiating 120 min by UV light (365 nm), which were 54.38% for E. coli and 44.89% for Staphylococcus aureus, respectively. The analysis of physical properties revealed that addition of TiO2 nanoparticles to gelatin films significantly increased the tensile strength and elongation at break, while decreased its water vapor permeability. The light barrier measurements indicated that these films were highly transparent, and they had excellent barrier properties against UVC light at the same time. The results demonstrated the feasibility of incorporating nanoparticles to improve the properties of gelatin films, and it is of significance in utilizing the gelatin and titanium dioxide to produce biodegradable nanocomposite film as packaging material in food industry. Copyright © 2015 Elsevier B.V. All rights reserved.

Processing-structure-properties relationships in PLA nanocomposite films

NASA Astrophysics Data System (ADS)

Di Maio, L.; Scarfato, P.; Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Incarnato, L.

2014-05-01

This work deals on the possibility to improve performances of PLA-based nanocomposite films, for packaging applications, through conveniently tuning materials and processing conditions in melt compounding technology. In particular, two types of polylactic acid and different types of filler selected from montmorillonites and bentonites families were used to prepare the hybrid systems by using a twin-screw extruder. The effect of biaxial drawing on morphology and properties of the nanocomposites, produced by film blowing, was investigated.

High oxygen nanocomposite barrier films based on xylan and nanocrystalline cellulose

Treesearch

Amit Saxena; Thomas J. Elder; Jeffrey Kenvin; Arthur J. Ragauskas

2010-01-01

The goal of this work is to produce nanocomposite film with low oxygen permeability by casting an aqueous solution containing xylan, sorbitol and nanocrystalline cellulose. The morphology of the resulting nanocomposite films was examined by scanning electron microscopy and atomic force microscopy which showed that control films containing xylan and sorbitol had a more...

Physicochemical and antifungal properties of bio-nanocomposite film based on gelatin-chitin nanoparticles.

PubMed

Sahraee, Samar; Milani, Jafar M; Ghanbarzadeh, Babak; Hamishehkar, Hamed

2017-04-01

The gelatin-based nanocomposite films containing chitin nanoparticles (N-chitin) with concentrations of 0, 3, 5 and 10% were prepared and their physical, thermal and anti-microbial properties were investigated. Scanning electron microscopy (SEM) micrographs showed that N-chitin size distribution was around 60-70nm which dispersed appropriately at low concentration in gelatin matrix. The results showed that incorporation of N-chitin significantly influenced apparent color and transparency of the gelatin films. The reduced water vapor permeability (WVP) and solubility and higher surface hydrophobicity of the nanocomposite films were obtained by enhancing N-chitin concentration in film formulation. The use of N-chitin up to 5% concentration in the gelatin based nanocomposite film led to improved mechanical properties. Also, the results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed improved stability of nanocomposite films against melting and degradation at high temperatures in comparison to neat gelatin film. The well compatibility of chitin nanoparticles with gelatin polymer was concluded from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) plots. Finally, the gelatin based nanocomposite films had anti-fungal properties against Aspergillus niger in the contact surface zone. Increasing the concentration of N-chitin up to 5% enlarged inhibition zone diameter, but the nanocomposite film containing 10% N-chitin showed smaller inhibition zone. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical synthesis and characterization of chitosan/silver nanocomposites films and their potential antibacterial activity.

PubMed

Shah, Aamna; Hussain, Izhar; Murtaza, Ghulam

2018-05-12

This study provides the optimum preparation parameters for functional chitosan silver nanocomposite (CSN) films with promising antibacterial efficacy though prepared with very low silver nitrate (AgNO 3 ) concentration. Chitosan nano‑silver composites were fabricated by In-situ chemical method utilizing the reducing ability of sodium borohydride (NaBH 4 ) and afterward casted into films. Utilization of response surface methodology, NCSS, and SigmaPlot for the optimization of CSN and their predicted antibacterial efficacy assessment of the selected bacterial strains (standard and clinical) was the essential part of the study. The cumulative silver ions released from the CSN films was examined by AAS and was found pH dependent. The developed nanocomposite films exhibited strong antibacterial activity against ATCC strains of Gram-positive Staphylococcus aureus, Gram-negative bacteria (Pseudomonas aeruginosa) and clinically isolated strains of MRSA. The antibacterial activity CSN films were compared with three commercially available dressings (Aquacel Ag®, Bactigras®, and Kaltostat®) and Quench cream. Statistical analysis of the results indicated that the developed CSN films were equally or even more effective than commercial products. Thus the fabricated CSN films may act as a potential candidate to overcome the emerging antibiotic resistance particularly in hospital-acquired skin infections caused by MRSA. Copyright © 2018. Published by Elsevier B.V.

Biopolymer-modified graphite oxide nanocomposite films based on benzalkonium chloride-heparin intercalated in graphite oxide

NASA Astrophysics Data System (ADS)

Meng, Na; Zhang, Shuang-Quan; Zhou, Ning-Lin; Shen, Jian

2010-05-01

Heparin is a potent anticoagulant agent that interacts strongly with antithrombin III to prevent the formation of fibrin clots. In the present work, poly(dimethylsiloxane)(PDMS)/graphite oxide-benzalkonium chloride-heparin (PDMS/modified graphite oxide) nanocomposite films were obtained by the solution intercalation technique as a possible drug delivery system. The heparin-benzalkonium chloride (BAC-HEP) was intercalated into graphite oxide (GO) layers to form GO-BAC-HEP (modified graphite oxide). Nanocomposite films were characterized by XRD, SEM, TEM, ATR-FTIR and TGA. The modified graphite oxide was observed to be homogeneously dispersed throughout the PDMS matrix. The effect of modified graphite oxide on the mechanical properties of the nanocomposite film was investigated. When the modified graphite oxide content was lower than 0.2 wt%, the nanocomposites showed excellent mechanical properties. Furthermore, nanocomposite films become delivery systems that release heparin slowly to make the nanocomposite films blood compatible. The in vitro studies included hemocompatibility testing for effects on platelet adhesion, platelet activation, plasma recalcification profiles, and hemolysis. Results from these studies showed that the anticoagulation properties of PDMS/GO-BCA-HEP nanocomposite films were greatly superior to those for no treated PDMS. Cell culture assay indicated that PDMS/GO-BCA-HEP nanocomposite films showed enhanced cell adhesion.

Structural mechanical and antibacterial properties of HPMC/SF-AgNPs nanocomposite films

NASA Astrophysics Data System (ADS)

Harish, K. V.; Rao, B. Lakshmeesha; Asha, S.; Vipin, C.; Sangappa, Y.

2018-04-01

In the present study, Hydroxypropyl Methylcellulose (HPMC) pure and HPMC/SF-AgNPs biopolymer nanocomposite films were prepared by simple solution casting method. The prepared nanocomposite films were characterized using UV-Visible spectroscopy(UV-Vis), X-ray diffraction (XRD) measurements. The mechanical properties of HPMC/SF-AgNPs nanocomposites were found to be decrease with increase in the AgNP's concentrations. The HPMC/SF-AgNPs nanocomposites showed very good antibacterial activity against human pathogens P. aeruginosa, E.coli, and S.aureus.

Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application.

PubMed

Park, B J; Sung, J H; Park, J H; Choi, J S; Choi, H J

2008-05-01

Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.

Effect of halloysite content on carboxymethyl cellulose/halloysite nanotube bio-nanocomposite films

NASA Astrophysics Data System (ADS)

Suppiah, Kathiravan; Leng, Teh Pei; Husseinsyah, Salmah; Rahman, Rozyanty; Keat, Yeoh Cheow

2017-04-01

Carboxymethyl cellulose/halloysite nanotube (CMC/HNT) bio-nanocomposite films were prepared by solution casting method. The effect of HNT content on tensile properties and morphology were studied. The results showed that the tensile strength of the CMC/HNT bio-nanocomposite films achieved optimum at 10 wt% of HNT content. The elongation at break and modulus of elasticity increased with increasing HNT content. The morphology of CMC/HNT bio-nanocomposite films showed that the poor distribution of HNT filler was observed at 20 wt% of HNT content.

Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

PubMed Central

Liu, Peng; Chen, Ying; Yu, Zhiwu

2016-01-01

A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570), and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrscopy, X-ray diffractometry (XRD), contact angle meter (CA), and scanning electron microscope (SEM). The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570). Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures. PMID:28774141

Nano CaCO₃ imprinted starch hybrid polyethylhexylacrylate\\polyvinylalcohol nanocomposite thin films.

PubMed

Prusty, Kalyani; Swain, Sarat K

2016-03-30

Starch hybrid polyethylhexylacrylate (PEHA)/polyvinylalcohol (PVA) nanocomposite thin films are prepared by different composition of nano CaCO3 in aqueous medium. The chemical interaction of nano CaCO3 with PEHA in presence of starch and PVA is investigated by Fourier transforms infrared spectroscopy (FTIR). X-ray diffraction (XRD) is used in order to study the change in crystallite size and d-spacing during the formation of nanocomposite thin film. The surface morphology of nanofilms is studied by scanning electron microscope (SEM). The topology and surface roughness of the films is noticed by atomic force microscope (AFM). The tensile strength, thermal stability and thermal conductivity of films are increased with increase in concentrations of CaCO3 nanopowder. The chemical resistance and biodegradable properties of the nanocomposite thin films are also investigated. The growth of bacteria and fungi in starch hybrid PEHA film is reduced substantially with imprint of nano CaCO3. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optical, structural and electrochromic behavior studies on nanocomposite thin film of aniline, o-toluidine and WO3

NASA Astrophysics Data System (ADS)

Najafi-Ashtiani, Hamed; Bahari, Ali

2016-08-01

In the field of materials for electrochromic (EC) applications much attention was paid to the derivatives of aniline. We report on the optical, structural and electrochromic properties of electrochromic thin film based on composite of WO3 nanoparticles and copolymer of aniline and o-toluidine prepared by electrochemical polymerization method on fluorine doped tin oxide (FTO) coated glass. The thin film was studied by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy. The morphology of prepared thin film was characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and the thermal gravimetric analysis (TGA) as well. The optical spectra of nanocomposite thin film were characterized in the 200-900 nm wavelength range and EC properties of nanocomposite thin film were studied by cyclic voltammetry (CV). The calculation of optical band gaps of thin film exhibited that the thin film has directly allowed transition with the values of 2.63 eV on first region and 3.80 eV on second region. Dispersion parameters were calculated based on the single oscillator model. Finally, important parameters such as dispersion energy, oscillator energy and lattice dielectric constant were determined and compared with the data from other researchers. The nonlinear optical properties such as nonlinear optical susceptibility, nonlinear absorption coefficient and nonlinear refractive index were extracted. The obtained results of nanocomposite thin film can be useful for the optoelectronic applications.

Methods of making non-covalently bonded carbon-titania nanocomposite thin films and applications of the same

DOEpatents

Liang, Yu Teng; Vijayan, Baiju K.; Gray, Kimberly A.; Hersam, Mark C.

2016-07-19

In one aspect, a method of making non-covalently bonded carbon-titania nanocomposite thin films includes: forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

Physical-mechanical properties of agar/κ-carrageenan blend film and derived clay nanocomposite film.

PubMed

Rhim, Jong-Whan

2012-12-01

Binary blend films with different mixing ratio of agar and κ-carrageenan were prepared using a solution casting method with and without nanoclay and the effect of their composition on the mechanical, water vapor barrier, and water resistance properties was tested. The tensile strength (TS) of the κ-carrageenan film was greater than that of agar film. The water vapor permeability (WVP) of the agar film was lower than that of κ-carrageenan film, the swelling ratio (SR) and water solubility (WS) of κ-carrageenan film were higher than those of agar film. Each property of the binary blend films varied proportionately depending on the mixing ratio of each component. The XRD result indicated that the nanocomposite with agar/κ-carrageenan/clay (Cloisite(®) Na(+)) was intercalated. Consequently, the mechanical strength, water vapor barrier properties, and water contact angle (CA) were significantly (P < 0.05) improved through nanocomposite formation. © 2012 Institute of Food Technologists®

Study on swift heavy ions induced modifications of Ag-ZnO nanocomposite thin film

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.; Siva Kumar, V. V.

2017-03-01

In the present work, swift heavy ion (SHI) irradiation induced modifications in structural and optical properties of Ag-ZnO nanocomposite thin films have been investigated. Ag-ZnO nanocomposite (NCs) thin films were synthesized by RF magnetron sputtering technique and irradiated with 100 MeV Ag7+ ions at three different fluences 3 × 1012, 1 × 1013 and 3 × 1013 ions/cm2. Rutherford Backscattering Spectrometry revealed Ag concentration to be ∼8.0 at.%, and measured thickness of the films was ∼55 nm. Structural properties of pristine and irradiated films have been analyzed by X-ray diffraction analysis and found that variation in crystallite size of the film with ion irradiation. X-ray photoelectron spectroscopy (XPS) indicates the formation of Ag-ZnO nanocomposite thin film with presence of Ag, Zn and O elements. Oxidation state of Ag and Zn also estimated by XPS analysis. Surface plasmon resonance (SPR) of Ag nanoparticle has appeared at ∼475 nm in the pristine thin film, which is blue shifted by ∼30 nm in film irradiated at fluence of 3 × 1012 ions/cm2 and completely disappeared in film irradiated at higher fluences, 1 × 1013 and 3 × 1013 ions/cm2. A marginal change in the optical band gap of Ag-ZnO nanocomposite thin film is also found with increasing ion fluence. Surface morphology of pristine and irradiated films have been studied using Atomic Force Microscopy (AFM). Raman and Photo-luminance (PL) spectra of nanocomposite thin films have been investigated to understand the ion induced modifications such as lattice defects and disordering in the nanocomposite thin film.

Transparent 'solution' of ultrathin magnesium hydroxide nanocrystals for flexible and transparent nanocomposite films.

PubMed

Wang, Jie-Xin; Sun, Qian; Chen, Bo; Wu, Xi; Zeng, Xiao-Fei; Zhang, Cong; Zou, Hai-Kui; Chen, Jian-Feng

2015-05-15

Transparent solutions of nanocrystals exhibit many unique properties, and are thus attractive materials for numerous applications. However, the synthesis of transparent nanocrystal solutions of magnesium hydroxide (MH) with wide applications is yet to be realized. Here, we report a facile two-step process, which includes a direct reactive precipitation in alcohol phase instead of aqueous phase combined with a successive surface modification, to prepare transparent alcohol solutions containing lamellar MH nanocrystals with an average size of 52 nm and an ultrathin thickness of 1-2 nm, which is the thinnest MH nanoplatelet reported in the literatures. Further, highly flexible and transparent nanocomposite films are fabricated with a solution mixing method by adding the transparent MH nanocrystal solutions into PVB solution. Considering the simplicity of the fabrication process, high transparency and good flexibility, this MH/polymer nanocomposite film is promising for flame-resistant applications in plastic electronics and optical devices with high transparency, such as flexible displays, optical filters, and flexible solar cells.

Optical properties of diamond like carbon nanocomposite thin films

NASA Astrophysics Data System (ADS)

Alam, Md Shahbaz; Mukherjee, Nillohit; Ahmed, Sk. Faruque

2018-05-01

The optical properties of silicon incorporated diamond like carbon (Si-DLC) nanocomposite thin films have been reported. The Si-DLC nanocomposite thin film deposited on glass and silicon substrate by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process. Fourier transformed infrared spectroscopic analysis revealed the presence of different bonding within the deposited films and deconvolution of FTIR spectra gives the chemical composition i.e., sp3/sp2 ratio in the films. Optical band gap calculated from transmittance spectra increased from 0.98 to 2.21 eV with a variation of silicon concentration from 0 to 15.4 at. %. Due to change in electronic structure by Si incorporation, the Si-DLC film showed a broad photoluminescence (PL) peak centered at 467 nm, i.e., in the visible range and its intensity was found to increase monotonically with at. % of Si.

Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

NASA Astrophysics Data System (ADS)

Niknezhad, Setareh

The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted

Nanocomposite films

DOEpatents

Mitlin, David; , Ophus, Colin; Evoy, Stephane; Radmilovic, Velimir; Mohammadi, Reza; Westra, Ken; Nelson-Fitzpatrick, Nathaniel; Lee, Zonghoon

2010-07-20

A thin-film composition of nanocrystal molybdenum in an amorphous metallic matrix may be formed by co-sputtering Mo with aluminum or nickel. NEMS cantilevers may be formed from the film. The films exhibit high nanoindentation hardness and a reduction in roughness and intrinsic stress, while maintaining resistivity in the metallic range.

Effect of annealing temperatures on the morphology and structural properties of PVDF/MgO nanocomposites thin films

NASA Astrophysics Data System (ADS)

Rozana, M. D.; Arshad, A. N.; Wahid, M. H. M.; Habibah, Z.; Sarip, M. N.; Rusop, M.

2018-05-01

This study investigates the effect of annealing on the topography, morphology and crystal phases of poly(vinylideneflouride)/Magnesium Oxide (MgO) nanocomposites thin films via AFM, FESEM and ATR-FTIR. The nanocomposites thin films were annealed at temperatures ranging from 70°C to 170°C. The annealed PVDF/MgO nanocomposites thin films were then cooled at room temperature before removal from the oven. This is to restructure the crystal lattice and to reduce imperfection for the PVDF/MgO nanocomposites thin films. PVDF/MgO nanocomposites thin films with annealing temperatures of 70°C, 90°C and 110°C showed uniform distribution of MgO nanoparticles, relatively low average surface roughness and no visible of defects. High application of annealing temperature on PVDF/MgO nanocomposites thin films caused tear-like defects on the thin films surface as observed by FESEM. The PVDF/MgO nanocomposites thin films annealed at 70°C was found to be a favourable film to be utilized in this study due to its enhanced β-crystalites of PVDF as evident in ATR-FTIR spectra.

High energy density and efficiency achieved in nanocomposite film capacitors via structure modulation

NASA Astrophysics Data System (ADS)

Zeng, Yi; Shen, Zhong-Hui; Shen, Yang; Lin, Yuanhua; Nan, Ce-Wen

2018-03-01

Flexible dielectric polymer films with high energy storage density and high charge-discharge efficiency have been considered as promising materials for electrical power applications. Here, we design hierarchical structured nanocomposite films using nonlinear polymer poly(vinylidene fluoride-HFP) [P(VDF-HFP)] with inorganic h-boron nitride (h-BN) nanosheets by electrospinning and hot-pressing methods. Our results show that the addition of h-BN nanosheets and the design of the hierarchical multilayer structure in the nanocomposites can remarkably enhance the charge-discharge efficiency and energy density. A high charge-discharge efficiency of 78% and an energy density of 21 J/cm3 can be realized in the 12-layered PVDF/h-BN nanocomposite films. Phase-field simulation results reveal that the spatial distribution of the electric field in these hierarchical structured films affects the charge-discharge efficiency and energy density. This work provides a feasible route, i.e., structure modulation, to improve the energy storage performances for nanocomposite films.

Development of biodegradable metaloxide/polymer nanocomposite films based on poly-ε-caprolactone and terephthalic acid.

PubMed

Varaprasad, Kokkarachedu; Pariguana, Manuel; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Sadiku, Emmanuel Rotimi

2017-01-01

The present investigation describes the development of metal-oxide polymer nanocomposite films from biodegradable poly-ε-caprolactone, disposed poly(ethylene terephthalate) oil bottles monomer and zinc oxide-copper oxide nanoparticles. The terephthalic acid and zinc oxide-copper oxide nanoparticles were synthesized by using a temperature-dependent precipitation technique and double precipitation method, respectively. The terephthalic acid synthesized was confirmed by FTIR analysis and furthermore, it was characterized by thermal analysis. The as-prepared CuO-ZnO nanoparticles structure was confirmed by XRD analysis and its morphology was analyzed by SEM/EDS and TEM. Furthermore, the metal-oxide polymer nanocomposite films have excellent mechanical properties, with tensile strength and modulus better than pure films. The metal-oxide polymer nanocomposite films that were successfully developed show a relatively brighter colour when compared to CuO film. These new metal-oxide polymer nanocomposite films can replace many non-degradable plastics. The new metal-oxide polymer nanocomposite films developed are envisaged to be suitable for use in industrial and domestic packaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermal and rheological properties of L-polylactide/polyethylene glycol/silicate nanocomposites films.

PubMed

Ahmed, Jasim; Varshney, Sunil K; Auras, Rafael; Hwang, Sung W

2010-10-01

The melt rheology and thermal properties of polylactide (PLA)-based nanocomposite films that were prepared by solvent casting method with L-PLA, polyethylene glycol (PEG), and montmorillonite clay were studied. The neat PLA showed predominantly solid-like behavior (G' > G″) and the complex viscosity (η*) decreased systematically as the temperature increased from 184 to 196 °C. The elastic modulus (G') of PLA/clay blend showed a significant improvement in the magnitude in the melt, while clay concentration was at 6% wt or higher. At similar condition, PEG dramatically reduced dynamic modulii and complex viscosity of PLA/PEG blend as function of concentration. A nanocomposite blend of PLA/PEG/clay (74/20/6) when compared to the neat polymer and PLA/PEG blend exhibited intermediate values of elastic modulus (G') and complex viscosity (η*) with excellent flexibility. Thermal analysis of different clay loading blends indicated that the melting temperature (T(m)) and glass transition temperature (T(g)) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the T(g) and the T(m) of the blends (PLA/PEG and PLA/PEG/clay) significantly, however, crystallinity increased in the similar condition. The transmission electron microscopy (TEM) image of nanocomposite films indicated good compatibility between PLA and PEG, whereas clay was not thoroughly distributed in the PLA matrix and remained as clusters. The percent crystallinity obtained by X-ray was significantly higher than that of differential scanning calorimeter (DSC) data for PLA.

Transport, mechanical and global migration data of multilayer copolyamide nanocomposite films with different layouts.

PubMed

Scarfato, P; Garofalo, E; Di Maio, L; Incarnato, L

2017-06-01

Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to "Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging" by Garofalo et al. (2017) [1]. Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2], [3], [4]. The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

Acetylene Gas-Sensing Properties of Layer-by-Layer Self-Assembled Ag-Decorated Tin Dioxide/Graphene Nanocomposite Film

PubMed Central

Jiang, Chuanxing; Yin, Nailiang; Yao, Yao; Shaymurat, Talgar; Zhou, Xiaoyan

2017-01-01

This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. An optimal temperature of 90 °C was determined, and the Ag–SnO2/rGO nanocomposite sensor exhibited excellent sensing behaviors towards acetylene, in terms of response, repeatability, stability and response/recovery characteristics, which were superior to the pure SnO2 and SnO2/rGO film sensors. The sensing mechanism of the Ag–SnO2/rGO sensor was attributed to the synergistic effect of the ternary nanomaterials, and the heterojunctions created at the interfaces between SnO2 and rGO. This work indicates that the Ag–SnO2/rGO nanocomposite is a good candidate for constructing a low-temperature acetylene sensor. PMID:28927021

Characteristic time scales of coalescence of silver nanocomposite and nanoparticle films induced by continuous wave laser irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paeng, Dongwoo; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu; Lee, Daeho

2014-08-18

In-situ optical probing has been performed to analyze and compare the characteristic coalescence time scales of silver ion-doped polyvinylalcohol nanocomposite (Ag-PVA NC) and polyvinylpyrrolidone-capped silver nanoparticle (Ag-PVP NP) films subjected to continuous wave laser irradiation. The Ag-PVA NC yielded conductive metallic patterns by photothermal reduction of PVA, formation of nanoparticles from silver ions and their subsequent coalescence. On the other hand, Ag-PVP NP thin films produced conductive patterns through only coalescence of nanoparticles. Upon laser irradiation, Ag-PVA NC and Ag-PVP NP films exhibited different coalescence characteristics.

Microstructural parameters and high third order nonlinear absorption characteristics of Mn-doped PbS/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Ramezanpour, B.; Mahmoudi Chenari, Hossein; Sadigh, M. Khadem

2017-11-01

In this work, undoped and Mn-doped PbS/PVA nanocomposite films have been successfully fabricated using the simple solution-casting method. Their crystalline structure was examined by X-ray powder diffraction (XRD). XRD pattern show the formation of cubic structure of PbS for Mn-doped PbS in PVA matrix. Microstructure parameters of Mn-doped PbS/PVA nanocomposite films were obtained through the size-strain plot (SSP) method. The thermal stability of the nanocomposite film was determined using Thermogravimetric analysis (TGA). Furthermore, Z-scan technique was used to investigate the optical nonlinearity of nanocomposite films by a continuous-wave laser irradiation at the wavelength of 655 nm. This experimental results show that undoped PbS/PVA nanocomposite films indicate high nonlinear absorption characteristics. Moreover, the nanocomposite films with easy preparation characteristics, high thermal stability and nonlinear absorption properties can be used as an active element in optics and photonic devices.

Enhanced mechanical properties of hydrothermal carbamated cellulose nanocomposite film reinforced with graphene oxide.

PubMed

Gan, Sinyee; Zakaria, Sarani; Syed Jaafar, Sharifah Nabihah

2017-09-15

Cellulose carbamate (CC) was synthesized via hydrothermal process and mixed with graphene oxide (GO) to form a homogeneous cellulose matrix nanocomposite films. The properties of CC/GO nanocomposite films fabricated using simple solution-mixing method with different GO loadings were studied. Transmission electron microscope analysis showed the exfoliation of self-synthesized GO nanosheets within the CC matrix. X-ray diffraction results confirmed the crystalline structure of CC/GO films as the CC/GO mass ratio increased from 100/0 to 100/4. The mechanical properties of CC/GO film were significantly improved as compared to neat CC film. From thermogravimetric analysis result, the introduction of GO enhanced the thermal stability and carbon yields. The 3D homogeneous porous structures of the CC/GO films were observed under Field emission scanning electron microscope. These improvements in nanocomposite film properties could be confirmed by Fourier transform infrared spectroscopy due to the strong and good interactions between CC and GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dielectric properties and effect of electrical aging on space charge accumulation in polyimide/TiO2 nanocomposite films

NASA Astrophysics Data System (ADS)

Zha, Jun-Wei; Dang, Zhi-Min; Song, Hong-Tao; Yin, Yi; Chen, George

2010-11-01

In situ polymerized polyimide/TiO2 (PI/TiO2) nanocomposite films with good electrical aging resistance are studied. Space charge distribution in the PI/TiO2 nanocomposite films are measured using the pulsed electroacoustic method. Dielectric properties of the films are measured in the frequency range of 102 Hz-106 Hz by an impedance analyzer (Agilent 4294A) at room temperature. These nanocomposite films are also characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). It is demonstrated that the nano-TiO2 particles strongly affect dielectric breakdown, lifetime and space charge distribution, and increase the voltage endurance of the nanocomposite films significantly. SEM analyses show that the nanocomposite films are destroyed after corona aging. The relation of space charge distribution with the concentration of the nano-TiO2 particles and the aging time is explored. Results show that an increase in dielectric permittivity of the nanocomposite films is observed with increasing filler concentration. However, the accumulation of space charge decreases with increasing nano-TiO2 particles concentration for the same corona aging time, and depends on the dielectric permittivity of the nanocomposite films.

Chitosan nanocomposite films: enhanced electrical conductivity, thermal stability, and mechanical properties.

PubMed

Marroquin, Jason B; Rhee, K Y; Park, S J

2013-02-15

A novel, high-performance Fe(3)O(4)/MWNT/Chitosan nanocomposite has been prepared by a simple solution evaporation method. A significant synergistic effect of Fe(3)O(4) and MWNT provided enhanced electrical conductivity, mechanical properties, and thermal stability on the nanocomposites. A 5% (wt) loading of Fe(3)O(4)/MWNT in the nanocomposite increased conductivity from 5.34×10(-5) S/m to 1.49×10(-2) S/m compared to 5% (wt) MWNT loadings. The Fe(3)O(4)/MWNT/Chitosan films also exhibited increases in tensile strength and modulus of 70% and 155%, respectively. The integral procedure decomposition temperature (IPDT) was enhanced from 501 °C to 568 °C. These effects resulted from a number of factors: generation of a greater number of conductive channels through interactions between MWNT and Fe(3)O(4) surfaces, a higher relative crystallinity, the antiplasticizing effects of Fe(3)O(4), a restricted mobility and hindrance of depolymerization of the Chitosan chain segments, as well as uniform distribution, improved dispersion, and strong interfacial adhesion between the MWNT and Chitosan matrix. Copyright © 2012 Elsevier Ltd. All rights reserved.

Chemical Synthesis and Optical Properties of CdS Poly(Lactic Acid) Nanocomposites and Their Transparent Fluorescent Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Cai-Feng; Cheng, Yu-Peng; Xie, He-Yi

2011-01-01

This paper describes the chemical synthesis of cadmium sulfide (CdS) polymer nanocomposites by covalently grafting poly(lactic acid) (PLA) onto the surfaces of CdS nanocrystals (NCs). Synthesis of the nanocomposites involved two steps. Lactic acid (LA) capped CdS NCs were first prepared by reacting cadmium chloride (CdCl2) with sodium sulfide (Na2S) using LA as the organic ligand in H2O/N,N-dimethylformamide (DMF) solution. Next CdS PLA nanocomposites were formed by in situ ring-opening polymerization of lactide on the surface of modified CdS NCs. Transparent fluorescent films were then successfully prepared by blending as-prepared CdS PLA nanocomposites with high-molecular-weight PLA. The as-prepared CdS NCsmore » and their nanocomposites were studied by transmission electron microscopic imaging, thermogravimetric analyses, and spectroscopic measurements (ultraviolet-visible absorption and photoluminescence). The spectroscopic studies revealed that the CdS polymer nanocomposites exhibited good optical properties in terms of their photoluminescence and transparency.« less

High Performances of Artificial Nacre-Like Graphene Oxide-Carrageenan Bio-Nanocomposite Films.

PubMed

Zhu, Wenkun; Chen, Tao; Li, Yi; Lei, Jia; Chen, Xin; Yao, Weitang; Duan, Tao

2017-05-16

This study was inspired by the unique multi-scale and multi-level 'brick-and-mortar' (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young's modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials.

High Performances of Artificial Nacre-Like Graphene Oxide-Carrageenan Bio-Nanocomposite Films

PubMed Central

Zhu, Wenkun; Chen, Tao; Li, Yi; Lei, Jia; Chen, Xin; Yao, Weitang; Duan, Tao

2017-01-01

This study was inspired by the unique multi-scale and multi-level ‘brick-and-mortar’ (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young’s modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials. PMID:28772897

Bio-active nanocomposite films based on nanocrystalline cellulose reinforced styrylquinoxalin-grafted-chitosan: Antibacterial and mechanical properties.

PubMed

Fardioui, Meriem; Meftah Kadmiri, Issam; Qaiss, Abou El Kacem; Bouhfid, Rachid

2018-07-15

In this study, active nanocomposite films based on cellulose nanocrystalline (NCC) reinforced styrylquinoxalin-grafted-chitosan are prepared by solvent-casting process. The structures of the two styrylquinoxaline derivatives were confirmed by FT-IR, 1 H, 13 C NMR spectral data and the study of the antibacterial activity against Escherichia coli (EC), Staphylococcus aureus (SA), Bacillus subtilis (BS) and Pseudomonas Aeruginosa (PA) exhibits that they have a good antibacterial activity against (PA). On their side, the styrylquinoxalin-g-chitosan films are able to inhibit the growth of (PA) through their contact area without being damaged by the antibacterial test conditions. The addition of 5wt% of NCCs as nano-reinforcements revealed no change at the level of antibacterial activity but led to an important improvement of the mechanical properties (more than 60% and 90% improvement in Young's modulus and tensile strength, respectively) of the modified-chitosan films. Thereby, the present nanocomposite films are prepared by a simple way and featured by good mechanical and antibacterial properties which enhance the possibility to use them as bio-based products for biomedical and food packaging. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation and characterization of a poly (1, 4-phenylenevinylene) derivative-based hybrid thin film nanocomposites with enhanced performance

NASA Astrophysics Data System (ADS)

Belhaj, Marwa; Jemmeli, Dhouha; Dridi, Cherif; Ben Salem, Balkiss; Jaballah, Najmeddine; Majdoub, Mustapha; Yatskiv, Roman; Grym, Jan

2018-05-01

In this study, a poly (1, 4-phenylenevinylene) derivative (PPV-C6) was synthesized via Gilch polycondensation, and its electrochemical and optical characteristics were determined by cyclic voltammetry analysis, ultraviolet-visible, and photoluminescence spectroscopy. The polymer exhibited semiconductor behavior with an optical band gap of about 2.02 eV. Thin-film hybrid nanocomposites were prepared based on PPV-C6 with a large range of concentrations of sol-gel synthesized surfactant-free ZnO nanoparticles (n-ZnO). We investigated the photophysical properties of nanocomposites with different weight ratios of n-ZnO. The optical absorption spectra of PPV-C6: n-ZnO nanocomposites exhibited moderate variation in terms of the optical band gap energy with respect to the pristine polymer. Photoluminescence spectra indicated that the optimum n-ZnO concentration was about 50 wt% to achieve photoluminescence quenching, which corresponded to the most homogeneous surface and efficient charge transfer due to optimal exciton dissociation. We established good correlations between the investigated properties.

Development of silane grafted ZnO core shell nanoparticles loaded diglycidyl epoxy nanocomposites film for antimicrobial applications.

PubMed

Suresh, S; Saravanan, P; Jayamoorthy, K; Ananda Kumar, S; Karthikeyan, S

2016-07-01

In this article a series of epoxy nanocomposites film were developed using amine functionalized (ZnO-APTES) core shell nanoparticles as the dispersed phase and a commercially available epoxy resin as the matrix phase. The functional group of the samples was characterized using FT-IR spectra. The most prominent peaks of epoxy resin were found in bare epoxy and in all the functionalized ZnO dispersed epoxy nanocomposites (ZnO-APTES-DGEBA). The XRD analysis of all the samples exhibits considerable shift in 2θ, intensity and d-spacing values but the best and optimum concentration is found to be 3% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposites supported by FT-IR results. From TGA measurements, 100wt% residue is obtained in bare ZnO nanoparticles whereas in ZnO core shell nanoparticles grafted DGEBA residue percentages are 37, 41, 45, 46 and 52% for 0, 1, 3, 5 and 7% ZnO-APTES-DGEBA respectively, which is confirmed with ICP-OES analysis. From antimicrobial activity test, it was notable that antimicrobial activity of 7% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposite film has best inhibition zone effect against all pathogens under study. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure and magnetic properties of spinel-perovskite nanocomposite thin films on SrTiO3 (111) substrates

NASA Astrophysics Data System (ADS)

Kim, Dong Hun; Yang, Junho; Kim, Min Seok; Kim, Tae Cheol

2016-09-01

Epitaxial CoFe2O4-BiFeO3 nanocomposite thin films were synthesized on perovskite structured SrTiO3 (001) and (111) substrates by combinatorial pulsed laser deposition and characterized using scanning electron microscopy, x-ray diffraction, and vibrating sample magnetometer. Triangular BiFeO3 nanopillars were formed in a CoFe2O4 matrix on (111) oriented SrTiO3 substrates, while CoFe2O4 nanopillars with rectangular or square top surfaces grew in a BiFeO3 matrix on (001) substrates. The magnetic hysteresis loops of nanocomposites on (111) oriented SrTiO3 substrates showed isotropic properties due to the strain relaxation while those of films on SrTiO3 (001) substrates exhibited a strong out-of-plane anisotropy originated from shape and strain effects.

Negative capacitance in (FeCoZr)-(PZT) nanocomposite films

NASA Astrophysics Data System (ADS)

Kołtunowicz, T. N.; Fedotova, J. A.; Zhukowski, P.; Saad, A.; Fedotov, A.; Kasiuk, J. V.; Larkin, A. V.

2013-03-01

In this work, attention was focused on the inductive contribution to the real part of admittance G(T, f) in (Fe0.45Co0.45Zr0.10)x(PZT)(1-x) nanocomposite films deposited in a mixed argon-oxygen atmosphere. The observed G(x, f, T) dependences for the films on the dielectric side of the insulator-metal transition demonstrated the negative capacitance (NC) effect that was maximal for the nanocomposites with 0.40 < x < 0.60, where the metallic FeCoZr nanoparticles were totally oxidized. The NC effect was explained by a specially developed model for the ac hopping conductance of the electrons between the fully oxidized nanoparticles embedded in the PZT matrix. In accordance with the model, under the determined conditions the observed structure of nanocomposites led to an increase in the hopping electron mean lifetime on nanoparticles and hence to the possibility of positive angles of the phase shifts θ and a proper NC (inductive-like contribution) effect.

Doxorubicin loaded carboxymethyl cellulose/graphene quantum dot nanocomposite hydrogel films as a potential anticancer drug delivery system.

PubMed

Javanbakht, Siamak; Namazi, Hassan

2018-06-01

Creating anticancer properties in the hydrogel film could make it as a candidate for treating cancer tissues. In this work, a novel hydrogel nanocomposite films with anticancer properties were designed via incorporation of graphene quantum dot (GQD) as a nanoparticle into carboxymethyl cellulose (CMC) hydrogel and using doxorubicin (DOX) as drug model with broad-spectrum anticancer properties. Drug release studies carried out at two different pHs and the MTT assay was evaluated for DOX-loaded CMC/GQD nanocomposite hydrogel films against blood cancer cells (K562). The prepared nanocomposite hydrogel films were characterized using Fourier transform infrared (FT-IR), UV-Vis spectroscopy, scanning electron microscopy (SEM), permeability and mechanical properties. The prepared CMC/GQD nanocomposite hydrogel films showed an improvement in vitro swelling, degradation, water vapor permeability and pH-sensitive drug delivery properties along with not significant toxicity against blood cancer cells (K562). According to the obtained results, this nanocomposite hydrogel films can be proposed to use as an anticancer film and drug delivery system. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of potassium sorbate on antimicrobial and physical properties of starch-clay nanocomposite films.

PubMed

Barzegar, Hassan; Azizi, Mohammad Hossein; Barzegar, Mohsen; Hamidi-Esfahani, Zohreh

2014-09-22

Using fresh foods which undergo the least processing operations developed widely in recent years. Active packaging is a novel method for preserving these products. Active starch-clay nanocomposite films which contained potassium sorbate (PS) at a level of 0, 5, 7.5 and 10 g PS/100 g starch were produced and their physical, mechanical and antimicrobial properties were evaluated. In order to evaluate antimicrobial properties of films Aspergillus niger was used. The results showed that 5% of the PS did not produce antimicrobial property in the film, but by increasing the content of the additive in film formulation, antimicrobial effect increased. PS increased water permeability and elongation at break of the films, but decreased tensile strength. The rate of PS migration into the semi-solid medium in starch-nanocomposites was lower than starch films. This shows that nanocomposite films could retain their antimicrobial property for longer time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of polylactic acid nanocomposite films reinforced with cellulose nanocrystals derived from coffee silverskin.

PubMed

Sung, Soo Hyun; Chang, Yoonjee; Han, Jaejoon

2017-08-01

Bio-nanocomposite films based on polylactic acid (PLA) matrix reinforced with cellulose nanocrystals (CNCs) were developed using a twin-screw extruder. The CNCs were extracted from coffee silverskin (CS), which is a by-product of the coffee roasting process. They were extracted by alkali treatment followed by sulfuric acid hydrolysis. They were used as reinforcing agents to obtain PLA/CNC nanocomposites by addition at different concentrations (1%, 3%, and 5% CNCs). Morphological, tensile, and barrier properties of the bio-nanocomposites were analyzed. The tensile strength and Young's modulus increased with both 1% and 3% CNCs. The water vapor permeability decreased gradually with increasing addition of CNCs up to 3% and good oxygen barrier properties were found for all nanocomposites. These results suggest that CNCs from CS can improve the physical properties of PLA-based biopolymer film. The developed PLA/CNC bio-nanocomposite films can potentially be used for biopolymer materials with enhanced barrier and mechanical properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Work function measurements of copper nanoparticle intercalated polyaniline nanocomposite thin films

NASA Astrophysics Data System (ADS)

Patil, U. V.; Ramgir, Niranjan S.; Bhogale, A.; Debnath, A. K.; Muthe, K. P.; Gadkari, S. C.; Kothari, D. C.

2017-05-01

The nature of contact between the electrode and the sensing material plays a crucial role in governing the sensing mechanism. Thin films of polyaniline (PANI) and copper-polyaniline nanocomposite (NC) have been deposited at room temperatures by in-situ oxidative polymerization of aniline in the presence of Cu nanoparticles. For sensing applications a thin film Au (gold) ˜100 nm is deposited and used as a conducting electrode. To understand the nature of contact (i.e., ohmic or Schottky) the work function of the conducting polyaniline and nanocomposite films were measured using Kelvin Probe method. I-V characteristics of PANI and NC films investigated at room temperatures further corroborates and confirms the formation of Ohmic contact as evident from work function measurements.

Dielectric tunability of vertically aligned ferroelectric-metal oxide nanocomposite films controlled by out-of-plane misfit strain

NASA Astrophysics Data System (ADS)

Wu, Huaping; Ma, Xuefu; Zhang, Zheng; Zhu, Jun; Wang, Jie; Chai, Guozhong

2016-04-01

A nonlinear thermodynamic model based on the vertically aligned nanocomposite (VAN) thin films of ferroelectric-metal oxide system has been developed to investigate the physical properties of the epitaxial Ba0.6Sr0.4TiO3 (BST) films containing vertical Sm2O3 (SmO) nanopillar arrays on the SrTiO3 substrate. The phase diagrams of out-of-plane lattice mismatch vs. volume fraction of SmO are calculated by minimizing the total free energy. It is found that the phase transformation and dielectric response of BST-SmO VAN systems are extremely dependent on the in-plane misfit strain, the out-of-plane lattice mismatch, the volume fraction of SmO phase, and the external electric field applied to the nanocomposite films at room temperature. In particular, the BST-SmO VAN systems exhibit higher dielectric properties than pure BST films. Giant dielectric response and maximum tunability are obtained near the lattice mismatch where the phase transition occurs. Under the in-plane misfit strain of umf=0.3 % and the out-of-plane lattice mismatch of u3=0.002 , the dielectric tunability can be dramatically enhanced to 90% with the increase of SmO volume fraction, which is well consistent with previous experimental results. This work represents an approach to further understand the dependence of physical properties on the lattice mismatch (in-plane and out-of-plane) and volume fraction, and to manipulate or optimize functionalities in the nanocomposite oxide thin films.

Preparation of Electrically Conductive Polystyrene/Carbon Nanofiber Nanocomposite Films

ERIC Educational Resources Information Center

Sun, Luyi; O'Reilly, Jonathan Y.; Tien, Chi-Wei; Sue, Hung-Jue

2008-01-01

A simple and effective approach to prepare conductive polystyrene/carbon nanofiber (PS/CNF) nanocomposite films via a solution dispersion method is presented. Inexpensive CNF, which has a structure similar to multi-walled carbon nanotubes, is chosen as a nanofiller in this experiment to achieve conductivity in PS films. A good dispersion is…

Understanding physicochemical properties changes from multi-scale structures of starch/CNT nanocomposite films.

PubMed

Liu, Siyuan; Li, Xiaoxi; Chen, Ling; Li, Lin; Li, Bing; Zhu, Jie

2017-11-01

From the view of multi-scale structures of hydroxypropyl starch (HPS)/carbon nanotube (CNT) nanocomposite films, the film physicochemical properties were affected by comprehensive factors including molecular interaction, short range molecular conformation, crystalline structure and aggregated structure. The less original HPS hydrogen bonding that was broken, less decreased order of HPS short range molecular conformation, lower film crystallinity and larger size of micro-ordered regions contributed to higher tensile strength and Young's modulus of the film with CNT content of 0.5% (g/g, CNT in HPS). The higher film overall crystallinity and larger size of micro-ordered regions of the film with CNT content of 0.05%-0.3% compared with those of control contributed to better film barrier property. The addition of CNT with the content of 0.05%-0.5% broke the original HPS hydrogen bonding and decreased the order of starch short range molecular conformation, which counteracted the positive effect of CNT on the thermal stability of the material, thus thermal degradation temperature of these nanocomposite films did not increase. But the sharp increase of film crystallinity increased film thermal degradation temperature. This study provided a better understanding of film physicochemical properties changes which guides to rational design of starch-based nanocomposite films for packaging and coating application. Copyright © 2017. Published by Elsevier B.V.

An Amperometric Immunosensor Based on Multi-Walled Carbon Nanotubes-Thionine-Chitosan Nanocomposite Film for Chlorpyrifos Detection

PubMed Central

Sun, Xia; Cao, Yaoyao; Gong, Zhili; Wang, Xiangyou; Zhang, Yan; Gao, Jinmei

2012-01-01

In this work, a novel amperometric immunosensor based on multi-walled carbon nanotubes-thionine-chitosan (MWCNTs-THI-CHIT) nanocomposite film as electrode modified material was developed for the detection of chlorpyrifos residues. The nanocomposite film was dropped onto a glassy carbon electrode (GCE), and then the anti-chlorpyrifos monoclonal antibody was covalently immobilized onto the surface of MWCNTs-THI-CHIT/GCE using the crosslinking agent glutaraldehyde (GA). The modification procedure was characterized by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, a linear relationship between the relative change in peak current of different pulse voltammetry (DPV) and the logarithm of chlorpyrifos solution concentration was obtained in the range from 0.1 to 1.0 × 105 ng/mL with a detection limit of 0.046 ng/mL. The proposed chlorpyrifos immunosensor exhibited high reproducibility, stability, and good selectivity and regeneration, making it a potential alternative tool for ultrasensitive detection of chlorpyrifos residues in vegetables and fruits. PMID:23443396

Non-conductive ferromagnetic carbon-coated (Co, Ni) metal/polystyrene nanocomposites films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takacs, H., E-mail: helene.takacs@gmail.com; LTM-CNRS-UJF, CEA, LETI, Minatec Campus, Grenoble 38054; Viala, B.

2016-03-07

This article reports non-conductive ferromagnetic properties of metal/polymer nanocomposite films intended to be used for RF applications. The nanocomposite arrangement is unique showing a core double-shell structure of metal-carbon-polystyrene: M/C//P{sub 1}/P{sub 2}, where M = Co, Ni is the core material, C = graphene or carbon is the first shell acting as a protective layer against oxidation, P{sub 1} = pyrene-terminated polystyrene is the second shell for electrical insulation, and P{sub 2} = polystyrene is a supporting matrix (// indicates actual grafting). The nanocomposite formulation is briefly described, and the film deposition by spin-coating is detailed. Original spin-curves are reported and analyzed. One key outcome is the achievementmore » of uniform and cohesive films at the wafer scale. Structural properties of films are thoroughly detailed, and weight and volume fractions of M/C are considered. Then, a comprehensive overview of DC magnetic and electrical properties is reported. A discussion follows on the magnetic softness of the nanocomposites vs. that of a single particle (theoretical) and the raw powder (experimental). Finally, unprecedented achievement of high magnetization (∼0.6 T) and ultra-high resistivity (∼10{sup 10 }μΩ cm) is shown. High magnetization comes from the preservation of the existing protective shell C, with no significant degradation on the particle net-moment, and high electrical insulation is ensured by adequate grafting of the secondary shell P{sub 1}. To conclude, the metal/polymer nanocomposites are situated in the landscape of soft ferromagnetic materials for RF applications (i.e., inductors and antennas), by means of two phase-diagrams, where they play a crucial role.« less

Switchable 3-0 magnetoelectric nanocomposite thin film with high coupling.

PubMed

McDannald, Austin; Ye, Linghan; Cantoni, Claudia; Gollapudi, Sreenivasulu; Srinivasan, Gopalan; Huey, Bryan D; Jain, Menka

2017-03-02

A mixed precursor solution method was used to deposit 3-0 nanocomposite thin films of PbZr 0.52 Ti 0.48 O 3 (PZT) and CoFe 2 O 4 (CFO). The piezoelectric behavior of PZT and magnetostrictive behavior of CFO allow for magnetoelectric (ME) coupling through strain transfer between the respective phases. High ME coupling is desired for many applications including memory devices, magnetic field sensors, and energy harvesters. The spontaneous phase separation in the 3-0 nanocomposite film was observed, with 25 nm CFO particle or nanophases distributed in discrete layers through the thickness of the PZT matrix. Magnetic-force microscopy images of the nanocomposite thin film under opposite magnetic poling conditions revealed in-plane pancake-like regions of higher concentration of the CFO nanoparticles. The constraints on the size and distribution of the CFO nanoparticles created a unique distribution in a PZT matrix and achieved values of ME coupling of 3.07 V cm -1 Oe -1 at a DC bias of 250 Oe and 1 kHz, increasing up to 25.0 V cm -1 Oe -1 at 90 kHz. Piezo-force microscopy was used to investigate the ferroelectric domain structure before and after opposite magnetic poling directions. It was found that in this nanocomposite, the polarization of the ferroelectric domains switched direction as a result of switching the direction of the magnetization by magnetic fields.

Synthesis and characterization of CdS/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Fang, Pengfei; Chen, Zhe; Wang, Shaojie

2007-08-01

A series CdS/PVA nanocomposite films with different amount of Cd salt have been prepared by means of the in situ synthesis method via the reaction of Cd 2+-dispersed poly vinyl-alcohol (PVA) with H 2S. The as-prepared films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectra, Fourier transform infrared spectroscope (FTIR) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The primary FTIR spectra of CdS/PVA nanocomposite in different processing stages have been discussed. The vibrational absorption peak of Cd sbnd S bond at 405 cm -1 was observed, which further testified the generation of CdS nanoparticles. The TGA results showed incorporation of CdS nanoparticles significantly altered the thermal properties of PVA matrix. The photoluminescence and UV-vis spectroscopy revealed that the CdS/PVA films showed quantum confinement effect.

Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jingyu; Xiao, Yihan; Xu, Ting

Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules withmore » a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. Lastly, the present studies opened a viable route to achieve designer functional composite thin films via kinetic control.« less

Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jingyu; Xiao, Yihan; Xu, Ting

Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules withmore » a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. The present studies opened a viable route to achieve designer functional composite thin films via kinetic control.« less

Achieving 3-D Nanoparticle Assembly in Nanocomposite Thin Films via Kinetic Control

DOE PAGES

Huang, Jingyu; Xiao, Yihan; Xu, Ting

2017-02-20

Nanocomposite thin films containing well-ordered nanoparticle (NP) assemblies are ideal candidates for the fabrication of metamaterials. Achieving 3-D assembly of NPs in nanocomposite thin films is thermodynamically challenging as the particle size gets similar to that of a single polymer chain. The entropic penalties of polymeric matrix upon NP incorporation leads to NP aggregation on the film surface or within the defects in the film. Controlling the kinetic pathways of assembly process provides an alternative path forward by arresting the system in nonequilibrium states. Here, we report the thin film 3-D hierarchical assembly of 20 nm NPs in supramolecules withmore » a 30 nm periodicity. By mediating the NP diffusion kinetics in the supramolecular matrix, surface aggregation of NPs was suppressed and NPs coassemble with supramolecules to form new 3-D morphologies in thin films. Lastly, the present studies opened a viable route to achieve designer functional composite thin films via kinetic control.« less

Pulsed photoinitiated fabrication of inkjet printed titanium dioxide/reduced graphene oxide nanocomposite thin films.

PubMed

Bourgeois, Briley; Luo, Sijun; Riggs, Brian; Ji, Yaping; Adireddy, Shiva; Schroder, Kurt; Farnsworth, Stan; Chrisey, Douglas; Escarra, Matthew

2018-08-03

This work reports a new technique for scalable and low-temperature processing of nanostructured TiO 2 thin films, allowing for practical manufacturing of TiO 2 -based devices such as perovskite solar cells at low-temperature or on flexible substrates. Dual layers of dense and mesoporous TiO 2 /graphitic oxide nanocomposite films are synthesized simultaneously using inkjet printing and pulsed photonic irradiation. Investigation of process parameters including precursor concentration (10-20 wt%) and exposure fluence (4.5-8.5 J cm -2 ) reveals control over crystalline quality, graphitic oxide phase, film thickness, dendrite density, and optical properties. Raman spectroscopy shows the E g peak, characteristic of anatase phase titania, increases in intensity with higher photonic irradiation fluence, suggesting increased crystallinity through higher fluence processing. Film thickness and dendrite density is shown to increase with precursor concentration in the printed ink. The dense base layer thickness was controlled between 20 and 80 nm. The refractive index of the films is determined by ellipsometry to be 1.92 ± 0.08 at 650 nm. Films exhibit an energy weighted optical transparency of 91.1%, in comparison to 91.3% of a thermally processed film, when in situ carbon materials were removed. Transmission and diffuse reflectance are used to determine optical band gaps of the films ranging from 2.98 to 3.38 eV in accordance with the photonic irradiation fluence and suggests tunability of TiO 2 phase composition. The sheet resistance of the synthesized films is measured to be 14.54 ± 1.11 Ω/□ and 28.90 ± 2.24 Ω/□ for films as-processed and after carbon removal, respectively, which is comparable to high temperature processed TiO 2 thin films. The studied electrical and optical properties of the light processed films show comparable results to traditionally processed TiO 2 while offering the distinct advantages of scalable manufacturing, low-temperature processing

Preparation and characterization of nanocrystalline cellulose/Eucommia ulmoides gum nanocomposite film.

PubMed

Sun, Qianqian; Zhao, Xinkun; Wang, Dongmei; Dong, Juane; She, Diao; Peng, Pai

2018-02-01

The nanocomposite films were prepared using Eucommia ulmoides gum (EUG) matrix reinforced with nanocrystalline cellulose (NCC) at different concentrations. Subsequently, the obtained films were characterized by Raman spectra, AFM, XRD, TGA, and DSC. Meanwhile, the wettability, mechanical, and water vapor barrier properties of these films were analyzed. AFM noticed that the average sizes of NCC were 81.95×50.17×13.06nm, while the size of molecular chain for EUG was 2530×57.33×1.28nm. In comparison with control film, a certain amount of NCC obviously improved elongation at break and enhanced their crystallinity and ΔH m . More importantly, NCC/EUG nanocomposite films presented lower thermal stability, glass transition temperature (T g ), melting temperature (T m ), and water vapor permeability (WVP) values, especially the WVP values of 4% NCC film were the lowest as 0.28×10 -9 , 0.30×10 -9 , and 0.58×10 -9 g/m/h/Pa at RH 34%, 55%, and 76%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Active packaging from chitosan-titanium dioxide nanocomposite film for prolonging storage life of tomato fruit.

PubMed

Kaewklin, Patinya; Siripatrawan, Ubonrat; Suwanagul, Anawat; Lee, Youn Suk

2018-06-01

The feasibility of active packaging from chitosan (CS) and chitosan containing nanosized titanium dioxide (CT) to maintain quality and extend storage life of climacteric fruit was investigated. The CT nanocomposite film and CS film were fabricated using a solution casting method and used as active packaging to delay ripening process of cherry tomatoes. Changes in firmness, weight loss, a*/b* color, lycopene content, total soluble solid, ascorbic acid, and concentration of ethylene and carbon dioxide of the tomatoes packaged in CT film, CS film, and control (without CT or CS films) were monitored during storage at 20°C. Classification of fruit quality as a function of different packaging treatments was visualized using linear discriminant analysis. Tomatoes packaged in the CT film evolved lower quality changes than those in the CS film and control. The results suggested that the CT film exhibited ethylene photodegradation activity when exposed to UV light and consequently delayed the ripening process and changes in the quality of the tomatoes. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation and characteristics of TFMB functionalized graphene oxide/polyimide nanocomposite films

NASA Astrophysics Data System (ADS)

Liu, Lin; Wang, Yiyao; Gao, Yixin

2018-04-01

Polyimide(PI), with its great thermal and mechanical properties, has been widely used in various fields, such as aerospace and microelectronics. However, with the development of high technology, common PI materials can not satisfy the demands, due to its high resistance. In this work, we used 2,2'- Bis(trifluoromethyl) benzidine(TFMB) to functionalize GO and further form GO-TFMB/PI nanocomposite film. In the end, we got GO-TFMB/PI nanocomposite films with excellent thermal stability, better toughness and better electrical conductivity. As shown in results, the incorporation of GO-TFMB maintained excellent thermal stability. With the addition of GO-TFMB, the resistivity of the composite film decreased continuously. And when the content of GO-TFMB was 0.8 wt%, the resistivity could achieve the excellent antistatic material standard.

Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. Q.; Pei, Y. T.; Shaha, K. P.

2009-06-01

This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a 'microstructural ruler' that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens ofmore » nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.« less

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-04-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-07-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Optical, mechanical and structural properties of PMMA/SiO2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Soni, Gyanesh; Srivastava, Subodh; Soni, Purushottam; Kalotra, Pankaj; Vijay, Y. K.

2018-01-01

We have fabricated PMMA/SiO2 nanocomposite flexible thin films of 60 μm thicknesses by using solution casting method in the presence of transverse electric field. In this paper, we have investigated the effect of SiO2 nanoparticle (NP) loading on optical and mechanical properties of the composite thin film. The SEM images show that nanocomposite thin films have a smoother and uniform morphology. The transmittance peak near 1103 cm-1 in FT-IR spectrum confirms the presence of SiO2 NPs in the composite thin film. It is observed that optical bandgap decreases with an increase in the SiO2 NP concentration. Dynamic mechanical analysis shows that presence of SiO2 NP enhances the mechanical strength of the composite thin film.

Preparation and characterization of gamma irradiated Starch/PVA/ZnO nanocomposite films

NASA Astrophysics Data System (ADS)

Akhavan, Azam; Khoylou, Farah; Ataeivarjovi, Ebrahim

2017-09-01

In this study starch/PVA/ZnO nanocomposite films with antibacterial activity were prepared and modified using gamma irradiation for packaging applications. ZnO nanoparticles (NPs) were synthesized from Zn(OH)2 using hydrothermal process and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared ZnO NPs were incorporated into blend films of starch and poly (vinyl alcohol) (PVA) with different concentrations from 0.1 to 1 wt% using solution casting method. The results of SEM confirmed good dispersion of ZnO NPs into the films while FTIR spectroscopy showed interactions between ZnO particles and starch/PVA blend. The nanocomposite films were irradiated at the dose range of 1-5 kGy. It was found that gamma irradiation induces a significant reduction in water absorptions of the films at the dose of 3 kGy. Different trends were observed for the tensile and elongation properties of the irradiated films. Based on the results, the bacterial growth on the films was effectively inhibited when the dosage of ZnO NPs was only 0.5 wt%.

Evaporation-induced self-assembly of quantum dots-based concentric rings on polymer-based nanocomposite films.

PubMed

Zhang, Shaofu; Luan, Weiling; Zhong, Qixin; Yin, Shaofeng; Yang, Fuqian

2016-10-12

The "ball-on-film" template is used to construct concentric rings on the surface of PMMA-QDs (polymethyl methacrylate - quantum dots) nanocomposite films via the evaporation of pure chloroform droplets, which are confined by a steel ball. The concentric rings consist of QDs, as revealed by the fluorescence images of the concentric rings. The photoluminescence intensity of the concentric rings increases with the increase of the distance to the ball center, suggesting that the amount of QDs accumulated around the contact line at individual stick state increases with the increase of the distance to the ball center. Both the wavelength and cross-sectional area (width) of the concentric rings increase approximately linearly with increasing distance to the ball center, independent of the ball size, the film thickness and the QDs concentration. For the PMMA-QDs nanocomposite films prepared from the same QDs concentration in chloroform, the thicker the PMMA-QDs nanocomposite film, the larger the wavelength for the same distance to the ball center. The effect of confinement of two steel balls on the surface patterns over the PMMA-QDs nanocomposite films is studied via a template of "two spheres on film". Symmetric surface patterns are formed. There exist two types of featureless zone between the two balls, depending on the distance between the two balls: one is the inner featureless zone and the other is the outer featureless zone. The size of both featureless zones increases with the increase of the ball distance.

Stretchable Electronic Sensors of Nanocomposite Network Films for Ultrasensitive Chemical Vapor Sensing.

PubMed

Yan, Hong; Zhong, Mengjuan; Lv, Ze; Wan, Pengbo

2017-11-01

A stretchable, transparent, and body-attachable chemical sensor is assembled from the stretchable nanocomposite network film for ultrasensitive chemical vapor sensing. The stretchable nanocomposite network film is fabricated by in situ preparation of polyaniline/MoS 2 (PANI/MoS 2 ) nanocomposite in MoS 2 suspension and simultaneously nanocomposite deposition onto prestrain elastomeric polydimethylsiloxane substrate. The assembled stretchable electronic sensor demonstrates ultrasensitive sensing performance as low as 50 ppb, robust sensing stability, and reliable stretchability for high-performance chemical vapor sensing. The ultrasensitive sensing performance of the stretchable electronic sensors could be ascribed to the synergistic sensing advantages of MoS 2 and PANI, higher specific surface area, the reliable sensing channels of interconnected network, and the effectively exposed sensing materials. It is expected to hold great promise for assembling various flexible stretchable chemical vapor sensors with ultrasensitive sensing performance, superior sensing stability, reliable stretchability, and robust portability to be potentially integrated into wearable electronics for real-time monitoring of environment safety and human healthcare. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biopolymer-based nanocomposites: effect of lignin acetylation in cellulose triacetate films

PubMed Central

Nevárez, Laura Alicia Manjarrez; Casarrubias, Lourdes Ballinas; Celzard, Alain; Fierro, Vanessa; Muñoz, Vinicio Torres; Davila, Alejandro Camacho; Lubian, José Román Torres; Sánchez, Guillermo González

2011-01-01

We have prepared all-biopolymer nanocomposite films using lignin as a filler and cellulose triacetate (CTA) as a polymer matrix, and characterized them by several analytical methods. Three types of lignin were tested: organosolv, hydrolytic and kraft, with or without acetylation. They were used in the form of nanoparticles incorporated at 1 wt% in CTA. Self-supported films were prepared by vapor-induced phase separation at controlled temperature (35–55 °C) and relative humidity (10–70%). The efficiency of acetylation of each type of lignin was studied and discussed, as well as its effects on film structure, homogeneity and mechanical properties. The obtained results are explained in terms of intermolecular filler-matrix interaction at the nanometer scale, for which the highest mechanical resistance was reached using hydrolytic lignin in the nanocomposite. PMID:27877425

Morphology and Admittance Spectroscopy of Cellulose Acetate/Graphene Quantum Dots Nanocomposites

NASA Astrophysics Data System (ADS)

Arthisree, D.; Joshi, Girish M.; Kumar, Annamalai Senthil

Graphene quantum dots (GQDs) are considered as fascinating materials feasible for biological, optoelectronic devices, energy and environmental applications. Casting nanocomposite films for technological application is a challenging research interest. Cellulose acetate (CA) is one of the most abundant, economic, environmental friendly and biodegradable biomaterials. It has been found that CA is a preferred composite matrix to prepare recasting films, due to its efficient antifouling feature. In the present investigation, we exhibited preparation of CA/GQD nanocomposite by solution blending as a function of GQD loading 0.1-0.5wt.%. Morphology and electrical properties were examined as a function of GQD loading. The nanocomposite was characterized by impedance spectroscopy, and the measured admittance (Y) was plotted against temperature across broadband frequency. The magnitude of Y exhibits direct relation under the varying temperature. The morphology of the nanocomposites was observed by atomic force microscope technique in contact mode. Collective observation from our results is that it can be revealed that CA/GQD nanocomposites are suitable for thermal sensing applications.

Optical studies of CdSe/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Kushwaha, Kamal Kumar; Ramrakhaini, Meera

2018-05-01

The nanocomposite films of CdSe nanocrystals in polyvinyl alcohol (PVA) matrix were synthesized by environmental friendly chemical method. These composites were characterized by X-ray diffraction which indicates the hexagonal crystalline structure of CdSe with crystal size up to a few nm. The crystal size is found to decrease by increasing PVA Concentration. The photoluminescence (PL) characteristics of these composite films with varying concentration of PVA as well as Cd2+ content have been investigated. The PL peak of CdSe was observed at 510 nm and higher intensity is observed by increasing PVA concentration without any change in position of PL peak. Due to proper passivation of surface states non-radiative transition are reduced which enhance the PL intensity. By increasing concentration of Cd2+ content in the CdSe/PVA nanocomposite films, smaller CdSe nanocrystals were obtained giving higher intensity and blue shift in the PL peak due to enhanced oscillator strength and quantum confinement effect. The PL peak in green and blue region makes these composite films promising materials for optical display devices. The Refractive index of these composites was also measured at sodium line with the help of Abee's refractometer and was found in the range of 2.20-2.45. It is seen that refractive index varies with polymer concentration. This may be useful for their potential application in anti-reflection coating, display devices and optical sensors.

Rheological and thermal properties of polylactide/silicate nanocomposites films.

PubMed

Ahmed, Jasim; Varshney, Sunil K; Auras, Rafeal

2010-03-01

Polylactide (DL)/polyethylene glycol/silicate nanocomposite blended biodegradable films have been prepared by solvent casting method. Rheological and thermal properties were investigated for both neat amorphous polylactide (PLA-DL form) and blend of montmorillonite (clay) and poly (ethylene glycol) (PEG). Melt rheology of the PLA individually and blends (PLA/clay; PLA/PEG; PLA/PEG/clay) were performed by small amplitude oscillation shear (SAOS) measurement. Individually, PLA showed an improvement in the viscoelastic properties in the temperature range from 180 to 190 degrees C. Incorporation of nanoclay (3% to 9% wt) was attributed by significant improvements in the elastic modulus (G') of PLA/clay blend due to intercalation at higher temperature. Both dynamic modulii of PLA/PEG blend were significantly reduced with addition of 10% PEG. Rheometric measurement could not be conducted while PLA/PEG blends containing 25% PEG. A blend of PLA/PEG/clay (68/23/9) showed liquid-like properties with excellent flexibility. Thermal analysis of different clay loading films indicated that the glass transition temperatures (T(g)) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the T(g) of the blend (PLA/PEG and PLA/PEG/clay) significantly. Both rheological and thermal analysis data supported plasticization and flexibility of the blended films. It is also interesting to study competition between PLA and PEG for the intercalation into the interlayer spacing of the clay. This study indicates that PLA/montmorillonite blend could serve as effective nano-composite for packaging and other applications.

Development of an antimicrobial material based on a nanocomposite cellulose acetate film for active food packaging.

PubMed

Rodríguez, Francisco J; Torres, Alejandra; Peñaloza, Ángela; Sepúlveda, Hugo; Galotto, María J; Guarda, Abel; Bruna, Julio

2014-01-01

Nanocomposites based on biopolymers have been recognised as potential materials for the development of new ecofriendly food packaging. In addition, if these materials incorporate active substances in their structure, the potential applications are much higher. Therefore, this work was oriented to develop nanocomposites with antimicrobial activity based on cellulose acetate (CA), a commercial organoclay Cloisite30B (C30B), thymol (T) as natural antimicrobial component and tri-ethyl citrate (TEC) as plasticiser. Nanocomposites were prepared by a solvent casting method and consisted of 5% (w/w) of C30B, 5% (w/w) of TEC and variable content of T (0%, 0.5% and 2% w/w). To evaluate the effect of C30B into the CA matrix, CA films without this organoclay but with T were also prepared. All nanocomposites showed the intercalation of CA into the organoclay structure; furthermore this intercalation was favoured when 2% (w/w) of T was added to the nanocomposite. In spite of the observed intercalation, the presence of C30B inside the CA matrices increased the opacity of the films significantly. On the other hand, T showed a plasticiser effect on the thermal properties of CA nanocomposites decreasing glass transition, melting temperature and melting enthalpy. The presence of T in CA nanocomposites also allowed the control de Listeria innocua growth when these materials were placed in contact with this Gram-positive bacterium. Interestingly, antimicrobial activity was increased with the presence of C30B. Finally, studies on T release showed that the clay structure inside the CA matrix did not affect its release rate; however, this nanofiller affected the partition coefficient KP/FS which was higher to CA nanocomposites films than in CA films without organoclay. The results obtained in the present study are really promising to be applied in the manufacture of food packaging materials.

Storage stability of banana chips in polypropylene based nanocomposite packaging films.

PubMed

Manikantan, M R; Sharma, Rajiv; Kasturi, R; Varadharaju, N

2014-11-01

In this study, polypropylene (PP) based nanocomposite films of 15 different compositions of nanoclay, compatibilizer and thickness were developed and used for packaging and storage of banana chips. The effect of nanocomposite films on the quality characteristics viz. moisture content (MC), water activity (WA), total color difference(TCD), breaking force (BF), free fatty acid (FFA), peroxide value(PV), total plate count (TPC) and overall acceptability score of banana chips under ambient condition at every 15 days interval were studied for 120 days. All quality parameters of stored banana chips increased whereas overall acceptability scores decreased during storage. The elevation in FFA, BF and TCD of stored banana chips increased with elapse of storage period as well as with increased proportion of both nanoclay and compatibilizer but decreased by reducing the thickness of film. Among all the packaging materials, the WA of banana chips remained lower than 0.60 i.e. critical limit for microbial growth up to 90 days of storage. The PV of banana chips packaged also remained within the safe limit of 25 meq oxygen kg(-1) throughout the storage period. Among all the nanocomposite films, packaging material having 5 % compatibilizer, 2 % nanoclay & 100 μm thickness (treatment E) and 10 % compatibilizer, 4 % nanoclay & 120 μm thickness (treatment N) showed better stability of measured quality characteristics of banana chips than any other treatment.

Sustainable Energy-Storage Materials from Lignin-Graphene Nanocomposite-Derived Porous Carbon Film

DOE PAGES

Tran, Chau D.; Ho, Hoi Chun; Keum, Jong K.; ...

2017-05-30

We present a simple, green approach to fabricating porous free-standing carbon films. An alkaline solution of low-cost, renewable lignin and graphene oxide (GO) is cast, followed by simultaneous carbonization and activation. Lignin, which is the least valued product from several biomass processing industries, is an efficient source of carbon when used as an intercalating agent to separate graphene sheets derived from homogeneous GO/lignin nanocomposite films prepared from an aqueous alkaline (KOH) solution. After thermal treatment the GO/lignin films show complete dispersion of reduced GO sheets within amorphous lignin-derived carbon. Furthermore, the presence of KOH in the film produces activated carbon.more » The resulting activated carbon films display a specific surface area of up to 1744 m2 g 1 and consist of a balance of pore volumes with pore sizes below and above 1 nm. A two-electrode supercapacitor composed of these films in an aqueous electrolyte exhibits near-ideal capacitive behavior at an ultrahigh scan rate of 1 V s 1, while maintaining an excellent specific capacitance of 162 F g 1. Such outstanding performance of renewable carbon as a supercapacitor, in addition to the ease of electrode fabrication from a precursor containing 85 % lignin, offers a novel method for valorization of lignin-rich byproduct streams from biomass processing industries.« less

Sustainable Energy-Storage Materials from Lignin-Graphene Nanocomposite-Derived Porous Carbon Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tran, Chau D.; Ho, Hoi Chun; Keum, Jong K.

We present a simple, green approach to fabricating porous free-standing carbon films. An alkaline solution of low-cost, renewable lignin and graphene oxide (GO) is cast, followed by simultaneous carbonization and activation. Lignin, which is the least valued product from several biomass processing industries, is an efficient source of carbon when used as an intercalating agent to separate graphene sheets derived from homogeneous GO/lignin nanocomposite films prepared from an aqueous alkaline (KOH) solution. After thermal treatment the GO/lignin films show complete dispersion of reduced GO sheets within amorphous lignin-derived carbon. Furthermore, the presence of KOH in the film produces activated carbon.more » The resulting activated carbon films display a specific surface area of up to 1744 m2 g 1 and consist of a balance of pore volumes with pore sizes below and above 1 nm. A two-electrode supercapacitor composed of these films in an aqueous electrolyte exhibits near-ideal capacitive behavior at an ultrahigh scan rate of 1 V s 1, while maintaining an excellent specific capacitance of 162 F g 1. Such outstanding performance of renewable carbon as a supercapacitor, in addition to the ease of electrode fabrication from a precursor containing 85 % lignin, offers a novel method for valorization of lignin-rich byproduct streams from biomass processing industries.« less

Solution-processable alumina: PVP nanocomposite dielectric layer for high-performance organic thin-film transistors

NASA Astrophysics Data System (ADS)

Lin, Hui; Kong, Xiao; Li, Yiran; Kuang, Peng; Tao, Silu

2018-03-01

In this article, we have investigated the effect of nanocomposite gate dielectric layer built by alumina (Al2O3) and poly(4-vinyphenol) (PVP) with solution method which could enhance the dielectric capability and decrease the surface polarity. Then, we used modify layer to optimize the surface morphology of dielectric layer to further improve the insulation capability, and finally we fabricated the high-performance and low-voltage organic thin-film transistors by using this nanocomposite dielectric layer. The result shows that the devices with Al2O3:10%PVP dielectric layer with a modified layer exhibited a mobility of 0.49 cm2/Vs, I on/Ioff ratio of 7.8 × 104, threshold voltage of - 1.2 V, sub-threshold swing of 0.3 V/dec, and operating voltage as low as - 4 V. The improvement of devices performance was owing to the good insulation capability, appropriate capacitance of dielectric layer, and preferable interface contact, smaller crystalline size of active layer.

Investigation on sodium benzoate release from poly(butylene adipate-co-terephthalate)/organoclay/sodium benzoate based nanocomposite film and their antimicrobial activity.

PubMed

Mondal, Dibyendu; Bhowmick, Biplab; Maity, Dipanwita; Mollick, Md Masud R; Rana, Dipak; Rangarajan, Vivek; Sen, Ramkrishna; Chattopadhyay, Dipankar

2015-03-01

Polymeric nanocomposites embedded with nontoxic antimicrobial agents have recently gained potential industrial significance, mainly for their applicability to preserve food quality and ensure safety. In this study, a poly(butylene adipate-co-terephthalate) (PBAT)/organoclay (CMMT) based nanocomposite film doped with sodium benzoate (SB) as antimicrobial agent was prepared by a solution mixing process. A homogenous dispersion of organoclay (cetyltrimethylammonium-modified montmorillonite [CMMT]) in PBAT matrix was observed by X-ray diffraction and transmission electron microscopy. PBAT/CMMT nanocomposite film showed higher barrier properties against water and methanol vapor compared to the PBAT film. The release of SB from PBAT and its nanocomposite film was measured and the relevant data were fitted to the Weibull model. The higher values of Weibull's shape factor and scale parameter as corroborated by experimental findings indicated faster rate of SB release from PBAT/CMMT/SB nanocomposite film, when compared to the pristine PBAT film. Bacterial inhibition studies were accomplished against 2 food pathogenic bacteria, Bacillus subtilis and Staphylococcus aureus, by determining the zone of inhibition and corresponding growth profiles. Both bacterial inhibition studies and growth profiles established that PBAT/CMMT/SB demonstrated better antimicrobial activity than PBAT/SB film. Therefore, PBAT/CMMT/SB nanocomposite film can be used for food packaging application as it showed good barrier properties and antimicrobial activity against food pathogenic bacteria. © 2015 Institute of Food Technologists®

Biodegradation and cytotoxicity of ciprofloxacin-loaded hydroxyapatite-polycaprolactone nanocomposite film for sustainable bone implants.

PubMed

Nithya, Rajendran; Meenakshi Sundaram, Nachiappan

2015-01-01

In recent years there has been a steep increase in the number of orthopedic patients for many reasons. One major reason is osteomyelitis, caused by pyrogenic bacteria, with progressive infection of the bone or bone marrow and surrounding tissues. So antibiotics must be introduced during bone implantation to avoid prolonged infection. The objective of the study reported here was to prepare a composite film of nanocrystalline hydroxyapatite (HAp) and polycaprolactone (PCL) polymer loaded with ciprofloxacin, a frequently used antibiotic agent for bone infections. Nanocrystalline HAp was synthesized by precipitation method using the precursor obtained from eggshell. The nanocomposite film (HAp-PCL-ciprofloxacin) was prepared by solvent evaporation. Drug-release and biodegradation studies were undertaken by immersing the composite film in phosphate-buffered saline solution, while a cytotoxicity test was performed using the fibroblast cell line NIH-3T3 and osteoblast cell line MG-63. The pure PCL film had quite a low dissolution rate after an initial sharp weight loss, whereas the ciprofloxacin-loaded HAp-PCL nanocomposite film had a large weight loss due to its fast drug release. The composite film had higher water absorption than the pure PCL, and increasing the concentration of the HAp increased the water absorption. The in vitro cell-line study showed a good biocompatibility and bioactivity of the developed nanocomposite film. The prepared film will act as a sustainable bone implant in addition to controlled drug delivery.

Nanocomposite fibers and film containing polyolefin and surface-modified carbon nanotubes

DOEpatents

Chu,Benjamin; Hsiao, Benjamin S.

2010-01-26

Methods for modifying carbon nanotubes with organic compounds are disclosed. The modified carbon nanotubes have enhanced compatibility with polyolefins. Nanocomposites of the organo-modified carbon nanotubes and polyolefins can be used to produce both fibers and films having enhanced mechanical and electrical properties, especially the elongation-to-break ratio and the toughness of the fibers and/or films.

Impacts of zeolite nanoparticles on substrate properties of thin film nanocomposite membranes for engineered osmosis

NASA Astrophysics Data System (ADS)

Salehi, Tahereh Mombeini; Peyravi, Majid; Jahanshahi, Mohsen; Lau, Woei-Jye; Rad, Ali Shokuhi

2018-04-01

In this work, microporous substrates modified by zeolite nanoparticles were prepared and used for composite membrane making with the aim of reducing internal concentration polarization (ICP) effect of membranes during engineered osmosis applications. Nanocomposite substrates were fabricated via phase inversion technique by embedding nanostructured zeolite (clinoptilolite) in the range of 0-0.6 wt% into matrix of polyethersulfone (PES) substrate. Of all the substrates prepared, the PES0.4 substrate (with 0.4 wt% zeolite) exhibited unique characteristics, i.e., increased surface porosity, lower structural parameter ( S) (from 0.78 to 0.48 mm), and enhanced water flux. The thin film nanocomposite (TFN) membrane made of this optimized substrate was also reported to exhibit higher water flux compared to the control composite membrane during forward osmosis (FO) and pressure-retarded osmosis (PRO) test, without compromising reverse solute flux. The water flux of such TFN membrane was 43% higher than the control TFC membrane (1.93 L/m2 h bar) with salt rejection recorded at 94.7%. An increment in water flux is ascribed to the reduction in structural parameter, leading to reduced ICP effect.

Hydrothermal Synthesis Au-Bi2Te3 Nanocomposite Thermoelectric Film with a Hierarchical Sub-Micron Antireflection Quasi-Periodic Structure.

PubMed

Tian, Junlong; Zhang, Wang; Zhang, Yuan; Xue, Ruiyang; Wang, Yuhua; Zhang, Zhijian; Zhang, Di

2015-06-03

In this work, Au-Bi(2)Te(3) nanocomposite thermoelectric film with a hierarchical sub-micron antireflection quasi-periodic structure was synthesized via a low-temperature chemical route using Troides helena (Linnaeus) forewing (T_FW) as the biomimetic template. This method combines chemosynthesis with biomimetic techniques, without the requirement of expensive equipment and energy intensive processes. The microstructure and the morphology of the Au-Bi(2)Te(3) nanocomposite thermoelectric film was analyzed by X-ray diffraction (XRD), field-emission scanning-electron microscopy (FESEM), and transmission electron microscopy (TEM). Coupled the plasmon resonances of the Au nanoparticles with the hierarchical sub-micron antireflection quasi-periodic structure, the Au-Bi(2)Te(3) nanocomposite thermoelectric film possesses an effective infrared absorption and infrared photothermal conversion performance. Based on the finite difference time domain method and the Joule effect, the heat generation and the heat source density distribution of the Au-Bi(2)Te(3) nanocomposite thermoelectric film were studied. The heterogeneity of heat source density distribution of the Au-Bi(2)Te(3) nanocomposite thermoelectric film opens up a novel promising technique for generating thermoelectric power under illumination.

Carbon nanotubes/fluorinated polymers nanocomposite thin films for electrical contacts lubrication

NASA Astrophysics Data System (ADS)

Benedetto, A.; Viel, P.; Noël, S.; Izard, N.; Chenevier, P.; Palacin, S.

2007-09-01

The need to operate in extreme environmental conditions (ultra high vacuum, high temperatures, aerospatial environment, …) and the miniaturization toward micro electromechanical systems is demanding new materials in the field of low-level electrical contacts lubrication. Dry and chemically immobilized lubrication is expected to be an alternative to the traditional wet lubricants oils. With the goal to conciliate electrical conductivity and lubricant properties we designed nanocomposite thin films composed of a 2D carbon nanotubes network embedded in an organic matrix. The nanotubes networks were deposited on gold surfaces modified by electrochemical cathodic grafting of poly(acrylonitrile). The same substrate served for covalently bonding the low-friction organic matrix. Three different matrixes were tested: a perfluorinated oligomer chemically grafted and two different polyfluorinated acrylates electrochemically grafted. The nanocomposite thin films have been characterized by ATR FT-IR, XPS and Raman spectroscopy. We measured the effects of the different matrixes and the nanotubes addition on the tribological properties and on the contact resistances of the films.

Effect of Surfactant Type and Sonication Energy on the Electrical Conductivity Properties of Nanocellulose-CNT Nanocomposite Films.

PubMed

Siljander, Sanna; Keinänen, Pasi; Räty, Anna; Ramakrishnan, Karthik Ram; Tuukkanen, Sampo; Kunnari, Vesa; Harlin, Ali; Vuorinen, Jyrki; Kanerva, Mikko

2018-06-20

We present a detailed study on the influence of sonication energy and surfactant type on the electrical conductivity of nanocellulose-carbon nanotube (NFC-CNT) nanocomposite films. The study was made using a minimum amount of processing steps, chemicals and materials, to optimize the conductivity properties of free-standing flexible nanocomposite films. In general, the NFC-CNT film preparation process is sensitive concerning the dispersing phase of CNTs into a solution with NFC. In our study, we used sonication to carry out the dispersing phase of processing in the presence of surfactant. In the final phase, the films were prepared from the dispersion using centrifugal cast molding. The solid films were analyzed regarding their electrical conductivity using a four-probe measuring technique. We also characterized how conductivity properties were enhanced when surfactant was removed from nanocomposite films; to our knowledge this has not been reported previously. The results of our study indicated that the optimization of the surfactant type clearly affected the formation of freestanding films. The effect of sonication energy was significant in terms of conductivity. Using a relatively low 16 wt. % concentration of multiwall carbon nanotubes we achieved the highest conductivity value of 8.4 S/cm for nanocellulose-CNT films ever published in the current literature. This was achieved by optimizing the surfactant type and sonication energy per dry mass. Additionally, to further increase the conductivity, we defined a preparation step to remove the used surfactant from the final nanocomposite structure.

Fabrication and characterization of polyvinyl alcohol/metal (Ca, Mg, Ti) doped zirconium phosphate nanocomposite films for scaffold-guided tissue engineering application.

PubMed

Kalita, Himani; Pal, Pallabi; Dhara, Santanu; Pathak, Amita

2017-02-01

Nanocomposite films of polyvinyl alcohol (PVA) and zirconium phosphate (ZrP)/doped ZrP (doped with Ca, Mg, Ti) nanoparticles have been developed by solvent casting method to assess their potential as matrix material in scaffold-guided tissue engineering application. The prepared ZrP and doped ZrP nanoparticles as well as the nanocomposite films were characterized by various spectroscopic and microscopic techniques. Nanoindentation studies revealed improved nanomechanical properties in the PVA/doped ZrP nanocomposite films (highest for PVA/Ti doped ZrP: hardness=262.4MPa; elastic modulus=5800MPa) as compared to the PVA/ZrP and neat PVA films. In-vitro cell culture experiments carried out to access the cellular viability, attachment, proliferation, and migration on the substrates, using mouse fibroblast (3T3) cell lines, inferred enhanced bioactivity in the PVA/doped ZrP nanocomposite films (highest for PVA/Ca doped ZrP) in contrast to PVA/ZrP and neat PVA films. Controlled biodegradability as well as swelling behavior, superior bioactivity and improved mechanical properties of the PVA/doped ZrP nanocomposite films make them promising matrix materials for scaffold-guided tissue engineering application. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-assembled Co-BaZrO 3 nanocomposite thin films with ultra-fine vertically aligned Co nanopillars

DOE PAGES

Huang, Jijie; Li, Leigang; Lu, Ping; ...

2017-05-11

A simple one-step pulsed laser deposition (PLD) method has been applied to grow self-assembled metal-oxide nanocomposite thin films. The as-deposited Co-BaZrO 3 films show high epitaxial quality with ultra-fine vertically aligned Co nanopillars (diameter <5 nm) embeded in BZO matrix. The diameter of the nanopillars can be further tuned by varying the deposition frequency. The metal and oxide phases grow separately without inter-diffusion or mixing. Taking advantage of this unique structure, a high saturation magnetization of ~1375 emu/cm 3 in the Co- BaZrO 3 nanocomposites has been achieved and further confirmed by Lorentz microscopy imaging in TEM. Furthermore, the coercivitymore » values of this nanocomposite thin films range from 600 Oe (20 Hz) to 1020 Oe (2 Hz), which makes the nanocomposite an ideal candidate for high-density perpendicular recording media.« less

Analysis of ultraviolet exposure effects on the surface properties of epoxy/graphene nanocomposite films on Mylar substrate

NASA Astrophysics Data System (ADS)

Clausi, Marialaura; Santonicola, M. Gabriella; Schirone, Luigi; Laurenzi, Susanna

2017-05-01

In this paper, we present a study of the effects generated by exposure to UV-C radiation on nanocomposite films made of graphene nanoplatelets dispersed in an epoxy matrix. The nanocomposite films, at different nanoparticle size and concentration, were fabricated on Mylar substrate using the spin coating process. The effects of UV-C irradiation on the surface hydrophobicity and on the electrical properties of the epoxy/graphene films were investigated using contact angle measurements and electrical impedance spectroscopy, respectively. According to our results, the UV-C irradiation selectively degrades the polymer matrix of the nanocomposite films, giving rise to more conductive and hydrophobic layers due to exposure of the graphene component of the composite material. The results presented here have important implications in the design of spacecraft components and structures destined for long-term space missions.

Pd-Ni-MWCNT nanocomposite thin films: preparation and structure

NASA Astrophysics Data System (ADS)

Kozłowski, Mirosław; Czerwosz, ElŻbieta; Sobczak, Kamil

2017-08-01

The properties of nanocomposite palladium-nickel-multi-walled (Pd-Ni-MWCNT) films deposited on aluminum oxide (Al2O3) substrate have been prepared and investigated. These films were obtained by 3 step process consisted of PVD/CVD/PVD methods. The morphology and structure of the obtained films were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques at various stages of the film formation. EDX spectrometer was used to measurements of elements segregation in the obtained film. TEM and STEM (Scanning Transmission Electron Microscopy) observations showed MWCNTs decorated with palladium nanoparticles in the film obtained in the last step of film formation (final PVD process). The average size of the palladium nanoparticles observed both on MWCNTs and carbonaceous matrix does not exceed 5 nm. The research was conducted on the use of the obtained films as potential sensors of gases (e.g. H2, NH3, CO2) and bio-sensors or optical sensors.

L-Arginine modified multi-walled carbon nanotube/sulfonated poly(ether ether ketone) nanocomposite films for biomedical applications

NASA Astrophysics Data System (ADS)

Kaya, Hatice; Bulut, Osman; Kamali, Ali Reza; Ege, Duygu

2018-06-01

Favorable implant-tissue interactions are crucial to achieve successful osseointegration of the implants. Poly(ether ether ketone) (PEEK) is an interesting alternative to titanium in orthopedics because of its low cost, high biocompatibility and comparable mechanical properties with cancellous bone. Despite these advantages; however, the untreated surface of PEEK fails to osseointegrate due to its bioinert and hydrophobic behavior. This paper deals with the surface modification of PEEK with a novel method. For this, PEEK was first treated with concentrated sulfuric acid to prepare sulfonated PEEK (SPEEK) films using a solvent casting method. Then, 1 and 2 wt% multi-walled carbon nanotube was incorporated into SPEEK to form nanocomposite films. The samples were characterized with Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy. After successful preparation of the nanocomposite films, L-arginine was covalently conjugated on the nanocomposite films to further improve their surface properties. Subsequently, the samples were characterized using X-ray Photoemission Spectroscopy (XPS), water contact angle measurements and Atomic Force Microscopy (AFM) and Dynamic Mechanical Thermal Analysis (DMTA). Finally, cell culture studies were carried out by using Alamar Blue assay to evaluate the biocompatibility of the films. The results obtained indicate the successful preparation of L-arginine-conjugated MWCNT/SPEEK nanocomposite films. The modified surface shows potential to improve implants' mechanical and biological performances.

Thermomechanical properties of polymer nanocomposites: Exploring a unified relationship with planar polymer films

NASA Astrophysics Data System (ADS)

Bansal, Amitabh

The thermal and mechanical response of polymers, which provide limitations to their practical use, are greatly improved by the addition of a small fraction of an inorganic nanofiller. However, the resulting changes in polymer properties are poorly understood, primarily due to the non-uniform spatial distribution of nanoparticles. This research explores the properties of polystyrene filed with silica nanoparticles and illustrates for the first time that the thermodynamic properties of "polymer nanocomposites" are quantitatively equivalent to the well-understood case of planar polymer films with a uniform thickness. These ideas are quantified by drawing a direct analogy between thin film thickness and an appropriate average ligament thickness measured using electron microscopy. The change in polymer glass transition temperatures with decreasing ligament thickness were found to be quantitatively equivalent to the corresponding thin film data. In combination with viscoelastic properties of the nanocomposites that are in quantitative agreement with data from thin films, these conclusions provide a facile means of understanding and predicting the thermomechanical properties and, potentially, the engineering properties of practically relevant polymer nanocomposites. Grafting of high molecular weight polystyrene onto the silica nanoparticles greatly improves the dispersion quality of nanofillers and also provides a means to tailor the thermo-mechanical properties in nanocomposites. It is concluded that the grafted polystyrene is akin to polymer brushes on flat surfaces. The mobility and stiffness of these grafted chains are expected to be low as compared to the free polymer. In this context a mechanism for the increase in glass transition is proposed: (1) the stiff grafted chains will tend to decrease mobility and thus increase glass transition, (2) the extent of interdigitation of the grafted polystyrene into the matrix will determine the extent to which the nanocomposite

Development of Noncytotoxic Chitosan–Gold Nanocomposites as Efficient Antibacterial Materials

PubMed Central

2014-01-01

This work describes the synthesis and characterization of noncytotoxic nanocomposites either colloidal or as films exhibiting high antibacterial activity. The biocompatible and biodegradable polymer chitosan was used as reducing and stabilizing agent for the synthesis of gold nanoparticles embedded in it. Herein, for the first time, three different chitosan grades varying in the average molecular weight and deacetylation degree (DD) were used with an optimized gold precursor concentration. Several factors were analyzed in order to obtain antimicrobial but not cytotoxic nanocomposite materials. Films based on chitosan with medium molecular weight and the highest DD exhibited the highest antibacterial activity against biofilm forming strains of Staphylococcus aureus and Pseudomonas aeruginosa. The resulting nanocomposites did not show any cytotoxicity against mammalian somatic and tumoral cells. They produced a disruptive effect on the bacteria wall while their internalization was hindered on the eukaryotic cells. This selectivity and safety make them potentially applicable as antimicrobial coatings in the biomedical field. PMID:25522372

Development of LLDPE based active nanocomposite films with nanoclays impregnated with volatile compounds.

PubMed

Tornuk, Fatih; Sagdic, Osman; Hancer, Mehmet; Yetim, Hasan

2018-05-01

In this study, a novel procedure was performed for grafting of nanoclays (montmorillonite (MMT) and halloysite (HNT)) with essential oil constituents (thymol (THY), eugenol (EUG) and carvacrol (CRV)) using Tween 80 as surfactant and then the nanoclay particles were incorporated into LLDPE pellets (5 wt%) to produce active nanocomposite films using a twin screw extruder. The resulting nanocomposite films were analyzed for antimicrobial and antioxidant capacity as well as thickness, mechanical, color, barrier, thermal properties and surface morphology and molecular composition. Release of the active compounds from the films at the refrigerated and room temperature conditions were also tested. The results showed that the films had strong in vitro antibacterial activity against pathogenic bacteria (Salmonella Typhimurium, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus) while their effect against lactic acid bacteria (Lactobacillus rhamnosus and Lb. casei) was limited. The lowest and highest DPPH scavenging ability levels were 65.59% and % 87.92, belonged to THY-MMT and EUG-MMT, respectively. Release of active compounds at 24 °C was much more rapid than at 4 °C. CRV-HNT and THY-HNT provided slower release than the other films. SEM results showed that nanoclays were uniformly dispersed in the polymer matrix with exceptional agglomerates. Incorporation of the active nanoclays significantly (P > 0.05) improved tensile strength and elongation of the films. The results confirmed that LLDPE based active nanocomposite films could be successfully produced due to its good interaction with MMT and HNT, activated with THY, EUG and CRV. Copyright © 2018 Elsevier Ltd. All rights reserved.

Migration of nanosized layered double hydroxide platelets from polylactide nanocomposite films.

PubMed

Schmidt, B; Katiyar, V; Plackett, D; Larsen, E H; Gerds, N; Koch, C Bender; Petersen, J H

2011-01-01

Melt-extruded L-polylactide (PLA) nanocomposite films were prepared from commercially available PLA and laurate-modified Mg-Al layered double hydroxide (LDH-C12). Three films were tested for total migration as well as specific migration of LDH, tin, laurate and low molecular weight PLA oligomers (OLLA). This is the first reported investigation on the migration properties of PLA-LDH nanocomposite films. The tests were carried out as part of an overall assessment of the suitability of such films for use as food contact materials (FCM). Total migration was determined according to a European standard method. All three films showed migration of nanosized LDH, which was quantified using acid digestion followed by inductively coupled plasma mass spectrometric (ICP-MS) detection of (26)Mg. Migration of LDH from the films was also confirmed by examining migrates using transmission electron microscopy (TEM) and was attributed indirectly to the significant PLA molecular weight reduction observed in extruded PLA-LDH-C12 films. Migration of tin was detected in two of the film samples prepared by dispersion of LDH-C12 using a masterbatch technique and migration of the laurate organomodifier took place from all three film types. The results indicate that the material properties are in compliance with the migration limits for total migration and specific lauric acid migration as set down by the EU legislation for FCM, at least if a reduction factor for fresh meat is taken into consideration. The tin detected arises from the use of organotin catalysts in the manufacture of PLA.

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE PAGES

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.; ...

2018-04-10

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Effects of preparation methods on the structure and mechanical properties of wet conditioned starch/montmorillonite nanocomposite films.

PubMed

Müller, Péter; Kapin, Éva; Fekete, Erika

2014-11-26

TPS/Na-montmorillonite nanocomposite films were prepared by solution and melt blending. Clay content changed between 0 and 25 wt% based on the amount of dry starch. Structure, tensile properties, and water content of wet conditioned films were determined as a function of clay content. Intercalated structure and VH-type crystallinity of starch were found for all the nanocomposites independently of clay and plasticizer content or preparation method, but at larger than 10 wt% clay content nanocomposites prepared by melt intercalation contained aggregated particles as well. In spite of the incomplete exfoliation clay reinforces TPS considerably. Preparation method has a strong influence on mechanical properties of wet conditioned films. Mechanical properties of the conditioned samples prepared by solution homogenization are much better than those of nanocomposites prepared by melt blending. Water, which was either adsorbed or bonded in the composites in conditioning or solution mixing process, respectively, has different effect on mechanical properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thickness dependent optical properties of PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films deposited by spray pyrolysis technique on ITO substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thakur, Anjna, E-mail: anjna56@gmail.com; Thakur, Priya; Yadav, Kamlesh, E-mail: kamlesh.yadav001@gmail.com

2016-05-06

In this paper, poly (ethyl methacrylate) (PEMA) and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films for 2, 3, 4 and 5 minutes have been deposited by spray pyrolysis technique on indium tin oxide (ITO) coated substrate. The effect of thickness of the film on the morphological and optical properties of PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films are studied. The morphological and optical properties of pure PEMA and (PEMA){sub 0.85}/(ZnO){sub 0.15} nanocomposite films are compared. The field emission scanning electron microscopy (FESEM) shows that as the thickness of film increases, uniformity of films increases. It is found from UV-Visible spectra that themore » energy band gap decreases with increasing the deposition time and refractive index increases with increasing the thickness of the film. The band gap of the nanocomposites is found less than the pure polymer film and opposite trend is observed for refractive index. The optical absorption of PEMA/ZnO nanocomposite films is higher than pure PEMA film. The thickness of the nanocomposite film plays a significant role in the tunability of the optical properties.« less

Synthesis and applications of MANs/poly(MMA-co-BA) nanocomposite latex by miniemulsion polymerization

PubMed Central

Chen, Huayao; Zhou, Xinhua; Gunasekaran, Sundaram

2017-01-01

We have synthesized core-shell structured 3-methacryloxypropyltrimethoxysilane (MPS) functionalized antimony-doped tin oxide nanoparticles (MANs)–poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-BA, PMB) nanocomposite latex particles via miniemulsion polymerization method. Polymerizable anionic surfactant DNS-86 (allyloxy polyoxyethylene(10) nonyl ammonium sulfate) was first introduced to synthesize core-shell nanocomposite. The morphologies of synthesized MANs and MANs/PMB latex nanocomposite particles were studied with transmission electron microscopy, which revealed particles, on average 70 nm in size, with a core-shell structure. Owing to the uniformity and hydrophobicity of MANs, the MANs-embedded PMB latex nanocomposite can be tailored more precisely than other nanoparticles-embedded nanocomposites. Films incorporating 10 wt% of MANs in the MAN/PMB latex nanocomposite exhibit good transmittance in the visible region, and excellent opacity in the near infrared region. The MANs/PMB nanocomposite film also appears suitable for heat insulation applications. PMID:29291076

Characterization of the new biodegradable WPI/clay nanocomposite films based on kefiran exopolysaccharide.

PubMed

Zolfi, Mohsen; Khodaiyan, Faramarz; Mousavi, Mohammad; Hashemi, Maryam

2015-06-01

Physico-mechanical, thermal and structural characteristics of nanocomposite film composed of kefiran-whey protein isolate (WPI)-montmorillonite (MMT; 1, 3 and 5 % w/w) were studied. Incorporation of MMT significantly affected the mechanical attributes of the kefiran-WPI films. The tensile strength and Young's modulus increased and the percentage of elongation at break decreased as the MMT content increased. Moisture content, moisture absorption and water solubility decreased as the MMT concentration increased. Differential scanning calorimetry indicated that the glass transition temperature for kefiran-WPI film was -12.5 °C and was noticeably affected by an increase in MMT. X-ray diffraction analysis showed formation of an exfoliated structure with the addition of small amounts of MMT to the kefiran-WPI matrix. Intercalation and some exfoliation occurred up to 5 % (wt) increase in MMT. Scanning electron microscopy demonstrated ideal dispersion for MMT nanoparticles into the structure of the bio-nanocomposite films.

Carbon Nanotube/Conductive Additive/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Watson, Kent A.; Delozier, Donavon M.; Connell, John W.

2003-01-01

Thin film membranes of space environmentally stable polymeric materials possessing low color/solar absorptivity (alpha) are of interest for potential applications on Gossamer spacecraft. In addition to these properties, sufficient electrical conductivity is required in order to dissipate electrostatic charge (ESC) build-up brought about by the charged orbital environment. One approach to achieve sufficient electrical conductivity for ESC mitigation is the incorporation of single wall carbon nanotubes (SWNTs). However, when the SWNTs are dispersed throughout the polymer matrix, the nanocomposite films tend to be significantly darker than the pristine material resulting in a higher alpha. The incorporation of conductive additives in combination with a decreased loading level of SWNTs is one approach for improving alpha while retaining conductivity. Taken individually, the low loading level of conductive additives and SWNTs is insufficient in achieving the percolation level necessary for electrical conductivity. When added simultaneously to the film, conductivity is achieved through a synergistic effect. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

Preparation of mesoporous carbon nitride structure by the dealloying of Ni/a-CN nanocomposite films

NASA Astrophysics Data System (ADS)

Zhou, Han; Shen, Yongqing; Huang, Jie; Liao, Bin; Wu, Xianying; Zhang, Xu

2018-05-01

The preparation of mesoporous carbon nitride (p-CN) structure by the selective dealloying process of Ni/a-CN nanocomposite films is investigated. The composition and structure of the Ni/a-CN nanocomposite films and porous carbon nitride (p-CN) films are determined by scan electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Phase separated structure including nickel carbide phase and the surrounding amorphous carbon nitride (a-CN) matrix are detected for the as-deposited films. Though the bulk diffusion is introduced in the film during the annealing process, the grain sizes for the post-annealed films are around 10 nm and change little comparing with the ones of the as-deposited films, which is associated with the thermostability of the CN surrounding in the film. The p-CN skeleton with its pore size around 12.5 nm is formed by etching the post-annealed films, indicative of the stability of the phase separated structure during the annealing process.

Antibacterial effect of visible light reactive TiO2/Ag nanocomposite thin film on the orthodontic appliances.

PubMed

Yun, Kwidug; Oh, Gyejeong; Vang, Mongsook; Yang, Hongso; Lim, Hyunpil; Koh, Jeongtae; Jeong, Woonjo; Yoon, Dongjoo; Lee, Kyungku; Lee, Kwangmin; Park, Sangwon

2011-08-01

This study evaluated the antibacterial effect of a visible light reactive TiO2/Ag nanocomposite thin film on dental orthodontic wire (STS 304 wire). The growth of S. mutans and A. actinomycetemcomitans was suppressed on the specimens coated with TiO2/Ag compared to the uncoated specimens. The antibacterial effect of the TiO2/Ag nanocomposite thin film was improved under visible light irradiation.

Adjustable magnetoelectric effect of self-assembled vertical multiferroic nanocomposite films by the in-plane misfit strain and ferromagnetic volume fraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Huaping, E-mail: wuhuaping@gmail.com; Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540; Chai, Guozhong

The strain-mediated magnetoelectric (ME) property of self-assembled vertical multiferroic nanocomposite films epitaxially grown on cubic substrates was calculated by a nonlinear thermodynamic theory combined with the elastic theory. The dependent relations of phase state of ferroelectric films with the in-plane misfit strain, out-of-plane misfit strain, temperature, and volume fraction of ferromagnetic phase were confirmed. The effects of in-plane misfit strain and ferromagnetic volume fraction on the polarization and dielectric constant of ferroelectric films at room temperature were elaborately analyzed for the vertical BaTiO{sub 3}-CoFe{sub 2}O{sub 4} and PbTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films. Our calculated results confirmed the relationship amongmore » ME effect and in-plane misfit strain and ferromagnetic volume fraction in the nanocomposite films. The ME voltage coefficients of vertical BaTiO{sub 3}-CoFe{sub 2}O{sub 4} and PbTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films displayed various maximums and abrupt points at special phases and phase transition boundaries. The ME voltage coefficients of lead-free BaTiO{sub 3}-CoFe{sub 2}O{sub 4} nanocomposite films epitaxially grown on different substrates could reach a comparative value of ∼2 V·cm{sup −1}·Oe{sup −1} under the controllable in-plane misfit strain induced by substrate clamping. Our results provided an available method for the optimal design of vertical multiferroic nanocomposites with adjustable ME effect by optimizing the ferromagnetic volume fraction and substrate type.« less

Room temperature magneto-transport properties of nanocomposite Fe-In2O3 thin films

NASA Astrophysics Data System (ADS)

Tambasov, Igor A.; Gornakov, Kirill O.; Myagkov, Victor G.; Bykova, Liudmila E.; Zhigalov, Victor S.; Matsynin, Alexey A.; Yozhikova, Ekaterina V.

2015-12-01

A ferromagnetic Fe-In2O3 nanocomposite thin film has been synthesized by the thermite reaction Fe2O3+In→Fe-In2O3. Measurements of the Hall carrier concentration, Hall mobility and magnetoresistance have been conducted at room temperature. The nanocomposite Fe-In2O3 thin film had n=1.94·1020 cm-3, μ=6.45 cm2/Vs and negative magnetoresistance. The magnetoresistance for 8.8 kOe was ~-0.22%.The negative magnetoresistance was well described by the weak localization and model proposed by Khosla and Fischer.

Self-assembly of mesoscopically ordered chromatic polydiacetylene/silica nanocomposites

NASA Technical Reports Server (NTRS)

Lu, Y.; Yang, Y.; Sellinger, A.; Lu, M.; Huang, J.; Fan, H.; Haddad, R.; Lopez, G.; Burns, A. R.; Sasaki, D. Y.;

W:Al 2O 3 nanocomposite thin films with tunable optical properties prepared by atomic layer deposition

DOE PAGES

Babar, Shaista; Mane, Anil U.; Yanguas-Gil, Angel; ...

2016-06-17

Here, a systematic alteration in the optical properties of W:Al 2O 3 nanocomposite films is demonstrated by precisely varying the W cycle percentage (W%) from 0 to 100% in Al 2O 3 during atomic layer deposition. The direct and indirect band energies of the nanocomposite materials decrease from 5.2 to 4.2 eV and from 3.3 to 1.8 eV, respectively, by increasing the W% from 10 to 40. X-ray absorption spectroscopy reveals that, for W% < 50, W is present in both metallic and suboxide states, whereas, for W% ≥ 50, only metallic W is seen. This transition from dielectric tomore » metallic character at W% ~ 50 is accompanied by an increase in the electrical and thermal conductivity and the disappearance of a clear band gap in the absorption spectrum. The density of the films increases monotonically from 3.1 g/cm 3 for pure Al 2O 3 to 17.1 g/cm 3 for pure W, whereas the surface roughness is greatest for the W% = 50 films. The W:Al 2O 3 nanocomposite films are thermally stable and show little change in optical properties upon annealing in air at 500 °C. These W:Al 2O 3 nanocomposite films show promise as selective solar absorption coatings for concentrated solar power applications.« less

Size dependent nonlinear optical properties of spin coated zinc oxide-polystyrene nanocomposite films

NASA Astrophysics Data System (ADS)

Jeeju, Pullarkat P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

2012-11-01

Using simple wet chemical method at room temperature, zinc oxide (ZnO) nanoparticles embedded in polystyrene (PS) matrix were synthesized. The size of the ZnO nanoparticles could be varied by varying the precursor concentration, reaction time and stirring speed. Transparent films of ZnO/PS nanocomposites of thickness around 1 μm were coated on ultrasonically cleaned glass substrates by spin coating. The optical absorptive nonlinearity in ZnO/PS nanocomposite films was investigated using open aperture Z-scan technique with nanosecond laser pulses at 532 nm. The results indicate optical limiting type nonlinearity in the films due to two-photon absorption in ZnO. These films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The observed nonlinear absorption is strongly dependent on particle size and the normalized transmittance could be reduced to as low as 0.43 by the suitable choice of the ZnO nanoparticle size. These composite films can hence be used as efficient optical limiters for sensor protection. The much-pronounced nonlinear response of these composite films, compared to pure ZnO, combined with the improved stability of ZnO nanoparticles in the PS matrix offer prospects of application of these composite films in the fabrication of stable non-linear optical devices.

Ti 3 C 2 T x (MXene)–polyacrylamide nanocomposite films

DOE PAGES

Naguib, Michael; Saito, Tomonori; Lai, Sophia; ...

2016-07-20

Polymer nanocomposite films are of great interest due to their enhanced properties over base polymers. By incorporating 2D titanium carbide a representative of a new family of 2D materials, MXenes, as nanofillers into a water soluble polyacrylamide (PAM) matrix, the resulting films benefit from the flexibility, robustness, and processability of PAM, as well as the conductivity and mechanical properties of MXene fillers. We report on manufacturing and characterization of MXene-PAM nanocomposite films. Dimethylsulfoxide (DMSO) intercalation in-between the Ti 3C 2-based MXene layers led to full delamination of the MXene layers and hence a uniform dispersion of hydrophilic MXene nanosheets inmore » aqueous PAM solutions was achieved. Moreover, the polymer composite solutions of up to 75 wt.% MXene loading were sonicated and cast onto large Teflon trays and dried at room temperature to produce shiny black films. The observation of reduced 0002 peaks of Ti 3C 2T x phase in X-ray diffraction patterns and TEM images indicate the presence of well dispersed nanoflakes. The as-prepared composite films are flexible and the conductivity was increased significantly to 3 x 10 -3 S cm -1 for 6 wt. % MXene-PAM films. With high MXene loading, some non-uniformity between the top and bottom surfaces was observed. This could be due to the segregation of MXene layers in composite films during drying. Finally, the power law dependence of conductivity above the percolation threshold is presented through detailed conductivity measurements.« less

Processing and properties of eco-friendly bio-nanocomposite films filled with cellulose nanocrystals from sugarcane bagasse.

PubMed

El Achaby, Mounir; El Miri, Nassima; Aboulkas, Adil; Zahouily, Mohamed; Bilal, Essaid; Barakat, Abdellatif; Solhy, Abderrahim

2017-03-01

Novel synthesis strategy of eco-friendly bio-nanocomposite films have been exploited using cellulose nanocrystals (CNC) and polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) blend matrix as a potential in food packaging application. The CNC were extracted from sugarcane bagasse using sulfuric acid hydrolysis, and they were successfully characterized regarding their morphology, size, crystallinity and thermal stability. Thereafter, PVA/CMC-CNC bio-nanocomposite films, at various CNC contents (0.5-10wt%), were fabricated by the solvent casting method, and their properties were investigated. It was found that the addition of 5wt% CNC within a PVA/CMC increased the tensile modulus and strength by 141% and 83% respectively, and the water vapor permeability was reduced by 87%. Additionally, the bio-nanocomposites maintained the same transparency level of the PVA/CMC blend film (transmittance of ∼90% in the visible region), suggesting that the CNC were dispersed at the nanoscale. In these bio-nanocomposites, the adhesion properties and the large number of functional groups that are present in the CNC's surface and the macromolecular chains of the PVA/CMC blend are exploited to improve the interfacial interactions between the CNC and the blend. Consequently, these eco-friendly structured bio-nanocomposites with superior properties are expected to be useful in food packaging applications. Copyright © 2016. Published by Elsevier B.V.

Vapor phase polymerization deposition of conducting polymer/graphene nanocomposites as high performance electrode materials.

PubMed

Yang, Yajie; Li, Shibin; Zhang, Luning; Xu, Jianhua; Yang, Wenyao; Jiang, Yadong

2013-05-22

In this paper, we report chemical vapor phase polymerization (VPP) deposition of novel poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene nanocomposites as solid tantalum electrolyte capacitor cathode films. The PEDOT/graphene films were successfully prepared on porous tantalum pentoxide surface as cathode films through the VPP procedure. The results indicated that the high conductivity nature of PEDOT/graphene leads to the decrease of cathode films resistance and contact resistance between PEDOT/graphene and carbon paste. This nanocomposite cathode film based capacitor showed ultralow equivalent series resistance (ESR) ca. 12 mΩ and exhibited better capacitance-frequency performance than the PEDOT based capacitor. The leakage current investigation revealed that the device encapsulation process does not influence capacitor leakage current, indicating the excellent mechanical strength of PEDOT-graphene films. The graphene showed a distinct protection effect on the dielectric layer from possible mechanical damage. This high conductivity and mechanical strength graphene based conducting polymer nanocomposites indicated a promising application future for organic electrode materials.

Preparation and characterization of polymeric nanocomposite films for application as protective coatings

NASA Astrophysics Data System (ADS)

Gagliardi, S.; Rondino, F.; D'Erme, C.; Persia, F.; Menchini, F.; Santarelli, M. L.; Paulke, B.-R.; Enayati, A. L.; Falconieri, M.

2017-08-01

Addiction of ceramic nanoparticles to acrylic polymers provides a simple and effective means to produce paints with important properties, such as mechanical resistance and tailored wettability, even though for optimal performances, an engineered nanoparticle distribution would be desirable. In this paper we report on the realization and on the morphological and functional characterization of nanocomposites where the nanophase is distributed on the surface of acrylic polymer films, in order to enhance the expression of surface-related properties. To this aim, commercial titanium oxide and silicon oxide nanopowders were dispersed in water and the suspensions were air-sprayed on polymeric films prepared by paint brushing, thus producing a nanostructured ceramic surface coating. Control of the pH of suspensions and acrylic acid functionalization of the surface of titania were used together with high power ultrasonic treatments in order to control dimension of the aggregates in the sprayed suspensions. Optical microscopy, mechanical profilometry, and atomic force microscopy were used to characterize the nanocomposite surface morphology and correlate it to the coating functional properties, evaluated through mechanical abrasion tests and contact angle measurements; also, colorimetry on coated stones was performed in order to test the impact of the coatings on the aesthetical appearance and their photostability under UV irradiation. Results show that the nanostructured ceramic layer slightly improves the resistance of coatings to mechanical abrasion in case of polymer films prepared from latexes. The nanocomposite surface layer does not affect the wettability of the polymer, which remained slightly hydrophilic; this behavior is likely due to inadequate distribution of the nanophase. On the other hand UV-induced superhydrophilicity was observed when the concentration of surface titania nanoparticles is about 0.6 mg/cm2. Colorimetric analysis on historical and Carrara

Improvement of food packaging related properties in whey protein isolate‑based nanocomposite films and coatings by addition of montmorillonite nanoplatelets

NASA Astrophysics Data System (ADS)

Schmid, Markus; Merzbacher, Sarah; Brzoska, Nicola; Müller, Kerstin; Jesdinszki, Marius

2017-11-01

In the present study the effects of the addition of montmorillonite (MMT) nanoplatelets on whey protein isolate (WPI)-based nanocomposite films and coatings were investigated. The main objective was the development of WPI-based MMT-nanocomposites with enhanced barrier and mechanical properties. WPI-based nanocomposite cast-films and coatings were prepared by dispersing 0 % (reference sample), 3 %, 6 %, 9 % (w/w protein) MMT, or, depending on the protein concentration, also 12 % and 15 % (w/w protein) MMT into native WPI-based dispersions, followed by subsequent denaturation during the drying and curing process. The natural MMT nanofillers could be randomly dispersed into film-forming WPI-based nanodispersions, displaying good compatibility with the hydrophilic biopolymer matrix. As a result, by addition of 15 % (w/w protein) MMT into 10 % (w/w dispersion) WPI-based cast-films or coatings, the oxygen permeability (OP) was reduced by 91 % for glycerol-plasticized and 84 % for sorbitol-plasticized coatings, water vapor transmission rate (WVTR) was reduced by 58 % for sorbitol-plasticized cast-films. Due to the addition of MMT- nanofillers the Young’s modulus and tensile strength improved by 315 % and 129 %, respectively, whereas elongation at break declined by 77 % for glycerol-plasticized cast-films. In addition, comparison of plasticizer type revealed that sorbitol-plasticized cast-films were generally stiffer and stronger, but less flexible compared glycerol-plasticized cast-films. Viscosity measurements demonstrated good processability and suitability for up-scaled industrial processes of native WPI-based nanocomposite dispersions, even at high nanofiller-loadings. These results suggest that the addition of natural MMT- nanofillers into native WPI-based matrices to form nanocomposite films and coatings holds great potential to replace well-established, fossil-based packaging materials for at least certain applications such as oxygen barriers as part of

Thermally tunable VO2-SiO2 nanocomposite thin-film capacitors

NASA Astrophysics Data System (ADS)

Sun, Yifei; Narayanachari, K. V. L. V.; Wan, Chenghao; Sun, Xing; Wang, Haiyan; Cooley, Kayla A.; Mohney, Suzanne E.; White, Doug; Duwel, Amy; Kats, Mikhail A.; Ramanathan, Shriram

2018-03-01

We present a study of co-sputtered VO2-SiO2 nanocomposite dielectric thin-film media possessing continuous temperature tunability of the dielectric constant. The smooth thermal tunability is a result of the insulator-metal transition in the VO2 inclusions dispersed within an insulating matrix. We present a detailed comparison of the dielectric characteristics of this nanocomposite with those of a VO2 control layer and of VO2/SiO2 laminate multilayers of comparable overall thickness. We demonstrated a nanocomposite capacitor that has a thermal capacitance tunability of ˜60% between 25 °C and 100 °C at 1 MHz, with low leakage current. Such thermally tunable capacitors could find potential use in applications such as sensing, thermal cloaks, and phase-change energy storage devices.

Experimental Evidence of Dipolar Interaction in Bilayer Nanocomposite Magnets

DTIC Science & Technology

2010-11-25

corporated to improve experimental systems. However, re- ported bulk nanocomposite magnets exhibit (BH)max val- ues that are far below the...Appl Phys A DOI 10.1007/s00339-010-6073-6 Experimental evidence of dipolar interaction in bilayer nanocomposite magnets A.J. Zambano · H. Oguchi · I...Abstract We use magnetic thin film hard/non/soft-mag- netic trilayer systems to probe the nature of the hard–soft phase interaction and the role

Thin-film transistors with a graphene oxide nanocomposite channel.

PubMed

Jilani, S Mahaboob; Gamot, Tanesh D; Banerji, P

2012-12-04

Graphene oxide (GO) and graphene oxide-zinc oxide nanocomposites (GO-ZnO) were used as channel materials on SiO(2)/Si to fabricate thin-film transistors (TFT) with an aluminum source and drain. Pure GO-based TFT showed poor field-effect characteristics. However, GO-ZnO-nanocomposite-based TFT showed better field-effect performance because of the anchoring of ZnO nanostructures in the GO matrix, which causes a partial reduction in GO as is found from X-ray photoelectron spectroscopic data. The field-effect mobility of charge carriers at a drain voltage of 1 V was found to be 1.94 cm(2)/(V s). The transport of charge carriers in GO-ZnO was explained by a fluctuation-induced tunneling mechanism.

Photonic structures based on hybrid nanocomposites

NASA Astrophysics Data System (ADS)

Husaini, Saima

In this thesis, photonic structures embedded with two types of nanomaterials, (i) quantum dots and (ii) metal nanoparticles are studied. Both of these exhibit optical and electronic properties different from their bulk counterpart due to their nanoscale physical structure. By integrating these nanomaterials into photonic structures, in which the electromagnetic field can be confined and controlled via modification of geometry and composition, we can enhance their linear and nonlinear optical properties to realize functional photonic structures. Before embedding quantum dots into photonic structures, we study the effect of various host matrices and fabrication techniques on the optical properties of the colloidal quantum dots. The two host matrices of interest are SU8 and PMMA. It is shown that the emission properties of the quantum dots are significantly altered in these host matrices (especially SU8) and this is attributed to a high rate of nonradiative quenching of the dots. Furthermore, the effects of fabrication techniques on the optical properties of quantum dots are also investigated. Finally a microdisk resonator embedded with quantum dots is fabricated using soft lithography and luminescence from the quantum dots in the disk is observed. We investigate the absorption and effective index properties of silver nanocomposite films. It is shown that by varying the fill factor of the metal nanoparticles and fabrication parameters such as heating time, we can manipulate the optical properties of the metal nanocomposite. Optimizing these parameters, a silver nanocomposite film with a 7% fill factor is prepared. A one-dimensional photonic crystal consisting of alternating layers of the silver nanocomposite and a polymer (Polymethyl methacrylate) is fabricated using spin coating and its linear and nonlinear optical properties are investigated. Using reflectivity measurements we demonstrate that the one-dimensional silver-nanocomposite-dielectric photonic crystal

Metal (Ag/Ti)-Containing Hydrogenated Amorphous Carbon Nanocomposite Films with Enhanced Nanoscratch Resistance: Hybrid PECVD/PVD System and Microstructural Characteristics.

PubMed

Constantinou, Marios; Nikolaou, Petros; Koutsokeras, Loukas; Avgeropoulos, Apostolos; Moschovas, Dimitrios; Varotsis, Constantinos; Patsalas, Panos; Kelires, Pantelis; Constantinides, Georgios

2018-03-30

This study aimed to develop hydrogenated amorphous carbon thin films with embedded metallic nanoparticles (a-C:H:Me) of controlled size and concentration. Towards this end, a novel hybrid deposition system is presented that uses a combination of Plasma Enhanced Chemical Vapor Deposition (PECVD) and Physical Vapor Deposition (PVD) technologies. The a-C:H matrix was deposited through the acceleration of carbon ions generated through a radio-frequency (RF) plasma source by cracking methane, whereas metallic nanoparticles were generated and deposited using terminated gas condensation (TGC) technology. The resulting material was a hydrogenated amorphous carbon film with controlled physical properties and evenly dispersed metallic nanoparticles (here Ag or Ti). The physical, chemical, morphological and mechanical characteristics of the films were investigated through X-ray reflectivity (XRR), Raman spectroscopy, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) and nanoscratch testing. The resulting amorphous carbon metal nanocomposite films (a-C:H:Ag and a-C:H:Ti) exhibited enhanced nanoscratch resistance (up to +50%) and low values of friction coefficient (<0.05), properties desirable for protective coatings and/or solid lubricant applications. The ability to form nanocomposite structures with tunable coating performance by potentially controlling the carbon bonding, hydrogen content, and the type/size/percent of metallic nanoparticles opens new avenues for a broad range of applications in which mechanical, physical, biological and/or combinatorial properties are required.

Optical properties of PbS/PVP nanocomposites films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Mitesh H., E-mail: miteshpatel7204@gmail.com; Chaudhuri, Tapas K.; Patel, Vaibhav K.

2016-05-06

PbS/Polyvinylpyrrolidone (PVP) nanocomposites films with different volume fraction of PbS have been deposited from single molecular precursors. X-ray diffraction patterns conforms the formation of PbS nanocrystals in PVP matrix. The transmission spectra of the films in the wavelength range of 300 to 2400 nm show the absorption edges are blue shifted due to formation of PbS Nanoparticles. The band gap determined are 2.4, 1.5 and 1.25 eV for PbS volume fraction of 8.5, 16, 27%, respectively. The corresponding refractive indices, n determined from Fresnel relation are 1.8, 2, and 2.35 which are in between that of PbS (4.2) and PVP (1.48).

Ag+12 ion induced modifications of structural and optical properties of ZnO-PMMA nanocomposite films

NASA Astrophysics Data System (ADS)

Sharma, Sarla; Vyas, Rishi; Vijay, Y. K.

2013-02-01

The influence of swift heavy ion (SHI) irradiation on structural and photoluminescence (PL) properties of ZnO-PMMA nanocomposite films, prepared by solution casting method, was studied. The ZnO-PMMA nanocomposite films were irradiated using 120 MeV Ag+12 ions at different fluences varying from 1×1011 to 1×1013 ions/cm2. The intensity of the X-ray diffraction peaks is increased at the high fluence, without evolution of any new peak. A shift in absorption edge (i.e. shift in optical band gap) towards higher wavelength was observed after irradiation and PL from ZnO-PMMA nanocomposite films is found to increase up to a critical fluence and then found to be suppressed for higher fluence (1×1012 ion/cm2). The change in photoluminescence after irradiation can be attributed to the change in microstructure of PMMA matrix as well as the agglomeration of ZnO nanoparticles.

Inorganic nanocomposite films with polymer nanofillers made by the concurrent multi-beam multi-target pulsed laser deposition

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Sarkisov, Sergey S.; Mele, Paolo; Saini, Shrikant; Moore, Shaelynn; Bastian, Tyler; Dorlus, Wydglif; Zhang, Xiaodong; Koplitz, Brent

2017-08-01

We report on the new class of inorganic nanocomposite films with the inorganic phase hosting the polymer nanofillers made by the concurrent multi-beam multi-target pulsed laser deposition of the inorganic target material and matrix assisted pulsed laser evaporation of the polymer (MBMT-PLD/MAPLE). We used the exemplary nanocomposite thermoelectric films of aluminum-doped ZnO known as AZO with the nanofillers made of poly(methyl methacrylate) known as PMMA on various substrates such as SrTiO3, sapphire, fused silica, and polyimide. The AZO target was ablated with the second harmonic (532 nm) of the Nd:YAG Q-switched laser while PMMA was evaporated from its solution in chlorobenzene frozen in liquid nitrogen with the fundamental harmonic (1064 nm) of the same laser (50 Hz pulse repetition rate). The introduction of the polymer nanofillers increased the electrical conductivity of the nanocomposite films (possibly due to the carbonization of PMMA and the creation of additional channels of electric current) three times and reduced the thermal conductivity by 1.25 times as compared to the pure AZO films. Accordingly, the increase of the thermoelectric figure-of merit ZT would be 4 times. The best performance was observed for the sapphire substrates where the films were the most uniform. The results point to a huge potential of the optimization of a broad variety of optical, opto-electronic, and solar-power nanocomposite inorganic films by the controllable introduction of the polymer nanofillers using the MBMT-PLD/MAPLE method.

A sulphonated carbon dot-chitosan hybrid hydrogel nanocomposite as an efficient ion-exchange film for Ca2+ and Mg2+ removal

NASA Astrophysics Data System (ADS)

Baruah, Upama; Konwar, Achyut; Chowdhury, Devasish

2016-04-01

We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution.We have developed a hybrid hydrogel nanocomposite film via conjugation of oxidised carbon dots synthesized from 11-mercaptoundecanoic acid with chitosan. The potential applicability of the film was then successfully tested for the removal of Ca2+ and Mg2+ ions from solution. Electronic supplementary information (ESI) available: The ESI includes the detailed synthesis and characterization of carbon dots both before and after oxidation and of the carbon dot-chitosan nanocomposite films viz. DLS, SEM, UV-visible, FTIR, PL spectroscopy and TGA. See DOI: 10.1039/c6nr01129b

Photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films in an aerated 0.5 M NaCl solution

NASA Astrophysics Data System (ADS)

Boonserm, Aleena; Kruehong, Chaiyaput; Seithtanabutara, Varinrumpai; Artnaseaw, Apichart; Kwakhong, Panomkorn

2017-10-01

This research aimed to investigate the photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films using electrochemical measurements in an aerated 0.5 M NaCl solution under white light illumination. The CdS/TiO2 nanocomposite films were prepared by chemical bath deposition technique in a solution of cadmium and sulfide ions. The high resolution images of CdS/TiO2 nanocomposite films were provided by field emission scanning electron microscope. Theirs chemical identification and quantitative compositional information, crystallinity and actual chemical compounds formed were determined by energy dispersive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The results indicated that the photoelectrochemical activity of the films depended strongly on CdS content. From the preparation of CdS/TiO2 nanocomposite films by 5, 10 and 15 dipping cycles in the chemical solutions, the best photoelectrochemical response was revealed by the 10 dipping cycles-prepared film. Galvanic couple testing demonstrated that the photoelectrochemical response of the film decreased continuously compared to that of anodized nanoporous TiO2 substrate which described by photocorrosion of CdS nanoparticles. In addition, chloride-ion attack also induced pitting corrosion leading to fluctuation and deterioration of photoelectrochemical response. CdO2 and Cd(OH)2 depositions were found as the main photocorrosion products on collapsed nanostructured-surface. The relevance between photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite film was discussed in detail.

Graphene Oxide/Poly(3-hexylthiophene) Nanocomposite Thin-Film Phototransistor for Logic Circuit Applications

NASA Astrophysics Data System (ADS)

Mansouri, S.; Coskun, B.; El Mir, L.; Al-Sehemi, Abdullah G.; Al-Ghamdi, Ahmed; Yakuphanoglu, F.

2018-04-01

Graphene is a sheet-structured material that lacks a forbidden band, being a good candidate for use in radiofrequency applications. We have elaborated graphene-oxide-doped poly(3-hexylthiophene) nanocomposite to increase the interlayer distance and thereby open a large bandgap for use in the field of logic circuits. Graphene oxide/poly(3-hexylthiophene) (GO/P3HT) nanocomposite thin-film transistors (TFTs) were fabricated on silicon oxide substrate by spin coating method. The current-voltage ( I- V) characteristics of TFTs with various P3HT compositions were studied in the dark and under light illumination. The photocurrent, charge carrier mobility, subthreshold voltage, density of interface states, density of occupied states, and I ON/ I OFF ratio of the devices strongly depended on the P3HT weight ratio in the composite. The effects of white-light illumination on the electrical parameters of the transistors were investigated. The results indicated that GO/P3HT nanocomposite thin-film transistors have high potential for use in radiofrequency applications, and their feasibility for use in digital applications has been demonstrated.

Mechanical comparison of a polymer nanocomposite to a ceramic thin-film anti-reflective filter.

PubMed

Druffel, Thad; Geng, Kebin; Grulke, Eric

2006-07-28

Thin-film filters on optical components have been in use for decades and, for those industries utilizing a polymer substrate, the mismatch in mechanical behaviour has caused problems. Surface damage including scratches and cracks induces haze on the optical filter, reducing the transmission of the optical article. An in-mold anti-reflective (AR) filter incorporating 1/4-wavelength thin films based on a polymer nanocomposite is outlined here and compared with a traditional vacuum deposition AR coating. Nanoindentation and nanoscratch techniques are used to evaluate the mechanical properties of the thin films. Scanning electron microscopy (SEM) images of the resulting indentations and scratches are then compared to the force deflection curves to further explain the phenomena. The traditional coatings fractured by brittle mechanisms during testing, increasing the area of failure, whereas the polymer nanocomposite gave ductile failure with less surface damage.

Enhanced antibacterial performance of hybrid semiconductor nanomaterials: ZnO/SnO 2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Talebian, Nasrin; Nilforoushan, Mohammad Reza; Zargar, Elahe Badri

2011-10-01

The nano-sized coupled oxides ZnO/SnO 2 thin films in a molar ratio of 2:1 (Z2S), 1:1 (ZS) and 1:2 (ZS2) were prepared using sol-gel dip coating method and characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. Escherichia coli ( E. coli, ATCC 25922) was selected as a model for the Gram-negative bacteria to evaluate antibacterial property of composite samples compared with single ZnO (Z) and single SnO 2 (S) films. The antibacterial activity has been studied applying the so-called antibacterial drop test under UV illumination. The bactericidal activity was estimated by relative number of bacteria survived calculated from the number of viable cells which form colonies on the nutrient agar plates. The influence of the SnO 2-ZnO nanocomposite composition on the structural features and on the antibacterial properties of the thin films are reported and discussed. It is found that all coatings exhibited a high antibacterial activity. The coupled oxide photocatalyst Z2S has better photocatalytic activity to bacteria inactivation than ZS, ZS2, Z and S films. Furthermore, nanostructured films were active even in the absence of irradiation.

Preparation and characterization of bio-nanocomposite films based on soy protein isolate and montmorillonite using melt extrusion

USDA-ARS?s Scientific Manuscript database

The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and montmorillo...

Thermal hydrogen reduction for preservation of mesoporous silica film nanocomposites with a hexagonal structure containing amphiphilic triphenylene

NASA Astrophysics Data System (ADS)

Lintang, Hendrik O.; Jalani, Mohamad Azani; Yuliati, Leny

2017-11-01

We highlight that columnar assembly of self-assembled templates was successfully utilized using sol-gel technique of mesostructured silica for the quality improvement of transparent mesoporous film nanocomposites with a hexagonal structure through appropriate heat treatment methods and self-assembled templates in the removal of organic components. In contrast to the reported mesostructured silica film nanocomposites containing columnar assembly of trinuclear gold(I) pyrazolate complex ([Au3Pz3]C10TEG/silicahex) with calcination at 450 °C, mesostructured silica film nanocomposites from self-assembled template of triphenylene bearing amphiphilic decoxy triethylene glycol side chains (TPC10TEG/silicahex) can be completely collapsed upon calcination at 450 °C. This hexagonal structure can be only preserved with calcination at 250 °C although intensity of its main diffraction peak of d100 at 2θ of 3.70° was significantly decreased. On the other hands, thermal hydrogen reduction at the same temperature was found to be the best heat treatment to preserve the quality of mesoporous silica film nanocomposites with decreasing in intensity of diffraction peak up to 30%. Such phenomenon might be caused by slow decomposition of organic components with the presence of hydrogen gas upon heating to shrinkage the silica wall from interpenetration of ethylene glycol segments of the side chains and to open bonding of benzene ring from the core.

Preparation and characterization of Chitosan/Konjac glucomannan/CdS nanocomposite film with low infrared emissivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Feng-Ying; Zhou, Yu-Ming, E-mail: fchem@seu.edu.cn; Sun, Yan-qing

Novel organic-inorganic nanocomposite films were prepared with Chitosan (CS), Konjac glucomannan (KGM) and CdS by one-step synthesis. As-prepared films were characterized by IR spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared emissometer (IR). The results indicated that grown CdS dendrites were formed with reaction time of 12 h for Cd{sup 2+} and CS/KGM, and were well dispersed in CS/KGM with an average diameter of 40 nm. The CS/KGM/CdS nanocomposite films had significantly low infrared emissivity. When the mole ratio of CdS to summation of CS and KGM construction units was 1.0 with CdS size of 10-20 nm,more » the film got the lowest infrared emissivity value of 0.011, which could be attributed to the strong synergism effect existing between CS/KGM and CdS dendrites.« less

Transparent cellulose/polyhedral oligomeric silsesquioxane nanocomposites with enhanced UV-shielding properties.

PubMed

Feng, Ye; Zhang, Jinming; He, Jiasong; Zhang, Jun

2016-08-20

The solubility of eight types of polyhedral oligomeric silsesquioxane (POSS) derivatives in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) and the dispersion of POSS in cellulose matrix were examined. Only a special POSS containing both aminophenyl and nitrophenyl groups (POSS-AN, NH2:NO2=2:6) was selected to prepare nanocomposites, because of its good solubility in AmimCl and high stability during the preparation process. POSS-AN nanoparticles were uniformly dispersed in a cellulose matrix with a size of 30-40nm, and so the resultant cellulose/POSS-AN nanocomposite films were transparent. The mechanical properties of the films achieved a maximum tensile strength of 190MPa after addition of 2wt% POSS-AN. Interestingly, all of the cellulose/POSS-AN films exhibited high UV-absorbing capability. For the 15wt% cellulose/POSS-AN film, the transmittance of UVA (315-400nm) and UVB (280-315nm) was only 9.1% and nearly 0, respectively. The UV aging and shielding experiments showed that the transparent cellulose/POSS-AN nanocomposite films possessed anti-UV aging and UV shielding properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation and Characterization of Surface Photocatalytic Activity with NiO/TiO₂ Nanocomposite Structure.

PubMed

Chen, Jian-Zhi; Chen, Tai-Hong; Lai, Li-Wen; Li, Pei-Yu; Liu, Hua-Wen; Hong, Yi-You; Liu, Day-Shan

2015-07-13

This study achieved a nanocomposite structure of nickel oxide (NiO)/titanium dioxide (TiO₂) heterojunction on a TiO₂ film surface. The photocatalytic activity of this structure evaluated by decomposing methylene blue (MB) solution was strongly correlated to the conductive behavior of the NiO film. A p -type NiO film of high concentration in contact with the native n -type TiO₂ film, which resulted in a strong inner electrical field to effectively separate the photogenerated electron-hole pairs, exhibited a much better photocatalytic activity than the controlled TiO₂ film. In addition, the photocatalytic activity of the NiO/TiO₂ nanocomposite structure was enhanced as the thickness of the p -NiO film decreased, which was beneficial for the migration of the photogenerated carriers to the structural surface.

Flexible and conductive MXene films and nanocomposites with high capacitance

DOE PAGES

Ling, Zheng; Ren, Chang E.; Zhao, Meng-Qiang; ...

2014-11-11

MXenes, a new family of 2D materials, combine hydrophilic surfaces with metallic conductivity. Delamination of MXene produces single-layer nanosheets with thickness of about a nanometer and lateral size of the order of micrometers. The high aspect ratio of delaminated MXene renders it promising nanofiller in multifunctional polymer nanocomposites. In this study, Ti 3C 2T x MXene was mixed with either a charged polydiallyldimethylammonium chloride (PDDA) or an electrically neutral polyvinyl alcohol (PVA) to produce Ti 3C 2T x/polymer composites. The as-fabricated composites are flexible and have electrical conductivities as high as 2.2 × 10 4 S/m in the case ofmore » the Ti 3C 2T x/PVA composite film and 2.4 × 10 5 S/m for pure Ti 3C 2T x films. The tensile strength of the Ti 3C 2T x/PVA composites was significantly enhanced compared with pure Ti 3C 2T x or PVA films. The intercalation and confinement of the polymer between the MXene flakes not only increased flexibility but also enhanced cationic intercalation, offering an impressive volumetric capacitance of ~530 F/cm 3 for MXene/PVA-KOH composite film at 2 mV/s. Finally, to our knowledge, this study is a first, but crucial, step in exploring the potential of using MXenes in polymer-based multifunctional nanocomposites for a host of applications, such as structural components, energy storage devices, wearable electronics, electrochemical actuators, and radiofrequency shielding, to name a few.« less

Preparation and Characterization of Polyimide/Organoclay Nanocomposites

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Johnston, N. J.; Smith, J. G., Jr.; Connell, J. W.

2002-01-01

Organically modified montmorrrillonite clay, containing a long chain aliphatic quarternary ammonium cation, was used to prepare polyimide/organoclay hybrids. Several approaches were examined in an attempt to achieve fully exfoliated nanocomposites. These included simple mixing of the clay in a pre-made high molecular weight poly(amide acid) solution; simple mixing followed by sonication of the organoclay/poly(amide acid) solutions; and the preparation of high molecular weight poly(amide acid)s in the presence of the organoclay dispersed in N-methyl-2-pyrrolidinone (NMP). The best results were obtained using the in-situ polymerization approach. The resulting nanocomposite films (both amide acid and imide), containing 3-8% by weight of organoclay, were characterized by differential scanning calorimetry (DSC), dynamic thermogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin film tensile properties. A significant degree of dispersion was observed in the nanocomposite films of the amide acid and the imide. After thermal treatment of amide acid films to effect imidization, in both air and nitrogen, the films were visually darker than control films without clay and the level of clay dispersion appeared to have decreased. In the latter case, the separation between the layers of the clay decreased to a spacing less than that present in the original organoclay. These observations suggest that thermal degradation of the aliphatic quarternary ammonium cation occurred likely during thermal treatment to effect imidization and solvent removal. These thermal degradation effects were less pronounced when thermal treatment was performed under nitrogen. The polyimide/organoclay hybrid films exhibited higher room temperature tensile moduli and lower strength and elongation to break than the control films.

Enhanced energy density and thermostability in polyimide nanocomposites containing core-shell structured BaTiO3@SiO2 nanofibers

NASA Astrophysics Data System (ADS)

Wang, Junchuan; Long, Yunchen; Sun, Ying; Zhang, Xueqin; Yang, Hong; Lin, Baoping

2017-12-01

High energy density polymer nanocomposites with high-temperature resistance are quite desirable for film capacitors and many other power electronics. In this study, polyimide-based (PI) nanocomposite films containing the core-shell structured barium titanate@silicon dioxide (BT@SiO2) nanofibers have been successfully synthesized by the solution casting method. In the BT@SiO2/PI nanocomposite films, the dielectric permittivity as well as the breakdown strength increase significantly. The SiO2 shell layers with moderate dielectric permittivity could effectively mitigate the local field concentration induced by the large mismatch between the dielectric permittivity of BT and PI, which contributes to the enhancement of the breakdown strength of the PI nanocomposite films. As a result, the PI nanocomposite film filled with 3 vol% BT@SiO2 nanofibers exhibits a maximal energy density of 2.31 J cm-3 under the field of 346 kV/mm, which is 62% over the pristine PI (1.42 J cm-3 at 308 kV/mm) and about 200% greater than the best commercial polymer, i.e. biaxially oriented polypropylenes (BOPP) (≈1.2 J cm-3). The thermogravimetric analysis results indicate that the BT@SiO2/PI nanocomposite films have good thermal stability below 500 °C.

Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

DOEpatents

Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

2014-02-04

Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

Nanocomposite thin films for triggerable drug delivery.

PubMed

Vannozzi, Lorenzo; Iacovacci, Veronica; Menciassi, Arianna; Ricotti, Leonardo

2018-05-01

Traditional drug release systems normally rely on a passive delivery of therapeutic compounds, which can be partially programmed, prior to injection or implantation, through variations in the material composition. With this strategy, the drug release kinetics cannot be remotely modified and thus adapted to changing therapeutic needs. To overcome this issue, drug delivery systems able to respond to external stimuli are highly desirable, as they allow a high level of temporal and spatial control over drug release kinetics, in an operator-dependent fashion. Areas covered: On-demand drug delivery systems actually represent a frontier in this field and are attracting an increasing interest at both research and industrial level. Stimuli-responsive thin films, enabled by nanofillers, hold a tremendous potential in the field of triggerable drug delivery systems. The inclusion of responsive elements in homogeneous or heterogeneous thin film-shaped polymeric matrices strengthens and/or adds intriguing properties to conventional (bare) materials in film shape. Expert opinion: This Expert Opinion review aims to discuss the approaches currently pursued to achieve an effective on-demand drug delivery, through nanocomposite thin films. Different triggering mechanisms allowing a fine control on drug delivery are described, together with current challenges and possible future applications in therapy and surgery.

Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite.

PubMed

Kumar, P; Sandeep, K P; Alavi, S; Truong, V D; Gorga, R E

2010-06-01

The nonbiodegradable and nonrenewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified montmorillonite (MMT) were prepared using melt extrusion. The effect of different type (Cloisite 20A and Cloisite 30B) and content (0% to 15%) of modified MMT on the structure (degree of intercalation and exfoliation) and properties (color, mechanical, dynamic mechanical, thermal stability, and water vapor permeability) of SPI-MMT bio-nanocomposite films were investigated. Extrusion of SPI and modified MMTs resulted in bio-nanocomposites with exfoliated structures at lower MMT content (5%). At higher MMT content (15%), the structure of bio-nanocomposites ranged from intercalated for Cloisite 20A to disordered intercalated for Cloisite 30B. At an MMT content of 5%, bio-nanocomposite films based on modified MMTs (Cloisite 20A and Cloisite 30B) had better mechanical (tensile strength and percent elongation at break), dynamic mechanical (glass transition temperature and storage modulus), and water barrier properties as compared to those based on natural MMT (Cloisite Na(+)). Bio-nanocomposite films based on 10% Cloisite 30B had mechanical properties comparable to those of some of the plastics that are currently used in food packaging applications. However, much higher WVP values of these films as compared to those of existing plastics might limit the application of these films to packaging of high moisture foods such as fresh fruits and vegetables.

Synthesis and characterization of HDPE/N-MWNT nanocomposite films.

PubMed

Chouit, Fairouz; Guellati, Ounassa; Boukhezar, Skander; Harat, Aicha; Guerioune, Mohamed; Badi, Nacer

2014-01-01

In this work, a series of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) with several weight percentages (0.1, 0.4, 0.8, and 1.0 wt.%) were synthesized by catalytic chemical vapor deposition (CCVD) technique. The N-MWCNTs were first characterized and then dispersed in high-density polyethylene (HDPE) polymer matrix to form a nanocomposite. The HDPE/N-MWCNT nanocomposite films were prepared by melt mixing and hot pressing; a good dispersion in the matrix and a good N-MWCNT-polymer interfacial adhesion have been verified by scanning electron microscopy (SEM). Raman spectroscopy measurements have been performed on prepared samples to confirm the presence and nature of N-MWNTs in HDPE matrix. The X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of HDPE matrix was not affected by the incorporation of the N-MWNTs.

Synthesis and characterization of HDPE/N-MWNT nanocomposite films

PubMed Central

2014-01-01

In this work, a series of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) with several weight percentages (0.1, 0.4, 0.8, and 1.0 wt.%) were synthesized by catalytic chemical vapor deposition (CCVD) technique. The N-MWCNTs were first characterized and then dispersed in high-density polyethylene (HDPE) polymer matrix to form a nanocomposite. The HDPE/N-MWCNT nanocomposite films were prepared by melt mixing and hot pressing; a good dispersion in the matrix and a good N-MWCNT-polymer interfacial adhesion have been verified by scanning electron microscopy (SEM). Raman spectroscopy measurements have been performed on prepared samples to confirm the presence and nature of N-MWNTs in HDPE matrix. The X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of HDPE matrix was not affected by the incorporation of the N-MWNTs. PMID:25024676

Structure and physical properties of starch/poly vinyl alcohol/sodium montmorillonite nanocomposite films.

PubMed

Ali, Samer S; Tang, Xiaozhi; Alavi, Sajid; Faubion, Jon

2011-12-14

Nanocomposites of starch, poly vinyl alcohol (PVOH), and sodium montmorillonite (Na(+)MMT) were produced by solution mixing and cast into films. Tensile strength (TS) and elongation at the break (E%) of the films ranged from 11.60 to 22.35 MPa and 28.93-211.40%, respectively, while water vapor permeability (WVP) ranged from 0.718 to 1.430 g·mm/kPa·h·m(2). In general, an increase in Na(+)MMT content (0-20%) enhanced TS and decreased E% and WVP. Use of higher molecular weight PVOH increased both TS and E% and also decreased WVP. Mechanical properties were negatively affected, but water vapor barrier properties improved with increasing starch content (0-80%). X-ray diffraction and transmission electron microscopy were used to analyze the nanostructure, and molecular conformations and interactions in the multicomponent nanocomposites were inferred from glass transition behavior. Interactions between starch and PVOH were strongest, followed by polymer/clay interactions. On the basis of this insight, a conceptual model was presented to explain the phenomena of intercalation and exfoliation in the starch/PVOH/Na(+)MMT nanocomposites.

Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

2003-01-01

A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

Emphasizing the role of surface chemistry on hydrophobicity and cell adhesion behavior of polydimethylsiloxane/TiO2 nanocomposite films.

PubMed

Yousefi, Seyedeh Zahra; Tabatabaei-Panah, Pardis-Sadat; Seyfi, Javad

2018-07-01

Improving the bioinertness of materials is of great importance for developing biomedical devices that contact human tissues. The main goal of this study was to establish correlations among surface morphology, roughness and chemistry with hydrophobicity and cell adhesion in polydimethylsiloxane (PDMS) nanocomposites loaded with titanium dioxide (TiO 2 ) nanoparticles. Firstly, wettability results showed that the nanocomposite loaded with 30 wt.% of TiO 2 exhibited a superhydrophobic behavior; however, the morphology and roughness analysis proved that there was no discernible difference between the surface structures of samples loaded with 20 and 30 wt.% of nanoparticles. Both cell culture and MTT assay experiments showed that, despite the similarity between the surface structures, the sample loaded with 30 wt.% nanoparticles exhibits the greatest reduction in the cell viability (80%) as compared with the pure PDMS film. According to the X-ray photoelectron spectroscopy results, the remarkable reduction in cell viability of the superhydrophobic sample could be majorly attributed to the role of surface chemistry. The obtained results emphasize the importance of adjusting the surface properties especially surface chemistry to gain the optimum cell adhesion behavior. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanocomposites biodegradable coating on BOPET films to enhance hot seal strength properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbaro, G., E-mail: giovannibarbaro@email.it; Galdi, M. R., E-mail: mrgaldi@unisa.it; Di Maio, L., E-mail: ldimaio@unisa.it

2015-12-17

The coating technology is a strategic solution to improve the properties of flexible packaging films. Indeed, additional functional layers are often designed and added as coating on the substrate, in order to improve the characteristic of the flexible packaging and to meet the requirements for the desired gas or vapour barrier, for adhesion and sealing, or for improving the film printability, its aesthetics and durability. Moreover, this technology allows to functionalize a polymeric substrate applying materials with different chemistry, rheology, thermal and structural characteristics. BOPET films are widely used for food packaging applications thanks to their good gas barrier andmore » mechanical properties, high transparency and for the excellent printability. In regard to sealing performance, BOPET films show poor sealing properties so they are mostly submitted to lamination processes with polyethylene. Nevertheless, this solution compromises the PET recyclability and influences the gas permeability of the multilayer PET based structures. The aim of this work is to investigate on the effect of nanocomposite biodegradable coatings for BOPET substrates in enhancing the heat sealing strength of eco-compatible PET/PLA films. At this regards, different percentages of Cloisite C30B (0%, 2% and 4%{sub wt/wt}) have been added to PLA by solution intercalation technique and the nanocomposite biodegradable materials produced have been applied on BOPET commercial films by casting. The BOPET coated films have been characterized in order to evaluate the heat sealing strength and the mechanical, gas permeability and surface properties. The results have shown that the addition of nanoclay in PLA coating significantly enhance the hot tack properties of the PET/PLA system produced, while the oxygen and water vapour permeability are slightly increased if compared to pure BOPET films.« less

Nanocomposites biodegradable coating on BOPET films to enhance hot seal strength properties

NASA Astrophysics Data System (ADS)

Barbaro, G.; Galdi, M. R.; Di Maio, L.; Incarnato, L.

2015-12-01

The coating technology is a strategic solution to improve the properties of flexible packaging films. Indeed, additional functional layers are often designed and added as coating on the substrate, in order to improve the characteristic of the flexible packaging and to meet the requirements for the desired gas or vapour barrier, for adhesion and sealing, or for improving the film printability, its aesthetics and durability. Moreover, this technology allows to functionalize a polymeric substrate applying materials with different chemistry, rheology, thermal and structural characteristics. BOPET films are widely used for food packaging applications thanks to their good gas barrier and mechanical properties, high transparency and for the excellent printability. In regard to sealing performance, BOPET films show poor sealing properties so they are mostly submitted to lamination processes with polyethylene. Nevertheless, this solution compromises the PET recyclability and influences the gas permeability of the multilayer PET based structures. The aim of this work is to investigate on the effect of nanocomposite biodegradable coatings for BOPET substrates in enhancing the heat sealing strength of eco-compatible PET/PLA films. At this regards, different percentages of Cloisite C30B (0%, 2% and 4%wt/wt) have been added to PLA by solution intercalation technique and the nanocomposite biodegradable materials produced have been applied on BOPET commercial films by casting. The BOPET coated films have been characterized in order to evaluate the heat sealing strength and the mechanical, gas permeability and surface properties. The results have shown that the addition of nanoclay in PLA coating significantly enhance the hot tack properties of the PET/PLA system produced, while the oxygen and water vapour permeability are slightly increased if compared to pure BOPET films.

Polyaniline-ZnO nanocomposites as ethanol gas sensors

NASA Astrophysics Data System (ADS)

Talegaonkar, Janhavi; Patil, Y. B.; Patil, D. R.

2018-05-01

Polyaniline and it`s nanocomposites with ZnO were successfully synthesized by photo-induced polymerization method with various concentrations of ZnO, followed by characterizations viz. SEM, EDAX, XRD, FTIR and UV-Vis. Thick films of synthesized powders were fabricated by screen printing technique for monitoring various gases at different operating temperatures and at various gas concentrations. CuO activated polyaniline-ZnO nano-composite exhibits maximum response of ethanol gas at room temperature. The sensor exhibits high sensitivity, highest selectivity, quick response, fast recovery, long term stability, etc. An exceptional sensitivity was found to low concentrations of ethanol gas at room temperature and no cross sensitivity was observed even to high concentrations of other hazardous and polluting gases. The efforts have been made to develop the ethanol sensor based on PANI and its nanocomposites. The effects of microstructure and surfactant concentration on the ethanol response, selectivity, response and recovery of the sensor in the presence of ethanol gas were studied and discussed.

Structural and optical properties of SiC-SiO2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Bozetine, I.; Keffous, A.; Kaci, S.; Menari, H.; Manseri, A.

2018-03-01

This study deals with the deposition of thin films of a SiC-SiO2nanocomposite deposited on silicon substrates. The deposition is carried out by a co-sputtering RF magnetron 13.56 MHz, using two targets a polycristallin 6H-SiC and sprigs of SiO2. In order to study the influence of the deposition time on the morphology, the structural and optical properties of the thin films produced, two series of samples were prepared, namely a series A with a 30 min deposition time and a series B of one hour duration. The samples were investigated using different characterization techniques such as Scanning Electron Microscope (SEM), X-ray Diffraction (DRX), Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry (SIMS) and photoluminescence. The results obtained, reveal an optical gap varies between 1.4 and 2.4 eV depending on the thickness of the film; thus depending on the deposition time. The SIMS profile recorded the presence of oxygen (16O) on the surface, which the signal beneath the silicon signal (28Si) and carbon (12C) signals, which confirms that the oxide (SiO2) is the first material deposited at the interface film - substrate with an a-OSiC structure. The photoluminescence (PL) measurement exhibits two peaks, centred at 390 nm due to the oxide and at 416 nm due probably to the nanocrystals of SiC crystals, note that when the deposition time increases, the intensity of the PL drops drastically, result in agreement with dense and smooth film.

Synthesis of Nm-PHB (nanomelanin-polyhydroxy butyrate) nanocomposite film and its protective effect against biofilm-forming multi drug resistant Staphylococcus aureus.

PubMed

Kiran, George Seghal; Jackson, Stephen A; Priyadharsini, Sethu; Dobson, Alan D W; Selvin, Joseph

2017-08-22

Melanin is a dark brown ubiquitous photosynthetic pigment which have many varied and ever expanding applications in fabrication of radio-protective materials, food packaging, cosmetics and in medicine. In this study, melanin production in a Pseudomonas sp. which was isolated from the marine sponge Tetyrina citirna was optimized employing one-factor at a time experiments and characterized for chemical nature and stability. Following sonication nucleated nanomelanin (Nm) particles were formed and evaluated for antibacterial and antioxidant properties. Nanocomposite film was fabricated using combinations (% w/v) of polyhydroxy butyrate-nanomelanin (PHB:Nm) blended with 1% glycerol. The Nm was found to be spherical in shape with a diameter of 100-140 nm and showed strong antimicrobial activity against both Gram positive and Gram negative bacteria. The Nm-PHB nanocomposite film was homogeneous, smooth, without any cracks, and flexible. XRD and DSC data indicated that the film was crystalline in nature, and was thermostable up to 281.87 °C. This study represents the first report on the synthesis of Nm and fabrication of Nm-PHB nanocomposite film which show strong protective effect against multidrug resistant Staphyloccoccus aureus. Thus this Nm-PHB nanocomposite film may find utility as packaging material for food products by protecting the food products from oxidation and bacterial contamination.

Polyvinylpyrrolidone/reduced graphene oxide nanocomposites thin films coated on quartz crystal microbalance for NO2 detection at room temperature

NASA Astrophysics Data System (ADS)

Huang, Junlong; Xie, Guangzhong; Zhou, Yong; Xie, Tao; Tai, HuiLing; Yang, Guangjin

2014-08-01

Polyvinylpyrrolidone (PVP)/reduced graphene oxide (RGO) nanocomposites are sprayed on quartz crystal microbalance (QCM) for NO2 sensing. The thin films are characterized by Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-VIS). The experimental results reveal that PVP/RGO sensor exhibits higher sensitivity and shorter recovery time than those of PVP. Besides, the response to 20 ppm NO2 is higher than other gases such as CO, CO2 and NH3 even at 100ppm. When the PVP/RGO sensor is exposed to these gases, the good selectivity to NO2 makes the sensor ideal for NO2 detection.

Giant room temperature magnetoelectric response in strain controlled nanocomposites

NASA Astrophysics Data System (ADS)

Rafique, Mohsin; Herklotz, Andreas; Dörr, Kathrin; Manzoor, Sadia

2017-05-01

We report giant magnetoelectric coupling at room temperature in a self-assembled nanocomposite of BiFeO3-CoFe2O4 (BFO-CFO) grown on a BaTiO3 (BTO) crystal. The nanocomposite consisting of CFO nanopillars embedded in a BFO matrix exhibits weak perpendicular magnetic anisotropy due to a small out-of-plane compression (˜0.3%) of the magnetostrictive (CFO) phase, enabling magnetization rotation under moderate in-plane compression. Temperature dependent magnetization measurements demonstrate strong magnetoelastic coupling between the BaTiO3 substrate and the nanocomposite film, which has been exploited to produce a large magnetoelectric response in the sample. The reorientation of ferroelectric domains in the BTO crystal upon the application of an electric field (E) alters the strain state of the nanocomposite film, thus enabling control of its magnetic anisotropy. The strain mediated magnetoelectric coupling coefficient α = μ o d M / d E calculated from remnant magnetization at room temperature is 2.6 × 10-7 s m-1 and 1.5 × 10-7 s m-1 for the out-of-plane and in-plane orientations, respectively.

Room temperature synthesis and optical studies on Ag and Au mixed nanocomposite polyvinylpyrrolidone polymer films.

PubMed

Udayabhaskar, R; Mangalaraja, R V; Manikandan, D; Arjunan, V; Karthikeyan, B

2012-12-01

Optical properties of silver, gold and bimetallic (Au:Ag) nanocomposite polymer films which are prepared by chemical method have been reported. The experimental data was correlated with the theoretical calculations using Mie theory. We adopt small change in the theoretical calculations of bimetallic/mixed particle nanocomposite and the theory agrees well with the experimental data. Polyvinylpyrrolidone (PVP) was used as reducing and capping agent. Fourier transform infrared spectroscopy (FTIR) study reveals the presence of different functional groups, the possible mechanism that leads to the formation of nanoparticles by using PVP alone as reducing agent. Optical absorption spectra of Ag and Au nanocomposite polymers show a surface plasmon resonance (SPR) band around 430 and 532 nm, respectively. Thermal annealing effect on the prepared samples at 60 °C for different time durations result in shift of SPR band maximum and varies the full width at half maximum (FWHM). Absorption spectra of Au:Ag bimetallic films show bands at 412 and 547 nm confirms the presence of Ag and Au nanoparticles in the composite. Copyright © 2012 Elsevier B.V. All rights reserved.

Nanocomposite synthesis and photoluminescence properties of MeV Au-ion beam modified Ni thin films

NASA Astrophysics Data System (ADS)

Siva, Vantari; Datta, Debi P.; Singh, Avanendra; Som, T.; Sahoo, Pratap K.

2016-01-01

We report on the synthesis and properties of nano-composites from thin Ni films on Silica matrix using Au-ion beam. When 2.2 MeV Au-ions are irradiated on 5 nm Ni film on Silica, the surface morphology changes drastically with ion fluence. In fact, within a fluence range of 5 × 1014-1 × 1016 ions/cm2, a sharp increase in surface roughness follows after an initial surface smoothening. The depth profiles extracted from Rutherford backscattering spectra demonstrates the diffusion of Ni and Au into the silica matrix. The photoluminescence spectra of the irradiated samples reveal the development of two bands centered at 3.3 eV and 2.66 eV, respectively. Deconvolution of those bands shows five different emission peaks, corresponding to different luminescence centers, which confirms the existence of Ni-Au nanocomposites in silica matrix. The optical and structural modifications are understood in terms of ion induced local heating and mass transport due to thermal spikes, which leads to nanocomposite formation in silica.

Polyaniline-carboxymethyl cellulose nanocomposite for cholesterol detection.

PubMed

Barik, Abdul; Solanki, Pratima R; Kaushik, Ajeet; Ali, Azahar; Pandey, M K; Kim, C G; Malhotra, B D

2010-10-01

Cholesterol oxidase (ChOx) has been covalently immobilized onto polyaniline-carboxymethyl cellulose (PANI-CMC) nanocomposite film deposited onto indium-tin-oxide (ITO) coated glass plate using glutaraldehyde as a cross-linker. Fourier transform infrared (FTIR) spectroscopic and electrochemical studies have been used to characterize the PANI-CMC/ITO nanocomposite electrode and ChOx/PANI-CMC/ITO bioelectrode. Scanning electron microscopy (SEM) studies reveal the formation of PANI-CMC nanocomposite fibers of size approximately 150 nm in diameter. The ChOx/PANI-CMC/ITO bioelectrode exhibits linearity as 0.5-22 mM, detection limit as 1.31 mM, sensitivity as 0.14 mA/mM cm2, response time as 10 s and shelf-life of about 10 weeks when bioelectrode is stored at 4 degrees C. The low value of Michaelis-Menten constant (K(m)) obtained as 2.71 mM reveals high affinity of immobilized ChOx for PANI-CMC/ITO nanocomposite electrode.

Carbon Nanotube/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Watson, K. A.; Thompson, C. M.; Connell, J. W.

2002-01-01

Low solar absorptivity, space environmentally stable polymeric materials possessing sufficient electrical conductivity for electrostatic charge dissipation (ESD) are of interest for potential applications on spacecraft as thin film membranes on antennas, solar sails, large lightweight space optics, and second surface mirrors. One method of imparting electrical conductivity while maintaining low solar absorptivity is through the use of single wall carbon nanotubes (SWNTs). However, SWNTs are difficult to disperse. Several preparative methods were employed to disperse SWNTs into the polymer matrix. Several examples possessed electrical conductivity sufficient for ESD. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

Dimensional effects on the tunneling conductivity of gold-implanted nanocomposite films

NASA Astrophysics Data System (ADS)

Grimaldi, C.; Cattani, M.; Salvadori, M. C.

2015-03-01

We study the dependence of the electrical conductivity on the gold concentration of Au-implanted polymethylmethacrylate (PMMA) and alumina nanocomposite thin films. For Au contents larger than a critical concentration, the conductivity of Au-PMMA and Au-alumina is well described by percolation in two dimensions, indicating that the critical correlation length for percolation is larger than the thickness of the films. Below the critical loading, the conductivity is dominated by tunneling processes between isolated Au particles dispersed in PMMA or alumina continuous matrices. Using an effective medium analysis of the tunneling conductivity, we show that Au-PMMA behaves as a tunneling system in two dimensions, as the film thickness is comparable to the mean Au particle size. On the contrary, the conductivity of Au-alumina films is best described by tunneling in three dimensions, although the film thickness is only a few times larger than the particle size. We interpret the enhancement of the effective dimensionality of Au-alumina films in the tunneling regime as due to the larger film thickness as compared to the mean interparticle distances.

Fabrication, characterization and in-vitro cytotoxicity of magnetic nanocomposite polymeric film for multi-functional medical application

NASA Astrophysics Data System (ADS)

Zhao, Lingyun; Xu, Xiaoyu; Wang, Xiaowen; Zhang, Xiaodong; Gao, Fuping; Tang, Jintian

2009-07-01

Cancer comprehensive treatment has been fully acknowledged as it can provide an effective multimodality approach for fighting cancers. In this study, various innovative technologies for cancer treatment including cancer nanotechnology, chemotherapy by sustainable release, as well as magnetic induction hyperthermia (MIH) have been integrated for the purpose of cancer comprehensive treatment. Briefly, such kind of treatment can be realized by applying of the tailored magnetic nanoparticles (MNPs) composite polymeric film. Fe3O4 MNPs acting as the agent for MIH, and anti-cancer drug docetaxel as chemotherapeutic agent were incorporated within the biodegradable polymeric film. Physiochemical characterizations on MNPs and the film have been systematically carried out by various instrumental analyses. Our results demonstrated that the film has been successfully fabricated by the solvent cast method. Hyperthermia could be induced by stimulating the nanocomposite film under an alternative magnetic field (AMF). The incorporation of MNPs, as well as hyperthermia would facilitate the drug release from the polymeric film. The in-vitro cytotoxicity results indicated the bi-modal cancer treatment approach for combined MIH and chemotherapy is more effective than the mono-modal treatment by docetaxel treatment. The magnetic nanocomposite film can realize cancer comprehensive treatment thus has great potential in clinical application.

Bio-functionalized graphene–graphene oxide nanocomposite based electrochemical immunosensing

PubMed Central

Sharma, Priyanka; Tuteja, Satish K.; Bhalla, Vijayender; Shekhawat, G.; Dravid, Vinayak P.; Suri, C.Raman

2014-01-01

We report a novel in-situ electrochemical synthesis approach for the formation of functionalized graphene–graphene oxide (fG–GO) nanocomposite on screen-printed electrodes (SPE). Electrochemically controlled nanocomposite film formation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. Further insight into the nanocomposite has been accomplished by the Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) spectroscopy. Configured as a highly responsive screen-printed immunosensor, the fG–GO nanocomposite on SPE exhibits electrical and chemical synergies of the nano-hybrid functional construct by combining good electronic properties of functionalized graphene (fG) and the facile chemical functionality of graphene oxide (GO) for compatible bio-interface development using specific anti-diuron antibody. The enhanced electrical properties of nanocomposite biofilm demonstrated a significant increase in electrochemical signal response in a competitive inhibition immunoassay format for diuron detection, promising its potential applicability for ultra-sensitive detection of range of target analytes. PMID:22884654

Dynamic Mechanical Characterization of Thin Film Polymer Nanocomposites

NASA Technical Reports Server (NTRS)

Herring, Helen M.; Gates, Thomas S. (Technical Monitor)

2003-01-01

Many new materials are being produced for aerospace applications with the objective of maximizing certain ideal properties without sacrificing others. Polymer composites in various forms and configurations are being developed in an effort to provide lighter weight construction and better thermal and electrical properties and still maintain adequate strength and stability. To this end, thin film polymer nanocomposites, synthesized for the purpose of influencing electrical conductivity using metal oxide particles as filler without incurring losses in mechanical properties, were examined to determine elastic modulus and degree of dispersion of particles. The effects of various metal oxides on these properties will be discussed.

Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Crsbnd C films

NASA Astrophysics Data System (ADS)

Nygren, Kristian; Andersson, Matilda; Högström, Jonas; Fredriksson, Wendy; Edström, Kristina; Nyholm, Leif; Jansson, Ulf

2014-06-01

It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Crsbnd C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 °C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Crsbnd C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 °C were X-ray amorphous and 500 °C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl (sat. KCl) in hot 1 mM H2SO4 resulted in oxidation of Crsbnd C, yielding Cr2O3 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Crsbnd C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes.

Roll-to-Roll Continuous Manufacturing Multifunctional Nanocomposites by Electric-Field-Assisted "Z" Direction Alignment of Graphite Flakes in Poly(dimethylsiloxane).

PubMed

Guo, Yuanhao; Chen, Yuwei; Wang, Enmin; Cakmak, Miko

2017-01-11

A roll-to-roll continuous process was developed to manufacture large-scale multifunctional poly(dimethylsiloxane) (PDMS) films embedded with thickness direction ("Z" direction) aligned graphite nanoparticles by application of electric field. The kinetics of particle "Z" alignment and chain formation was studied by tracking the real-time change of optical light transmission through film thickness direction. Benefiting from the anisotropic structure of aligned particle chains, the electrical and thermal properties of the nanocomposites were dramatically enhanced through the thickness direction as compared to those of the nanocomposites containing the same particle loading without electrical field alignment. With 5 vol % graphite loading, 250 times higher electrical conductivity, 43 times higher dielectric permittivity, and 1.5 times higher thermal conductivity was achieved in the film thickness direction after the particles were aligned under electrical field. Moreover, the aligned nanocomposites with merely 2 vol % graphite particles exhibit even higher electric conductivity and dielectric permittivity than those of the nonaligned nanocomposites at random percolation threshold (10 vol % particles), as the "electric-field-directed" percolation threshold concentration is substantially decreased using this process. As the graphite loading increases to 20 vol %, the aligned nanocomposites exhibit thermal conductivity as high as 6.05 W/m·K, which is 35 times the thermal conductivity of pure matrix. This roll-to-roll electric field continuous process provides a simple, low-cost, and commercially viable method to manufacture multifunctional nanocomposites for applications as embedded capacitor, electromagnetic (EM) shielding, and thermal interface materials.

MEMS sensor material based on polypyrrole carbon nanotube nanocomposite: film deposition and characterization

NASA Astrophysics Data System (ADS)

Teh, Kwok-Siong; Lin, Liwei

2005-11-01

Conductive polymer-based nanocomposite has been utilized as a MEMS sensing material via a one-step, selective on-chip deposition process at room temperature. A doped polypyrrole (PPy) variant synthesized by incorporating multi-walled carbon nanotube (MWCNT) into electropolymerized PPy has been shown to improve the sensing performance utilizing a two-terminal, micro-gap chemiresistor architecture. The dodecylbenzenesulfonate (DBS)-doped PPy-MWCNT nanocomposites are found to be responsive to oxidants, such as hydrogen peroxide (H2O2), and this effect can be extended to glucose detection using H2O2 as a proxy material. The oxidant sensing effect is demonstrated by subjecting a glucose oxidase (GOx)-laden PPy-MWCNT nanocomposite film to various concentrations of glucose solution. Such PPy-MWCNT nanocomposite, when applied in a chemiresistor configuration, obviates the need for reference electrode and electron mediators, by measuring the direct and reversible, oxidation-reduction induced conductivity change. Experimentally, GOx-laden, doped PPy-MWCNT is tested to be sensitive to glucose concentration up to 20 mM, which covers the physiologically important range for diabetics of 0-20 mM.

The Enhancement Of UV Sensor Response By Zinc Oxide Nanorods / Reduced Graphene Oxide Bilayer Nanocomposites Film

NASA Astrophysics Data System (ADS)

Mohammed, Ali A. A.; Suriani, AB; Jabur, Akram R.

2018-05-01

Zinc oxide nanorods (ZnO NRs) / reduced graphene oxide (rGO) nanocomposites assisted by sodium dodecyl sulfate surfactant (ZnO NRs/rGO-SDS) showed a good response for UV sensor application that has sensitivity of around ∼32.54. Whereas, the UV sensor response on pristine ZnO NRs showed almost 15 times lower response than the ZnO NRs/rGO-SDS nanocomposites. The pristine ZnO NRs were prepared by sol-gel immersion method before rGO solution was sprayed on the ZnO films using spraying method. The GO solution was produced via electrochemical exfoliation method at 0.1 M SDS electrolyte then the solution was reduced using hydrazine hydrate under 24 hours magnetic stirring at a temperature of around ∼100 °C. The samples were characterized using energy dispersive X-ray, field emission scanning electron microscope, micro-Raman, ultraviolet visible, X-ray diffraction, UV lamp and four-point probe measurement. The aim of this study was to improve the UV sensor response based on ZnO/rGO-SDS nanocomposites. In conclusion, the fabricated ZnO NRs/rGO-SDS nanocomposites assisted with SDS is a good candidate for the use in UV sensor applications as compared to pristine ZnO NRs films.

PET based nanocomposite films for microwave packaging applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galdi, M. R., E-mail: mrgaldi@unisa.it; Olivieri, R.; Liguori, L.

In recent years, changes in life standards have promoted the diffusion of Ready to Cook (RTC) and Ready to Eat (RTE) products for microwave ovens. However, the main limits in microwave (MW) ovens usage are often related to the proper choice of packaging materials suitable for such technology. In fact, packages for microwaveable RTC and RTE foods should ensure adequate preservation of the product before cooking/heating such as high barriers to gases and aromas and adequate control of water vapor transmission. In addition, microwaveable packaging material must be transparent to MW, thermally stable and resistant to the mechanical stress inducedmore » by the accumulation in the head space of volatile substances produced during the cooking. Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to MW. In the last years a great interest is devoted to developing innovative solution based on the use of additives or systems that act as susceptors or heating enhancers for improving the characteristics of polymers in cooking/heating in MW ovens. The present work was focused on the production and characterization of nanocomposite copolyester based films suitable for microwaveable food packaging applications. The matrices selected consist in two PET copolymers modified with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages (0%, 2% and 4%wt/wt) of Cloisite 20A (C20A). Films were analyzed for evaluating the effect of nanofiller on the morphology and barrier properties. Moreover, to verify the effectiveness of the designed systems in reducing the cooking times of meat products, MW heating tests were carried out on pork meat hamburgers in MW oven at varying supplied powers. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancers of

PET based nanocomposite films for microwave packaging applications

NASA Astrophysics Data System (ADS)

Galdi, M. R.; Olivieri, R.; Liguori, L.; Albanese, D.; Di Matteo, M.; Di Maio, L.

2015-12-01

In recent years, changes in life standards have promoted the diffusion of Ready to Cook (RTC) and Ready to Eat (RTE) products for microwave ovens. However, the main limits in microwave (MW) ovens usage are often related to the proper choice of packaging materials suitable for such technology. In fact, packages for microwaveable RTC and RTE foods should ensure adequate preservation of the product before cooking/heating such as high barriers to gases and aromas and adequate control of water vapor transmission. In addition, microwaveable packaging material must be transparent to MW, thermally stable and resistant to the mechanical stress induced by the accumulation in the head space of volatile substances produced during the cooking. Polymeric materials are good candidates for microwaveable packaging thanks to their transparency to MW. In the last years a great interest is devoted to developing innovative solution based on the use of additives or systems that act as susceptors or heating enhancers for improving the characteristics of polymers in cooking/heating in MW ovens. The present work was focused on the production and characterization of nanocomposite copolyester based films suitable for microwaveable food packaging applications. The matrices selected consist in two PET copolymers modified with carbon black (ULTRA STD) and with titanium oxide (ULTRA NA). Nanocomposite co-extruded multilayer films were produced using different percentages (0%, 2% and 4%wt/wt) of Cloisite 20A (C20A). Films were analyzed for evaluating the effect of nanofiller on the morphology and barrier properties. Moreover, to verify the effectiveness of the designed systems in reducing the cooking times of meat products, MW heating tests were carried out on pork meat hamburgers in MW oven at varying supplied powers. The cooking tests have pointed out that the selected matrices are efficient in reducing cooking times and that even low concentration of C20A acts as heating enhancers of PET.

Enhanced mechanical, thermal and antimicrobial properties of poly(vinyl alcohol)/graphene oxide/starch/silver nanocomposites films.

PubMed

Usman, Adil; Hussain, Zakir; Riaz, Asim; Khan, Ahmad Nawaz

2016-11-20

In the present work, synthesis of poly(vinyl alcohol)/graphene oxide/starch/silver (PVA/GO/Starch/Ag) nanocomposites films is reported. Such films have been characterized and investigated for their mechanical, thermal and antimicrobial properties. The exfoliation of GO in the PVA matrix occurs owing to the non-covalent interactions of the polymer chains of PVA and hydrophilic surface of the GO layers. Presence of GO in PVA and PVA/starch blends were found to enhance the tensile strength of the nanocomposites system. It was found that the thermal stability of PVA as well as PVA/starch blend systems increased by the incorporation of GO where strong physical bonding between GO layers and PVA/starch blends is assumed to cause thermal barrier effects. Antimicrobial properties of the prepared films were investigated against Escherichia coli and Staphylococcus aureus. Our results show enhanced antimicrobial properties of the prepared films where PVA-GO, PVA-Ag, PVA-GO-Ag and PVA-GO-Ag-Starch showed antimicrobial activity in ascending order. Copyright © 2016 Elsevier Ltd. All rights reserved.

High barrier multilayer packaging by the coextrusion method: The effect of nanocomposites and biodegradable polymers on flexible film properties

NASA Astrophysics Data System (ADS)

Thellen, Christopher T.

The objective of this research was to investigate the use of nanocomposite and multilayer co-extrusion technologies for the development of high gas barrier packaging that is more environmentally friendly than many current packaging system. Co-extruded bio-based and biodegradable polymers that could be composted in a municipal landfill were one direction that this research was aimed. Down-gauging of high performance barrier films using nanocomposite technology and co-extrusion was also investigated in order to reduce the amount of solid waste being generated by the packaging. Although the research is focused on military ration packaging, the technologies could easily be introduced into the commercial flexible packaging market. Multilayer packaging consisting of poly(m-xylylene adipamide) nanocomposite layers along with adhesive and tie layers was co-extruded using both laboratory and pilot-scale film extrusion equipment. Co-extrusion of biodegradable polyhydroxyalkanoates (PHA) along with polyvinyl alcohol (PVOH) and tie layers was also accomplished using similar co-extrusion technology. All multilayer films were characterized for gas barrier, mechanical, and thermal properties. The biodegradability of the PVOH and PHA materials in a marine environment was also investigated. The research has shown that co-extrusion of these materials is possible at a research and pilot level. The use of nanocomposite poly(m-xylylene adipamide) was effective in down-gauging the un-filled barrier film to thinner structures. Bio-based PHA/PVOH films required the use of a malefic anhydride grafted PHA tie layer to improve layer to layer adhesion in the structure to avoid delamination. The PHA polymer demonstrated a high rate of biodegradability/mineralization in the marine environment while the rate of biodegradation of the PVOH polymer was slower.

Thermoluminescence of the Films, Nanocomposites, and Solutions of the Silicon Organic Polymer Poly(di- n-hexyl silane)

NASA Astrophysics Data System (ADS)

Ostapenko, N. I.; Kerita, O. A.; Ostapenko, Yu. V.

2018-03-01

A comparative study of low-temperature thermoluminescence (5-120 K) of silicon organic polymer poly(di-n-hexyl silane) films, nanocomposites (when the polymer is introduced into nanopores of silica MCM-41 and SBA-15 with diameter of pores 2.8 and 10 nm) as well as solutions of polymer in tetrahydrofuran with different concentrations from 10-3 to 10-5 mol/L was carried out. It was shown that it is possible to control the number of charge carrier traps, as well as their energy distribution by changing the diameter of silica nanopores. It is established that maxima and FWHMs of the thermoluminescence curves of nanocomposites significantly depend on the pore diameter of the nanoporous silica. This result agrees with the data obtained in the investigation of polymer solutions. In the nanocomposite with a minimum pore diameter (2.8 nm), the number and depth of the traps as well as dispersion of their energy are significantly reduced compared to their values in the polymer film.

Study of the structure of 3D-ordered macroporous GaN-ZnS:Mn nanocomposite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurdyukov, D. A., E-mail: kurd@gvg.ioffe.ru; Shishkin, I. I.; Grudinkin, S. A.

A film-type 3D-ordered macroporous GaN-ZnS:Mn nanocomposite with the structure of an inverted opal is fabricated. Structural studies of the nanocomposite are performed, and it is shown that GaN and ZnS:Mn introduced into the pores of the silica opal are nanocrystallites misoriented with respect to each other. It is shown that the nanocomposite is a structurally perfect 3D photonic crystal. The efficiency of using a buffer of GaN crystallites to preclude interaction between the surface of the spherical a-SiO{sub 2} particles forming the opal matrix and chemically active substances introduced into the pores is demonstrated.

Laser Deposition of Polymer Nanocomposite Thin Films and Hard Materials and Their Optical Characterization

DTIC Science & Technology

2013-12-05

visible light on instruments such as microscope tips and micro- surgical tools. Hard carbon known as diamond-like carbon films produced by pulsed laser ...visible (610 nm) LED source and a supplemental infra-red 980-nm laser diode (for the studies of the upconversion fluorescence). The basic package...5/2013 Final Performance Report 15 Sep 2012- 14 Sep 2013 LASER DEPOSITION OF POLYMER NANOCOMPOSITE THIN FILMS AND HARD MATERIALS AND THEIR OPTICAL

Evolution and tailoring of plasmonic properties in Ag:ZrO2 nanocomposite films by swift heavy ion irradiation

NASA Astrophysics Data System (ADS)

Kumar, Manish; Kulriya, P. K.; Pivin, J. C.; Avasthi, D. K.

2011-02-01

Ag:ZrO2 nanocomposite films have been synthesized by a sol-gel dip coating process at room temperature, followed by irradiation using swift heavy ions. The effect of electronic energy loss and fluences on the evolution and consequently on the tailoring of plasmonic properties of films has been studied. The optical study exhibits that color of films converts from transparent in pristine form into shiny yellow when films are irradiated by 100 MeV Ag ions at a fluence of 3×1012 ions/cm2. However, irradiation by 120 MeV O ions up to the fluence of 1 × 1014 ions/cm2 does not induce any coloration in films. The coloration is attributed to the evolution of plasmonic feature resulting in a surface plasmon resonance (SPR) induced absorption peak in the visible region. Increase in fluence from 3 × 1012 to 6 × 1013 ions/cm2 of 100 MeV Ag ions induces a redshift in SPR induced peak position from 434 to 487 nm. Microstructural studies confirms the conversion of Ag2O3 (in pristine films) into cubic phase of metallic Ag and the increase of average size of particles with the increasing fluence up to 6 × 1013 ions/cm2. Further increase in fluence leads to the dissolution of Ag atoms in the ZrO2 matrix.

Development of regenerated cellulose/halloysite nanotube bionanocomposite films with ionic liquid.

PubMed

Soheilmoghaddam, Mohammad; Wahit, Mat Uzir

2013-07-01

In this study, novel nanocomposite films based on regenerated cellulose/halloysite nanotube (RC/HNT) have been prepared using an environmentally friendly ionic liquid 1-butyl-3-methylimidazolium chloride (BMIMCl) through a simple green method. The structural, morphological, thermal and mechanical properties of the RC/HNT nanocomposites were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), thermal analysis and tensile strength measurements. The results obtained revealed interactions between the halloysite nanotubes and regenerated cellulose matrix. The thermal stability and mechanical properties of the nanocomposite films, compared with pure regenerated cellulose film, were significantly improved When the halloysite nanotube (HNT) loading was only 2 wt.%, the 20% weight loss temperature (T20) increased 20°C. The Young's modulus increased from 1.8 to 4.1 GPa, while tensile strength increased from 35.30 to 60.50 MPa when 8 wt.% halloysite nanotube (HNT) was incorporated, interestingly without loss of ductility. The nanocomposite films exhibited improved oxygen barrier properties and water absorption resistance compared to regenerated cellulose. Copyright © 2013 Elsevier B.V. All rights reserved.

Optical characterization of the new nanocomposite SBMA/Eu(TTA)3(Ph3PO)2

NASA Astrophysics Data System (ADS)

Bordian, Olga; Verlan, Victor; Culeac, Ion; Iovu, Mihail; Zubareva, Vera; Nistor, Iurie

2015-02-01

We describe a new nanocomposite material based on the copolymer of styrene with butyl methacrylate (1:1) (SBMA), and coordinating compound of Europium(III) Eu(TTA)3(Ph3PO)2. The SBMA/Eu(TTA)3(Ph3PO)2 nanocomposite was prepared by a simple technology and can be obtained in the form of optical fibers, thin films and planar waveguides on various substrates with large area. Experimental results on optical transmission and photoluminescence spectroscopy are presented. The nanocomposite exhibits a strong photoluminescence emission in the range 560-750 nm, with the main photoluminescence band at 613 nm.

Dielectric characteristics of CaCu3Ti4O12/P(VDF-TrFE) nanocomposites

NASA Astrophysics Data System (ADS)

Zhang, Lin; Shan, Xiaobing; Wu, Peixuan; Cheng, Z.-Y.

2012-06-01

Composite thin film is highly desirable for the dielectric applications. In order to develop composite thin film, a nanocomposite, in which nanosized CaCu3Ti4O12 (CCTO) particles are used as filler and P(VDF-TrFE) 55/45 mol% copolymer is used as polymer matrix, is investigated. The contents of CCTO in the nanocomposites range from 0% to 50 vol%. The dielectric property of these nanocomposites was characterized at frequencies ranging from 100 Hz to 1 MHz and at temperatures ranging from 200 K to 370 K. A dielectric constant of 62 with a loss of 0.05 was obtained in nanocomposite with 50 vol% CCTO at room temperature at 1 kHz. At the phase transition temperature (˜340 K) of the copolymer, a dielectric constant of 150 with a loss less than 0.1 was obtained in this nanocomposite. It is found that the dielectric loss of the nanocomposites is dominated by the polymer which has a relaxation process. Comparing to composites made using microsized CCTO, the nanocomposites exhibit a much lower dielectric loss and a lower dielectric constant. This indicates that the nanosized CCTO particles have a lower dielectric constant than the microsized CCTO particles.

Innovative Linear Low Density Polyethylene Nanocomposite Films Reinforced with Organophilic Layered Double Hydroxides: Fabrication, Morphology and Enhanced Multifunctional Properties.

PubMed

Xie, Jiazhuo; Wang, Haijun; Wang, Zhou; Zhao, Qinghua; Yang, Yuechao; Waterhouse, Geoffrey I N; Hao, Lei; Xiao, Zihao; Xu, Jing

2018-01-08

Herein, we reported the successful development of novel nanocomposite films based on linear low density polyethylene (LLDPE) with enhanced anti-drop, optical, mechanical, thermal and water vapor barrier properties by introducing organophilic layered double hydroxides (OLDHs) nanosheets. OLDHs loadings were varied from 0-6 wt.%. Structural analyses using the Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) indicated that the OLDHs nanosheets were homogeneously dispersed with an ordered alignment in the LLDPE matrix. The LLDPE film containing 2 wt.% OLDHs (denoted as OLDHs-2) showed the optimal mechanical, thermal and water vapor barrier properties, whilst the anti-drop and optical performance of the films improved with increasing OLDHs content. The enhanced antidrop properties of the composite films relative to pristine LLDPE can be expected to effectively reduce agricultural losses to disease when the films are applied as agricultural films, whilst the superior light transmittance and water-retaining properties of the composite films will boost agricultural production. Results presented suggest that multifunctional LLDPE/OLDHs nanocomposites show great promise as low cost agricultural plastic films.

Dielectric behaviour of montmorillonite/cyanoethylated cellulose nanocomposites.

PubMed

Madusanka, Nadeesh; Shivareddy, Sai G; Eddleston, Mark D; Hiralal, Pritesh; Oliver, Rachel A; Amaratunga, Gehan A J

2017-09-15

A dielectric nanocomposite based oncyanoethylatedcellulose (CRS) and MMT nanoclay was successfully prepared with different weight percentages (5%, 10% and 15%) of MMT. MMT nanoplatets obtained via sonication of MMT nanoclay in acetone for a prolonged period was used in the preparation of CRS-MMT nanocomposites. CRS-MMT thin films on SiO 2 /Si wafers are used to form metal-insulator-metal (MIM) type capacitors. At 1kHz CRS-MMT nanocomposites exhibited high dielectric constants (ε r ) of 71, 55 and 42 with low leakage current densities (10 -6 -10 -7 A/cm 2 ) for nanocomposites with 5%, 10% and 15% weight of MMT respectively, higher than values of pure CRS (21), Na-MMT(10). Reduction of ε r with higher MMT loading can be attributed to a network formation as evidenced via strong bonding interactions between CRS and MMT leading to a lower molecular mobility. The leakage is studied using conductive atomic force microscopy (C-AFM) indicates that leakage pathways are associated with MMT nanoplatelets embedded in the CRS polymer matrix. Copyright © 2017. Published by Elsevier Ltd.

Nanocrystal-polymer nanocomposite electrochromic device

DOEpatents

Milliron, Delia; Runnerstrom, Evan; Helms, Brett; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2015-12-08

Described is an electrochromic nanocomposite film comprising a solid matrix of an oxide based material, the solid matrix comprising a plurality of transparent conducting oxide (TCO) nanostructures dispersed in the solid matrix and a lithium salt dispersed in the solid matrix. Also described is a near infrared nanostructured electrochromic device having a functional layer comprising the electrochromic nanocomposite film.

Smart window coating based on F-TiO2-KxWO3 nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance

PubMed Central

Liu, Tongyao; Liu, Bin; Wang, Jing; Yang, Linfen; Ma, Xinlong; Li, Hao; Zhang, Yihong; Yin, Shu; Sato, Tsugio; Sekino, Tohru; Wang, Yuhua

2016-01-01

A series of smart window coated multifunctional NIR shielding-photocatalytic films were fabricated successfully through KxWO3 and F-TiO2 in a low-cost and environmentally friendly process. Based on the synergistic effect of KxWO3 and F-TiO2, the optimal proportion of KxWO3 to F-TiO2 was investigated and the FT/2KWO nanocomposite film exhibited strong near-infrared, ultraviolet light shielding ability, good visible light transmittance, high photocatalytic activity and excellent hydrophilic capacity. This film exhibited better thermal insulation capacity than ITO and higher photocatalytic activity than P25. Meanwhile, the excellent stability of this film was examined by the cycle photocatalytic degradation and thermal insulation experiments. Overall, this work is expected to provide a possibility in integrating KxWO3 with F-TiO2, so as to obtain a multifunctional NIR shielding-photocatalytic nanocomposite film in helping solve the energy crisis and deteriorating environmental issues. PMID:27265778

Plasma - enhanced dispersion of metal and ceramic nanoparticles in polymer nanocomposite films

NASA Astrophysics Data System (ADS)

Maguire, Paul; Liu, Yazi; Askari, Sadegh; Patel, Jenish; Macia-Montero, Manuel; Mitra, Somak; Zhang, Richao; Sun, Dan; Mariotti, Davide

2015-09-01

In this work we demonstrate a facile method to synthesize a nanoparticle/PEDOT:PSS hybrid nanocomposite material in aqueous solution through atmospheric pressure direct current (DC) plasma processing at room temperature. Both metal (Au) and ceramic (TiO2) nanoparticle composite films have been fabricated. Nanoparticle dispersion is enhanced considerable and remains stable. TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased nanoparticle/PEDOT:PSS nanocomposite electrical conductivity has been observed. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma processed Au or TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are thought to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer bonding. This is expected to have a significant benefit in materials processing with inorganic nanoparticles for applications in energy storage, photocatalysis and biomedical sensors. Engineering and Physical Sciences Research Council (EPSRC: EP/K006088/1, EP/K006142, Nos. EP/K022237/1).

BaTiO3/PVDF Nanocomposite Film with High Energy Storage Density

NASA Astrophysics Data System (ADS)

Wang, Xiaohui

2016-03-01

A gradated multilayer BaTiO3/poly(vinylidenefluoride) thin film structure is presented to achieve both a higher breakdown strength and a superior energy-storage capability. Key to the process is the sequential deposition of uniform dispersions of the single component source, which generate a blended PVDF-BTO-PVDF structure prior to full evaporation of solvent, and thermal treatment of the dielectric. The result is like sandwich structure with partial 0-3 character. The central layer designed to provide the high electric displacement, is composed of high volume fraction 6-10 nm BTO nanocrystals produced by a TEG-sol method. The outer layers of the structure are predominantly PVDF, with a significantly lower volume fraction of BTO, taking advantage of the higher dielectric strength for pure PVDF at the electrode-nanocomposite interface. The film is mechanically flexible, and can be removed from the substrate, with total thicknesses in the range 1.2 - 1.5 μm. Parallel plate capacitance devices improved dielectric performances, compared to reported values for BTO-PVDF 0-3 nanocomposites, with a maximal discharged energy density of 19.4J/cm3 and dielectric breakdown strengths of up to 495 kV/mm.

Epitaxial YBa2Cu3O7-x nanocomposite films and coated conductors from BaMO3 (M = Zr, Hf) colloidal solutions

NASA Astrophysics Data System (ADS)

Obradors, X.; Puig, T.; Li, Z.; Pop, C.; Mundet, B.; Chamorro, N.; Vallés, F.; Coll, M.; Ricart, S.; Vallejo, B.; Pino, F.; Palau, A.; Gázquez, J.; Ros, J.; Usoskin, A.

2018-04-01

Superconducting nanocomposites are the best material choice to address the performance required in power applications and magnets working under high magnetic fields. However, it is still challenging to sort out how to achieve the highest superconducting performance using attractive and competitive manufacturing processes. Colloidal solutions have been recently developed as a novel and very promising low cost route to manufacture nanocomposite coated conductors. Well dispersed and stabilized preformance nanoparticle solutions are first prepared with high concentrations and then mixed with the YBa2Cu3O7 metalorganic precursor solutions to generate colloidal solutions to grow the nanocomposite films. Here we demonstrate, for the first time, that non-reactive BaZrO3 and BaHfO3 perovskite preformed nanoparticles are suitable for growing high quality thin and thick films, and coated conductors with a homogeneous distribution and controlled particle size using this fabrication method. Additionally, we extend the nanoparticle content of the nanocomposites up to 20%-25% mol without any degradation of the superconducting properties. Thick nanocomposite films, up to 0.8 μm, have been prepared with a single deposition of low-fluorine solutions using an ink jet printing dispenser and we demonstrate that the preformed nanoparticles display only a very limited coarsening during the growth process and so high critical current densities J c (B) under high magnetic fields. These films show the highest critical currents achieved so far based on the colloidal solution approach, I c = 220 A/cm-w at 77 K and self-field, and they still have a high potential for further increase in the film thickness. Finally, we also show that nanocomposite YBa2Cu3O7-BaZrO3 coated conductors based on an alternating beam assisted deposited YSZ buffer layer on stainless steel metallic substrates can be developed based on these novel colloidal solutions. Non-reactive preformed oxide perovskite

Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

PubMed

Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

2013-06-26

The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

Fabrication and physical properties of transparent poly (methyl-methacrylate)-layered silicate nanocomposites

NASA Astrophysics Data System (ADS)

Vasiliu, Elena

Transparent polymer nanocomposites have promising potential for protective coating applications with improved surface resistance, higher temperature performance and low gas permeability for containers and films. Extremely thin protective layers are required for improved performance of various electronic devices in aviation, aerospace and medical equipment as well as for lenses and fiber optics in optical communications. This research study developed a method for fabricating optically transparent nanocomposites of poly(methyl-methacrylate)(PMMA) and a commercial organically-modified layered silicate CloisiteRTM 6A (C6A). The nanocomposites were produced by dispersing C6A and PMMA separately in a common solvent xylene followed by mixing the two solutions by mechanical stirring and/or ultrasonic agitation and then removing the solvent by evaporation. Processing conditions such as the mixing methods and times and the rates of solvent removal were investigated in order to achieve a high degree of dispersion and exfoliation of C6A in the polymer matrix and produce a nanocomposite material with high optical transparency. Small-angle x-ray scattering (SAXS) was used to monitor the morphology of the C6A after each processing step. Thin films of PMMA/C6A nanocomposites were produced by casting and spraying. SAXS results suggest that C6A was partially exfoliated in the composite material with an average of 2 to 3 platelets per crystallite. Transmission electron microscopy (TEM) confirmed the existence of both exfoliated and intercalated C6A in PMMA. One mm thick discs were obtained by molding the sprayed films. The optical transmission of the nanocomposite films and discs was measured with an UV/VIS spectrometer. The spectroscopic results served to identify the best process for producing PMMA-C6A films of high optical transparency. Even the nanocomposite films containing up to 20 wt.% C6A prepared by this process exhibited optical transmittance in the range of 80 to 90

Active nanocomposite films based on soy proteins-montmorillonite- clove essential oil for the preservation of refrigerated bluefin tuna (Thunnus thynnus) fillets.

PubMed

Echeverría, Ignacio; López-Caballero, María Elvira; Gómez-Guillén, María Carmen; Mauri, Adriana Noemi; Montero, María Pilar

2018-02-02

This manuscript evaluates the potential application of active nanocomposite films based on soy protein isolate (SPI)-montmorillonite (MMT)-clove essential oil (CEO) to the preservation of muscle fillets of bluefin tuna (Thunnus thynnus) during refrigerated storage, and furthermore analyzes whether the clay diffuses from the package to food. SPI films with: CEO (SPI-CEO), MMT (SPI-MMT), or both CEO and MMT (SPI-MMT-CEO), were prepared and used to cover tuna fillets during 17days of storage at 2°C. Polyethylene films were also used as control. Protein films nanoreinforced with 10g MMT/100g SPI and activated with CEO were able to decrease microbial growth (evaluated by TVBN and microorganism counts) and lipid autooxidation (evaluated according to the TBA index, FTIR and color parameters) of tuna fillets during the storage period studied. The presence of clay seemed to favor the release of the active principles of clove oil by prolonging its antimicrobial (especially effective to inhibit Pseudomonas spp.) and antioxidant activity over time without observing the diffusion of the clay's own metals (Si and Al) from the nanocomposite materials to the muscle of fish. These results are encouraging for the use of nanocomposite films in food packaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced energy density and thermal conductivity in poly(fluorovinylidene-co-hexafluoropropylene) nanocomposites incorporated with boron nitride nanosheets exfoliated under assistance of hyperbranched polyethylene.

PubMed

Ye, Huijian; Lu, Tiemei; Xu, Chunfeng; Zhong, Mingqiang; Xu, Lixin

2018-03-02

Polymer dielectric film with a large dielectric constant, high energy density and enhanced thermal conductivity are of significance for the development of impulse capacitors. However, the fabrication of polymer dielectrics combining high energy density and thermal conductivity is still a challenge at the moment. Here we demonstrate the facile exfoliation of hexagonal boron nitride nanosheets (BNNSs) in common organic solvents under sonication with the assistance of hyperbranched polyethylene (HBPE). The noncovalent CH-π interactions between the nanosheets and HBPE ensure the dispersion of BNNSs in organic solvents with high concentrations, because of the highly branched chain structure of HBPE. Subsequently, the resultant BNNSs with a few defects are distributed uniformly in the poly(fluorovinylidene-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films prepared via simple solution casting. The BNNS/P(VDF-HFP) nanocomposite exhibits outstanding dielectric properties, high energy density and high thermal conductivity. The dielectric constant of the 0.5 wt% nanocomposite film is 35.5 at 100 Hz with an energy density of 5.6 J cm -3 at 325 MV m -1 and a high charge-discharge efficiency of 79% due to the depression of the charge injection and chemical species ionization in a high field. Moreover, a thermal conductivity of 1.0 wt% nanocomposite film reaches 0.91 W·m -1  · K -1 , which is 3.13 times higher than that of the fluoropolymer matrix. With dipole accumulation and orientation in the interfacial zone, lightweight, flexible BNNS/P(VDF-HFP) nanocomposite films with high charge-discharge performance and thermal conductivity, exhibit promising applications in relatively high-temperature electronics and energy storage devices.

Enhanced energy density and thermal conductivity in poly(fluorovinylidene-co-hexafluoropropylene) nanocomposites incorporated with boron nitride nanosheets exfoliated under assistance of hyperbranched polyethylene

NASA Astrophysics Data System (ADS)

Ye, Huijian; Lu, Tiemei; Xu, Chunfeng; Zhong, Mingqiang; Xu, Lixin

2018-03-01

Polymer dielectric film with a large dielectric constant, high energy density and enhanced thermal conductivity are of significance for the development of impulse capacitors. However, the fabrication of polymer dielectrics combining high energy density and thermal conductivity is still a challenge at the moment. Here we demonstrate the facile exfoliation of hexagonal boron nitride nanosheets (BNNSs) in common organic solvents under sonication with the assistance of hyperbranched polyethylene (HBPE). The noncovalent CH-π interactions between the nanosheets and HBPE ensure the dispersion of BNNSs in organic solvents with high concentrations, because of the highly branched chain structure of HBPE. Subsequently, the resultant BNNSs with a few defects are distributed uniformly in the poly(fluorovinylidene-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films prepared via simple solution casting. The BNNS/P(VDF-HFP) nanocomposite exhibits outstanding dielectric properties, high energy density and high thermal conductivity. The dielectric constant of the 0.5 wt% nanocomposite film is 35.5 at 100 Hz with an energy density of 5.6 J cm-3 at 325 MV m-1 and a high charge-discharge efficiency of 79% due to the depression of the charge injection and chemical species ionization in a high field. Moreover, a thermal conductivity of 1.0 wt% nanocomposite film reaches 0.91 W·m-1 · K-1, which is 3.13 times higher than that of the fluoropolymer matrix. With dipole accumulation and orientation in the interfacial zone, lightweight, flexible BNNS/P(VDF-HFP) nanocomposite films with high charge-discharge performance and thermal conductivity, exhibit promising applications in relatively high-temperature electronics and energy storage devices.

Chitosan nanocomposite films based on Ag-NP and Au-NP biosynthesis by Bacillus Subtilis as packaging materials.

PubMed

Youssef, Ahmed M; Abdel-Aziz, Mohamed S; El-Sayed, Samah M

2014-08-01

Chitosan-silver (CS-Ag) and Chitosan-gold (CS-Au) nanocomposites films were synthesized by a simple chemical method. A local bacterial isolate identified as Bacillus subtilis ss subtilis was found to be capable to synthesize both silver nanoparticles (Ag-NP) and gold nanoparticles (Au-NP) from silver nitrate (AgNO3) and chloroauric acid (AuCl(4-)) solutions, respectively. The biosynthesis of both Ag-NP and Au-NP characterize using UV/vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and then added to chitosan by different ratios (0.5, 1 and 2%). The prepared chitosan nanocomposites films were characterize using UV, XRD, SEM and TEM. Moreover, the antibacterial activity of the prepared films was evaluated against gram positive (Staphylococcus aureus) and gram negative bacteria (Pseudomonas aerugenosa), fungi (Aspergillus niger) and yeast (Candida albicans). Therefore, these materials can be potential used as antimicrobial agents in packaging applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of nanoclay type on the physical and antimicrobial properties of PVOH-based nanocomposite films

USDA-ARS?s Scientific Manuscript database

Polyvinyl alcohols-based nanocomposite films were fabricated with four types of montmorillonite (MMT) nanoclay, including 18-amino stearic acid (I.24TL), methyl, bis hydroxyethyl, octadecyl ammonium (I.34TCN), di-methyl, di-hydrogenated tallow ammonium/siloxane (I.44PSS) organically modified MMT, an...

AC/DC electrical conduction and dielectric properties of PMMA/PVAc/C60 down-shifting nanocomposite films

NASA Astrophysics Data System (ADS)

El-Bashir, S. M.; Alwadai, N. M.; AlZayed, N.

2018-02-01

Polymer nanocomposite films were prepared by doping fullerene C60 in polymer blend composed of polymethacrylate/polyvinyl acetate blends (PMMA/PVAc) using solution cast technique. The films were characterized by differential scanning calorimeter (DSC), Transmission electron microscope (TEM), DC/AC electrical conductivity and dielectric measurements in the frequency range (100 Hz- 1 MHz). The glass transition temperature, Tg, was increased by increasing the concentration of fullerene C60; this property reflects the increase of thermal stability by increasing the nanofiller content. The DC and AC electrical conductivities were enhanced by increasing C60 concentration due to the electron hopping or tunneling between filled and empty localized states above Tg. The relaxation time was determined from the αβ -relaxations and found to be attenuated by increasing the temperature as a typical behavior of amorphous polymers. The calculated values of thermodynamic parameters revealed the increase of molecular stability by increasing the doping concentration; this feature supports the application of PMMA/PVAc/C60 nanocomposite films in a wide scale of solar energy conversion applications such as luminescent down-shifting (LDS) coatings for photovoltaic cells.

New strain states and radical property tuning of metal oxides using a nanocomposite thin film approach

DOE PAGES

MacManus-Driscoll, Judith; Suwardi, Ady; Kursumovic, Ahmed; ...

2015-05-05

Auxetic-like strain states were generated in self-assembled nanocomposite thin films of (Ba 0.6Sr 0.4TiO 3) 1–x – (Sm 2O 3) x(BSTO – SmO). A switch from auxetic-like to elastic-like strain behavior was observed for x > 0.50, when the SmO switched from being nanopillars in the BSTO matrix to being the matrix with BSTO nanopillars embedded in it. A simple model was adopted to explain how in-plane strain varies with x. At high x (0.75), strongly enhanced ferroelectric properties were obtained compared to pure BSTO films. Furthermore, the nanocomposite method represents a powerful new way to tune the properties ofmore » a wide range of strongly correlated metal oxides whose properties are very sensitive to strain.« less

Fabrication and performance of polymer-nanocomposite anti-reflective thin films deposited by RIR-MAPLE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singaravelu, S.; Mayo, D. C.; Park, H-. K.

2014-07-01

Design of polymer anti-reflective (AR) optical coatings for plastic substrates is challenging because polymers exhibit a relatively narrow range of refractive indices. Here, we report synthesis of a four-layer AR stack using hybrid polymer: nanoparticle materials deposited by resonant infrared matrix-assisted pulsed laser evaporation. An Er: YAG laser ablated frozen solutions of a high-index composite containing TiO2 nanoparticles and poly(methylmethacrylate) (PMMA), alternating with a layer of PMMA. The optimized AR coatings, with thicknesses calculated using commercial software, yielded a coating for polycarbonate with transmission over 97 %, scattering <3 %, and a reflection coefficient below 0.5 % across the visiblemore » range, with a much smaller number of layers than would be predicted by a standard thin film calculation. The TiO2 nanoparticles contribute more to the enhanced refractive index of the high-index layers than can be accounted for by an effective medium model of the nanocomposite.« less

Electric Transport Phenomena of Nanocomposite Organic Polymer Thin Films

NASA Astrophysics Data System (ADS)

Jira, Nicholas C.; Sabirianov, Ildar; Ilie, Carolina C.

We discuss herein the nanocomposite organic thin film diodes for the use of plasmonic solar cells. This experimental work follows the theoretical calculations done for plasmonic solar cells using the MNPBEM toolbox for MatLab. These calculations include dispersion curves and amount of light scattering cross sections for different metallic nanoparticles. This study gives us clear ideas on what to expect from different metals, allowing us to make the best choice on what to use to obtain the best results. One specific technique for light trapping in thin films solar cells utilizes metal nanoparticles on the surface of the semiconductor. The characteristics of the metal, semiconductor interface allows for light to be guided in between them causing it to be scattered, allowing for more chances of absorption. The samples were fabricated using organic thin films made from polymers and metallic nanoparticles, more specifically Poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer and silver or gold nanoparticles. The two fabrication methods applied include spin coating and Langmuir-Blodgett technique. The transport properties are obtained by analyzing the I-V curves. We will also discuss the resistance, resistivity, conductance, density of charge carriers. SUNY Oswego SCAC Grant.

Manipulation of ZnO composition affecting electrical properties of MEH-PPV: ZnO nanocomposite thin film via spin coating for OLEDs application

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. Morphology, optical and electrical of nanocomposites thin films based on poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanotetrapods with various ZnO composition (0 wt% to 0.4 wt%) have been investigated. The MEH-PPV: ZnO nanocomposite thin film was deposited using spin-coating method. Surface morphology was characterized using field emission scanning electron microscopy and shows the uniform dispersion of MEH-PPV and ZnO phases for sample deposited at 0.2 wt%. The photoluminescence (PL) spectra shows the visible emission intensities increased when the ZnO composition increased. The current-voltage (I-V) measurement shows the highest conductivity of nanocomposite thin film deposited at 0.2 wt% of ZnO is 7.40 × 10-1 S. cm-1. This study will provide better performance and suitable for optoelectronic device especially OLEDs application.

Au-C allotrope nano-composite films at extreme conditions generated by intense ultra-short laser

NASA Astrophysics Data System (ADS)

Khan, Saif A.; Saravanan, K.; Tayyab, M.; Bagchi, S.; Avasthi, D. K.

2016-07-01

Structural evolution of gold-carbon allotrope nano-composite films under relativistically intense, ultra-short laser pulse irradiation is studied in this work. Au-C nano-composite films, having 4 and 10 at.% of Au, were deposited by co-sputtering technique on silicon substrates. Au-C60 NC films with 2.5 at.% Au were deposited on 12 μm thick Al foil using co-evaporation technique. These samples were radiated with single pulse from 45 fs, 10 TW Ti:Sapphire Laser at RRCAT at an intensity of 3 × 1018 W cm-2. The morphological and compositional changes were investigated using scanning electron microscopy (SEM) and Rutherford back-scattering spectrometry (RBS) techniques. Laser pulse created three morphologically distinct zones around the point of impact on samples with silicon substrates. The gold content in 600 μm circular region around a point of impact is found to reduce by a factor of five. Annular rings of ∼70 nm in diameter were observed in case of Au-C NC film after irradiation. Laser pulse created a hole of about 400 μm in the sample with Al foil as substrate and wavy structures of 6 μm wavelength are found to be created around this hole. The study shows radial variation in nano-structure formation with varying local intensity of laser pulse.

Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

NASA Astrophysics Data System (ADS)

Sreeram, Arvind

(IL) could be obtained in a single step reaction. The incorporation of IL in the film, not only greatly improved its mechanical properties, by acting as a plasticizer, but also imparted a dual mechanism of charge transport. The segments of conjugated double bonds imparted electronic conductivity to the films, and the IL resulted in ionic conductivity. The presence of both electronic and ionic conduction pathways in the films was confirmed by electrochemical impedance spectroscopy (EIS). These IL-imbibed conjugated polymer films are promising as materials for electrochemical energy conversion and storage. In the third part of this work, conjugated polymer films containing multiwalled carbon nanotubes (MWNT) and graphene nanoplatelets (GNP) were synthesized and characterized. PPV--MWNT nanocomposite films and PA--GNP nanocomposite films were characterized using a variety of analytical techniques including transmission electron microscopy, quasistatic and dynamic nanoindentaiton, electrochemical impedance spectroscopy, and cyclic voltammetry. Potential application of these films is in electrochemical supercapacitors.

Stress transfer and matrix-cohesive fracture mechanism in microfibrillated cellulose-gelatin nanocomposite films.

PubMed

Quero, Franck; Padilla, Cristina; Campos, Vanessa; Luengo, Jorge; Caballero, Leonardo; Melo, Francisco; Li, Qiang; Eichhorn, Stephen J; Enrione, Javier

2018-09-01

Microfibrillated cellulose (MFC) obtained from eucalyptus was embedded in gelatin from two sources; namely bovine and salmon gelatin. Raman spectroscopy revealed that stress is transferred more efficiently from bovine gelatin to the MFC when compared to salmon gelatin. Young's modulus, tensile strength, strain at failure and work of fracture of the nanocomposite films were improved by ∼67, 131, 43 y 243% respectively when using salmon gelatin as matrix material instead of bovine gelatin. Imaging of the tensile fracture surface of the MFC-gelatin nanocomposites revealed that crack formation occurs predominantly within bovine and salmon gelatin matrices rather than within the MFC or at the MFC/gelatin interface. This suggests that the mechanical failure mechanism in these nanocomposite materials is predominantly governed by a matrix-cohesive fracture mechanism. Both strength and flexibility are desirable properties for composite coatings made from gelatin-based materials, and so the findings of this study could assist in their utilization in the food and pharmaceutical industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of Content of Al2O3 on Structure and Properties of Nanocomposite Nb-B-Al-O films

NASA Astrophysics Data System (ADS)

Liu, Na; Dong, Lei; Dong, Lei; Yu, Jiangang; Pan, Yupeng; Wan, Rongxin; Gu, Hanqing; Li, Dejun

2015-11-01

Nb-B-Al-O nanocomposite films with different power of Al2O3 were successfully deposited on the Si substrate via multi-target magnetron co-sputtering method. The influences of Al2O3's content on structure and properties of obtained nanocomposite films through controlling Al2O3's power were investigated. Increasing the power of Al2O3 can influence the bombarding energy and cause the momentum transfer of NbB2. This can lead to the decreasing content of Al2O3. Furthermore, the whole films showed monocrystalline NbB2's (100) phase, and Al2O3 shaded from amorphous to weak cubic-crystalline when decreasing content of Al2O3. This structure and content changes were proof by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). When NbB2 grains were far from each other in lower power of Al2O3, the whole films showed a typical nanocomposite microstructure with crystalline NbB2 grains embedded in a matrix of an amorphous Al2O3 phase. Continuing increasing the power of Al2O3, the less content of Al2O3 tended to cause crystalline of cubic-Al2O3 between the close distances of different crystalline NbB2 grains. The appearance of cubic-crystallization Al2O3 can help to raise the nanocomposite films' mechanical properties to some extent. The maximum hardness and elastic modulus were up to 21.60 and 332.78 GPa, which were higher than the NbB2 and amorphous Al2O3 monolithic films. Furthermore, this structure change made the chemistry bond of O atom change from the existence of O-Nb, O-B, and O-Al bonds to single O-Al bond and increased the specific value of Al and O. It also influenced the hardness in higher temperature, which made the hardness variation of different Al2O3 content reduced. These results revealed that it can enhance the films' oxidation resistance properties and keep the mechanical properties at high temperature. The study highlighted the importance of controlling the Al2O3's content to prepare

Elastic properties of nc-TiN /a-Si3N4 and nc-TiN /a-BN nanocomposite films by surface Brillouin scattering

NASA Astrophysics Data System (ADS)

Manghnani, Murli H.; Tkachev, Sergey N.; Zinin, Pavel V.; Glorieoux, Christ; Karvankova, Pavla; Veprek, Stan

2005-03-01

The hardness of nanocomposite (nc) films developed recently appears to reach the hardness of diamond. High hardness is commonly attributed to the granular structure of nanocomposites (Hall-Petch effect) [E. O. Hall, Proc. Phys. Soc. Lond. B 64, 747 (1951); N. J. Petch, J. Iron Steel Inst. 174, 25 (1953)]. However, grain size in nanocomposites is generally small (5-15nm) and falls in the region where the Hall-Petch effect does not apply. The objective of the present study is to report the elastic properties of the superhard nanocomposites determined by means of surface Brillouin scattering (SBS), and to compare the results with those obtained by nanoindentation. Two types of nanocomposite films were studied: nc-TiN /a-Si3N4 and nc-TiN /a-BN. The SBS measurements presented yield values of Young's modulus significantly larger than those obtained from the slope of unloading indentation curve. This discrepancy is attributed to the lack of the validity of the assumptions behind the Sneddon's derivation of the formula used for the calculation of the Young's modulus from the indentation data.

Device level optimization of poly(vinylidene fluoride-trifluoroethylene)–zinc oxide polymer nanocomposite thin films for ferroelectric applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

C K, Subash, E-mail: cksubash08@gmail.com; Valiyaneerilakkal, Uvais; Varghese, Soney

Polymer nanocomposite was prepared using poly(vinylidene fluoride-trifluoroethylene) and zinc oxide (ZnO) nanopowder, which are ferroelectric in nature. Nanocomposite was prepared in various concentrations(0.2, 0.4, 0.8, and 1 wt. %) using probe ultra-sonication, followed by spin coating and annealing at 120 °C for 2 h to improve the formation of β-phase. Metal-ferroelectric-metal capacitor was fabricated using this optimized thin film as a ferroelectric layer. Device level optimization was carried out by polarization-electric field (P-E) hysteresis studies of this film, which shows polarization enhancement of composite. Various characterization techniques like atomic force microscopy, Fourier transform infra-red spectroscopy (FT-IR), Differential scanning calorimetry, and X-ray diffractionmore » were used to study the β-phase formation of nancomposite. The capacitance–voltage (C-V) and current-voltage (I-V) characteristics were studied through varying frequency and temperature. C-V measurements show an increase of 79% in the capacitance of polymer nanocomposite, which can be used for the fabrication of ferroelectric devices.« less

Poly(vinylidene fluoride) Flexible Nanocomposite Films with Dopamine-Coated Giant Dielectric Ceramic Nanopowders, Ba(Fe0.5Ta0.5)O3, for High Energy-Storage Density at Low Electric Field.

PubMed

Wang, Zhuo; Wang, Tian; Wang, Chun; Xiao, Yujia; Jing, Panpan; Cui, Yongfei; Pu, Yongping

2017-08-30

Ba(Fe 0.5 Ta 0.5 )O 3 /poly(vinylidene fluoride) (BFT/PVDF) flexible nanocomposite films are fabricated by tape casting using dopamine (DA)-modified BFT nanopowders and PVDF as a matrix polymer. After a surface modification of installing a DA layer with a thickness of 5 nm, the interfacial couple interaction between BFT and PVDF is enhanced, resulting in less hole defects at the interface. Then the dielectric constant (ε'), loss tangent (tan δ), and AC conductivity of nanocomposite films are reduced. Meanwhile, the value of the reduced dielectric constant (Δε') and the strength of interfacial polarization (k) are introduced to illustrate the effect of DA on the dielectric behavior of nanocomposite films. Δε' can be used to calculate the magnitude of interfacial polarization, and the strength of the dielectric constant contributed by the interface can be expressed as k. Most importantly, the energy-storage density and energy-storage efficiency of nanocomposite films with a small BFT@DA filler content of 1 vol % at a low electric field of 150 MV/m are enhanced by about 15% and 120%, respectively, after DA modification. The high energy-storage density of 1.81 J/cm 3 is obtained in the sample. This value is much larger than the reported polymer-based nanocomposite films. In addition, the outstanding cycle and bending stability of the nanocomposite films make it a promising candidate for future flexible portable energy devices.

Resistive switching effect of N-doped MoS2-PVP nanocomposites films for nonvolatile memory devices

NASA Astrophysics Data System (ADS)

Wu, Zijin; Wang, Tongtong; Sun, Changqi; Liu, Peitao; Xia, Baorui; Zhang, Jingyan; Liu, Yonggang; Gao, Daqiang

2017-12-01

Resistive memory technology is very promising in the field of semiconductor memory devices. According to Liu et al, MoS2-PVP nanocomposite can be used as an active layer material for resistive memory devices due to its bipolar resistive switching behavior. Recent studies have also indicated that the doping of N element can reduce the band gap of MoS2 nanosheets, which is conducive to improving the conductivity of the material. Therefore, in this paper, we prepared N-doped MoS2 nanosheets and then fabricated N-doped MoS2-PVP nanocomposite films by spin coating. Finally, the resistive memory [C. Tan et al., Chem. Soc. Rev. 44, 2615 (2015)], device with ITO/N-doped MoS2-PVP/Pt structure was fabricated. Study on the I-V characteristics shows that the device has excellent resistance switching effect. It is worth mentioning that our device possesses a threshold voltage of 0.75 V, which is much better than 3.5 V reported previously for the undoped counterparts. The above research shows that N-doped MoS2-PVP nanocomposite films can be used as the active layer of resistive switching memory devices, and will make the devices have better performance.

Synthesis and characterization of new nanocomposites films using alanine-Cu-functionalized graphene oxide as nanofiller and PVA as polymeric matrix for improving of their properties

NASA Astrophysics Data System (ADS)

Abdolmaleki, Amir; Mallakpour, Shadpour; Karshenas, Azam

2017-09-01

In the synthesis of polymer-graphene nanocomposites, for improving properties of nanocomposites, two factors dispersion and strong interfacial interactions between graphene and the polymer, are essential. In the present work, poly(vinyl alcohol) PVA/GO-Cu-alanine nanocomposite films were manufactured using concentrations 0, 1, 3 and 5 wt% of GO-Cu-alanine in water solution. For this purpose, L-alanine amino acid was located on the surface and edges of GO through copper(II) ion as a coordinating function. Then, flexible PVA/GO-Cu-alanine nanocomposite films were fabricated using GO-Cu-alanine as filler and PVA as matrix. Due to the existence of affective interaction between GO-Cu-alanine and PVA matrix, the acquired PVA/GO-Cu-alanine nanocomposites demonstrated great thermal and mechanical properties. Properties of manufactured materials were characterized by Fourier transform infrared, X-ray photoelectron spectroscopies (XPS), X-ray diffraction (XRD), Thermal gravimetric analysis, elemental analysis, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX).

Structural and growth aspects of electron beam physical vapor deposited NiO-CeO{sub 2} nanocomposite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuanr, Sushil Kumar; K, Suresh Babu, E-mail: sureshbabu.nst@pondiuni.edu.in

2016-03-15

Deposition of composite materials as thin film by electron beam physical vapor deposition technique (EB-PVD) still remains as a challenge. Here, the authors report the deposition of NiO-CeO{sub 2} (30/70 wt. %) composites on quartz substrate by EB-PVD. Two NiO-CeO{sub 2} nanocomposite targets—one as green compact and the other after sintering at 1250 °C—were used for the deposition. Though the targets varied with respect to physical properties such as crystallite size (11–45 nm) and relative density (44% and 96%), the resultant thin films exhibited a mean crystallite size in the range of 20–25 nm underlining the role of physical nature of deposition. In spitemore » of the crystalline nature of the targets and similar elemental concentration, a transformation from amorphous to crystalline structure was observed in thin films on using sintered target. Postannealing of the as deposited film at 800 °C resulted in a polycrystalline structure consisting of CeO{sub 2} and NiO. Deposition using pure CeO{sub 2} or NiO as target resulted in the preferential orientation toward (111) and (200) planes, respectively, showing the influence of adatoms on the evaporation and growth process of NiO-CeO{sub 2} composite. The results demonstrate the influence of electron beam gun power on the adatom energy for the growth process of composite oxide thin films.« less

Role of silver nanotube on conductivity, dielectric permittivity and current voltage characteristics of polyvinyl alcohol-silver nanocomposite film

NASA Astrophysics Data System (ADS)

Mukherjee, P. S.; Das, A. K.; Dutta, B.; Meikap, A. K.

2017-12-01

A comprehensive study on the prevailing conduction mechanism, dielectric relaxation and current voltage behaviour of Polyvinyl alcohol (PVA) - Silver (Ag) nanotube composite film has been reported. Introduction of Ag nanotubes enhances the conductivity and dielectric permittivity of film. Film shows semiconducting behaviour with two activation energies. The dc conductivity of the nanocomposite film obeys the adiabatic small polaron model. The dielectric permittivity can be analysed by modified Cole-Cole model. A non-Debye type asymmetric behaviour has been observed in the sample. The back to back Schottky diode concept has been used to describe the current-voltage characteristic of the composite film.

Supported porous carbon and carbon-CNT nanocomposites for supercapacitor applications

NASA Astrophysics Data System (ADS)

Schopf, Dimitri; Es-Souni, Mohammed

2016-03-01

Supported porous carbon and porous carbon-MWCNT-nanocomposite films are produced by pyrolysis of porous polyvinylidene fluoride (PVDF) or porous PVDF-MWCNT-nanocomposite films on thermally resistant substrates. All films are characterized by SEM, RAMAN and XRD. The application of these films as supercapacitors is explored with outstanding supercapacitance values ranging from 80 to 120 F g-1 (up to 70 mF cm-2) in a three-electrode set-up in 1 M KOH, depending on microstructure. Additionally, the implementation of porous nanocarbon-MWCNT-nanocomposite films as electrodes in a symmetrical supercapacitor device is investigated. In all cases, long-term charge-discharge stability is demonstrated.

Influence of PA6 nanocomposite films on the stability of vacuum-aged beef loins during storage in modified atmospheres.

PubMed

Picouet, P A; Fernandez, A; Realini, C E; Lloret, E

2014-01-01

A masterbatch of polyamide 6 (PA6) containing dispersed nanoclays, was used to fabricate a novel multilayer film for vacuum packed meat. Performance of the nanocomposite was compared to a control PA6 multilayer and a high barrier commercial film. Addition of nanoclays improved oxygen barrier properties, UV-blocking capability and stiffness. Beef loins were vacuum-aged using the three films for 0 7, 14 and 21 days at 2°C. After each ageing time, beef steaks were packaged in commercial trays and high oxygen atmosphere and stored at 4°C for 9 days. Beef quality parameters and gas content were studied during display time in MAP (1, 3, 6 and 9 d). Beef quality parameters were not influenced by the packaging materials used during ageing and the performance of nanocomposites was comparable to high barrier films. Ageing had a positive impact on the stabilization of redness up to day 6 in MAP. Thereafter, oxymyoglobin content and oxidation levels were negatively influenced by ageing. © 2013.

Photocatalytic degradation of metronidazole and methylene blue by PVA-assisted Bi2WO6-CdS nanocomposite film under visible light irradiation

NASA Astrophysics Data System (ADS)

Rajendran, Ranjith; Varadharajan, Krishnakumar; Jayaraman, Venkatesan; Singaram, Boobas; Jeyaram, Jayaprakash

2018-02-01

The enhanced photocatalytic performance of nanocomposite is synthesized via the hydrothermal method and characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence spectroscopy (PL). Under visible light irradiation, PVA assisted Bi2WO6-CdS nanocomposite film displayed enhanced photocatalytic efficiency and inhibition of photocorrosion as compared with pure CdS, pure Bi2WO6 and Bi2WO6-CdS composite. The PVA assisted Bi2WO6-CdS composite film catalyst showed stable catalytic performance until seven successive runs with 92% of methylene blue(MB) degradation, and easy to recover after degradation of organic pollutant. PVA assisted Bi2WO6-CdS nanocomposite film has optimal band edge position for superior photocatalytic degradation. Furthermore, the trapping experiment was carried out using different scavenger for active species. Among the active species, OH· are the most responsive species which play a vital role in the degradation of metronidazole and MB.

Smart Nacre-inspired Nanocomposites.

PubMed

Peng, Jingsong; Cheng, Qunfeng

2018-03-15

Nacre-inspired nanocomposites with excellent mechanical properties have achieved remarkable attention in the past decades. The high performance of nacre-inspired nanocomposites is a good basis for the further application of smart devices. Recently, some smart nanocomposites inspired by nacre have demonstrated good mechanical properties as well as effective and stable stimuli-responsive functions. In this Concept, we summarize the recent development of smart nacre-inspired nanocomposites, including 1D fibers, 2D films and 3D bulk nanocomposites, in response to temperature, moisture, light, strain, and so on. We show that diverse smart nanocomposites could be designed by combining various conventional fabrication methods of nacre-inspired nanocomposites with responsive building blocks and interface interactions. The nacre-inspired strategy is versatile for different kinds of smart nanocomposites in extensive applications, such as strain sensors, displays, artificial muscles, robotics, and so on, and may act as an effective roadmap for designing smart nanocomposites in the future. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of type and content of modified montmorillonite on the structure and properties of bio-nanocomposite films based on soy protein isolate and montmorillonite

USDA-ARS?s Scientific Manuscript database

The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified mo...

Ionic Conductivity Increased by Two Orders of Magnitude in Micrometer-Thick Vertical Yttria-Stabilized ZrO 2 Nanocomposite Films

DOE PAGES

Lee, Shinbuhm; Zhang, Wenrui; Khatkhatay, Fauzia; ...

2015-09-03

We design and create a unique cell geometry of templated micrometer-thick epitaxial nanocomposite films which contain ~20 nm diameter yttria-stabilized ZrO 2 (YSZ) nanocolumns, strain coupled to a SrTiO 3 matrix. We also enhanced the ionic conductivity of these nanocolumnsby over 2 orders of magnitude compared to plain YSZ films. Concomitant with the higher ionic conduction is the finding that the YSZ nanocolumns in the films have much higher crystallinity and orientation, compared to plain YSZ films. Hence, “oxygen migration highways” are formed in the desired out-of-plane direction. This improved structure is shown to originate from the epitaxial coupling ofmore » the YSZ nanocolumns to the SrTiO 3 film matrix and from nucleation of the YSZ nanocolumns on an intermediate nanocomposite base layer of highly aligned Sm-doped CeO 2 nanocolumns within the SrTiO 3 matrix. Furthermore, this intermediate layer reduces the lattice mismatch between the YSZ nanocolumns and the substrate. Vertical ionic conduction values as high as 10 –2 Ω –1 cm –1 were demonstrated at 360 °C (300 °C lower than plain YSZ films), showing the strong practical potential of these nanostructured films for use in much lower operation temperature ionic devices.« less

Facile synthesis of high strength hot-water wood extract films with oxygen-barrier performance

PubMed Central

Chen, Ge-Gu; Fu, Gen-Que; Wang, Xiao-Jun; Gong, Xiao-Dong; Niu, Ya-Shuai; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

2017-01-01

Biobased nanocomposite films for food packaging with high mechanical strength and good oxygen-barrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated FCMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm3 μm/day·m2·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of high-performance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging. PMID:28112259

Facile synthesis of high strength hot-water wood extract films with oxygen-barrier performance

NASA Astrophysics Data System (ADS)

Chen, Ge-Gu; Fu, Gen-Que; Wang, Xiao-Jun; Gong, Xiao-Dong; Niu, Ya-Shuai; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

2017-01-01

Biobased nanocomposite films for food packaging with high mechanical strength and good oxygen-barrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated FCMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm3 μm/day·m2·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of high-performance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging.

Polymer Nanocomposite Film with Metal Rich Surface Prepared by In Situ Single-Step Formation of Palladium Nanoparticles: An Interesting Way to Combine Specific Functional Properties.

PubMed

Thompson, David; Kranbuehl, David; Espuche, Eliane

2016-10-18

This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles. This specific morphology leads to obtaining an optically reflective film. The metal nanoparticles act as gas diffusion barriers for helium, oxygen, and carbon dioxide; they induce a tortuosity effect which allows dividing the gas permeation coefficients by a factor near to 2 with respect to the neat polyimide matrix. Moreover, the ability of the in situ synthesized palladium nanoparticles to entrap hydrogen is evidenced. The nanocomposite film properties can be modulated as a function of the location of the film metal-rich surface with respect to the hydrogen feed. The synthesized nanocomposite could represent a major interest for a wide variety of applications, from specific coatings for aerospace or automotive industry, to catalysis applications or sensors.

The preparation of γ-crystalline non-electrically poled photoluminescant ZnO-PVDF nanocomposite film for wearable nanogenerators

NASA Astrophysics Data System (ADS)

Jana, Santanu; Garain, Samiran; Ghosh, Sujoy Kumar; Sen, Shrabanee; Mandal, Dipankar

2016-11-01

Polyvinylidene fluoride (PVDF) films are filled with various mass fractions (wt%) of zinc oxide nanoparticles (ZnO-NPs) to fabricate the high performance of a wearable polymer composite nanogenerator (PCNG). The ZnO-NPs can induced a fully γ-crystalline phase in PVDF, where traditional electrical poling is not necessary for the generation of piezoelectric properties. The PCNG delivers up to 28 V of open circuit voltage and 450 nA of short circuit current by simple repeated human finger imparting (under a pressure amplitude of 8.43 kPa) that generates sufficient power to turn on at least 48 commercial blue light emitting diodes (LEDs) instantly. Furthermore, it also successfully charged the capacitors, signifying practical applicability as a piezoelectric based nanogenerator for self-powering devices. The applicability of PCNG by wearable means is clarified when it gives rise to a sensible response, say up to 400 mV of output voltage synchronized with the PCNG embedded human finger in a bending and releasing gesture. UV-visible absorption spectral analysis revealed the possibility of estimating a change in the optical band gap value (E g), refractive index (n) and optical activation energy (E a) in different concentrations of ZnO-NP incorporated PVDF nanocomposite films, and it possesses a useful methodology where ZnO-NPs can be used as an optical probe. Near blue light emission is observed from photoluminescence spectra, which are clearly shown from a Commission Internationale de L’Eclairage (CIE) diagram. The piezoelectric charge coefficient of the nanocomposite film is estimated to be -6.4 pC/N, where even electrical poling treatment is not employed. In addition, dielectric properties have been studied to understand the role of molecular kinetic and interfacial polarization occurring in nanocomposite films at different applied frequencies.

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitompul, Johnner, E-mail: sitompul@che.itb.ac.id; Setyawan, Daru, E-mail: daru.setyawan@gmail.com; Kim, Daniel Young Joon, E-mail: daniel.kim12321@gmail.com

2016-04-19

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were thenmore » characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.« less

Polyimide Nanocomposites Prepared from High-Temperature, Reduced Charge Organoclays

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Ladislaw, J. S.; Smith, J. G., Jr.; Connell, J. W.

2003-01-01

Montmorillonite clays modified with the dihydrochloride salt of 1,3-bis(3-aminophenoxy)benzene (APB) were used in the preparation of polyimide/organoclay hybrid films. Organoclays with varying surface charge based upon APB were prepared and examined for their dispersion behavior in the polymer matrix. High molecular weight poly(amide acid) solutions were prepared in the presence of the organoclays. Films were cast and subsequently heated to 300C to cause imidization. The resulting nanocomposite films, containing 3 wt% of organoclay, were characterized by transmission electron microscopy and X-ray diffraction. The clay's cation exchange capacity (CEC) played a key role in determining the extent of dispersion in the polyimide matrix. Considerable dispersion was observed in some of the nanocomposite films. The most effective organoclay was found to have a CEC of 0.70 meq/g. Nanocomposite films prepared with 3-8 wt% of this organoclay were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin-film tensile testing. High levels of clay dispersion could be achieved even at the higher clay loadings. Results from mechanical testing revealed that while the moduli of the nanocomposites increased with increasing clay loadings, both strength and elongation decreased.

Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

PubMed

Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

2010-06-01

The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

Combined antibacterial/tissue regeneration response in thermal burns promoted by functional chitosan/silver nanocomposites.

PubMed

Luna-Hernández, E; Cruz-Soto, M E; Padilla-Vaca, F; Mauricio-Sánchez, R A; Ramirez-Wong, D; Muñoz, R; Granados-López, L; Ovalle-Flores, L R; Menchaca-Arredondo, J L; Hernández-Rangel, A; Prokhorov, E; García-Rivas, J L; España-Sánchez, B L; Luna-Bárcenas, G

2017-12-01

We report the combined antibacterial/tissue regeneration responses to thermal burns promoted by functional chitosan/silver nanocomposites (CS/nAg) with ultralow silver content (0.018wt.%, 7-30nm). Our approach allows one to produce CS/nAg nanocomposites without silver nanoparticles (nAg) agglomeration, with bactericide potency higher than 1wt.% of nAg (ca. 10nm) content and, promoting the healing process in controlled thermal burns. CS/nAg films exhibit high antibacterial activity against S. aureus and P. aeruginosa after 1.5h of incubation, demonstrating the bacterial penetration into hydrated films and their interaction with nAg. Additionally, exceptional healing of induced thermal burns was obtained by increasing myofibroblasts, collagen remodeling, and blood vessel neoformation. These factors are associated with epiderma regeneration after 7days of treatment with no nAg release. Our results corroborate the controlled synthesis of nAg embedded in CS matrix with combined antibacterial/biocompatibility properties aiming to produce functional nanocomposites with potential use in wound dressing and health care applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Improved oxygen reduction reaction catalyzed by Pt/Clay/Nafion nanocomposite for PEM fuel cells.

PubMed

Narayanamoorthy, B; Datta, K K R; Eswaramoorthy, M; Balaji, S

2012-07-25

A novel Pt nanoparticle (Pt NP) embedded aminoclay/Nafion (Pt/AC/N) nanocomposite catalyst film was prepared for oxygen reduction reaction by sol-gel method. The prepared nanocomposite films were surface characterized using XRD and TEM and thermal stability was studied by TGA. The prepared film has firmly bound Pt NP and could exhibit an improved electro-reduction activity compared to vulcan carbon/Nafion supported Pt NP (Pt/VC/N). Moreover, the Pt/AC/N film possessed good stability in the acidic environment. The limiting current density of the Pt/AC/N film with 35.4 μg/cm(2) of Pt loading was found to be 4.2 mA/cm(2), which is 30% higher than that of the Pt/VC/N. The maximum H2O2 intermediate formation was found to be ∼1.6% and the reaction found to follow a four electron transfer mechanism. Accelerated durability test for 2000 potential cycles showed that ca. 78% of initial limiting current was retained. The results are encouraging for possible use of the Pt/AC/N as the free-standing electrocatalyst layer for polymer electrolyte membrane fuel cells.

Magnetization enhancement due to incorporation of non-magnetic nitrogen content in (Co{sub 84}Zr{sub 16})N{sub x} nano-composite films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Jitendra, E-mail: jitendra@ceeri.ernet.in; Akhtar, Jamil; Academy of Scientific and Innovative Research, New Delhi 110001

We report the magnetic, electronic, and structural properties of nano-composite (Co{sub 84}Zr{sub 16})N{sub x} or CZN films prepared by reactive co-sputter deposition method. As-deposited CZN films have shown enhancement in magnetization (M{sub s}) with incorporation of nitrogen content, which is related to the evolution of nano-composite phase. X-ray diffraction study has confirmed poly-crystalline growth of CZN films with fcc(331) and fcc(422) phases. High-resolution transmission electron microscope study reveals that CZN films are composed of ordered and crystalline ferromagnetic Co nano-clusters, which are embedded in the nano-composite matrix. Photoemission measurements show the change in the intensity near the Fermi level mostmore » likely due to defects and shift in the core-levels binding energy with nitrogen concentration. Raman spectroscopy data show an increase in the intensity of the Raman lines with nitrogen concentration upto 20%. However, the intensity is significantly lower for 30% sample. This indicates that less nitrogen or defect states are being substituted into the lattice above 20% and is consistent with the observed magnetic behavior. Our studies indicate that defects induced due to the incorporation of non-magnetic nitrogen content play a key role to enhance the magnetization.« less

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

NASA Astrophysics Data System (ADS)

Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

2016-06-01

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

Nanocomposite films based on CMC, okra mucilage and ZnO nanoparticles: Physico mechanical and antibacterial properties.

PubMed

Mohammadi, Hamid; Kamkar, Abolfazl; Misaghi, Ali

2018-02-01

This work examined the physico mechanical parameters and antibacterial activity of CMC/okra mucilage (OM) blend films containing ZnO nanoparticles (NPs). Different proportions of CMC and okra mucilage (100/0; 70/30; 60/40 and 50/50 respectively), were mixed and casted to posterior analysis of formed films. The more colored films were obtained by higher contents of okra mucilage and adding ZnO nanoparticles. The incorporation of ZnO NPs into CMC film decreased the elongation at the break (EB) value of the films and increased the tensile strength (TS) value of the film. With increase in CMC concentration in the films, higher water vapor permeability and higher solubility in water were achieved. Microstructure analysis using SEM showed a smooth and compact surface morphology, homogeneous structure, and a rough surface for CMC, CMC+ZnO, and CMC/OM30%+ZnO, respectively. Nanocomposite films presented antibacterial activity against tested bacteria. Films contained okra mucilage showed more antibacterial activity. The inhibitory activities of resultant films were stronger against S. aureus than E. coli. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and properties of hybrid monodispersed magnetic α-Fe2O3 based chitosan nanocomposite film for industrial and biomedical applications.

PubMed

Singh, Jay; Srivastava, M; Dutta, Joydeep; Dutta, P K

2011-01-01

In this study, hydrothermally prepared magnetic α-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the α-Fe2O3 nanoparticles were pure α-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal and spherical monodispersed α-Fe2O3 nanoparticles were encapsulated into the spherical dumb shaped CH-α-Fe2O3 nanocomposite film with a mean diameter of ∼87 and ∼110 nm respectively. The α-Fe2O3 nanoparticles and CH-α-Fe2O3 nanocomposite film were also characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Magnetic measurements revealed that the saturated magnetization (Ms) and remanent magnetization (Mr) of the pure α-Fe2O3 nanoparticles reached 0.573 emu/g and 0.100 emu/g respectively and the nanoparticles showed the characteristics of weak ferromagnetic before and after coating with CH. Copyright © 2010 Elsevier B.V. All rights reserved.

Low Temperature Reactive Sputtering of Thin Aluminum Nitride Films on Metallic Nanocomposites

PubMed Central

Ramadan, Khaled Sayed Elbadawi; Evoy, Stephane

2015-01-01

Piezoelectric aluminum nitride thin films were deposited on aluminum-molybdenum (AlMo) metallic nanocomposites using reactive DC sputtering at room temperature. The effect of sputtering parameters on film properties was assessed. A comparative study between AlN grown on AlMo and pure aluminum showed an equivalent (002) crystallographic texture. The piezoelectric coefficients were measured to be 0.5±0.1 C m-2 and 0.9±0.1 C m-2, for AlN deposited on Al/0.32Mo and pure Al, respectively. Films grown onto Al/0.32Mo however featured improved surface roughness. Roughness values were measured to be 1.3nm and 5.4 nm for AlN films grown on AlMo and on Al, respectively. In turn, the dielectric constant was measured to be 8.9±0.7 for AlN deposited on Al/0.32Mo seed layer, and 8.7±0.7 for AlN deposited on aluminum; thus, equivalent within experimental error. Compatibility of this room temperature process with the lift-off patterning of the deposited AlN is also reported. PMID:26193701

Enhanced self-repairing capability of sol-gel derived SrTiO3/nano Al2O3 composite films

NASA Astrophysics Data System (ADS)

Yao, Manwen; Peng, Yong; Xiao, Ruihua; Li, Qiuxia; Yao, Xi

2016-08-01

SrTiO3/nano Al2O3 inorganic nanocomposites were prepared by using a conventional sol-gel spin coating process. For comparison, SrTiO3 films doped by equivalent amount of sol-Al2O3 have also been investigated. Aluminum deposited by using vacuum evaporation was used as the top electrode. The nanocomposites exhibited a significantly enhanced dielectric strength of 506.9 MV/m, which was increased by 97.4% as compared with the SrTiO3 films doped with sol-Al2O3. The leakage current maintained of the same order of microampere until the ultimate breakdown of the nanocomposites. The excellent electrical performances are ascribed to the anodic oxidation reaction in origin, which can repair the internal and/or surface defects of the films.

Preparation and Characterization of Space Durable Polymer Nanocomposite Films from Functionalized Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Connell, J. W.; Smith, J. G.; Watson, K. A.

2003-01-01

Low color, flexible, space durable polyimide films with inherent, robust electrical conductivity have been under investigation as part of a continuing materials development activity for future NASA space missions involving Gossamer structures. Electrical conductivity is needed in these films to dissipate electrostatic charge build-up that occurs due to the orbital environment. One method of imparting conductivity is through the use of single walled carbon nanotubes (SWNTs). However, the incompatibility and insolubility of the SWNTs severely hampers their dispersion in polymeric matrices. In an attempt to improve their dispersability, SWNTs were functionalized by the reaction with an alkyl hydrazone. After this functionalization, the SWNTs were soluble in select solvents and dispersed more readily in the polymer matrix. The functionalized SWNTs were characterized by Raman spectroscopy and thermogravimetric analysis (TGA). The functionalized nanotubes were dispersed in the bulk of the films using a solution technique. The functionalized nanotubes were also applied to the surface of polyimide films using a spray coating technique. The resultant polyimide nanocomposite films were evaluated for nanotube dispersion, electrical conductivity, mechanical, and optical properties and compared with previously prepared polyimide-SWNT samples to assess the effects of SWNT functionalization.

Natural gum-assisted phthalocyanine immobilization in electroactive nanocomposites: physicochemical characterization and sensing applications.

PubMed

Zampa, Maysa F; de Brito, Ana Cristina F; Kitagawa, Igor L; Constantino, Carlos J L; Oliveira, Osvaldo N; da Cunha, Helder N; Zucolotto, Valtencir; dos Santos, José Ribeiro; Eiras, Carla

2007-11-01

Natural gums have been traditionally applied in cosmetics and the food industry, mainly as emulsification agents. Due to their biodegradability and excellent mechanical properties, new technological applications have been proposed involving their use with conventional polymers forming blends and composites. In this study, we take advantage of the polyelectrolyte character exhibited by the natural gum ChichA (Sterculia striata), extracted in the Northeastern region of Brazil, to produce electroactive nanocomposites. The nanocomposites were fabricated in the form of ultrathin films by combining a metallic phthalocyanine (nickel tetrasulfonated phthalocyanine, NiTsPc) and the ChichA gum in a tetralayer architecture, in conjunction with conventional polyelectrolytes. The presence of the gum led to an efficient adsorption of the phthalocyanine and enhanced the electrochemical response of the films. Upon combining the electrochemical and UV-vis absorption data, energy diagrams of the ChichA/NiTsPc-based system were obtained. Furthermore, modified electrodes based on gum/phthalocyanine films were able to detect dopamine at concentrations as low as 10-5 M.

Electronic excitation induced modifications of structural, electrical and optical properties of Cu-C60 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Inani, H.; Singhal, R.; Sharma, P.; Vishnoi, R.; Ojha, S.; Chand, S.; Sharma, G. D.

2017-09-01

High energy ion irradiation significantly affects the size and shape of nanoparticles in composites. Low concentration metal fraction embedded in fullerene matrix in form of nanocomposites was synthesized by thermal co-evaporation method. Swift heavy ion irradiation was performed with 120 MeV Au ion beam on Cu-C60 nanocomposites at different fluences 1 × 1012, 3 × 1012, 6 × 1012, 1 × 1013 and 3 × 1013 ions/cm2. Absorption spectra demonstrated that absorption intensity of nanocomposite thin film was increased whereas absorption modes of fullerene C60 were diminished with fluence. Rutherford backscattering spectroscopy was also performed to estimate the thickness of the film and atomic metal fraction in matrix and found to be 45 nm and 3%, respectively. Transmission electron microscopy was performed for structural and particle size evaluation of Cu nanoparticles (NPs) in fullerene C60 matrix. A growth of Cu nanoparticles is observed at a fluence of 3 × 1013 ions/cm2 with a bi-modal distribution in fullerene C60. Structural evolution of fullerene C60 matrix with increasing fluence of 120 MeV Au ion beam is studied by Raman spectroscopy which shows the amorphization of matrix (fullerene C60) at lower fluence. The growth of Cu nanoparticles is explained using the phenomena of Ostwald ripening.

Impact of Sweet Potato Starch-Based Nanocomposite Films Activated With Thyme Essential Oil on the Shelf-Life of Baby Spinach Leaves

PubMed Central

Issa, Aseel; Ibrahim, Salam A.; Tahergorabi, Reza

2017-01-01

Salmonella Typhimurium (S. Typhi) and Escherichia coli (E. coli) have been responsible for an increasing number of outbreaks linked to fresh produce, such as baby spinach leaves, in the last two decades. More recently, antimicrobial biodegradable packaging systems have been attracting much attention in the food packaging industry as eco-friendly alternatives to conventional plastic packaging. The objective of this study was to evaluate the effect of antibacterial nanocomposite films on inoculated spinach leaves and on the sensory properties of these leaves during eight days of refrigerated storage. In this study, an antibacterial film comprised of sweet potato starch (SPS), montmorillonite (MMT) nanoclays and thyme essential oil (TEO) as a natural antimicrobial agent was developed. Our results showed that the incorporation of TEO in the film significantly (p < 0.05) reduced the population of E. coli and S. Typhi on fresh baby spinach leaves to below detectable levels within five days, whereas the control samples without essential oil maintained approximately 4.5 Log colony forming unit (CFU)/g. The sensory scores for spinach samples wrapped in films containing TEO were higher than those of the control. This study thus suggests that TEO has the potential to be directly incorporated into a SPS film to prepare antimicrobial nanocomposite films for food packaging applications. PMID:28587199

Polyolefin nanocomposites

DOEpatents

Chaiko, David J.

2007-01-02

The present invention relates to methods for the preparation of clay/polymer nanocomposites. The methods include combining an organophilic clay and a polymer to form a nanocomposite, wherein the organophilic clay and the polymer each have a peak recrystallization temperature, and wherein the organophilic clay peak recrystallization temperature sufficiently matches the polymer peak recrystallization temperature such that the nanocomposite formed has less permeability to a gas than the polymer. Such nanocomposites exhibit 2, 5, 10, or even 100 fold or greater reductions in permeability to, e.g., oxygen, carbon dioxide, or both compared to the polymer. The invention also provides a method of preparing a nanocomposite that includes combining an amorphous organophilic clay and an amorphous polymer, each having a glass transition temperature, wherein the organophilic clay glass transition temperature sufficiently matches the polymer glass transition temperature such that the nanocomposite formed has less permeability to a gas than the polymer.

Giant Faraday Rotation in Metal-Fluoride Nanogranular Films.

PubMed

Kobayashi, N; Ikeda, K; Gu, Bo; Takahashi, S; Masumoto, H; Maekawa, S

2018-03-21

Magneto-optical Faraday effect is widely applied in optical devices and is indispensable for optical communications and advanced information technology. However, the bismuth garnet Bi-YIG is only the Faraday material since 1972. Here we introduce (Fe, FeCo)-(Al-,Y-fluoride) nanogranular films exhibiting giant Faraday effect, 40 times larger than Bi-YIG. These films have a nanocomposite structure, in which nanometer-sized Fe, FeCo ferromagnetic granules are dispersed in a Al,Y-fluoride matrix.

Ultra-stretchable and skin-mountable strain sensors using carbon nanotubes-Ecoflex nanocomposites.

PubMed

Amjadi, Morteza; Yoon, Yong Jin; Park, Inkyu

2015-09-18

Super-stretchable, skin-mountable, and ultra-soft strain sensors are presented by using carbon nanotube percolation network-silicone rubber nanocomposite thin films. The applicability of the strain sensors as epidermal electronic systems, in which mechanical compliance like human skin and high stretchability (ϵ > 100%) are required, has been explored. The sensitivity of the strain sensors can be tuned by the number density of the carbon nanotube percolation network. The strain sensors show excellent hysteresis performance at different strain levels and rates with high linearity and small drift. We found that the carbon nanotube-silicone rubber based strain sensors possess super-stretchability and high reliability for strains as large as 500%. The nanocomposite thin films exhibit high robustness and excellent resistance-strain dependency for over ~1380% mechanical strain. Finally, we performed skin motion detection by mounting the strain sensors on different parts of the body. The maximum induced strain by the bending of the finger, wrist, and elbow was measured to be ~ 42%, 45% and 63%, respectively.

Bismuth pyrochlore-based thin films for dielectric energy storage

NASA Astrophysics Data System (ADS)

Michael, Elizabeth K.

end member increased the dielectric breakdown strength. This combination of a high breakdown strength and a moderate permittivity led to a high discharged energy storage density for all film compositions. For example, at a measurement frequency of 10 kHz, bismuth zinc niobate exhibited a maximum recoverable energy storage density of 60.8 +/- 2.0 J/cm 3, while bismuth zinc tantalate exhibited a recoverable energy storage density of 60.7 +/- 2.0 J/cm3. Intermediate compositions of bismuth zinc niobate tantalate were explored to maximize the energy storage density of the substitutional solid solution. At an optimized concentration of ten mole percent tantalum, the maximum recoverable 10 kHz energy storage density was ˜66.9 +/- 2.4 J/cm3. These films of bismuth zinc niobate tantalate (Bi1.5Zn0.9Nb1.35Ta0.15O 6.9) sustained a maximum field of 5.5 MV/cm at 10 kHz, and demonstrated a relative permittivity of 122 +/- 4. The films maintained a high energy storage density above 20 J/cm3 though temperatures of 200°C. The second major objective of this work was to integrate complex oxides processed at temperatures below 350°C onto flexible polyimide substrates for potential use in flexible energy storage applications. Nanocomposite films consisting of a nanocrystalline fluorite related to delta-bismuth oxide in an amorphous matrix were prepared by reducing the citric acid concentration of the precursor solution, relative to the crystalline films. These solutions were batched with the composition Bi1.5Zn0.9Nb 1.35Ta0.15O6.9. The nanocomposite had a relative permittivity of 50 +/- 2 and dielectric losses on the order of 0.03 +/- 0.01. For measurement frequencies of 1 kHz and 10 kHz, the nanocomposite demonstrated a breakdown strength of 3.8 MV/cm, and a room-temperature energy storage density of approximately 40.2 +/- 1.7 J/cm3. To determine the suitability of the nanocomposite films for use in flexible applications, free-standing flexible nanocomposite films underwent

In situ diazonium-modified flexible ITO-coated PEN substrates for the deposition of adherent silver-polypyrrole nanocomposite films.

PubMed

Samanta, Soumen; Bakas, Idriss; Singh, Ajay; Aswal, Dinesh K; Chehimi, Mohamed M

2014-08-12

In this paper, we report a simple and versatile process of electrografting the aryl multilayers onto indium tin oxide (ITO)-coated flexible poly(ethylene naphthalate) (PEN) substrates using a diazonium salt (4-pyrrolylphenyldiazonium) solution, which was generated in situ from a reaction between the 4-(1H-pyrrol-1-yl)aniline precursor and sodium nitrite in an acidic medium. The first aryl layer bonds with the ITO surface through In-O-C and Sn-O-C bonds which facilitate the formation of a uniform aryl multilayer that is ∼8 nm thick. The presence of the aryl multilayer has been confirmed by impedance spectroscopy as well as by electron-transfer blocking measurements. These in situ diazonium-modified ITO-coated PEN substrates may find applications in flexible organic electronics and sensor industries. Here we demonstrate the application of diazonium-modified flexible substrates for the growth of adherent silver/polpyrrole nanocomposite films using surface-confined UV photopolymerization. These nanocomposite films have platelet morphology owing to the template effect of the pyrrole-terminated aryl multilayers. In addition, the films are highly doped (32%). This work opens new areas in the design of flexible ITO-conductive polymer hybrids.

Structural and electromagnetic properties of NiAlxFe2-xO4/SiO2 nanocomposite films deposited using a sol-gel spin-coating method

NASA Astrophysics Data System (ADS)

Wang, Li; Li, Xuejian; Li, Ji; Liu, Mei; Xu, Shichong; Li, Haibo

2017-12-01

NiAlxFe2-xO4/SiO2 (0 ≤ x ≤ 1.0) nanocomposite films deposited on Si(1 0 0) substrates were prepared by a sol-gel spin-coating method. The influences of Al3+ content and annealing temperature on the structural and electromagnetic properties of the nanocomposite films were investigated. The results indicated that NiAlxFe2-xO4 in the nanocomposite films crystallized after annealing at 1073 K and above. When the doping content x increased from 0 to 1.0, the lattice constants and the average crystallite sizes of the NiAlxFe2-xO4 nanoparticles decreased. The saturation magnetization and coercivity of the films were inversely proportional to the Al3+ content. The maximum value of saturation magnetization (361.6 emu/cm3) and the minimum value of coercivity (18.6 kA/m) were obtained for x of 0.2. When the annealing temperature increased from 1073 to 1473 K, the lattice constant and the average crystallite size of the NiAl0.2Fe1.8O4 nanoparticles increased from 0.8322 to 0.8349 nm and 4 to 28 nm, respectively, and the saturation magnetization and coercivity of the films increased from 214.8 to 464.5 emu/cm3 and 8.2 to 26.9 kA/m, respectively. Moreover, the DC resistivity of the films increased with increasing Al3+ content and annealing temperature.

Eeonomer 200F®: A High-Performance Nanofiller for Polymer Reinforcement—Investigation of the Structure, Morphology and Dielectric Properties of Polyvinyl Alcohol/Eeonomer-200F® Nanocomposites for Embedded Capacitor Applications

NASA Astrophysics Data System (ADS)

Deshmukh, Kalim; Ahamed, M. Basheer; Deshmukh, Rajendra R.; Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Pasha, S. K. Khadheer; AlMaadeed, Mariam Al-Ali; Polu, Anji Reddy; Chidambaram, K.

2017-04-01

In the present study, Eeonomer 200F® was used as a high-performance nanofiller to prepare polyvinyl alcohol (PVA)-based nanocomposite films using a simple and eco-friendly solution casting technique. The prepared PVA/Eeonomer nanocomposite films were further investigated using various techniques including Fourier transform infrared spectroscopy, x-ray diffraction, thermogravimetric analysis, polarized optical microscopy, scanning electron microscopy and mechanical testing. The dielectric behavior of the nanocomposites was examined over a broad frequency range from 50 Hz to 20 MHz and temperatures ranging from 40°C to 150°C. A notable improvement in the thermal stability of the PVA was observed with the incorporation of Eeonomer. The nanocomposites also demonstrated improved mechanical properties due to the fine dispersion of the Eeonomer, and good compatibility and strong interaction between the Eeonomer and the PVA matrix. A significant improvement was observed in the dielectric properties of the PVA upon the addition of Eeonomer. The nanocomposites containing 5 wt.% Eeonomer exhibited a dielectric constant of about 222.65 (50 Hz, 150°C), which was 18 times that of the dielectric constant (12.33) of neat PVA film under the same experimental conditions. These results thus indicate that PVA/Eeonomer nanocomposites can be used as a flexible high-k dielectric material for embedded capacitor applications.

Efficient upconversion polymer-inorganic nanocomposite thin film emitters prepared by the double beam matrix assisted pulsed laser evaporation (DB-MAPLE)

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Burkett, Allan; Blackwell, Ashley; Taylor, Keylantra; Walker, Vernell; Sarkisov, Sergey; Koplitz, Brent

2014-09-01

We report on fabrication and investigation of optical and morphological properties of highly efficient (a quantum yield of 1%) upconversion polymer-inorganic nanocomposite thin film emitters prepared by the new technique of double beam matrix assisted pulsed laser evaporation (DB-MAPLE). Polymer poly(methyl methacrylate) (PMMA) host was evaporated on a silicon substrate using a 1064-nm pulsed laser beam using a target made of frozen (to the temperature of liquid nitrogen) solution of PMMA in chlorobenzene. Concurrently, the second 532-nm pulsed beam from the same laser was used to impregnate the polymer host with the inorganic nanoparticulate made of the rare earth upconversion compounds NaYF4: Yb3+, Er3+, NaYF4: Yb3+, Ho3+, and NaYF4: Yb3+, Tm3+. The compounds were initially synthesized using the wet process, baked, and compressed in solid pellet targets. The proposed DB-MAPLE method has the advantage of making highly homogeneous nanocomposite films with precise control of the doping rate due to the optimized overlapping of the plumes produced by the ablation of the organic and inorganic target with the infrared and visible laser beams respectively. X-ray diffraction, electron and atomic force microscopy, and optical fluorescence spectroscopy indicated that the inorganic nanoparticulate preserved its crystalline structure and upconversion properties (strong emission in green, red, and blue bands upon illumination with 980-nm laser diode) after being transferred from the target in the polymer nanocomposite film. The produced films can be used in applications varying from the efficiency enhancement of the photovoltaic cells, optical sensors and biomarkers to anti-counterfeit labels.

Dynamic piezoresistive response of hybrid nanocomposites

NASA Astrophysics Data System (ADS)

Gbaguidi, Audrey; Anees, Muhammad; Namilae, Sirish; Kim, Daewon

2017-04-01

Hybrid nanocomposites with carbon nanotubes and graphitic platelets as fillers are known to exhibit remarkable electrical and mechanical properties with many potential strain and damage sensing applications. In this work, we fabricate hybrid nanocomposites with carbon nanotube sheet and coarse graphite platelets as fillers with epoxy matrix. We then examine the electromechanical behavior of these nanocomposites under dynamic loading. The electrical resistivity responses of the nanocomposites are measured in frequency range of 1 Hz to 50 Hz with different levels of induced strains. Axial cycling loading is applied using a uniaxial electrodynamic shaker, and transverse loading is applied on end-clamped specimen using modified speakers. In addition, a dynamic mechanical analysis of nanocomposite specimen is performed to characterize the thermal and dynamic behavior of the nanocomposite. Our results indicate that these hybrid nanocomposites exhibit a distinct piezoresistive response under a wide range of dynamic loading conditions, which can be beneficial for potential sensing applications.

Chitosan-Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm.

PubMed

Konwar, Achyut; Kalita, Sanjeeb; Kotoky, Jibon; Chowdhury, Devasish

2016-08-17

We report a robust biofilm with antimicrobial properties fabricated from chitosan-iron oxide coated graphene oxide nanocomposite hydrogel. For the first time, the coprecipitation method was used for the successful synthesis of iron oxide coated graphene oxide (GIO) nanomaterial. After this, films were fabricated by the gel-casting technique aided by the self-healing ability of the chitosan hydrogel network system. Both the nanomaterial and the nanocomposite films were characterized by techniques such as scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Measurements of the thermodynamic stability and mechanical properties of the films indictaed a significant improvement in their thermal and mechanical properties. Moreover, the stress-strain profile indicated the tough nature of the nanocomposite hydrogel films. These improvements, therefore, indicated an effective interaction and good compatibility of the GIO nanomaterial with the chitosan hydrogel matrix. In addition, it was also possible to fabricate films with tunable surface properties such as hydrophobicity simply by varying the loading percentage of GIO nanomaterial in the hydrogel matrix. Fascinatingly, the chitosan-iron oxide coated graphene oxide nanocomposite hydrogel films displayed significant antimicrobial activities against both Gram-positive and Gram-negative bacterial strains, such as methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli, and also against the opportunistic dermatophyte Candida albicans. The antimicrobial activities of the films were tested by agar diffusion assay and antimicrobial testing based on direct contact. A comparison of the antimicrobial activity of the chitosan-GIO nanocomposite hydrogel films with those of individual chitosan-graphene oxide and chitosan-iron oxide nanocomposite films demonstrated a higher antimicrobial activity for the former in both types of tests. In vitro hemolysis

Thermal-induced structural and optical investigations of Agsbnd ZnO nanocomposite thin films

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.

2018-07-01

In the present paper, we have successfully synthesized Agsbnd ZnO nanocomposite thin films by RF-magnetron sputtering technique at room temperature. Systematic investigations of thermal-induced structural and optical modifications in Agsbnd ZnO thin films have been observed and described. The Agsbnd ZnO thin films were annealed at three different temperatures of 300 °C, 400 °C and 500 °C in vacuum to prevent the oxidation of Ag. The presence and formation of Ag nanoparticles were estimated by transmission electron microscopy. X-ray diffraction analysis revealed the structural information about the crystalline quality of ZnO. The crystallinity as well as the crystallite size of the films have been found to be improved with annealing temperatures. The estimated crystallite size was ∼15.8 nm for as-deposited film and 19.0 nm for the film at a higher temperature. The chemical composition and structural analysis of as-deposited film were carried out by X-ray photoelectron spectroscopy. A very sharp absorption band appeared at ∼540 nm for Ag NPs that is associated with the surface plasmon resonance band of Ag. A noticeable red shift of about ∼12 nm has been recorded for films annealed at 500 °C. Atomic force microscopy has been utilized to examine the surface morphology of the as-deposited and annealed films. The grain size was found to be increase with increasing annealing temperature, while no significant changes were observed in the roughness of Agsbnd ZnO thin films. Raman spectroscopy revealed lattice defects and disordering in the films after the thermal annealing.

Fine tuning the color-transition temperature of thermoreversible polydiacetylene/zinc oxide nanocomposites: The effect of photopolymerization time.

PubMed

Traiphol, Nisanart; Faisadcha, Kunruethai; Potai, Ruttayapon; Traiphol, Rakchart

2015-02-01

An ability to control the thermochromic behaviors of polydiacetylene (PDA)-based materials is very important for their utilization. Recently, our group has developed the PDA/zinc oxide (ZnO) nanocomposites, which exhibit reversible thermochromism (Traiphol et al., 2011). In this study, we present our continuation work demonstrating a rather simple method for fine tuning their color-transition temperature. The PDA/ZnO nanocomposites are prepared by varying photopolymerization time, which in turn affects the length of PDA conjugated backbone. We have found that the increase of photopolymerization time from 1 to 120min results in systematically decrease of the color-transition temperature from about 85 to 40°C. These PDA/ZnO nanocomposites still exhibit reversible thermochromism. The PDA/ZnO nanocomposites embedded in polyvinyl alcohol films show two-step color-transition processes, the reversible blue to purple and then irreversible purple to orange. Interestingly, the increase of photopolymerization time causes an increase of the irreversible color-transition temperature. Our method is quite simple and cheap, which can provide a library of PDA-based materials with controllable color-transition temperature. Copyright © 2014 Elsevier Inc. All rights reserved.

Anomalous Drag Reduction and Hydrodynamic Interactions of Nanoparticles in Polymer Nanocomposite Thin Films

NASA Astrophysics Data System (ADS)

Basu, Jaydeep; Begam, Nafisa; Chandran, Sivasurender; Sprung, Michael

2015-03-01

One of the central dogma of fluid physics is the no-slip boundary condition whose validity has come under intense scrutiny, especially in the fields of micro and nanofluidics. Although various studies show the violation of the no-slip condition its effect on flow of colloidal particles in viscous media has been rarely explored. Here we report unusually large reduction of effective drag experienced by polymer grafted nanoparticles moving through a highly viscous film of polymer, well above its glass transition temperature. The extent of drag reduction increases with decreasing temperature and polymer film thickness. We also observe apparent divergence of the wave vector dependent hydrodynamic interaction function of these nanoparticles with an anomalous power law exponent of ~ 2 at the lowest temperatures and film thickness. Such strong hydrodynamic interactions are not expected in polymer melts where these interactions are known to be screened to molecular dimensions. We provide evidence for the presence of large hydrodynamic slip at the nanoparticle-polymer interface and demonstrate its tunability with temperature and confinement. Our study suggests novel physics emerging in dynamics nanoparticles due to confinement and interface wettability in thin films of polymer nanocomposites.

Influence of Food with High Moisture Content on Oxygen Barrier Property of Polyvinyl Alcohol (PVA)/Vermiculite Nanocomposite Coated Multilayer Packaging Film.

PubMed

Kim, Jung Min; Lee, Min Hyeock; Ko, Jung A; Kang, Dong Ho; Bae, Hojae; Park, Hyun Jin

2018-02-01

This study investigates the potential complications in applying nanoclay-based waterborne coating to packaging films for food with high moisture content. Multilayer packaging films were prepared by dry laminating commercially available polyvinyl alcohol (PVA)/vermiculite nanocomposite coating films and linear low-density polyethylene film, and the changes in oxygen barrier properties were investigated according to different relative humidity using 3 types of food simulants. When the relative humidity was above 60%, the oxygen permeability increased sharply, but this was reversible. Deionized water and 3% acetic acid did not cause any large structural change in the PVA/vermiculite nanocomposite but caused a reversible deterioration of the oxygen barrier properties. In contrast, 50% ethanol, a simulant for the semifatty food, induced irreversible structural changes with deterioration of the oxygen barrier property. These changes are due to the characteristics of PVA rather than vermiculite. We believe this manuscript would be of interest to the wide group of researchers, organizations, and companies in the field of developing nanoclay-based gas barrier packaging for foods with high moisture content. Hence, we wish to diffuse our knowledge to the scientific community. © 2018 Institute of Food Technologists®.

Optical properties of MgF2 nano-composite films dispersed with noble metal nanoparticles synthesized by sol-gel method

NASA Astrophysics Data System (ADS)

Wakaki, Moriaki; Soujima, Nobuaki; Shibuya, Takehisa

2015-03-01

Porous MgF2 films synthesized by a sol-gel method exhibit the lowest refractive index among the dielectric optical materials and are the most useful materials for the anti-reflection coatings. On the other hand, surface plasmon resonance (SPR) absorptions of noble metal nanoparticles in various solid matrices have been extensively studied. New functional materials like a SERS (Surface Enhanced Raman Spectroscopy) tips are expected by synthesizing composite materials between porous MgF2 films featured by the network of MgF2 nanoparticles and noble metal nanoparticles introduced within the network. In this study, fundamental physical properties including morphology and optical properties are characterized for these materials to make clear the potential of the composite system. Composite materials of MgF2 films dispersed with noble metal (Ag, Au) nanoparticles were prepared using the sol-gel technique with various annealing temperatures and densities of noble metal nanoparticles. The structural morphology was analyzed by an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The size and shape distributions of the metal nanoparticles were observed using a transmission electron microscope (TEM). The optical properties of fabricated composite films were characterized by UV-Vis-NIR and FT-IR spectrophotometers. The absorption spectra due to the surface plasmon resonance (SPR) of the metal nanoparticles were analyzed using the dielectric function considering the effective medium approximation, typically Maxwell-Garnett model. The Raman scattering spectra were also studied to check the enhancement effect of specimen dropped on the MgF2: Ag nano-composite films deposited on Si substrate. Enhancement of the Raman intensity of pyridine solution specimen was observed.

Whey protein isolate/cellulose nanofibre/TiO2 nanoparticle/rosemary essential oil nanocomposite film: Its effect on microbial and sensory quality of lamb meat and growth of common foodborne pathogenic bacteria during refrigeration.

PubMed

Alizadeh Sani, Mahmood; Ehsani, Ali; Hashemi, Mohammad

2017-06-19

The use of biodegradable nanocomposite films in active packaging is of great importance since they can have a controlled release of antimicrobial compounds. This study was conducted to evaluate the efficacy of whey protein isolate (WPI)/cellulose nanofibre (CNF) nanocomposite films containing 1.0% (w/w) titanium dioxide (TiO 2 ) and 2.0% (w/v) rosemary essential oil (REO) in preserving the microbial and sensory quality of lamb meat during the storage at 4±1°C. Initially, the best concentration of each compound to be added to the film was determined by micro-dilution and disc diffusion methods. The microbial and sensory properties of lamb meat were controlled in two groups (control and treatment) over 15days of storage. Then, the samples were analysed for total viable count (TVC), Pseudomonas spp. count, Enterobacteriaceae count, Lactic acid bacteria (LAB) count, inoculated Staphylococcus aureus count, Listeria monocytogenes count, and Escherichia coli O 157 :H 7 count. Microbial analysis and nine-point hedonic scale was applied for the sensory analysis. Results indicated that the use of nanocomposite films significantly reduced the bacterial counts of treatment group. Higher inhibition effect was observed on Gram-positive bacteria than on Gram-negative bacteria (P<0.05). The microbial and sensory evaluations also showed that the use of nanocomposite films significantly increased the shelf life of treated meat (15days) compared to the control meat (6days). Based on the results of this study, the edible nanocomposite films were effective in preserving the microbial and sensory qualities of lamb meat; therefore, this application is recommended in meat especially red meat. Copyright © 2017 Elsevier B.V. All rights reserved.

Flexible and transparent polyimide films containing two-dimensional alumina nanosheets templated by graphene oxide for improved barrier property.

PubMed

Tseng, I-Hsiang; Tsai, Mei-Hui; Chung, Chi-Wei

2014-08-13

Unique two-dimensional alumina nanosheets (Alns) using graphene oxide (GO) as templates are fabricated and successfully incorporated with organo-soluble polyimide (PI) to obtain highly transparent PI nanocomposite films with improved moisture barrier property. The effects of filler types and contents on water vapor transmission rate (WVTR) and transparency of PI are systematically studied. The hydroxyl groups on GO react with aluminum isopropoxide via sol-gel process to obtain alumina coverd-GO (Al-GO), and then thermal decomposition is applied to obtain Alns. Alns are the most efficient fillers among others to restrict the diffusion of water vapor within PI matrix and simultaneously maintain the transparency of PI. XRD pattern, TEM, and AFM images confirm the sheet-like morphology of Alns with ultrahigh aspect ratio. With only 0.01 wt % of Alns, the PI nanocomposite film exhibits the most significant reduction of 95% in WVTR as compared to that of pure PI film. Most importantly, the resultant PI/Alns-0.01 film exhibits excellent optical transparency and high mechanical strength and great thermal stability.

Probing localized strain in solution-derived YB a2C u3O7 -δ nanocomposite thin films

NASA Astrophysics Data System (ADS)

Guzman, Roger; Gazquez, Jaume; Mundet, Bernat; Coll, Mariona; Obradors, Xavier; Puig, Teresa

2017-07-01

Enhanced pinning due to nanoscale strain is unique to the high-Tc cuprates, where pairing may be modified with lattice distortion. Therefore a comprehensive understanding of the defect landscape is required for a broad range of applications. However, determining the type and distribution of defects and their associated strain constitutes a critical task, and for this aim, real-space techniques for atomic resolution characterization are necessary. Here, we use scanning transmission electron microscopy (STEM) to study the atomic structure of individual defects of solution-derived YB a2C u3O7 (YBCO) nanocomposites, where the inclusion of incoherent secondary phase nanoparticles within the YBCO matrix dramatically increases the density of Y1B a2C u4O8 (Y124) intergrowths, the commonest defect in YBCO thin films. The formation of the Y124 is found to trigger a concatenation of strain-derived interactions with other defects and the concomitant nucleation of intrinsic defects, which weave a web of randomly distributed nanostrained regions that profoundly transform the vortex-pinning landscape of the YBCO nanocomposite thin films.

Anisotropic elasticity of quasi-one-component polymer nanocomposites.

PubMed

Voudouris, Panayiotis; Choi, Jihoon; Gomopoulos, Nikos; Sainidou, Rebecca; Dong, Hongchen; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Fytas, George

2011-07-26

The in-plane and out-of-plane elastic properties of thin films of "quasi-one-component" particle-brush-based nanocomposites are compared to those of "classical" binary particle-polymer nanocomposite systems with near identical overall composition using Brillouin light scattering. Whereas phonon propagation is found to be independent of the propagation direction for the binary particle/polymer blend systems, a pronounced splitting of the phonon propagation velocity along the in-plane and out-of-plane film direction is observed for particle-brush systems. The anisotropic elastic properties of quasi-one-component particle-brush systems are interpreted as a consequence of substrate-induced order formation into layer-type structures and the associated breaking of the symmetry of the film. The results highlight new opportunities to engineer quasi-one-component nanocomposites with advanced control of structural and physical property characteristics based on the assembly of particle-brush materials.

Sliding friction of nanocomposite WC1-x/C coatings: transfer film and its influence on tribology.

PubMed

Liu, Y; Gubisch, M; Spiess, L; Schaefer, J A

2009-06-01

The transfer film on steel spheres formed in reciprocating sliding against nanocomposite coatings based on nanocrystalline WC1-x in amorphous carbon matrix is characterized and correlated with the tribological properties measured by a precision microtribometer. With the presence of transfer film, a coefficient of friction approximately 0.13 and a depth wear rate approximately 0.35 x 10(-10) m/N.Pass were obtained. The central zone of the transfer film covering approximately 25% of the Hertz contact area is intact while cracks and wear debris are found in the vast peripheral area. It is also heavily oxidized due to the absence of carbon, which is located at the peripherals and acts as lubricants. We propose that the oxidation of WC and adhesion of the oxides to the surface of sphere is the main mechanism for the buildup of the transfer films. With the thickening of the film, the internal stress increases. Under the shear stress, spalling and cracking of the transfer film take place. The overall tribological performance of the coatings is therefore a competing process of buildup and spalling of transfer films.

Nanocomposites of rice and banana flours blend with montmorillonite: partial characterization.

PubMed

Rodríguez-Marín, María L; Bello-Pérez, Luis A; Yee-Madeira, Hernani; Zhong, Qixin; González-Soto, Rosalía A

2013-10-01

Rice and banana flours are inexpensive starchy materials that can form films with more improved properties than those made with their starch because flour and starch present different hydrophobicity. Montmorillonite (MMT) can be used to further improve the properties of starch-based films, which has not received much research attention for starchy flours. The aim of this work was to evaluate the mechanical and barrier properties of nanocomposite films of banana and rice flours as matrix material with addition of MMT as a nanofiller. MMT was modified using citric acid to produce intercalated structures, as verified by the X-ray diffraction pattern. The intercalated MMT was blended with flour slurries, and films were prepared by casting. Nanocomposite films of banana and rice flours presented an increase in the tensile at break and elongation percentage, respectively, more than their respective control films without MMT. This study showed that banana and rice flours could be alternative raw materials to use in making nanocomposite films. Copyright © 2013 Elsevier B.V. All rights reserved.

Controlled release of metformin from chitosan-based nanocomposite films containing mesoporous MCM-41 nanoparticles as novel drug delivery systems.

PubMed

Shariatinia, Zahra; Zahraee, Zahra

2017-09-01

Biocompatible nanocomposite films based on blended chitosan and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (BP) polymers containing metformin (MET) drug and MCM-41 or MCM-41-APS (APS=aminopropylsilane) nanoparticles (NPs) were designed and fabricated in order to prepare novel drug delivery systems which are useful for controlled drug release purposes. The total pore volume and mesopore volume of MCM-41 were measured equal to 1.08 and 1.05 cm 3 /g but those of MCM-41-APS were 0.54 and 0.26 cm 3 /g indicating smaller values for the APS functionalized material. The film thickness was the highest for CS-BP-G-10%MET (70μm) but it was the smallest for the CS-BP-G-4%MCM-41 (49μm). For all of the films, the swelling percent was the highest in acidic medium but it was decreased in PBS and the least water uptake occurred in the alkaline environment. The lowest and the highest water uptake was observed for the films incorporated with 4%MCM-41NPs and 4%MCM-41-APS-10%MET, respectively. The SEM micrographs of the films after three days water uptake in pH=4 medium exhibited that all of the films were stable against cracking and/or tearing. It was found that increasing the MCM-41 or MCM-41-APS amount within the films decreased the elongation at break but enhanced the tensile stress. The release of the MET was sharply increased within ∼22-24h (burst release) but after that the drug release was slowly enhanced during 15days (sustained release). Finally, it was concluded that the film 4% MCM-41-APS-10%MET NPs was the most promising drug delivery system because it had improved hydrophilicity, hydrolytic stability, biocompatibility, mechanical and drug release properties. Copyright © 2017 Elsevier Inc. All rights reserved.

Nutraceutically inspired pectin-Mg(OH)₂ nanocomposites for bioactive packaging applications.

PubMed

Moreira, Francys K V; De Camargo, Lais A; Marconcini, José M; Mattoso, Luiz H C

2013-07-24

This paper reports on the development of bioactive edible films based on pectin as a dietary matrix and magnesium hydroxide (Mg(OH)2) nanoplates as a reinforcing filler. Nanocomposites of high-methoxyl (HM) and low-methoxyl (LM) pectins were prepared using the casting method at concentrations of Mg(OH)2 ranging from 0.5 to 5 wt %. Atomic force microscopy and FTIR spectroscopy were employed to characterize the nanocomposite structure. The tensile properties and thermal stability of the nanocomposites were also examined to ascertain the effect of Mg(OH)2 inclusion and degree of methoxylation. The results provided evidence that the Mg(OH)2 nanoplates were uniformly dispersed and interacted strongly with the film matrix. The mechanical and thermal properties were significantly improved in the nanocomposite films compared to the control. Mg(OH)2 nanoplates were more effective in improving properties of LM pectin. Preliminary migration studies using arugula leaves confirmed that pectin-Mg(OH)2 nanocomposites can release magnesium hydroxide by contact, demonstrating their potential for magnesium supplementation in bioactive packaging.

Properties of solid solutions, doped film, and nanocomposite structures based on zinc oxide

NASA Astrophysics Data System (ADS)

Lashkarev, G. V.; Shtepliuk, I. I.; Ievtushenko, A. I.; Khyzhun, O. Y.; Kartuzov, V. V.; Ovsiannikova, L. I.; Karpyna, V. A.; Myroniuk, D. V.; Khomyak, V. V.; Tkach, V. N.; Timofeeva, I. I.; Popovich, V. I.; Dranchuk, N. V.; Khranovskyy, V. D.; Demydiuk, P. V.

2015-02-01

A study of the properties of materials based on the wide bandgap zinc oxide semiconductor, which are promising for application in optoelectronics, photovoltaics and nanoplasmonics. The structural and optical properties of solid solution Zn1-xCdxO films with different cadmium content, are studied. The samples are grown using magnetron sputtering on sapphire backing. Low-temperature photoluminescence spectra revealed emission peaks associated with radiative recombination processes in those areas of the film that have varying amounts of cadmium. X-ray phase analysis showed the presence of a cadmium oxide cubic phase in these films. Theoretical studies of the solid solution thermodynamic properties allowed for a qualitative interpretation of the observed experimental phenomena. It is established that the growth of the homogeneous solid solution film is possible only at high temperatures, whereas regions of inhomogeneous composition can be narrowed through elastic deformation, caused by the mismatch of the film-backing lattice constants. The driving forces of the spinodal decomposition of the Zn1-xCdxO system are identified. Fullerene-like clusters of Znn-xCdxOn are used to calculate the bandgap and the cohesive energy of ZnCdO solid solutions. The properties of transparent conductive ZnO films, doped with Group III donor impurities (Al, Ga, In), are examined. It is shown that oxygen vacancies are responsible for the hole trap centers in the zinc oxide photoconductivity process. We also examine the photoluminescence properties of metal-ZnO nanocomposite structures, caused by surface plasmons.

Thin-Film Nanocomposite Membrane with the Minimum Amount of MOF by the Langmuir-Schaefer Technique for Nanofiltration.

PubMed

Navarro, Marta; Benito, Javier; Paseta, Lorena; Gascón, Ignacio; Coronas, Joaquín; Téllez, Carlos

2018-01-10

An innovative procedure for positioning a monolayer of hydrophilic metal organic framework (MOF) MIL-101(Cr) (MIL, Materials of Institute Lavoisier) nanoparticles (NPs) in thin-film nanocomposite (TFN) membranes has been implemented by transferring a Langmuir-Schaefer (LS) film of the MOF in between the polyamide thin layer at the top and the cross-linked asymmetric polyimide (P84) support at the bottom. The presence and layout of the LS-MIL-101(Cr) monolayer in the TFN membrane was confirmed by scanning transmission electron microscopy imaging with a high-angle annular dark-field detector images and X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy, and atomic force microscopy analyses. This methodology requires the smallest amount of MOF reported to date, 3.8 μg cm -2 , and promotes the formation of a defect-free ultrathin MOF film. Although conventional TFN membranes tend to show MOF agglomerates that could contribute to the formation of unselective defects, LS-TFN membranes, characterized by a homogeneous and continuous MOF coating, exhibit an optimal membrane performance, without a significant decrease in selectivity. Outstanding methanol permeances, one of the best results reported to date, of 10.1 ± 0.5 L m -2 h -1 bar -1 when filtering sunset yellow and of 9.5 ± 2.1 L m -2 h -1 bar -1 when filtering rose bengal have been achieved in LS-TFN membranes with a rejection higher than 90% in all cases. Methanol permeates through the polyamide and the LS-MIL-101(Cr) monolayer, greatly enhanced by the MOF pore system, in comparison to thin-film composite and conventional TFN membranes (7.5 ± 0.7 and 7.7 ± 1.1 L m -2 h -1 bar -1 when filtering sunset yellow), respectively, in which polyamide areas free of MOF NPs are present.

Ag/C:F Antibacterial and hydrophobic nanocomposite coatings

NASA Astrophysics Data System (ADS)

Kylián, Ondřej; Kratochvíl, Jiří; Petr, Martin; Kuzminova, Anna; Slavínská, Danka; Biederman, Hynek; Beranová, Jana

Silver-based nanomaterials that exhibit antibacterial character are intensively studied as they represent promising weapon against multi-drug resistant bacteria. Equally important class of materials represent coatings that have highly water repellent nature. Such materials may be used for fabrication of anti-fogging or self-cleaning surfaces. The aim of this study is to combine both of these valuable material characteristics. Antibacterial and highly hydrophobic Ag/C:F nanocomposite films were fabricated by means of gas aggregation source of Ag nanoparticles and sputter deposition of C:F matrix. The nanocomposite coatings had three-layer structure C:F base layer/Ag nanoparticles/C:F top layer. It is shown that the increasing number of Ag nanoparticles in produced coatings leads not only in enhancement of their antibacterial activity, but also causes substantial increase of their hydrophobicity. Under optimized conditions, the coatings are super-hydrophobic with water contact angle equal to 165∘ and are capable to induce 6-log reduction of bacteria presented in solution within 4h.

Electrochemical synthesis of three-dimensional porous networks of nickel with different micro-nano structures for the fabrication of Ni/MnOx nanocomposites with enhanced supercapacitive performance

NASA Astrophysics Data System (ADS)

Ashassi-Sorkhabi, H.; La'le Badakhshan, P.

2017-10-01

We have electrochemically synthesized 3D-porous Ni/MnOx nanocomposites for supercapacitor applications. 3D porous micro-nanostructured networks of nickel were prepared using hydrogen bubbles as a dynamic template at different deposition potentials and times. The prepared nickel films were used then as 3D-porous substrates for anodic deposition of manganese oxide nanostructures. The effects of deposition potential and time on the structure of the prepared nickel scaffolds and especially on the capacitive behavior of the subsequently fabricated 3D-porous Ni/MnOx nanocomposites were investigated. The results show that the areal capacitance and especially the rate capability of prepared Ni/MnOx nanocomposites have improved with increasing the deposition potential or optimizing the deposition time of nickel films in the nanocomposites. The prepared 3D-porous Ni/MnOx nanocomposite, in which the nickel scaffold has been deposited at the potential of -6 V and duration of 90s, show almost the highest capacitive performance among all other prepared nanocomposites. This prepared nanocomposite, with the loading mass of 1.65 mg cm-2, showed the high areal capacitance of 654 mF cm-2 (396.4 F g-1) at the current density of 0.5 mA cm-2 (0.3 A g-1) in 0.5 M Na2SO4 solution. This nanocomposite also revealed the highest rate capability; the capacitance retention is about 63% (412 mF cm-2) with increasing the discharge rate from 0.5 to 20 mA cm-2, which is almost twice the observed amount of retention when the deposition potential of Ni films was -2 V (31%) or their deposition time was 45 s (34%). In addition, the prepared nanocomposite exhibited an outstanding cycling stability. The capacitance retention was about 98.91% after performing 2000 charge-discharge cycles.

Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

NASA Technical Reports Server (NTRS)

Yoonessi, Mitra; Gaier, James R.

2010-01-01

Graphene nanosheet bisphenol A polycarbonate nanocomposites (0.027 2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 C, exhibited dc electrical percolation threshold of approx.0.14 and approx.0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

Colorless polyimide/organoclay nanocomposite substrates for flexible organic light-emitting devices.

PubMed

Kim, Jin-Hoe; Choi, Myeon-Chon; Kim, Hwajeong; Kim, Youngkyoo; Chang, Jin-Hae; Han, Mijeong; Kim, Il; Ha, Chang-Sik

2010-01-01

We report the preparation and application of indium tin oxide (ITO) coated fluorine-containing polyimide/organoclay nanocomposite substrate. Fluorine-containing polyimide/organoclay nanocomposite films were prepared through thermal imidization of poly(amic acid)/organoclay mixture films, whilst on which ITO thin films were coated on the films using a radio-frequency planar magnetron sputtering by varying the substrate temperature and the ITO thickness. Finally the ITO coated fluorine-containing polyimide/organoclay nanocomposite substrate was employed to make flexible organic light-emitting devices (OLED). Results showed that the lower sheet resistance was achieved when the substrate temperature was high and the ITO film was thick even though the optical transmittance was slightly lowered as the thickness increased. approximately 10 nm width ITO nanorods were found for all samples but the size of clusters with the nanorods was generally increased with the substrate temperature and the thickness. The flexible OLED made using the present substrate was quite stable even when the device was extremely bended.

Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.

PubMed

Krishnan, P Santhana Gopala; Joshi, Mangala; Bhargava, Prachur; Valiyaveettil, Suresh; He, Chaobin

2005-07-01

Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.

Development of novel nano-composite membranes as introduction systems for mass spectrometers: Contrasting nano-composite membranes and conventional inlet systems

NASA Astrophysics Data System (ADS)

Miranda, Luis Diego

This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite membranes were finally coupled to the inlet system of an underwater mass spectrometer revealing their utility in field deployments.

Colossal Terahertz Magnetoresistance at Room Temperature in Epitaxial La0.7Sr0.3MnO3 Nanocomposites and Single-Phase Thin Films.

PubMed

Lloyd-Hughes, J; Mosley, C D W; Jones, S P P; Lees, M R; Chen, A; Jia, Q X; Choi, E-M; MacManus-Driscoll, J L

2017-04-12

Colossal magnetoresistance (CMR) is demonstrated at terahertz (THz) frequencies by using terahertz time-domain magnetospectroscopy to examine vertically aligned nanocomposites (VANs) and planar thin films of La 0.7 Sr 0.3 MnO 3 . At the Curie temperature (room temperature), the THz conductivity of the VAN was dramatically enhanced by over 2 orders of magnitude under the application of a magnetic field with a non-Drude THz conductivity that increased with frequency. The direct current (dc) CMR of the VAN is controlled by extrinsic magnetotransport mechanisms such as spin-polarized tunneling between nanograins. In contrast, we find that THz CMR is dominated by intrinsic, intragrain transport: the mean free path was smaller than the nanocolumn size, and the planar thin-film exhibited similar THz CMR to the VAN. Surprisingly, the observed colossal THz magnetoresistance suggests that the magnetoresistance can be large for alternating current motion on nanometer length scales, even when the magnetoresistance is negligible on the macroscopic length scales probed by dc transport. This suggests that colossal magnetoresistance at THz frequencies may find use in nanoelectronics and in THz optical components controlled by magnetic fields. The VAN can be scaled in thickness while retaining a high structural quality and offers a larger THz CMR at room temperature than the planar film.

Metal-insulator transition in nanocomposite VOx films formed by anodic electrodeposition

NASA Astrophysics Data System (ADS)

Tsui, Lok-kun; Hildebrand, Helga; Lu, Jiwei; Schmuki, Patrik; Zangari, Giovanni

2013-11-01

The ability to grow VO2 films by electrochemical methods would open a low-cost, easily scalable production route to a number of electronic devices. We have synthesized VOx films by anodic electrodeposition of V2O5, followed by partial reduction by annealing in Ar. The resulting films are heterogeneous, consisting of various metallic/oxide phases and including regions with VO2 stoichiometry. A gradual metal insulator transition with a nearly two order of magnitude change in film resistance is observed between room temperature and 140 °C. In addition, the films exhibit a temperature coefficient of resistance of ˜ -2.4%/ °C from 20 to 140 °C.

Fabrication of optically transparent chitin nanocomposites

NASA Astrophysics Data System (ADS)

Shams, M. Iftekhar; Ifuku, Shinsuke; Nogi, Masaya; Oku, Takeshi; Yano, Hiroyuki

2011-02-01

This paper demonstrates the preparation of chitin nanofibers from crab shells using a simple mechanical treatment. The nanofibers are small enough to retain the transparency of neat acrylic resin. Possessing hydroxyl and amine/ N-acetyl functionalities, water suspension of chitin nanofibers was vacuum-filtered 9 times faster than cellulose nanofibers to prepare a nanofiber sheet of 90 mm in diameter. This is a prominent advantage of chitin nanofibers over cellulose nanofibers in terms of commercial application. Interestingly, chitin acrylic resin films exhibited much higher transparency than cellulose acrylic resin films owing to the close affinity between less hydrophilic chitin and hydrophobic resin. Furthermore, the incorporation of chitin nanofibers contributes to the significant improvement of the thermal expansion and mechanical properties of the neat acrylic resin. The properties of high light transmittance and low thermal expansion make chitin nanocomposites promising candidates for the substrate in a continuous roll-to-roll process in the manufacturing of various optoelectronic devices such as flat panel displays, bendable displays, and solar cells.

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balasubramanian, B; Kraemer, KL; Valloppilly, SR

2011-09-13

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) moleculesmore » using a thermal evaporation source, prior to deposition as TiO2-VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO2 nanoparticles serve two purposes, namely to prevent the TiO2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO2-VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO2-VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.« less

Preparation of nano cellulose fibers and its application in kappa-carrageenan based film.

PubMed

Savadekar, N R; Karande, V S; Vigneshwaran, N; Bharimalla, A K; Mhaske, S T

2012-12-01

Bio-based nanocomposite films were successfully developed using nanofibrillated cellulose (NFC) as the reinforcing phase and kappa-carrageenan (KCRG) as the matrix. NFC was successfully synthesis from short stable cotton fibers by chemo-mechanical process. The bionanocomposites were prepared by incorporating 0.1, 0.2, 0.3, 0.4, 0.5, and 1wt% of the NFC into a KCRG matrix using a solution casting method there characterization was done in terms of thermal properties (DSC), morphology (SEM), water vapor transmission rate (WVTR), oxygen transmission rate (OTR), X-ray diffractograms (XRD), and tensile properties. The main conclusion arising from the analysis of the result is that the bionanocomposites containing 0.4wt% of NFC exhibited the highest enhancement in tensile strength it is almost 44% improvement. WVTR and OTR results showed improvement of all nanocomposite film compare to control KCRG film. Copyright © 2012 Elsevier B.V. All rights reserved.

Extreme Mechanical Behavior of Nacre-Mimetic Graphene-Oxide and Silk Nanocomposites.

PubMed

Xie, Wanting; Tadepalli, Sirimuvva; Park, Sang Hyun; Kazemi-Moridani, Amir; Jiang, Qisheng; Singamaneni, Srikanth; Lee, Jae-Hwang

2018-02-14

Biological materials have the ability to withstand extreme mechanical forces due to their unique multilevel hierarchical structure. Here, we fabricated a nacre-mimetic nanocomposite comprised of silk fibroin and graphene oxide that exhibits hybridized dynamic responses arising from alternating high-contrast mechanical properties of the components at the nanoscale. Dynamic mechanical behavior of these nanocomposites is assessed through a microscale ballistic characterization using a 7.6 μm diameter silica sphere moving at a speed of approximately 400 m/s. The volume fraction of graphene oxide in these composites is systematically varied from 0 to 32 vol % to quantify the dynamic effects correlating with the structural morphologies of the graphene oxide flakes. Specific penetration energy of the films rapidly increases as the distribution of graphene oxide flakes evolves from noninteracting, isolated sheets to a partially overlapping continuous sheet. The specific penetration energy of the nanocomposite at the highest graphene oxide content tested here is found to be significantly higher than that of Kevlar fabrics and close to that of pure multilayer graphene. This study evidently demonstrates that the morphologies of nanoscale constituents and their interactions are critical to realize scalable high-performance nanocomposites using typical nanomaterial constituents having finite dimensions.

Development of bioactive fish gelatin/chitosan nanoparticles composite films with antimicrobial properties.

PubMed

Hosseini, Seyed Fakhreddin; Rezaei, Masoud; Zandi, Mojgan; Farahmandghavi, Farhid

2016-03-01

The objective of this work was to develop active bio-based nanocomposite films from fish gelatin (FG) and chitosan nanoparticles (CSNPs) incorporated with Origanum vulgare L. essential oil (OEO). CSNPs were obtained by ionic gelation of chitosan with sodium tripolyphosphate, which presented a spherical morphology with size range of 40-80nm. Remarkable differences in the surface morphology were observed between the control and bioactive nanocomposite films as revealed by SEM and AFM images. FTIR results confirmed that an interaction between polymer matrix and essential oil had occurred, as shown by an increase in the amplitude of peaks at wavenumbers 1242cm(-1) and 1451cm(-1). Meanwhile, XRD peaks of OEO-containing films were more intense, indicating that the introduction of essential oil into the film matrix induces an increase in crystallinity. TGA analysis demonstrated that the addition of OEO had no impact on thermal stability of the films. Inclusion of OEO in the film matrix resulted in less resistant and more flexible films, with a decrease in water vapor permeability (WVP). The FG/CSNPs bioactive films exhibited distinctive antimicrobial activity against four test food pathogens, namely Staphylococcus aureus, Listeria monocytogenes, Salmonella enteritidis and Escherichia coli. Copyright © 2015 Elsevier Ltd. All rights reserved.

Size-controlled growth and antibacterial mechanism for Cu:C nanocomposite thin films.

PubMed

Javid, Amjed; Kumar, Manish; Yoon, Seokyoung; Lee, Jung Heon; Han, Jeon Geon

2016-12-21

The interdependence of 'size' and 'volume-fraction' hinders the identification of their individual role in the interface properties of metal nanoparticles (NPs) embedded in a matrix. Here, the case of Cu NPs embedded in a C matrix is presented for their profound antibacterial activity. Cu:C nanocomposite thin films with fixed Cu content (≈12 atomic%) are prepared using a plasma process where plasma energy controls the size of Cu NPs (from 9 nm to 16 nm). An inverse relationship between the size-effect on antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria is established through the real time monitoring of an aliquot by inductively coupled plasma mass spectrometry, which confirmed the inverse relationship of Cu ion release from the nanocomposite with varied Cu NP sizes. It was found that enhancing the total power density increases the plasma density as well as effective kinetic energy of the plasma species, which in turn creates a large number of nucleation sites and restricts the island kind of growth of Cu NPs. The mechanism of NP size-control is illustrated on the basis of ion density and nucleation and the growth regime of plasma species. This physical approach to NP size reduction anticipates a contamination-free competitive recipe of size-control to capping based chemical methods.

Optical limiting in gelatin stabilized Cu-PVP nanocomposite colloidal suspension

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Gedam, P. P.; Thakare, N. B.; Talwatkar, S. S.; Sunatkari, A. L.; Muley, G. G.

2018-05-01

This article illustrates investigations on optical limiting properties of Cu-PVP nanocomposite colloidal suspension. Gelatin stabilized Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, etc. for structural and linear optical studies. Optical limiting properties of Colloidal Cu-PVP nanocomposites have been investigated at 808 nm diode CW laser. Minimum optical limiting threshold was found for GCu3-PVP nanocomposites sample. The strong optical limiting is thermal in origin as CW laser is used and effects are attributed to thermal lensing effect.

Spin-coated Films of Squarylium Dye J-Aggregates Exhibiting Ultrafast Optical Responses

NASA Astrophysics Data System (ADS)

Tatsuura, Satoshi; Tian, Minquan; Furuki, Makoto; Sato, Yasuhiro; Pu, Lyong Sun; Wada, Osamu

2000-08-01

The formation of J-aggregates of squarylium dye derivatives in spin-coated films is reported. Squarylium dye derivatives with dipropylamino bases are found to spontaneously aggregate in a spin-coated film. Aggregation is promoted when dye molecules are dispersed in a poly(vinyl alcohol) film, and when a spin-coated film of dye molecules is heated in the presence of acid vapor. In particular, J-aggregates formed by exposure to acetic acid vapor show the narrowest spectral width. J-aggregates formed by the acid treatment method are stable at room temperature and the spectral full-width at half maximum of the J-band is 20 nm. Optical response of the acid-treated film is confirmed to exhibit a short relaxation time of bleached absorption of 300 fs.

Thermal-induced SPR tuning of Ag-ZnO nanocomposite thin film for plasmonic applications

NASA Astrophysics Data System (ADS)

Singh, S. K.; Singhal, R.

2018-05-01

The formation of silver (Ag) nanoparticles in a ZnO matrix were successfully synthesized by RF-magnetron sputtering at room temperature. As prepared Ag-ZnO nanocomposite (NCs) thin films were annealed in vacuum at three different temperatures of 300 °C, 400 °C and 500 °C, respectively. The structural modifications for as-deposited and annealed films were estimated by X-ray diffraction and TEM techniques. The crystalline behavior preferably along the c-axis of the hexagonal wurtzite structure was observed in as-deposited Ag-ZnO film and improved significantly with increasing the annealing temperature. The crystallite size of as-deposited film was measured to be 13.6 nm, and increases up to 28.5 nm at higher temperatures. The chemical composition and surface structure of the as-deposited films were estimated by X-ray photoelectron spectroscopy. The presence of Ag nanoparticles with average size of 8.2 ± 0.2 nm, was confirmed by transmission electron microscopy. The strong surface plasmon resonance (SPR) band was observed at the wavelength of ∼565 nm for as-deposited film and a remarkable red shift of ∼22 nm was recorded after the annealing treatment as confirmed by UV-visible spectroscopy. Atomic force microscopy confirmed the grain growth from 60.38 nm to 79.42 nm for as-deposited and higher temperature annealed film respectively, with no significant change in the surface roughness. Thermal induced modifications such as disordering and lattice defects in Ag-ZnO NCs thin films were carried out by Raman spectroscopy. High quality Ag-ZnO NCs thin films with minimum strain and tunable optical properties could be useful in various plasmonic applications.

All-cellulose nanocomposite film made from bagasse cellulose nanofibers for food packaging application.

PubMed

Ghaderi, Moein; Mousavi, Mohammad; Yousefi, Hossein; Labbafi, Mohsen

2014-04-15

All-cellulose nanocomposite (ACNC) film was produced from sugarcane bagasse nanofibers using N,N-dimethylacetamide/lithium chloride solvent. The average diameter of bagasse fibers (14 μm) was downsized to 39 nm after disk grinding process. X-ray diffraction showed that apparent crystallinity and crystallite size decreased relatively to an increased duration of dissolution time. Thermogravimetric analysis confirmed that thermal stability of the ACNC was slightly less than that of the pure cellulose nanofiber sheet. Tensile strength of the fiber sheet, nanofiber sheet and ACNC prepared with 10 min dissolution time were 8, 101 and 140 MPa, respectively. Water vapor permeability (WVP) of the ACNC film increased relatively to an increased duration of dissolution time. ACNC can be considered as a multi-performance material with potential for application in cellulose-based food packaging owing to its promising properties (tough, bio-based, biodegradable and acceptable levels of WVP). Copyright © 2014 Elsevier Ltd. All rights reserved.

Barrier and Mechanical Properties of Starch-Clay Nanocomposite Films

USDA-ARS?s Scientific Manuscript database

The poor barrier and mechanical properties of biopolymer-based food packaging can potentially be enhanced by the use of layered silicates (nanoclay) to produce nanocomposites. In this study, starch-clay nano-composites were synthesized by a melt extrusion method. Natural (MMT) and organically modifi...

Process for the preparation of metal-containing nanostructured films

NASA Technical Reports Server (NTRS)

Lu, Yunfeng (Inventor); Wang, Donghai (Inventor)

2006-01-01

Metal-containing nanostructured films are prepared by electrodepositing a metal-containing composition within the pores of a mesoporous silica template to form a metal-containing silica nanocomposite. The nanocomposite is annealed to strengthen the deposited metal-containing composition. The silica is then removed from the nanocomposite, e.g., by dissolving the silica in an etching solution to provide a self-supporting metal-containing nanostructured film. The nanostructured films have a nanowire or nanomesh architecture depending on the pore structure of the mesoporous silica template used to prepare the films.

Solution Coating of Pharmaceutical Nanothin Films and Multilayer Nanocomposites with Controlled Morphology and Polymorphism.

PubMed

Horstman, Elizabeth M; Kafle, Prapti; Zhang, Fengjiao; Zhang, Yifu; Kenis, Paul J A; Diao, Ying

2018-03-28

Nanosizing is rapidly emerging as an alternative approach to enhance solubility and thus the bioavailability of poorly aqueous soluble active pharmaceutical ingredients (APIs). Although numerous techniques have been developed to perform nanosizing of API crystals, precise control and modulation of their size in an energy and material efficient manner remains challenging. In this study, we present meniscus-guided solution coating as a new technique to produce pharmaceutical thin films of nanoscale thickness with controlled morphology. We demonstrate control of aspirin film thickness over more than 2 orders of magnitude, from 30 nm to 1.5 μm. By varying simple process parameters such as the coating speed and the solution concentration, the aspirin film morphology can also be modulated by accessing different coating regimes, namely the evaporation regime and the Landau-Levich regime. Using ellipticine-a poorly water-soluble anticancer drug-as another model compound, we discovered a new polymorph kinetically trapped during solution coating. Furthermore, the polymorphic outcome can be controlled by varying coating conditions. We further performed layer-by-layer coating of multilayer nanocomposites, with alternating thin films of ellipticine and a biocompatible polymer, which demonstrate the potential of additive manufacturing of multidrug-personalized dosage forms using this approach.

Optically Transparent Ferromagnetic Nanogranular Films with Tunable Transmittance

PubMed Central

Kobayashi, Nobukiyo; Masumoto, Hiroshi; Takahashi, Saburo; Maekawa, Sadamichi

2016-01-01

Developing optically transparent magnets at room temperature is an important challenge. They would bring many innovations to various industries, not only for electronic and magnetic devices but also for optical applications. Here we introduce FeCo-(Al-fluoride) nanogranular films exhibiting ferromagnetic properties with high optical transparency in the visible light region. These films have a nanocomposite structure, in which nanometer-sized FeCo ferromagnetic granules are dispersed in an Al-fluoride crystallized matrix. The optical transmittance of these films is controlled by changing the magnetization. This is a new type of magneto-optical effect and is explained by spin-dependent charge oscillation between ferromagnetic granules due to quantum-mechanical tunneling. PMID:27677710

Effect of annealing temperature on optical and electrical properties of ZrO2-SnO2 based nanocomposite thin films

NASA Astrophysics Data System (ADS)

Anitha, V. S.; Lekshmy, S. Sujatha; Berlin, I. John; Joy, K.

2014-01-01

Transparent nanocomposite ZrO2-SnO2 thin films were prepared by sol-gel dip-coating technique. Films were annealed at 500°C, 800°C and 1200°C respectively. X-ray diffraction(XRD) spectra showed a mixture of three phases: tetragonal ZrO2 and SnO2 and orthorhombic ZrSnO4. The grain size of all the three phases' increased with annealing temperature. An average transmittance greater than 85%(in UV-Visible region) is observed for all the films. The band gap for the films decreased from 4.79 eV to 4.62 eV with increase in annealing temperature from 500 to 1200 °C. The electrical resistivity increased with increase in annealing temperature. Such composite ZrO2-SnO2 films can be used in many applications and in optoelectronic devices.

Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies.

PubMed

Yashchenok, Alexey M; Gorin, Dmitry A; Badylevich, Mikhail; Serdobintsev, Alexey A; Bedard, Matthieu; Fedorenko, Yanina G; Khomutov, Gennady B; Grigoriev, Dmitri O; Möhwald, Helmuth

2010-09-21

Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign.

PLGA/Ag nanocomposites: in vitro degradation study and silver ion release.

PubMed

Fortunati, E; Latterini, L; Rinaldi, S; Kenny, J M; Armentano, I

2011-12-01

New nanocomposite films based on a biodegradable poly (DL-Lactide-co-Glycolide) copolymer (PLGA) and different concentration of silver nanoparticles (Ag) were developed by solvent casting. In vitro degradation studies of PLGA/Ag nanocomposites were conducted under physiological conditions, over a 5 week period, and compared to the behaviour of the neat polymer. Furthermore the silver ions (Ag(+)) release upon degradation was monitored to obtain information on the properties of the nanocomposites during the incubation. The obtained results suggest that the PLGA film morphology can be modified introducing a small percentage of silver nanoparticles that do not affect the degradation mechanism of PLGA polymer in the nanocomposite. However results clearly evinced the stabilizing effect of the Ag nanoparticles in the PLGA polymer and the mineralization process induced by the combined effect of silver and nanocomposite surface topography. The Ag(+) release can be controlled by the polymer degradation processes, evidencing a prolonged antibacterial effect.

Self-Assembled Heteroepitaxial Oxide Nanocomposite for Photoelectrochemical Solar Water Oxidation

PubMed Central

2016-01-01

We report on spontaneously phase ordered heteroepitaxial SrTiO3 (STO):ZnFe2O4 (ZFO) nanocomposite films that give rise to strongly enhanced photoelectrochemical solar water oxidation, consistent with enhanced photoinduced charge separation. The STO:ZFO nanocomposite yielded an enhanced photocurrent density of 0.188 mA/cm2 at 1.23 V vs a reversible hydrogen electrode, which was 7.9- and 2.6-fold higher than that of the plain STO film and ZFO film cases under 1-sun illumination, respectively. The photoelectrode also produced stable photocurrent and Faradaic efficiencies of H2 and O2 formation that were more than 90%. Incident-photon-to-current-conversion efficiency measurements, Tauc plots, Mott–Schottky plots, and electrochemical impedance spectroscopy measurements proved that the strongly enhanced photogenerated charge separation resulted from vertically aligned pseudosingle crystalline components, epitaxial heterojunctions, and a staggered band alignment of the components of the nanocomposite films. This study presents a completely new avenue for efficient solar energy conversion applications. PMID:27212792

A flexible mesoporous Li4Ti5O12-rGO nanocomposite film as free-standing anode for high rate lithium ion batteries

NASA Astrophysics Data System (ADS)

Zhu, Kunxu; Gao, Hanyang; Hu, Guoxin

2018-01-01

Advanced flexible electrode is crucial in the development of flexible energy storage devices for emerging wearable and portable electronics. Herein, a free-standing flexible mesoporous Li4Ti5O12-rGO (LTO-rGO) nanocomposite film is rationally designed and fabricated for lithium ion batteries (LIBs). This efficient synthesis involves the growth of lithium titanate hydrate (LTH) precursors on the graphene oxide (GO) by a hydrothermal reaction, assembly into LTH-GO film by vacuum filtration with some extra GO added, and subsequent conversion into LTO-rGO nanocomposite film through calcination. When rGO content in the LTO-rGO film is set, the addition sequence of GO is found to affect its textural and mechanical properties. The resultant free-standing LTO-rGO electrode, taking advantages of high Li4Ti5O12 loading of 73.9%, mesoporous layer-stacked channels with good electron/ion conductivity, good mechanical strength, and enlarged electrode/electrolyte contact area, delivers excellent electrochemical performance (e.g., specific capacity of 135.4 mAh g-1 at 40 C) over the electrode of conventional configuration. Moreover, no organic but all inorganic reagents are used in the synthesis, offering an eco-friendly, cost-efficient, and easily scalable way to fabricate binder-free flexible electrode for LIBs.

Electrospun PVA/Bentonite Nanocomposites Mats for Drug Delivery

PubMed Central

Ferrández-Rives, Mariola; Gómez Ribelles, José Luis

2017-01-01

Electrospun mats and films of polyvinyl alcohol (PVA) hydrogel are produced for drug delivery. To provide mechanical consistency to the gel a reinforcement by nanoclays is introduced in the polymer matrix. Four different suspensions of nanoparticles in the polymer solution are prepared in an adequate solvent. These suspensions are subjected to an electrospinning process to produce the nanofiber mat, while films are produced by casting. The influence of the process parameters over the nanofibers microstructure is analyzed by scanning electron microscopy (SEM). The effectiveness of nanoclay encapsulation in the nanocomposites is tested by a thermogravimetric analysis. A crosslinking reaction in solution is carried out to prevent the dissolution of the nanocomposites in aqueous media. A model protein (bovine serum albumin, BSA) is absorbed in the nanocomposites to characterize the release kinetics in phosphate-buffered saline (PBS). PMID:29261123

Carbon Nanotube-Poly(vinylalcohol) Nanocomposite Film Devices: Applications for Femtosecond Fiber Laser Mode Lockers and Optical Amplifier Noise Suppressors

NASA Astrophysics Data System (ADS)

Sakakibara, Youichi; Rozhin, Aleksey G.; Kataura, Hiromichi; Achiba, Yohji; Tokumoto, Madoka

2005-04-01

We fabricated single-wall carbon nanotube (SWNT)/poly(vinylalcohol) (PVA) nanocomposite freestanding films and examined their application in devices in which the saturable absorption of SWNTs at near-infrared optical telecommunication wavelengths can be utilized. In a passively mode-locked fiber laser, we integrated a 30-μm-thick SWNT/PVA film into a fiber connection adaptor with the film sandwiched by a pair of fiber ferrules. A ring fiber laser with a SWNT/PVA saturable absorber was operated very easily in the mode-locked short-pulse mode with a pulse width of about 500 fs. Reproducible stable device performance was confirmed. In examining noise suppression for optical amplifiers, mixed light of semiconductor amplified spontaneous emission (ASE) source and 370 fs laser pulses was passed through a 100-μm-thick SWNT/PVA film. The transmission loss of the femtosecond pulse light was smaller than that of the ASE light. This proved that the SWNT/PVA film has the ability to suppress ASE noise.

Colossal terahertz magnetoresistance at room temperature in epitaxial La 0.7Sr 0.3MnO 3 nanocomposites and single-phase thin films

DOE PAGES

Lloyd-Hughes, James; Mosley, C. D. W.; Jones, S. P. P.; ...

2017-03-13

Colossal magnetoresistance (CMR) is demonstrated at terahertz (THz) frequencies by using terahertz time-domain magnetospectroscopy to examine vertically aligned nanocomposites (VANs) and planar thin films of La 0.7Sr 0.3MnO 3. At the Curie temperature (room temperature), the THz conductivity of the VAN was dramatically enhanced by over 2 orders of magnitude under the application of a magnetic field with a non-Drude THz conductivity that increased with frequency. The direct current (dc) CMR of the VAN is controlled by extrinsic magnetotransport mechanisms such as spin-polarized tunneling between nanograins. In contrast, we find that THz CMR is dominated by intrinsic, intragrain transport: themore » mean free path was smaller than the nanocolumn size, and the planar thin-film exhibited similar THz CMR to the VAN. Surprisingly, the observed colossal THz magnetoresistance suggests that the magnetoresistance can be large for alternating current motion on nanometer length scales, even when the magnetoresistance is negligible on the macroscopic length scales probed by dc transport. This suggests that colossal magnetoresistance at THz frequencies may find use in nanoelectronics and in THz optical components controlled by magnetic fields. As a result, the VAN can be scaled in thickness while retaining a high structural quality and offers a larger THz CMR at room temperature than the planar film.« less

Graphene based nanocomposite hybrid electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Aphale, Ashish N.

There is an unmet need to develop high performance energy storage systems (ESS), capable of storing energy from both renewable and non-renewable sources to meet the current energy crisis and depletion of non-renewable sources. Amongst many available ESS, supercapacitors (ECs) are the most promising because they exhibit a high charge/discharge rate and power density, along with a long cycle life. The possibility of exploring the use of atomically thin carbon allotropes like graphene, carbon nanotubes (CNTs) and electrically conducting polymers (ECPs) such as polypyrrole (PPy) has been studied as a high performance conducting electrodes in supercapacitor application. A novel templated sustainable nanocomposite electrode has been fabricated using cellulose extracted from Cladophora c. aegagropila algae as component of the assembled supercapacitor device which later has been transitioned to a unique template-less freestanding nanocomposite supercapacitor electrode. The specific capacitance of polypyrrole-graphene-cellulose nanocomposite as calculated from cyclic voltammetry curve is 91.5 F g -1 at the scan rate 50 m Vs-1 in the presence of 1M NaCl electrolyte. The open circuit voltage of the device with polypyrrole -graphene-cellulose electrode was found to be around 225 m V and that of the polypyrrole -cellulose device is only 53 m V without the presence of graphene in the nanocomposite electrode. Understanding the fundamentals by fabricating template nanocomposite electrode, it led to fabricate a unique nanocomposite template-less freestanding film which comprises of polypyrrole-graphene-CNT hybrid. Various experiments have been performed using different electrolytes such ascorbic acid, sodium sulfate and sulfuric acid in different scan rates. The specific capacitance of polypyrrole-graphene-CNT nanocomposite with 0.1 wt% of graphene-CNT, as calculated from cyclic voltammetry curve is 450 F g-1 at the scan rate 5 m V s-1. For the first time a nanofibrous membrane has

Improved dielectric constant and breakdown strength of γ-phase dominant super toughened polyvinylidene fluoride/TiO2 nanocomposite film: an excellent material for energy storage applications and piezoelectric throughput

NASA Astrophysics Data System (ADS)

Mehebub Alam, Md; Ghosh, Sujoy Kumar; Sarkar, Debabrata; Sen, Shrabanee; Mandal, Dipankar

2017-01-01

Titanium dioxide (TiO2) nanoparticles (NPs) embedded γ-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m-1). It also exhibits a high energy density of 4 J cm-3 which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength. Owing to their electroactive nature and extraordinary mechanical properties, PNC films have a strong ability to fabricate the piezoelectric nanogenerators (PNGs) that have recently been an area of focus regarding mechanical energy harvesting. The feasibility of piezoelectric voltage generation from PNGs is demostrated under the rotating fan that also promises further utility such as rotational speed (RPM) determination.

Ductile all-cellulose nanocomposite films fabricated from core-shell structured cellulose nanofibrils.

PubMed

Larsson, Per A; Berglund, Lars A; Wågberg, Lars

2014-06-09

Cellulosic materials have many desirable properties such as high mechanical strength and low oxygen permeability and will be an important component in a sustainable biomaterial-based society, but unfortunately they often lack the ductility and formability offered by petroleum-based materials. This paper describes the fabrication and characterization of nanocomposite films made of core-shell modified cellulose nanofibrils (CNFs) surrounded by a shell of ductile dialcohol cellulose, created by heterogeneous periodate oxidation followed by borohydride reduction of the native cellulose in the external parts of the individual fibrils. The oxidation with periodate selectively produces dialdehyde cellulose, and the process does not increase the charge density of the material. Yet the modified cellulose fibers could easily be homogenized to CNFs. Prior to film fabrication, the CNF was shown by atomic force microscopy to be 0.5-2 μm long and 4-10 nm wide. The films were fabricated by filtration, and besides uniaxial tensile testing at different relative humidities, they were characterized by scanning electron microscopy and oxygen permeability. The strength-at-break at 23 °C and 50% RH was 175 MPa, and the films could, before rupture, be strained, mainly by plastic deformation, to about 15% and 37% at 50% RH and 90% RH, respectively. This moisture plasticization was further utilized to form a demonstrator consisting of a double-curved structure with a nominal strain of 24% over the curvature. At a relative humidity of 80%, the films still acted as a good oxygen barrier, having an oxygen permeability of 5.5 mL·μL/(m(2)·24 h·kPa). These properties indicate that this new material has a potential for use as a barrier in complex-shaped structures and hence ultimately reduce the need for petroleum-based plastics.

Two-phase nc-TiN/a-(C,CN{sub x}) nanocomposite films: A HRTEM and MC simulation study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, J.; Lu, Y. H.; Hu, X. J.

2013-06-18

The grain growth in two-phase nanocomposite Ti-C{sub x}-N{sub y} thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N{sub 2} gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CN{sub x}) phase was investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and Monte Carlo (MC) simulations. The HRTEM results revealed that amorphous-free solid solution Ti(C,N) thin films exhibited polycrystallites with different sizes, orientations and irregular shapes. The grain size varied in the range between several nanometers and several decade nanometers. Further increase of C content (up to {approx}19 at.% C) mademore » the amorphous phase wet nanocrystallites, which strongly hindered the growth of nanocrystallites. As a result, more regular Ti(C,N) nanocrystallites with an average size of {approx}5 nm were found to be separated by {approx}0.5-nm amorphous phases. When C content was further increased (up to {approx}48 at.% in this study), thicker amorphous matrices were produced and followed by the formation of smaller sized grains with lognormal distribution. Our MC analysis indicated that with increasing amorphous volume fraction (i.e. increasing C content), the transformation from nc/nc grain boundary (GB)-curvature-driven growth to a/nc GB-curvature-driven growth is directly responsible for the observed grain growth from great inhomogeneity to homogeneity process.« less

Influence of gamma irradiation on structural, thermal and antibacterial properties of HPMC/ZnO nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, B. Lakshmeesha; Madhukumar, R.; Latha, S.

This work was carried out to evaluate the effect of gamma irradiation on the structural, thermal and antibacterial properties of HPMC/ZnO nanocomposite films exposed to Cobalt-60 (Average energy: 1.25 MeV). The X-ray diffraction study revealed that the crystallite size (L in Å) decreased as irradiation dose increased. The crystallinity (X{sub c}) of the nanocomposites initially increased and at higher doses it was decreased. The thermal stability of the nanocomposites increased up to 50 kGy and after that decreased as the irradiation dose increased. But, HPMC/ZnO nanocomposite films, showed a promising range of antimicrobial activity against tested micro-organisms making nanocomposites suitablemore » for food packing and other biomedical applications.« less

Optical, electrochemical and hydrophilic properties of Y2O3 doped TiO2 nanocomposite films.

PubMed

Zhang, Xiangchao; Yang, Huaming; Tang, Aidong

2008-12-25

The 5% Y2O3 doped TiO2 nanocomposite film (YTF) deposited on ITO glass substrate has been synthesized by the sol-gel dip-coating method. The as-synthesized samples were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), voltage-current (V-I), electrochemical impedance spectroscopy (EIS) and ultraviolet-visible (UV-vis) analysis technologies. The crystalline structure, surface morphology and surface chemical composition of YTF sample have been primarily investigated. The results demonstrate that YTF is anatase crystalline phase with thickness of 480 nm and consists of spherical shape particles with a grain size of about 15.8 nm. The binding energy appears as a chemical shift, and relatively more Y and Ti species are present on the surface, indicating that active surfaces of the nanocomposite film have been enhanced with more oxygen vacancies Vö due to doping Y2O3 to TiO2. The absorption edge of YTF has a red shift, and the optical properties of YTF in visible light region have been obviously improved. The water contact angle is about 8 degrees after daylight lamp irradiation 60 min. An equivalent circuit model provided a reliable description for the electrochemical systems. Based on the Mott-Schottky equation, the donor concentration (ND) for YTF is 1.05 x 10(20) cm(-3), which enhances 1 order of magnitude than that for pure TiO2 film (TF), the flat-band potential (V(fb)) and the space charge layer (d(sc)) obviously decreased. With the incorporation of Y2O3 into TiO2, the optical, electrochemical and photoinduced hydrophilic properties of YTF in visible light region have obviously improved, indicating that YTF shows promising applications in solar energy conversion, self-cleaning and other potential fields.

Elastic Modulus and Thermal Conductivity of Thiolene/TiO2 Nanocomposites

PubMed Central

2017-01-01

Metal oxide based polymer nanocomposites find diverse applications as functional materials, and in particular thiol-ene/TiO2 nanocomposites are promising candidates for dental restorative materials. The important mechanical and thermal properties of the nanocomposites, however, are still not well understood. In this study, the elastic modulus and thermal conductivity of thiol-ene/TiO2 nanocomposite thin films with varying weight fractions of TiO2 nanoparticles are investigated by using Brillouin light scattering spectroscopy and 3ω measurements, respectively. As the TiO2 weight fraction increases from 0 to 90%, the effective elastic longitudinal modulus of the films increases from 6.2 to 37.5 GPa, and the effective thermal conductivity from 0.04 to 0.76 W/m K. The former increase could be attributed to the covalent cross-linking of the nanocomposite constituents. The latter one could be ascribed to the addition of high thermal conductivity TiO2 nanoparticles and the formation of possible conductive channels at high TiO2 weight fractions. The linear dependence of the thermal conductivity on the sound velocity, reported for amorphous polymers, is not observed in the present nanocomposite system. PMID:29755637

Carbon nanotube-polymer nanocomposite infrared sensor.

PubMed

Pradhan, Basudev; Setyowati, Kristina; Liu, Haiying; Waldeck, David H; Chen, Jian

2008-04-01

The infrared photoresponse in the electrical conductivity of single-walled carbon nanotubes (SWNTs) is dramatically enhanced by embedding SWNTs in an electrically and thermally insulating polymer matrix. The conductivity change in a 5 wt % SWNT-polycarbonate nanocomposite is significant (4.26%) and sharp upon infrared illumination in the air at room temperature. While the thermal effect predominates in the infrared photoresponse of a pure SWNT film, the photoeffect predominates in the infrared photoresponse of SWNT-polycarbonate nanocomposites.

Thermal stability increase in metallic nanoparticles-loaded cellulose nanocrystal nanocomposites.

PubMed

Goikuria, U; Larrañaga, A; Vilas, J L; Lizundia, E

2017-09-01

Due to the potential of CNC-based flexible materials for novel industrial applications, the aim of this work is to improve the thermal stability of cellulose nanocrystals (CNC) films through a straightforward and scalable method. Based of nanocomposite approach, five different metallic nanoparticles (ZnO, SiO 2 , TiO 2 , Al 2 O 3 and Fe 2 O 3 ) have been co-assembled in water with CNCs to obtain free-standing nanocomposite films. Thermogravimetric analysis (TGA) reveals an increased thermal stability upon nanoparticle. This increase in the thermal stability reaches a maximum of 75°C for the nanocomposites having 10wt% of Fe 2 O 3 and ZnO. The activation energies of thermodegradation process (E a ) determined according to Kissinger and Ozawa-Flynn-Wall methods further confirm the delayed degradation of CNC nanocomposites upon heating. Finally, the changes induced in the crystalline structure during thermodegradation were followed by wide angle X-ray diffraction (WAXD). It is also observed that thermal degradation proceeds at higher temperatures for nanocomposites having metallic nanoparticles. Overall, experimental findings here showed make nanocomposite approach a simple low-cost environmentally-friendly strategy to overcome the relatively poor thermal stability of CNCs when extracted via sulfuric acid assisted hydrolysis of cellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multifunctional zirconium oxide doped chitosan based hybrid nanocomposites as bone tissue engineering materials.

PubMed

Bhowmick, Arundhati; Jana, Piyali; Pramanik, Nilkamal; Mitra, Tapas; Banerjee, Sovan Lal; Gnanamani, Arumugam; Das, Manas; Kundu, Patit Paban

2016-10-20

This paper reports the development of multifunctional zirconium oxide (ZrO2) doped nancomposites having chitosan (CTS), organically modified montmorillonite (OMMT) and nano-hydroxyapatite (HAP). Formation of these nanocomposites was confirmed by various characterization techniques such as Fourier transform infrared spectroscopy and powder X-ray diffraction. Scanning electron microscopy images revealed uniform distribution of OMMT and nano-HAP-ZrO2 into CTS matrix. Powder XRD study and TEM study revealed that OMMT has partially exfoliated into the polymer matrix. Enhanced mechanical properties in comparison to the reported literature were obtained after the addition of ZrO2 nanoparticle into the nanocomposites. In rheological measurements, CMZH I-III exhibited greater storage modulus (G') than loss modulus (G″). TGA results showed that these nanocomposites are thermally more stable compare to pure CTS film. Strong antibacterial zone of inhibition and the lowest minimum inhibition concentration (MIC) value of these nanocomposites against bacterial strains proved that these materials have the ability to prevent bacterial infection in orthopedic implants. Compatibility of these nanocomposites with pH and blood of human body was established. It was observed from the swelling study that the swelling percentage was increased with decreasing the hydrophobic OMMT content. Human osteoblastic MG-63 cell proliferations were observed on the nanocomposites and cytocompatibility of these nanocomposites was also established. Moreover, addition of 5wt% OMMT and 5wt% nano-HAP-ZrO2 into 90wt% CTS matrix provides maximum tensile strength, storage modulus, aqueous swelling and cytocompatibility along with strong antibacterial effect, pH and erythrocyte compatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polymer-phyllosilicate nanocomposites and their preparation

DOEpatents

Chaiko, David J.

2007-01-09

Polymer-phyllosilicate nanocomposites that exhibit superior properties compared to the polymer alone, and methods-for producing these polymer-phyllosilicate nanocomposites, are provided. Polymeric surfactant compatabilizers are adsorbed onto the surface of hydrophilic or natural phyllosilicates to facilitate the dispersal and exfoliation of the phyllosilicate in a polymer matrix. Utilizing polymeric glycol based surfactants, polymeric dicarboxylic acids, polymeric diammonium surfactants, and polymeric diamine surfactants as compatabilizers facilitates natural phyllosilicate and hydrophilic organoclay dispersal in a polymer matrix to produce nanocomposites.

Graphene-conducting polymer nanocomposite as novel electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Gómez, Humberto; Ram, Manoj K.; Alvi, Farah.; Villalba, P.; Stefanakos, Elias (Lee); Kumar, Ashok

A novel graphene-polyaniline nanocomposite material synthesized using chemical precipitation technique is reported as an electrode for supercapacitors. The graphene (G)-polyaniline (PANI) nanocomposite film was dissolved in N-Methyl-2-pyrrolidone (NMP) and characterized using Raman, FTIR, Scanning Electron Microscopy, Transmission Electron Microscopy, and cyclic voltammetry (CV) techniques. The interesting composite structure could be observed using different ratios of graphene and aniline monomer. The supercapacitor is fabricated using G-PANI in N-Methyl-2-pyrrolidone (NMP) and G-PANI-Nafion films on graphite electrodes. A specific capacitance of 300-500 F g -1 at a current density of 0.1 A g -1 is observed over graphene-PANI nanocomposite materials. The aim of this study is to tailor the properties of the capacitors through the optimization of their components, and packaging towards a qualification for portable systems applications. Based on experimental data shown in this work, conducting polymer nanocomposite capacitor technology could be viable, and could also surpass existing technologies when such a novel approach is used.

Biocide immobilized OMMT-carbon dot reduced Cu2O nanohybrid/hyperbranched epoxy nanocomposites: Mechanical, thermal, antimicrobial and optical properties.

PubMed

De, Bibekananda; Gupta, Kuldeep; Mandal, Manabendra; Karak, Niranjan

2015-11-01

The present work demonstrated a transparent thermosetting nanocomposite with antimicrobial and photoluminescence attributes. The nanocomposites are fabricated by incorporation of different wt.% (1, 2 and 3) of a biocide immobilized OMMT-carbon dot reduced Cu2O nanohybrid (MITH-NH) in the hyperbranched epoxy matrix. MITH-NH is obtained by immobilization of 2-methyl-4-isothiazolin-3-one hydrochloride (MITH) at room temperature using sonication on OMMT-carbon dot reduced Cu2O nanohybid. The nanohybrid is prepared by reduction of cupric acetate using carbon dot as the reducing agent in the presence of OMMT at 70°C. The significant improvements in tensile strength (~2 fold), elongation at break (3 fold), toughness (4 fold) and initial thermal degradation temperature (30°C) of the pristine hyperbranched epoxy system are achieved by incorporation of 3wt.% of MITH-NH in it. The nanocomposites exhibit strong antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae and Pseudomonas aeruginosa bacteria and Candida albicans, a fungus. The nanocomposite also shows significant activity against biofilm formation compared to the pristine thermoset. Further, the nanocomposite films emit different colors on exposure of different wavelengths of UV light. The properties of these nanocomposites are also compared with the same nanohybrid without OMMT. Copyright © 2015. Published by Elsevier B.V.

Investigation of anticorrosion properties of nanocomposites of spray coated zinc oxide and titanium dioxide thin films on stainless steel (304L SS) in saline environment

NASA Astrophysics Data System (ADS)

P, Muhamed Shajudheen V.; S, Saravana Kumar; V, Senthil Kumar; Maheswari A, Uma; M, Sivakumar; Rani K, Anitha

2018-01-01

The present study reports the anticorrosive nature of nanocomposite thin films of zinc oxide and titanium dioxide on steel substrate (304L SS) using spray coating method. The morphology and chemical constituents of the nanocomposite thin film were characterized by field effect scanning electron microscopy and energy dispersive analysis of x-ray (EDAX) studies. From the EDAX studies, it was observed that nanocomposite coatings of desired stoichiometry can be synthesized using present coating technique. The cyclic voltametric techniques such as Tafel analysis and electrochemical impedance spectroscopy (EIS) analysis were conducted to study the anticorrosion properties of the coatings. The E corr values obtained from Tafel polarization curves of the sample coated with nanocomposites of ZnO and TiO2 in different ratios (5:1, 1:1 and 1:5) indicated that the corrosion resistance was improved compared to bare steel. The coating resistance values obtained from the Nyquist plot after fitting with equivalent circuit confirmed the improved anticorrosion performance of the coated samples. The sample coated with ZnO: TiO2 in the ratio 1:5 showed better corrosion resistance compared to other ratios. The Tafel and EIS studies were repeated after exposure to 5% NaCl for 390 h and the results indicated the anticorrosive nature of the coating in the aggressive environment. The root mean square deviation of surface roughness values calculated from the AFM images before and after salt spray indicated the stability of coating in the saline environment.

Colossal Room-Temperature Electrocaloric Effect in Ferroelectric Polymer Nanocomposites Using Nanostructured Barium Strontium Titanates.

PubMed

Zhang, Guangzu; Zhang, Xiaoshan; Yang, Tiannan; Li, Qi; Chen, Long-Qing; Jiang, Shenglin; Wang, Qing

2015-07-28

The electrocaloric effect (ECE) refers to conversion of thermal to electrical energy of polarizable materials and could form the basis for the next-generation refrigeration and power technologies that are highly efficient and environmentally friendly. Ferroelectric materials such as ceramic and polymer films exhibit large ECEs, but each of these monolithic materials has its own limitations for practical cooling applications. In this work, nanosized barium strontium titanates with systematically varied morphologies have been prepared to form polymer nanocomposites with the ferroelectric polymer matrix. The solution-processed polymer nanocomposites exhibit an extraordinary room-temperature ECE via the synergistic combination of the high breakdown strength of a ferroelectric polymer matrix and the large change of polarization with temperature of ceramic nanofillers. It is found that a sizable ECE can be generated under both modest and high electric fields, and further enhanced greatly by tailoring the morphology of the ferroelectric nanofillers such as increasing the aspect ratio of the nanoinclusions. The effect of the geometry of the nanofillers on the dielectric permittivity, polarization, breakdown strength, ECE and crystallinity of the ferroelectric polymer has been systematically investigated. Simulations based on the phase-field model have been carried out to substantiate the experimental results. With the remarkable cooling energy density and refrigerant capacity, the polymer nanocomposites are promising for solid-state cooling applications.

Bio-inspired layered chitosan/graphene oxide nanocomposite hydrogels with high strength and pH-driven shape memory effect.

PubMed

Zhang, Yaqian; Zhang, Min; Jiang, Haoyang; Shi, Jinli; Li, Feibo; Xia, Yanhong; Zhang, Gongzheng; Li, Huanjun

2017-12-01

The layered nanocomposite hydrogel films containing chitosan (CS) and graphene oxide (GO) have been prepared by water evaporation induced self-assembly and subsequent physical cross-linking in alkaline solution. The layered CS/GO hydrogel films obtained have a nacre-like brick-and-mortar microstructure, which contributes to their excellent mechanical properties. The tensile strength and elongation at break of the hydrogel films with 5wt% GO are 5.35MPa and 193.5%, respectively, which are comparable to natural costal cartilage. Furthermore, the CS/GO hydrogel films exhibited pH-driven shape memory effect, and this unique phenomenon is mainly attributed to the reversible transition of partial physically cross-linking corresponding to hydrogen bondings and hydrophobic interactions between CS polymer chains due to pH changing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of Plastizers on the Structure and Properties of Starch-Clay Nanocomposites

USDA-ARS?s Scientific Manuscript database

Biodegradable nanocomposites were successfully fabricated from corn starch and montmorillonite (MMT) nanoclays by melt extrusion processing. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and film propertie...

Nanocomposite of graphene and metal oxide materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2013-10-15

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Nanocomposite of graphene and metal oxide materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2012-09-04

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10C.

Nanocomposite of graphene and metal oxide materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2015-06-30

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Non-exhibition of Bragg phenomenon by chevronic sculptured thin films

NASA Astrophysics Data System (ADS)

Vepachedu, Vikas; McAtee, Patrick D.; Lakhtakia, Akhlesh

2017-08-01

The unit cell of a chevronic sculptured thin film (ChevSTF) comprises two identical columnar thin films (CTFs) except that the nanocolumns of the first are oriented at an angle Χ and nanocolumns of the second are oriented at an angle π - χ with respect to the interface of the two CTFs. A ChevSTF containing 10 unit cells was fabricated and its planewave reflectance and transmittance spectrums of this ChevSTF were measured. Despite its structural periodicity, the ChevSTF did not exhibit the Bragg phenomenon. Theoretical calculations with the CTFs modeled as biaxial dielectric materials indicated that the Bragg phenomenon would not be manifested for normal and near-normal incidence, but vestigial manifestation was possible for sufficiently oblique incidence.

Nanocomposites of polyimide and mixed oxide nanoparticles for high performance nanohybrid gate dielectrics in flexible thin film transistors

NASA Astrophysics Data System (ADS)

Kim, Ju Hyun; Hwang, Byeong-Ung; Kim, Do-Il; Kim, Jin Soo; Seol, Young Gug; Kim, Tae Woong; Lee, Nae-Eung

2017-05-01

Organic gate dielectrics in thin film transistors (TFTs) for flexible display have advantages of high flexibility yet have the disadvantage of low dielectric constant (low- k). To supplement low- k characteristics of organic gate dielectrics, an organic/inorganic nanocomposite insulator loaded with high- k inorganic oxide nanoparticles (NPs) has been investigated but high loading of high- k NPs in polymer matrix is essential. Herein, compositing of over-coated polyimide (PI) on self-assembled (SA) layer of mixed HfO2 and ZrO2 NPs as inorganic fillers was used to make dielectric constant higher and leakage characteristics lower. A flexible TFT with lower the threshold voltage and high current on/off ratio could be fabricated by using the hybrid gate dielectric structure of the nanocomposite with SA layer of mixed NPs on ultrathin atomic-layer deposited Al2O3. [Figure not available: see fulltext.

Synthesis of Transparent Aqueous ZrO2 Nanodispersion with a Controllable Crystalline Phase without Modification for a High-Refractive-Index Nanocomposite Film.

PubMed

Xia, Yi; Zhang, Cong; Wang, Jie-Xin; Wang, Dan; Zeng, Xiao-Fei; Chen, Jian-Feng

2018-05-30

The controllable synthesis of metal oxide nanoparticles is of fundamental and technological interest. In this article, highly transparent aqueous nanodispersion of ZrO 2 with controllable crystalline phase, high concentration, and long-term stability was facilely prepared without any modification via the reaction of inexpensive inorganic zirconium salt and sodium hydroxide in water under an acid surrounding, combined with hydrothermal treatment. The as-prepared transparent nanodispersion had an average particle size of 7 nm, a high stability of 18 months, and a high solid content of 35 wt %. ZrO 2 nanocrystals could be readily dispersed in many solvents with high polarity including ethanol, dimethyl sulfoxide, acetic acid, ethylene glycol, and N, N-dimethylformamide, forming stable transparent nanodispersions. Furthermore, highly transparent polyvinyl alcohol/ZrO 2 nanocomposite films with high refractive index were successfully prepared with a simple solution mixing route. The refractive index could be tuned from 1.528 to 1.754 (@ 589 nm) by changing the mass fraction (0-80 wt %) of ZrO 2 in transparent nanocomposite films.

Development of a flexible nanocomposite TiO2 film as a protective coating for bioapplications of superelastic NiTi alloys

NASA Astrophysics Data System (ADS)

Aun, Diego Pinheiro; Houmard, Manuel; Mermoux, Michel; Latu-Romain, Laurence; Joud, Jean-Charles; Berthomé, Gregory; Buono, Vicente Tadeu Lopes

2016-07-01

An experimental procedure to coat superelastic NiTi alloys with flexible TiO2 protective nanocomposite films using sol-gel technology was developed in this work to improve the metal biocompatibility without deteriorating its superelastic mechanical properties. The coatings were characterized by scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and glazing incidence X-ray diffraction. The elasticity of the film was tested in coated specimens submitted to three-point bending tests. A short densification by thermal treatment at 500 °C for 10 min yielded a bilayer film consisting of a 50 nm-thick crystallized TiO2 at the inner interface with another 50-nm-thick amorphous oxide film at the outer interface. This bilayer could sustain over 6.4% strain without cracking and could thus be used to coat biomedical instruments as well as other devices made with superelastic NiTi alloys.

Borate cross-linked graphene oxide-chitosan as robust and high gas barrier films

NASA Astrophysics Data System (ADS)

Yan, Ning; Capezzuto, Filomena; Lavorgna, Marino; Buonocore, Giovanna G.; Tescione, Fabiana; Xia, Hesheng; Ambrosio, Luigi

2016-05-01

Chitosan (CS) is one of the most promising polymers due to its biocompatibility, biodegradability, and natural abundance. However, its poor mechanical and barrier properties make it difficult to satisfy a wide range of applications. Herein, borate ions, originating from the hydrolysis of sodium tetraborate decahydrate (borax), have been used to crosslink chitosan and graphene oxide (GO) nanocomposites. Chitosan films consisting of 1.0 wt% boron and 1.0 wt% GO exhibit a significant improvement in both the toughness and oxygen barrier properties compared to pristine chitosan. In particular the tensile strength of the samples after thermal treatment increases by ~160% compared to pristine chitosan, whereas their oxygen permeability reduces by ~90%. This is ascribed to the chemical crosslinking between chitosan and GO nanoplatelets through borate ions, as well as the formation of a layered morphology with graphene nanoplatelets oriented parallel to the sample surface. The exceptional robust and high gas barrier film has promising application in the packaging industry. The borate-crosslinking chemistry represents the potential strategy for improving properties of other polymer nanocomposites.Chitosan (CS) is one of the most promising polymers due to its biocompatibility, biodegradability, and natural abundance. However, its poor mechanical and barrier properties make it difficult to satisfy a wide range of applications. Herein, borate ions, originating from the hydrolysis of sodium tetraborate decahydrate (borax), have been used to crosslink chitosan and graphene oxide (GO) nanocomposites. Chitosan films consisting of 1.0 wt% boron and 1.0 wt% GO exhibit a significant improvement in both the toughness and oxygen barrier properties compared to pristine chitosan. In particular the tensile strength of the samples after thermal treatment increases by ~160% compared to pristine chitosan, whereas their oxygen permeability reduces by ~90%. This is ascribed to the chemical

Incorporation of layered double nanomaterials in thin film nanocomposite nanofiltration membrane for magnesium sulphate removal

NASA Astrophysics Data System (ADS)

Hanis Tajuddin, Muhammad; Yusof, Norhaniza; Salleh, Wan Norharyati Wan; Fauzi Ismail, Ahmad; Hanis Hayati Hairom, Nur; Misdan, Nurasyikin

2018-03-01

Thin film nanocomposite (TFN) membrane with copper-aluminium layered double hydroxides (LDH) incorporated into polyamide (PA) selective layer has been prepared for magnesium sulphate salt removal. 0, 0.05, 0.1, 0.15, 0.2 wt% of LDH were dispersed in the trimesoyl chloride (TMC) in n-hexane as organic solution and embedded into PA layer during interfacial polymerization with piperazine. The fabricated membranes were further characterized to evaluate its morphological structure and membrane surface hydrophilicity. The TFN membranes performance were evaluated with divalent salt magnesium sulphate (MgSO4) removal and compared with thin film composite (TFC). The morphological structures of TFN membranes were altered and the surface hydrophilicity were enhanced with addition of LDH. Incorporation of LDH has improved the permeate water flux by 82.5% compared to that of TFC membrane with satisfactory rejection of MgSO4. This study has experimentally validated the potential of LDH to improve the divalent salt separation performance for TFN membranes.

Dewetting-Induced Photoluminescent Enhancement of Poly(lauryl methacrylate)/Quantum Dot Thin Films.

PubMed

Geldmeier, Jeffrey; Rile, Lexy; Yoon, Young Jun; Jung, Jaehan; Lin, Zhiqun; Tsukruk, Vladimir V

2017-12-19

A new method for enhancing photoluminescence from quantum dot (QD)/polymer nanocomposite films is proposed. Poly(lauryl methacrylate) (PLMA) thin films containing embedded QDs are intentionally allowed to undergo dewetting on substrates by exposure to a nonsolvent vapor. After controlled dewetting, films exhibited typical dewetting morphologies with increased amounts of scattering that served to outcouple photoluminescence from the film and reduce internal light propagation within the film. Up to a 5-fold enhancement of the film emission was achieved depending on material factors such as the initial film thickness and QD concentration within the film. An increase in initial film thickness was shown to increase the dewetted maximum feature size and its characteristic length until a critical thickness was reached where dewetting became inhibited. A unique light exposure-based photopatterning method is also presented for the creation of high contrast emissive patterns as guided by spatially controlled dewetting.

Data on the synthesis processes optimization of novel β-NiS film modified CdS nanoflowers heterostructure nanocomposite for photocatalytic hydrogen evolution.

PubMed

Zhang, Yu; Peng, Zhijian; Guan, Shundong; Fu, Xiuli

2018-02-01

The data presented in this article are related to a research article entitled 'Novel β-NiS film modified CdS nanoflowers heterostructure nanocomposite: extraordinarily highly efficient photocatalysts for hydrogen evolution' (Zhang et al., 2018) [1]. In this article, we report original data on the synthesis processes optimization of the proposed nanocomposite on the basis of their optimum photocatalytic performance together with the comparison on the results of literatures and comparative experiments. The composition, microstructure, morphology, photocatalytic hydrogen evolution and photocatalytic stability of the corresponding samples are included in this report. The data are presented in this format in order to facilitate comparison with data from other researchers in the field and understanding the mechanism of similar catalysts.

Synthesis, characterization, optical and antimicrobial studies of polyvinyl alcohol-silver nanocomposites

NASA Astrophysics Data System (ADS)

Mahmoud, K. H.

2015-03-01

Silver nanoparticles (Ag NPs) were synthesized by chemical reduction of silver salt (AgNO3) through sodium borohydride. The characteristic surface plasmon resonance band located at around 400 nm in the UV-Visible absorption spectrum confirmed the formation of Ag nanoparticles. Polyvinyl alcohol-silver (PVA-Ag) nanocomposite films were prepared by the casting technique. The morphology and interaction of PVA with Ag NPs were examined by transmission electron microscopy and FTIR spectroscopy. Optical studies show that PVA exhibited indirect allowed optical transition with optical energy gap of 4.8 eV, which reduced to 4.45 eV under addition of Ag NPs. Optical parameters such as refractive index, complex dielectric constant and their dispersions have been analyzed using Wemple and DiDomenco model. Color properties of the nanocomposites are discussed in the framework of CIE L∗u∗v∗ color space. The antimicrobial activity of the nanocomposite samples was tested against Gram positive bacteria (Staphylococcus aureus NCTC 7447 &Bacillus subtillis NCIB 3610), Gram negative bacteria (Escherichia coli, NTC10416 &Pseudomonas aeruginosa NCIB 9016) and fungi (Aspergillus niger Ferm - BAM C-21) using the agar diffusion technique. The antimicrobial study showed that PVA has moderate antibacterial activity against B. subtillis and the 0.04 wt% Ag NPs composite sample effect was strong against S. aureus.

Glucose Biosensor Based on Immobilization of Glucose Oxidase in Platinum Nanoparticles/Graphene/Chitosan Nanocomposite Film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Hong; Wang, Jun; Kang, Xinhuang

2009-09-01

The bionanocomposite film consisting of glucose oxidase/Pt/functional graphene sheets/chitosan (GOD/Pt/FGS/chitosan) for glucose sensing was described. With the electrocatalytic synergy of FGS and Pt nanoparticles to hydrogen peroxide, a sensitive biosensor with detection limit of 0.6 µM glucose was achieved. The biosensor also had good reproducibility, long term stability and negligible interfering signals from ascorbic acid and uric acid comparing to the response to glucose. The large surface area and good conductivity of graphene suggests that graphene is a potential candidate for sensor material. The hybrid nanocomposite glucose sensor provides new opportunity for clinical diagnosis and point-of-care applications.

Anisotropic silver nanoparticles as filler for the formation of hybrid nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vodnik, Vesna V., E-mail: vodves@vinca.rs; Šaponjić, Zoran, E-mail: saponjic@vinca.rs; Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com

2013-01-15

Graphical abstract: Display Omitted Highlights: ► Prismatic and plate-like Ag nanoparticles were used as a precursors for preparation Ag/poly(vinyl alcohol) nanocomposite films. ► Results showed that the degree of crystallinity of the polymer decreases with Ag nanoparticles content. ► The presence of Ag nanoparticles in PVA induces higher thermo-oxidative stability with respect to PVA. -- Abstract: Prismatic and plate-like silver nanoparticles (Ag NPs) were synthesized according to the seed-mediated method. These particles were used as precursors for preparation of homogenous, transparent and colored Ag/poly(vinyl alcohol) (PVA) nanocomposite films with different concentrations of Ag by solution-casting technique. Optical and structural characterizationmore » of these nanocomposites includes UV–visible spectroscopy, X-ray diffraction (XRD), FTIR spectroscopy and SEM measurements. Further, the effect of embedded nanoparticles on the thermal properties of the PVA matrix was studied. The value of the glass transition temperature of polymer is found to increase after embedding Ag NPs. Comparison of thermal properties of pure PVA and nanocomposite films showed that the thermo-oxidative stability of polymer slightly increased in the presence of Ag NPs. Furthermore, the effect of the Ag NPs on the crystallinity of polymer was also observed.« less

Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method.

PubMed

Rhim, Jong-Whan; Wang, Long-Feng; Lee, Yonghoon; Hong, Seok-In

2014-03-15

Silver nanoparticles (AgNPs) were prepared by a laser ablation method and composite films with the AgNPs and agar were prepared by solvent casting method. UV-vis absorbance test and transmission electron microscopy (TEM) analysis results revealed that non-agglomerated spherical AgNPs were formed by the laser ablation method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the AgNPs with the maximum absorption peaks of 400-407 nm. X-ray diffraction (XRD) test results also exhibited characteristic AgNPs crystals with diffraction peaks observed at 2θ values of 38.39°, 44.49°, and 64.45°, which were corresponding to (111), (200), and (220) crystallographic planes of face-centered cubic (fcc) silver crystals, respectively. Thermogravimetric analysis (TGA) results showed that thermal stability of the agar/AgNPs composite films was increased by the inclusion of metallic silver. Water vapor barrier properties and surface hydrophobicity of the agar/AgNPs films increased slightly with the increase in AgNPs content but they were not statistically significant (p>0.05), while mechanical strength and stiffness of the composite films decreased slightly (p<0.05). The agar/AgNPs films exhibited distinctive antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Multifunctional nanocomposites of carbon nanotubes and nanoparticles formed via vacuum filtration

DOEpatents

Hersam, Mark C; Ostojic, Gordana; Liang, Yu Teng

2013-10-22

In one aspect, the present invention provides a method of forming a film of nanocomposites of carbon nanotubes (CNTs) and platinum (Pt) nanoparticles. In one embodiment, the method includes the steps of (a) providing a first solution that contains a plurality of CNTs, (b) providing a second solution that contains a plurality of Pt nanoparticles, (c) combining the first solution and the second solution to form a third solution, and (d) filtering the third solution through a nanoporous membrane using vacuum filtration to obtain a film of nanocomposites of CNTs and Pt nanoparticles.

Chemical Functionalization, Self-Assembly, and Applications of Nanomaterials and Nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Tifeng; Yan, Xingbin; Balan, Lavinia

2014-01-01

This special issue addresses the research studies on chemical functionalization, self-assembly, and applications of nanomaterials and nanocomposites. It contains twentyfour articles including two reviews and twenty-two research articles. It is used to create new functional nanomaterials and nanocomposites with a variety of sizes and morphologies such as Zn/Al layered double hydroxide, tin oxide nanowires, FeOOH-modified anion resin, Au nanoclusters silica composite nanospheres, Ti-doped ZnO sol-composite films, TiO2/ZnO composite, graphene oxide nanocomposites, LiFePO4/C nanocomposites, and chitosan nanoparticles. These nanomaterials and nanocomposites have widespread applications in tissue engineering, antitumor, sensors, photoluminescence, electrochemical, and catalytic properties. In addition, this themed issue includes somemore » research articles about self-assembly systems covering organogels and Langmuir films. Furthermore, B. Blasiak et al. performed a literature survey on the recent advances in production, functionalization, toxicity reduction, and application of nanoparticles in cancer diagnosis, treatment, and treatment monitoring. P. Colson et al. performed a literature survey on the recent advances in nanosphere lithography due to its compatibility with wafer-scale processes as well as its potential to manufacture a wide variety of homogeneous one-, two-, or three-dimensional nanostructures.« less

Significantly improved dielectric performances of nanocomposites via loading two-dimensional core-shell structure Bi2Te3@SiO2 nanosheets

NASA Astrophysics Data System (ADS)

Chen, Jianwen; Wang, Xiucai; Yu, Xinmei; Fan, Yun; Duan, Zhikui; Jiang, Yewen; Yang, Faquan; Zhou, Yuexia

2018-07-01

Polymer/semiconductor-insulator nanocomposites can display high dielectric constants with a relatively low dissipation factor under low electric fields, and thus seem to promising for high energy density capacitors. Here, a novel nanocomposite films is developed by loading two-dimensional (2D) core-shell structure Bi2Te3@SiO2 nanosheets in the poly (vinylidene fluoride-hexafluoro propylene) (P(VDF-HFP)) polymer matrix. The 2D Bi2Te3 nanosheets were prepared through simple microwave-assisted method. The experimental results suggesting that the SiO2 shell layer between the fillers and polymer matrix could effectively improve the dielectric constant, dielectric loss, AC conductivity, and breakdown strength of composites films. The composite films load with 10 vol.% 2D Bi2Te3@SiO2 nanosheets exhibits a high dielectric constant of 70.3 at 1 kHz and relatively low dielectric loss of 0.058 at 1 kHz. The finite element simulation of electric field and electric current density distribution revealed that the SiO2 shell layer between the fillers and polymer matrix could effectively improve the energy loss, local electric field strength, and breakdown strength of composite films. Therefore, this work will provide a promising route to achieve high-performance capacitors.

Photocatalytic degradation of organic contaminants by g-C3N4/EPDM nanocomposite film: Viable, efficient and facile recoverable.

PubMed

Selvam, V; Senthil Kumar, P; Navaneetha Krishnan, G; Senthil Andavan, G T

2018-03-01

The original metal free graphitic carbon nitride/ethylene propylene diene monomer nanocomposite film (g-C 3 N 4 /EPDM NCF) was fabricated by facile solution cast method. g-C 3 N 4 /EPDM NCF with diameter (50mm) and thickness (4mm) was investigated towards the photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dye solution under visible light irradiation. The as synthesized g-C 3 N 4 /EPDM NCF was exhibited high crystalline nature with the crystalline size of 21.53nm, the smooth surface nature and the particle size was observed from the TEM analysis is 20nm. Furthermore, the influence of operational parameters was carried out which demonstrated that 100mg photocatalyst and 25μM of dye concentration were obtained as an optimized condition for the best photocatalytic degradation results. As a result of scavenger experiment, it was concluded that the hydroxyl radical (OH) was actively involved in the photocatalytic degradation. The g-C 3 N 4 /EPDM NCF were recoverable from the photocatalytic reaction system and the present find findings may open up a new platform for the simple handpicked photocatalyst. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal conversion of an iron nitride-silicon nitride precursor into a ferromagnetic nanocomposite

NASA Astrophysics Data System (ADS)

Maya, L.; Thompson, J. R.; Song, K. J.; Warmack, R. J.

1998-01-01

Iron nitride films, FeN, in a pure form and in the form of a nanocomposite in silicon nitride were prepared by reactive sputtering using iron or iron disilicide, respectively, as targets in a nitrogen plasma. Iron nitride decomposes into the elements by heating in vacuum to 800 °C. Intermediate phases such as Fe2N or Fe4N form at lower temperatures. The nanocomposites contain the iron phases as particles with an average size of ˜5 nm dispersed in the amorphous silicon nitride matrix. The magnetic properties of the nanocomposites were established. The precursor FeN-Si3N4 film is paramagnetic, while the Fe-Si3N4, obtained by heating in vacuum, is ferromagnetic and shows typical superparamagnetic behavior. These films are of interest as recording media with superior chemical and mechanical stability and may be encoded by localized heating.

Advances in rubber/halloysite nanotubes nanocomposites.

PubMed

Jia, Zhixin; Guo, Baochun; Jia, Demin

2014-02-01

The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

Combined Thermochromic And Plasmonic: Optical Responses In Novel Nanocomposite Au-VO2 Films Prepared By RF Inverted Cylindrical Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Kana, J. B. Kana; Ndjaka, J. M.; Manyala, N.; Nemraoui, O.; Beye, A. C.; Maaza, M.

2008-09-01

We prepared gold/Vanadium dioxide nanocomposites thin films by the rf reactive inverted cylindrical magnetron sputtering (ICMS) for the first time and report their enhanced surface plasmon resonance (SPR) tunable shift reversibility. ICMS has been attracting much attention for its ability for uniform coating of three-dimensional objects and high-rate deposition of dielectric materials. To investigate the optical properties of gold nanoparticles embedded in an active matrix (VO2) composite film was synthesized on corning glass substrates for several substrate temperatures ranging from 400 °C to 600 °C. The X-ray diffraction results demonstrated that the Au and VO2 were well crystallized. The optical transmission properties were measured from 300nm to 1100nm and the absorption peak due to the surface plasmon resonance (SPR) of Au nanoparticles were observed. Under external temperature stimuli, the tunable reversibility of the SPR shift was observed when the nanocomposites temperature varies from 20 °C to 100 °C. The enhancement of this shift of SPR was observed as the substrate temperature increases and it was found that the shift of SPR increased rapidly with increasing substrate temperature but then remained constant at ˜57 nm for substrate temperature higher than 500 °C.

Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films

PubMed Central

2013-01-01

Transition metal ferrites such as CoFe2O4, possessing a large magnetostriction coefficient and high Curie temperature (Tc > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0–3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe2O4 polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (Ms). An enhancement of the effective permittivity and saturation magnetization of the CoFe2O4-P(VDF-HFP) films was observed and directly compared with CoFe2O4-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe2O4-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of Ms up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe2O4-P(VDF-HFP) sample. PMID:24004499

Development of noncytotoxic silver–chitosan nanocomposites for efficient control of biofilm forming microbes† †Electronic supplementary information (ESI) available: ICP-MS, DLS, FTIR, contact angle measurements, TEM/EDS, cytotoxicity results. See DOI: 10.1039/c7ra08359a

PubMed Central

Kus-Liśkiewicz, Małgorzata; Sebastian, Victor; Irusta, Silvia; Kyzioł, Agnieszka

2017-01-01

Severe bacterial and fungal infections have become a major clinical and public health concern. Nowadays, additional efforts are needed to develop effective antimicrobial materials that are not harmful to human cells. This work describes the synthesis and characterization of chitosan–ascorbic acid–silver nanocomposites as films exhibiting high antimicrobial activity and non-cytotoxicity towards human cells. The reductive and stabilizing activity of both the biocompatible polymer chitosan and ascorbic acid were used in the synthesis of silver nanoparticles (AgNPs). Herein, we propose an improved composite synthesis based on medium average molecular weight chitosan with a high deacetylation degree, that together with ascorbic acid gave films with a uniform distribution of small AgNPs (<10 nm) exhibiting high antimicrobial activity against biofilm forming bacterial and fungal strains of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. At the same time, the resulting solid nanocomposites showed, at the same doses, reduced or totally excluded cytotoxicity on mammalian somatic and tumoral cells. Data obtained in the present study suggest that adequately designed chitosan–silver nanocomposites are powerful and promising materials for reducing pathogenic microorganism-associated infections without harmful effects towards mammalian cells. PMID:29308194

A Room Temperature Nitric Oxide Gas Sensor Based on a Copper-Ion-Doped Polyaniline/Tungsten Oxide Nanocomposite

PubMed Central

Wang, Shih-Han; Shen, Chi-Yen; Su, Jian-Ming; Chang, Shiang-Wen

2015-01-01

The parts-per-billion-level nitric oxide (NO) gas sensing capability of a copper-ion-doped polyaniline/tungsten oxide nanocomposite (Cu2+/PANI/WO3) film coated on a Rayleigh surface acoustic wave device was investigated. The sensor developed in this study was sensitive to NO gas at room temperature in dry nitrogen. The surface morphology, dopant distribution, and electric properties were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and Hall effect measurements, respectively. The Cu2+/PANI/WO3 film exhibited high NO gas sensitivity and selectivity as well as long-term stability. At 1 ppb of NO, a signal with a frequency shift of 4.3 ppm and a signal-to-noise ratio of 17 was observed. The sensor exhibited distinct selectivity toward NO gas with no substantial response to O2, NH3 and CO2 gases. PMID:25811223

Nanocomposites with high thermoelectric figures of merit

NASA Technical Reports Server (NTRS)

Dresselhaus, Mildred (Inventor); Ren, Zhifeng (Inventor); Chen, Gang (Inventor)

2008-01-01

The present invention is generally directed to nanocomposite thermoelectric materials that exhibit enhanced thermoelectric properties. The nanocomposite materials include two or more components, with at least one of the components forming nano-sized structures within the composite material. The components are chosen such that thermal conductivity of the composite is decreased without substantially diminishing the composite's electrical conductivity. Suitable component materials exhibit similar electronic band structures. For example, a band-edge gap between at least one of a conduction band or a valence band of one component material and a corresponding band of the other component material at interfaces between the components can be less than about 5k.sub.BT, wherein k.sub.B is the Boltzman constant and T is an average temperature of said nanocomposite composition.

Nanocomposites with High Thermoelectric Figures of Merit

NASA Technical Reports Server (NTRS)

Chen, Gang (Inventor); Ren, Zhifeng (Inventor); Dresselhaus, Mildred (Inventor)

2015-01-01

The present invention is generally directed to nanocomposite thermoelectric materials that exhibit enhanced thermoelectric properties. The nanocomposite materials include two or more components, with at least one of the components forming nano-sized structures within the composite material. The components are chosen such that thermal conductivity of the composite is decreased without substantially diminishing the composite's electrical conductivity. Suitable component materials exhibit similar electronic band structures. For example, a band-edge gap between at least one of a conduction band or a valence band of one component material and a corresponding band of the other component material at interfaces between the components can be less than about 5k(sub B)T, wherein k(sub B) is the Boltzman constant and T is an average temperature of said nanocomposite composition.

Nanocomposites with high thermoelectric figures of merit

NASA Technical Reports Server (NTRS)

Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Dresselhaus, Mildred (Inventor)

2012-01-01

The present invention is generally directed to nanocomposite thermoelectric materials that exhibit enhanced thermoelectric properties. The nanocomposite materials include two or more components, with at least one of the components forming nano-sized structures within the composite material. The components are chosen such that thermal conductivity of the composite is decreased without substantially diminishing the composite's electrical conductivity. Suitable component materials exhibit similar electronic band structures. For example, a band-edge gap between at least one of a conduction band or a valence band of one component material and a corresponding band of the other component material at interfaces between the components can be less than about 5k.sub.BT, wherein k.sub.B is the Boltzman constant and T is an average temperature of said nanocomposite composition.

Influence of Oxygen ions irradiation on Polyaniline/Single Walled Carbon Nanotubes nanocomposite

NASA Astrophysics Data System (ADS)

Patil, Harshada K.; Deshmukh, Megha A.; Gaikwad, Sumedh D.; Bodkhe, Gajanan A.; Asokan, K.; Yasuzawa, Mikito; Koinkar, Pankaj; Shirsat, Mahendara D.

2017-01-01

Influence of Oxygen ions (100 MeV) irradiation on Polyaniline (PANI)/Single Walled Carbon Nanotubes (SWNTs) nanocomposite was studied in the present investigation. PANI/SWNTs nanocomposite was synthesized by electrochemical Cyclic Voltammetry technique. Nanocomposite was exposed under SHI irradiation of Oxygen (100 MeV) ions for three different fluences such as 1×1010 ions/cm2, 5×1010 ions/cm2 and 1×1011 ions/cm2. The SHI irradiated PANI/SWNTs nanocomposite was investigated by using morphological (AFM), structural (XRD) and spectroscopy (FTIR) characterization. AFM study exhibits effects of SHI irradiation on morphology of the nanocomposite and root mean square roughness of the nanocomposite is observed to be decreased as fluence was increased. The FTIR absorption spectrum exhibits formation of new functional sites with the increase in intensity of absorption peaks, due to SHI irradiation. X-Ray Diffraction studies show a gradual decrease in the crystalline nature of the nanocomposite upon irradiation.

Preparation of UV-protective kefiran/nano-ZnO nanocomposites: physical and mechanical properties.

PubMed

Shahabi-Ghahfarrokhi, Iman; Khodaiyan, Faramarz; Mousavi, Mohammad; Yousefi, Hossein

2015-01-01

In this study, we investigated the effect of ZnO nanoparticles (ZN) as a UV-protective agent of kefiran biopolymers. Our results showed that with increasing ZN content, the tensile strength, elongation at break, and tensile energy to break the kefiran film and nanocomposites also increased. Kefiran nanocomposites with a ZN content higher than 2% produced a UV-protective film with good visual properties, low sensibility to water, and low water-vapor permeability. The thermal properties of all specimens, analyzed by DSC, showed that the ZN content had a negative effect on Tg and a positive effect on nanocomposites' melting point. TEM, SEM micrography and XRD spectrum analysis confirmed the hypothesis that ZNs act like a ball bearing, making movement of kefiran chains easier and increasing elongation at break, while simultaneously decreasing the Tg of kefiran nanocomposites. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation, characterization and properties of polymer-layered silicate nanocomposites

NASA Astrophysics Data System (ADS)

Fonseca, Claudia Alencar

Nanocomposites are a relatively new class of composites, that in the polymer area typically consist of particle-filled polymers where at least one dimension of the dispersed particles is in the nanometer range. Amongst all potential nanocomposite precursors, those based on clay and layered silicates have been more widely investigated. These nanocomposites exhibit markedly improved mechanical, thermal, optical and physico-chemical properties when compared to conventional (microscale) composites. In the present work, properties of nanocomposites of Ethylene Methacrylic Acid copolymers and organically modified Montmorillonite formed from the melt was investigated. Nanocomposites of Poly(vinyl alcohol) and Montmorillonite formed from solution was also studied.

Structural, microstructural and electrochemical properties of dispersed-type polymer nanocomposite films

NASA Astrophysics Data System (ADS)

Arya, Anil; Sharma, A. L.

2018-01-01

Free-standing solid polymer nanocomposite (PEO-PVC)  +  LiPF6-TiO2 films have been prepared through a standard solution-cast technique. The improvement in structural, microstructural and electrochemical properties has been observed on the dispersion of nanofiller in polymer salt complex. X-ray diffraction studies clearly reflect the formation of complex formation, as no corresponding salt peak appeared in the diffractograms. The Fourier transform infrared analysis suggested clear and convincing evidence of polymer-ion, ion-ion and polymer-ion-nanofiller interaction. The highest ionic conductivity of the prepared solid polymer electrolyte (SPE) films is ~5  ×  10-5 S cm-1 for 7 wt.% TiO2. The linear sweep voltammetry provides the electrochemical stability window of the prepared SPE films, about ~3.5 V. The ion transference number has been estimated, t ion  =  0.99 through the DC polarization technique. Dielectric spectroscopic studies were performed to understand the ion transport process in polymer electrolytes. All solid polymer electrolytes possess good thermal stability up to 300 °C. Differential scanning calorimetry analysis confirms the decrease of the melting temperature and signal of glass transition temperature with the addition of nanofiller, which indicates the decrease of crystallinity of the polymer matrix. An absolute correlation between diffusion coefficient (D), ion mobility (µ), number density (n), double-layer capacitance (C dl), glass transition temperature, melting temperature (T m), free ion area (%) and conductivity (σ) has been observed. A convincing model to study the role of nanofiller in a polymer salt complex has been proposed, which supports the experimental findings. The prepared polymer electrolyte system with significant ionic conductivity, high ionic transference number, and good thermal and voltage stability could be suggested as a potential candidate as electrolyte cum separator for the fabrication of a

Organic-inorganic nano-composite films for photonic applications made by multi-beam multi-target pulsed laser deposition with remote control of the plume directions

NASA Astrophysics Data System (ADS)

Darwish, Abdalla M.; Moore, Shaelynn; Mohammed, Aziz; Alexander, Deonte'; Bastian, Tyler; Dorlus, Wydglif; Sarkisov, Sergey S.; Patel, Darayas N.; Mele, Paolo; Koplitz, Brent

2016-09-01

There has been an explosive interest in the technique of laser assisted deposition of polymer nano-composite films exploiting the matrix assisted pulsed laser evaporation (MAPLE) with regard to the polymer host as can be judged form recent publications.1-4 In MAPLE, a frozen solution of a polymer in a relatively volatile solvent is used as a laser target. The solvent and concentration are selected so that first, the polymer of interest can dissolve to form a dilute, particulate free solution, second, the majority of the laser energy is initially absorbed by the solvent molecules and not by the solute molecules, and third, there is no photochemical reaction between the solvent and the solute. The light-material interaction in MAPLE can be described as a photothermal process. The photon energy absorbed by the solvent is converted to thermal energy that causes the polymer to be heated but the solvent to vaporize. As the surface solvent molecules are evaporated into the gas phase, polymer molecules are exposed at the gas-target matrix interface. The polymer molecules attain sufficient kinetic energy through collective collisions with the evaporating solvent molecules, to be transferred into the gas phase. By careful optimization of the MAPLE deposition conditions (laser wavelength, repetition rate, solvent type, concentration, temperature, and background gas and gas pressure), this process can occur without any significant polymer decomposition. The MAPLE process proceeds layer-by-layer, depleting the target of solvent and polymer in the same concentration as the starting matrix. When a substrate is positioned directly in the path of the plume, a coating starts to form from the evaporated polymer molecules, while the volatile solvent molecules are evacuated by the pump from the deposition chamber. In case of fabrication of polymer nanocomposites, MAPLE targets are usually prepared as nano-colloids of the additives of interest in the initial polymer solutions. Mixing

Facile preparation of polypyrrole/graphene oxide nanocomposites with large areal capacitance using electrochemical codeposition for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Haihan; Han, Gaoyi; Xiao, Yaoming; Chang, Yunzhen; Zhai, Hua-Jin

2014-10-01

A simple and low-cost electrochemical codeposition method has been introduced to fabricate polypyrrole/graphene oxide (PPy/GO) nanocomposites and the areal capacitance of conducting polymer/GO composites is reported for the first time. Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) are implemented to determine the PPy/GO nanocomposites are successfully prepared and the interaction between PPy and GO. The as-prepared PPy/GO nanocomposites show the curly sheet-like morphology, superior capacitive behaviors and cyclic stability. Furthermore, the varying deposition time is implemented to investigate the impact of the loading amount on electrochemical behavior of the composites, and a high areal capacitance of 152 mF cm-2 is achieved at 10 mV s-1 CV scan. However, the thicker films caused by the long deposition time would result in larger diffusion resistance of electrolyte ions, consequently exhibit the relatively lower capacitance value at the high current density. The GCD tests indicate moderate deposition time is more suitable for the fast charge/discharge. Considering the very simple and effective synthetic process, the PPy/GO nanocomposites with relatively high areal capacitance are competitive candidate for supercapacitor application, and its capacitive performances can be easily tuned by varying the deposition time.

Optical, structural and nonlinear optical properties of laser ablation synthesized Ag nanoparticles and photopolymer nanocomposites based on them

NASA Astrophysics Data System (ADS)

Zulina, Natalia A.; Pavlovetc, Ilia M.; Baranov, Mikhail A.; Denisyuk, Igor Yu.

2017-03-01

In this work Ag nanoparticles (NPs) stable colloid solution were prepared by laser ablation of chemically pure silver rod in liquid monomer isodecyl acrylate (IDA). Sizes of obtained nanoparticles were determined by scanning electron microscope and vary from 27 to 120 nm. Nanocomposites films were prepared from obtained stable colloid solution of AgNPs by photocuring. For aliphatic polymer IDA long molecules cross-linking Diurethane dimethacrylate, 1,6-Hexandiol diacrylate and Tetra (ethylene glycol) diacrylate were used. Prepared nanomaterials exhibit strong third-order nonlinear optical responses, which was estimated by using z-scan technique. The third-order nonlinear optical coefficients of the studied nanocomposites were found to be up to Reχ(3)=1.31×10-5 (esu) and Imχ(3)=7.64×10-5 (esu).

Preparation of pectin/silver nanoparticles composite films with UV-light barrier and properties.

PubMed

Shankar, Shiv; Tanomrod, Nattareya; Rawdkuen, Saroat; Rhim, Jong-Whan

2016-11-01

Silver nanoparticles (AgNPs) was synthesized by a green method using an aqueous extract of Caesalpinia mimosoides Lamk (CMLE) as reducing and stabilizing agents, and they were used for the preparation of pectin-based antimicrobial composite films. The AgNPs were spherical in shape with the size in the range of 20-80nm and showed the absorption peak around 500nm. The pectin/AgNPs composite film exhibited characteristic absorption peak of AgNPs at 480nm. The surface color and light transmittance of the pectin films were greatly influenced by the addition of AgNPs. The lightness of the films decreased, however, redness and yellowness of the films increased after incorporation of AgNPs. UV-light barrier property of the pectin film increased significantly with a little decrease in the transparency. Though there were no structural changes in the pectin film by the incorporation of CMLE and AgNPs as indicated by the FTIR results, the film properties such as thermal stability, mechanical strength, and water vapor barrier properties of the pectin films increased. The pectin/AgNPs nanocomposite films exhibited strong antibacterial activity against food-borne pathogenic bacteria, Escherichia coli and Listeria monocytogenes. Copyright © 2016 Elsevier B.V. All rights reserved.

The Antifungal Activity of Functionalized Chitin Nanocrystals in Poly (Lactid Acid) Films

PubMed Central

Salaberria, Asier M.; H. Diaz, Rene; Andrés, María A.; Fernandes, Susana C.M.; Labidi, Jalel

2017-01-01

As, in the market, poly (lactic acid) (PLA) is the most used polymer as an alternative to conventional plastics, and as functionalized chitin nanocrystals (CHNC) can provide structural and bioactive properties, their combination sounds promising in the preparation of functional nanocomposite films for sustainable packaging. Chitin nanocrystals were successfully modified via acylation using anhydride acetic and dodecanoyl chloride acid to improve their compatibility with the matrix, PLA. The nanocomposite films were prepared by extrusion/compression approach using different concentrations of both sets of functionalized CHNC. This investigation brings forward that both sets of modified CHNC act as functional agents, i.e., they slightly improved the hydrophobic character of the PLA nanocomposite films, and, very importantly, they also enhanced their antifungal activity. Nonetheless, the nanocomposite films prepared with the CHNC modified with dodecanoyl chloride acid presented the best properties. PMID:28772902

Carbon nanotube epoxy nanocomposites: the effects of interfacial modifications on the dynamic mechanical properties of the nanocomposites.

PubMed

Yoonessi, Mitra; Lebrón-Colón, Marisabel; Scheiman, Daniel; Meador, Michael A

2014-10-08

Surface functionalization of pretreated carbon nanotubes (CNT) using aromatic, aliphatic, and aliphatic ether diamines was performed. The pretreatment of the CNT consisted of either acid- or photo-oxidation. The acid treated CNT had a higher initial oxygen content compared to the photo-oxidized CNT and this resulted in a higher density of functionalization. X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) were used to verify the presence of the oxygenated and amine moieties on the CNT surfaces. Epoxy/0.1 wt % CNT nanocomposites were prepared using the functionalized CNT and the bulk properties of the nanocomposites were examined. Macroscale correlations between the interfacial modification and bulk dynamic mechanical and thermal properties were observed. The amine modified epoxy/CNT nanocomposites exhibited up to a 1.9-fold improvement in storage modulus (G') below the glass transition (Tg) and up to an almost 4-fold increase above the Tg. They also exhibited a 3-10 °C increase in the glass transition temperature. The aromatic diamine surface modified epoxy/CNT nanocomposites resulted in the largest increase in shear moduli below and above the Tg and the largest increase in the Tg. Surface examination of the nanocomposites with scanning electron microscopy (SEM) revealed indications of a greater adhesion of the epoxy resin matrix to the CNT, most likely due to the covalent bonding.

Use of Nanocomposites for Flexible Pressure Sensors =

NASA Astrophysics Data System (ADS)

Sepulveda, Alexandra Conceicao Teixeira

Polymer nanocomposites (PNCs) are defined as polymers bonded with nanoparticles to create materiais with improved properties. The development of this type of material is rapidly emerging as a multidisciplinary research activity, since their final properties can benefit many different fields of application, namely in the development of electrical devices as studied herein. A fabrication technique to produce conductive PNCs was developed in this work and used to fabricate flexible capacitive pressure sensors. The process is based on vertically aligned-carbon nanotubes (A-CNTs) embedded in a flexible and biocompatible matrix of polydimethylsiloxane (PDMS). Thin A-CNTs/PDMS nanocomposite films ( 400 mum) were produced using wetting of as-grown A-CNTs with uncured PDMS and the resulting nanocomposites were used to fabricate flexible pressure sensors. The sensing capability of this A-CNTs/PDMS nanocomposite is attributed to the distinctive combination of mechanical flexibility and electrical properties. The fabricated nanocomposites were characterized and mechanical and electrical properties evaluated. The PDMS is significantly modified by the reinforcing A-CNT fibers, demonstrating non-isotropic (as opposed to the isotropic neat PDMS) elastic properties ali different than the PDMS (Young's modulus of 0.8 MPa), including an anisotropy ratio of 4.8 and increases in the modulus of A-CNTs/PDMS nanocomposites over PDMS by more than 900 % and 100 %, in the CNTs longitudinal and transverse directions, respectively. Regarding the electrical measurements, A-CNTs/PDMS nanocomposites presented an electrical conductivity of 0.35 Sim. The rather low conductivity does not compromise the developed capacitive sensor, but since passive telemetry is required to measure and power the sensor, solutions to overcome this problem were also studied. The configuration of the developed flexible sensor is similar to typical silicon-based capacitive pressure sensors. It is composed of three thin

Low TCR nanocomposite strain gages

NASA Technical Reports Server (NTRS)

Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

2012-01-01

A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

Structural, morphological and optical properties of PEDOT:PSS/QDs nano-composite films prepared by spin-casting

NASA Astrophysics Data System (ADS)

Najeeb, Mansoor Ani; Abdullah, Shahino Mah; Aziz, Fakhra; Ahmad, Zubair; Rafique, Saqib; Wageh, S.; Al-Ghamdi, Ahmed A.; Sulaiman, Khaulah; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

2016-09-01

This paper describes the structural, morphological and optical properties of the nano-composite of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and quantum dots (QDs). The ZnSe and CdSe QDs have been synthesized, with the aid of Mercaptoacetic acid (MAA), by a colloidal method with an average size of 5 to 7 nm. QDs have been embedded in PEDOT:PSS using a simple solution processing approach and has been deposited as thin films by spin coating technique. The QDs embedded PEDOT:PSS enhances the light absorption spectra of samples, prominently in terms of absorption intensity which may consequently improve sensitivity of the optoelectronic devices.

Physical and mechanical properties of hybrid montmorillonite/zinc oxide reinforced carboxymethyl cellulose nanocomposites.

PubMed

Zahedi, Younes; Fathi-Achachlouei, Bahram; Yousefi, Ali Reza

2018-03-01

In this research, a novel carboxymethyl cellulose (CMC)-based nanocomposite films containing sodium montmorillonite (MMT) (5%wt) and zinc oxide (ZnO) (1, 2, 3 and 4%wt) nanoparticles (NPs) were fabricated via casting method. The results revealed that addition of NPs decreased water vapor permeability of the films by about 53%, while moisture content, density and glass transition temperature increased. The nanomaterials enhanced resistance of the nanocomposites against tensile stress at the expense of elongation at break. Nano-ZnO was very effective than nanoclay in UV-light blocking (99% vs. 60%) associated with sacrificing the films transparency. Formation of hydrogen bonds between the hydroxyl groups of CMC and MMT was evidenced by FTIR spectroscopy. According to the XRD analysis, clay nanolayers formed an exfoliated structure in the nanocomposites, whereas ZnO NPs raised crystallinity. SEM micrographs showed well-dispersed MMT and ZnO NPs through the films surface. Antibacterial test showed that vulnerability of Gram-positive S. aureus toward ZnO NPs was more than that of Gram-negative E. Coli. In conclusion, simultaneous incorporation of MMT and ZnO NPs improved the functional characteristics of CMC film and extended the potential for food packaging applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of ecofriendly UV-protective food packaging material by starch/TiO2 bio-nanocomposite: Characterization.

PubMed

Goudarzi, Vahid; Shahabi-Ghahfarrokhi, Iman; Babaei-Ghazvini, Amin

2017-02-01

In this study, ecofriendly starch/TiO 2 bio-nanocomposites were produced using with different nano-TiO 2 (TiO 2 ) content (1, 3, and 5 (wt%)). Physical, mechanical, thermal, water-vapor permeability (WVP) properties and UV transmittance were investigated. Our results showed that the increasing TiO 2 content increased the hydrophobicity of starch/TiO 2 films. WVP of the bio-nanocomposites was reduced, simultaneously. With increasing TiO 2 content, tensile strength and Young's modulus of the film specimens were reduced while elongation at break and tensile energy to break were increased. The thermal properties of specimens showed that glass transition temperature of the films increased but melting point of the specimen films was decreased by increasing TiO 2 content. Scanning electron microscopy observations demonstrated, the most of films' physical properties were in relation to their microstructures. The starch/TiO 2 nanocomposites effectively protect goods against UV light, and could potentially be applied as UV-shielding packaging materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Thin films composed of multiwalled carbon nanotubes, gold nanoparticles and myoglobin for humidity detection at room temperature.

PubMed

Qi, Zhi-mei; Wei, Mingdeng; Honma, Itaru; Zhou, Haoshen

2007-02-02

Optically transparent and electrically conductive nanocomposite thin films consisting of multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (GNPs) and myoglobin molecules that glue GNPs and MWCNTs together are fabricated for the first time on glass substrates from aqueous solution. The nanocomposite thin film is capable of varying its resistance, impedance or optical transmittance at room temperature in response to changes in ambient humidity. The conductometric sensitivity to relative humidity (RH) of the nanocomposite thin film is compared with those of the pure and Mb-functionalized MWCNT layers. The pure MWCNT layer shows a small increase in its resistance with increasing RH due to the effect of p-type semiconducting nanotubes present in the film. In contrast, a four times higher sensitivity to RH is observed for both the nanocomposite and Mb-functionalized MWCNT thin films. The sensitivity enhancement is attributable to swelling of the thin films induced by water absorption in the presence of Mb molecules, which increases the inter-nanotube spacing and thereby causes a further increase of the film resistance. A humidity change as low as DeltaRH=0.3 % has been readily detected by conductometry using the nanocomposite thin film.

Combined Thermochromic And Plasmonic: Optical Responses In Novel Nanocomposite Au-VO{sub 2} Films Prepared By RF Inverted Cylindrical Magnetron Sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kana, J. B. Kana; Department of physics, University of Yaounde I, P.O. Box 812 Yaounde; Ndjaka, J. M.

2008-09-23

We prepared gold/Vanadium dioxide nanocomposites thin films by the rf reactive inverted cylindrical magnetron sputtering (ICMS) for the first time and report their enhanced surface plasmon resonance (SPR) tunable shift reversibility. ICMS has been attracting much attention for its ability for uniform coating of three-dimensional objects and high-rate deposition of dielectric materials. To investigate the optical properties of gold nanoparticles embedded in an active matrix (VO{sub 2}) composite film was synthesized on corning glass substrates for several substrate temperatures ranging from 400 deg. C to 600 deg. C. The X-ray diffraction results demonstrated that the Au and VO{sub 2} weremore » well crystallized. The optical transmission properties were measured from 300nm to 1100nm and the absorption peak due to the surface plasmon resonance (SPR) of Au nanoparticles were observed. Under external temperature stimuli, the tunable reversibility of the SPR shift was observed when the nanocomposites temperature varies from 20 deg. C to 100 deg. C. The enhancement of this shift of SPR was observed as the substrate temperature increases and it was found that the shift of SPR increased rapidly with increasing substrate temperature but then remained constant at {approx}57 nm for substrate temperature higher than 500 deg. C.« less

Titanium dioxide-gold nanocomposite materials embedded in silicate sol-gel film catalyst for simultaneous photodegradation of hexavalent chromium and methylene blue.

PubMed

Pandikumar, Alagarsamy; Ramaraj, Ramasamy

2012-02-15

Aminosilicate sol-gel supported titanium dioxide-gold (EDAS/(TiO(2)-Au)(nps)) nanocomposite materials were synthesized by simple deposition-precipitation method and characterized. The photocatalytic oxidation and reduction activity of the EDAS/(TiO(2)-Au)(nps) film was evaluated using hexavalent chromium (Cr(VI)) and methylene blue (MB) dye under irradiation. The photocatalytic reduction of Cr(VI) to Cr(III) was studied in the presence of hole scavengers such as oxalic acid (OA) and methylene blue (MB). The photocatalytic degradation of MB was investigated in the presence and absence of Cr(VI). Presence of Au(nps) on the (TiO(2))(nps) surface and its dispersion in the silicate sol-gel film (EDAS/(TiO(2)-Au)(nps)) improved the photocatalytic reduction of Cr(VI) and oxidation of MB due to the effective interfacial electron transfer from the conduction band of the TiO(2) to Au(nps) by minimizing the charge recombination process when compared to the TiO(2) and (TiO(2)-Au)(nps) in the absence of EDAS. The EDAS/(TiO(2)-Au)(nps) nanocomposite materials provided beneficial role in the environmental remediation and purification process through synergistic photocatalytic activity by an advanced oxidation-reduction processes. Copyright © 2011 Elsevier B.V. All rights reserved.

A review on polyamide thin film nanocomposite (TFN) membranes: History, applications, challenges and approaches.

PubMed

Lau, W J; Gray, Stephen; Matsuura, T; Emadzadeh, D; Chen, J Paul; Ismail, A F

2015-09-01

This review focuses on the development of polyamide (PA) thin film nanocomposite (TFN) membranes for various aqueous media-based separation processes such as nanofiltration, reverse osmosis and forward osmosis since the concept of TFN was introduced in year 2007. Although the total number of published TFN articles falls far short of the articles of the well-known thin film composite (TFC) membranes, its growth rate is significant, particularly since 2012. Generally, by incorporating an appropriate amount of nanofiller into a thin selective PA layer of a composite membrane, one could produce TFN membranes with enhanced separation characteristics as compared to the conventional TFC membrane. For certain cases, the resulting TFN membranes demonstrate not only excellent antifouling resistance and/or greater antibacterial effect, but also possibly overcome the trade-off effect between water permeability and solute selectivity. Furthermore, this review attempts to give the readers insights into the difficulties of incorporating inorganic nanomaterials into the organic PA layer whose thickness usually falls in a range of several-hundred nanometers. It is also intended to show new possible approaches to overcome these challenges in TFN membrane fabrication. Copyright © 2015 Elsevier Ltd. All rights reserved.

Two-dimensional plasmons in the random impedance network model of disordered thin film nanocomposites

NASA Astrophysics Data System (ADS)

Olekhno, N. A.; Beltukov, Y. M.

2018-05-01

Random impedance networks are widely used as a model to describe plasmon resonances in disordered metal-dielectric nanocomposites. Two-dimensional networks are applied when considering thin films despite the fact that such networks correspond to the two-dimensional electrodynamics [Clerc et al., J. Phys. A 29, 4781 (1996), 10.1088/0305-4470/29/16/006]. In the present work, we propose a model of two-dimensional systems with the three-dimensional Coulomb interaction and show that this model is equivalent to the planar network with long-range capacitive links between distant sites. In the case of a metallic film, we obtain the well-known dispersion of two-dimensional plasmons ω ∝√{k } . We study the evolution of resonances with a decrease in the metal filling factor within the framework of the proposed model. In the subcritical region with the metal filling p lower than the percolation threshold pc, we observe a gap with Lifshitz tails in the spectral density of states (DOS). In the supercritical region p >pc , the DOS demonstrates a crossover between plane-wave two-dimensional plasmons and resonances of finite clusters.

Characterization of low-dose doxorubicin-loaded silica-based nanocomposites

NASA Astrophysics Data System (ADS)

Prokopowicz, Magdalena

2018-01-01

In this study, we synthesized multicomponent solid films of low-dose doxorubicin (DOX)-loaded polydimethylsiloxane (PDMS)-SiO2/CaP nanocomposites via sol-gel process combined with the method of evaporation-induced self-assembly (EISA) at low temperature. Nanomechanical properties (elasticity and adhesion) of the synthesized multicomponent films were determined by using atomic force microscopy with a PeakForce™ quantitative nanomechanical mapping imaging technique. Solid state of DOX in the synthesized films was studied by using UV-vis and fluorescence spectroscopy. The release profile of different concentrations of DOX loaded (1, 3, and 5 wt%) on the multicomponent films was assessed using USP Apparatus 4 and via UV-vis end analysis. Results indicate drug-component interactions on the overall morphology of domains (size and shape), nanomechanical properties, and release behavior of the DOX-loaded nanocomposites. We observed a progressive increase in surface roughness and mean adhesive value with increasing concentration of DOX loaded (0-5 wt%). In addition, for all the different concentrations of DOX-loaded, we observed a diffusion-controlled drug release.

Bimetallic nanocomposite as hole transport co-buffer layer in organic solar cell

NASA Astrophysics Data System (ADS)

Mola, Genene Tessema; Arbab, Elhadi A. A.

2017-12-01

Silver-zinc bimetallic nanocomposite (Ag:Zn BiM-NPs) was used as an inter-facial buffer layer in the preparation of thin film organic solar cell (TFOSC). The current investigation focuses on the effect of bimetallic nanoparticles on the performance of TFOSC. A number experiments were conducted by employing Ag:Zn nanocomposite buffer layer of thickness 1 nm at various positions of the device structure. In all cases, we found significant improvement on the power conversion efficiency of the solar cells. It is also noted that the open circuit voltage of the devices are decreasing when Ag:Zn form direct contact with the ITO electrode and without the inclusion of PEDOT:PSS. However, all results show that the introduction of Ag:Zn nanocomposite layer close to PEDOT:PSS could be beneficial to improve the charge transport processes in the preparation of thin film organic solar cell. The Ag:Zn BiM-NPs and the device properties were presented and discussed in terms of optical, electrical and film morphologies of the devices.

Crystallization, mechanical properties, and controlled enzymatic degradation of biodegradable poly(epsilon-caprolactone)/multi-walled carbon nanotubes nanocomposites.

PubMed

Qiu, Zhaobin; Wang, Huishan; Xu, Changling

2011-09-01

Biodegradable poly(epsilon-caprolactone) (PCL)/multi-walled carbon nanotubes containing carboxylic groups (f-MWNTs) nanocomposites were prepared via simple melt compounding at low f-MWNTs loading in this work. Scanning and transmission electron microscopy observations indicate a homogeneous and fine distribution of f-MWNTs throughout the PCL matrix. The effect of low f-MWNTs loading on the crystallization, mechanical properties, and controlled enzymatic degradation of PCL in the nanocomposites were studied in detail with various techniques. The experimental results indicate that the incorporation of f-MWNTs enhances both the nonisothermal crystallization peak temperature and the overall isothermal crystallization rate of PCL in the PCL/f-MWNTs nanocomposites relative to neat PCL; moreover, the incorporation of a small quantity of f-MWNTs has improved apparently the mechanical properties of the PCL/MWNTs nanocomposites compared to neat PCL. The enzymatic degradation of neat PCL and the PCL/f-MWNTs nanocomposites at low f-MWNTs loading was studied in detail. The variation of weight loss with enzymatic degradation time, the surface morphology change, the reduced film thickness, the appearance of f-MWNTs on the surface of the films, and the almost unchanged molecular weight after enzymatic degradation suggest that the enzymatic degradation of neat PCL and the PCL/f-MWNTs nanocomposites may proceed via surface erosion mechanism. The presence of f-MWNTs reduces the enzymatic degradation rate of the PCL matrix in the nanocomposites compared with that of the pure PCL film.

Physico-chemical properties of PMMA/ZnO nanocomposite capped with 1-chloro-9,10-bis (phenyl ethynyl) anthracene

NASA Astrophysics Data System (ADS)

Anandalli, Mallikarjun; Kanakaraj, T. M.; Hebbar, Vidyashree; Naik, Jagadish; Bhajantri, R. F.

2018-05-01

The nanocomposite films of polymethyl methacrylate (PMMA)/zinc oxide (ZnO) capped with different weight (0.25wt%,1wt%) percentage of fluorescence dye 1-chlor-9,10-bis (phenyl ethynyl anthracene (C30H17Cl) were prepared using solution casting method. ZnO powder dispersed in the polymer matrix uniformly, enhance the optical and physical properties of nanocomposite. Interaction of fluorescence dye and ZnO with polymer matrix gives the emerging applications, due to the fact that the dye C30H17Cl emits yellow light and it has wide band gap, hole transporting material. The prepared samples have been studied using the experimental techniques such as FTIR, UV-Visible (indirect energy gap plots), XRD, AFM. The FTIR used to confirm the peaks of ZnO nanoparticles dispersed in polymer matrix and interaction of the dye. From the UV-Visible technique, the optical band gap of the nanocomposites has been investigated, and the obtained optical band gap reduces with increase in weight % of dye in PMMA/ZnO. The AFM results show the surface morphology and smoothness of the nanocomposite films. The crystallinity of the PMMA/ZnO:C30H17Cl nanocomposite has been estimated using powder XRD patterns. The prepared nanocomposites films useful for the wide range of applications.

Polymer nanocomposite nanomechanical cantilever sensors: material characterization, device development and application in explosive vapour detection.

PubMed

Seena, V; Fernandes, Avil; Pant, Prita; Mukherji, Soumyo; Rao, V Ramgopal

2011-07-22

This paper reports an optimized and highly sensitive piezoresistive SU-8 nanocomposite microcantilever sensor and its application for detection of explosives in vapour phase. The optimization has been in improving its electrical, mechanical and transduction characteristics. We have achieved a better dispersion of carbon black (CB) in the SU-8/CB nanocomposite piezoresistor and arrived at an optimal range of 8-9 vol% CB concentration by performing a systematic mechanical and electrical characterization of polymer nanocomposites. Mechanical characterization of SU-8/CB nanocomposite thin films was performed using the nanoindentation technique with an appropriate substrate effect analysis. Piezoresistive microcantilevers having an optimum carbon black concentration were fabricated using a design aimed at surface stress measurements with reduced fabrication process complexity. The optimal range of 8-9 vol% CB concentration has resulted in an improved sensitivity, low device variability and low noise level. The resonant frequency and spring constant of the microcantilever were found to be 22 kHz and 0.4 N m(-1) respectively. The devices exhibited a surface stress sensitivity of 7.6 ppm (mN m(-1))(-1) and the noise characterization results support their suitability for biochemical sensing applications. This paper also reports the ability of the sensor in detecting TNT vapour concentration down to less than six parts per billion with a sensitivity of 1 mV/ppb.

Optimization of nanocomposite Au/TiO2 thin films towards LSPR optical-sensing

NASA Astrophysics Data System (ADS)

Rodrigues, M. S.; Costa, D.; Domingues, R. P.; Apreutesei, M.; Pedrosa, P.; Martin, N.; Correlo, V. M.; Reis, R. L.; Alves, E.; Barradas, N. P.; Sampaio, P.; Borges, J.; Vaz, F.

2018-04-01

Nanomaterials based on Localized Surface Plasmon Resonance (LSPR) phenomena are revealing to be an important solution for several applications, namely those of optical biosensing. The main reasons are mostly related to their high sensitivity, with label-free detection, and to the simplified optical systems that can be implemented. For the present work, the optical sensing capabilities were tailored by optimizing LSPR absorption bands of nanocomposite Au/TiO2 thin films. These were grown by reactive DC magnetron sputtering. The main deposition parameters changed were the number of Au pellets placed in the Ti target, the deposition time, and DC current applied to the Ti-Au target. Furthermore, the Au NPs clustering, a key feature to have biosensing responses, was induced by several post-deposition in-air annealing treatments at different temperatures, and investigated via SEM analysis. Results showed that the Au/TiO2 thin films with a relatively low thickness (∼100 nm), revealing concentrations of Au close to 13 at.%, and annealed at temperatures above 600 °C, had the most well-defined LSPR absorption band and thus, the most promising characteristics to be explored as optical sensors. The NPs formation studies revealed an incomplete aggregation at 300 and 500 ⁰C and well-defined spheroidal NPs for higher temperatures. Plasma treatment with Ar led to a gradual blue-shift of the LSPR absorption band, which demonstrates the sensitivity of the films to changes in the dielectric environment surrounding the NPs (essential for optical sensing applications) and the exposure of the Au nanoparticles (crucial for a higher sensitivity).

Poly (N-ethyl aniline)/Ag Nanocomposite as Humidity Sensor

NASA Astrophysics Data System (ADS)

Pande, Nishigandh S.; Jaspal, Dipika; Ambekar, Jalindar

Poly (N-ethyl aniline)/Ag organic-inorganic composite has been synthesized by a single step in situ chemical oxidative polymerization method. The synthesis of Poly (N-ethyl aniline)/Ag nanocomposite has been confirmed by X-ray diffraction (XRD), Ultraviolet-Vis Spectroscopy (UV-visible), Fourier transform infrared analysis (FTIR) and FE-SEM investigations. XRD spectral study exhibited major diffraction in the range 20-80∘ (2θ) and indicated the semicrystalline nature of poly (N-ethyl aniline)/Ag nanocomposite. Characteristic peaks in UV-visible and FTIR spectra of poly (N-ethyl aniline) switched to higher wave numbers in poly (N-ethyl aniline)/Ag nanocomposite. Peaks at 1789cm-1, 1595cm-1, 667cm-1 and 501cm-1 in FTIR spectrum confirmed the formation of poly (N-ethyl aniline)/Ag nanocomposite. FE-SEM photographs reported agglomerated granular particulate nature of poly (N-ethyl aniline)/Ag nanocomposite. Synthesized poly (N-ethyl aniline)/Ag nanocomposite exhibited a high response to humidity, good reproducibility and stability at room temperature. An appreciable response was shown in the presence of 40% humid atmosphere for up to successive four cycles. Composite sensitivity has been found to increase with the increasing concentration of humidity, at room temperature.

Synthesis of capped TiO2 nanocrystals of controlled shape and their use with MEH-PPV conjugated polymer to develop nanocomposite films for photovoltaic applications

NASA Astrophysics Data System (ADS)

Mighri, F.; Duong, Vu Thi Thuy; On, Do Trong; Ajji, A.

2014-05-01

This study presents the synthesis details of titanium dioxide (TiO2) nanoparticles (NPs) of different shapes (nanospheres, nanorods and nanorhombics) using oleic acid (OA) and oleyl amine (OM) as capping agents. In order to develop nanocomposite thin films for photovoltaic cells, these TiO2 NPs were carefully dispersed in 2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene (MEH-PPV) matrix. The properties of synthesized TiO2 NPs and MEH-PPV/TiO2 nanocomposites were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and Photoluminescence technique. It was found that the shape of NPs and the amount of OA and OM surfactants capped on their surface have an effect on their energy bandgap and also on the dispersion quality of MEH-PPV/TiO2 nanocomposites. Even though there was no evidence of chemical bonding between MEH-PPV matrix and TiO2 dispersed NPs, MEH-PPV/TiO2 nanocomposites showed very promising results for light absorption properties and charge transfer at the interface of the conjugated MEH-PPV matrix and TiO2 dispersed NPs, which are two main characteristics for photovoltaic materials.

Amino acid mediated synthesis of silver nanoparticles and preparation of antimicrobial agar/silver nanoparticles composite films.

PubMed

Shankar, Shiv; Rhim, Jong-Whan

2015-10-05

Silver nanoparticles (AgNPs) were synthesized using amino acids (tyrosine and tryptophan) as reducing and capping agents, and they were incorporated into the agar to prepare antimicrobial composite films. The AgNPs solutions exhibited characteristic absorption peak at 420 nm that showed a red shift to ∼434 nm after forming composite with agar. XRD data demonstrated the crystalline structure of AgNPs with dominant (111) facet. Apparent surface color and transmittance of agar films were greatly influenced by the AgNPs. The incorporation of AgNPs into agar did not exhibit any change in chemical structure, thermal stability, moisture content, and water vapor permeability. The water contact angle, tensile strength, and modulus decreased slightly, but elongation at break increased after AgNPs incorporation. The agar/AgNPs nanocomposite films possessed strong antibacterial activity against Listeria monocytogenes and Escherichia coli. The agar/AgNPs film could be applied to the active food packaging by controlling the food-borne pathogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physical properties of bifunctional BST/LSMO nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beltran-Huarac, Juan, E-mail: baristary26@gmail.com; Morell, Gerardo; Department of Physics, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico 00936

2014-02-28

We report the fabrication of bifunctional nanocomposites consisting of ferroelectric Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} (BST) and ferromagnetic La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) at different concentrations via a high-temperature solid state route. The structural, dielectric, electrical, magnetodielectric (MD), magnetoelectric (ME) and magnetic properties of BST/LSMO nanocomposites were systematically investigated over a wide range of temperatures and frequencies. The X-Ray Diffraction analyses reveal the nanocrystalline nature of the heterostructures, wherein both perovskite phases co-exist. No parasitic phases were observed. The study of the dielectric properties shows that the nanocomposites exhibit relaxor ferroelectric character, with ferroelectric-paraelectric phase transition temperatures around 287–292 K that domore » not follow the Curie-Weiss law. The electrical measurements indicate that ac conductivities of the nanocomposites follow the Jonscher's universal power law, with activation energies of 0.42–0.63 eV based on Arrhenius-type behavior at high temperatures. The nanocomposites exhibit well-defined ferromagnetic hysteresis loops at room temperature (RT). The MD and ME measurements at RT indicate that BST/LSMO exhibits a nonlinear ME effect at low frequencies, with a threshold near 0.5 T. The magnetocapacitance (MC{sub p}) measurements evidence a quadratic dependence on magnetic field, further confirming the multiferroic nature of BST/LSMO. The order of MC{sub p} was found to be ∼7% per Tesla. The analysis of the MC{sub p} measurements indicates that one of the BST/LSMO compositions studied can be considered as a new multiferroic compound.« less

Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ceylan, Abdullah, E-mail: aceylanabd@yahoo.com; Ozcan, Yusuf; Orujalipoor, Ilghar

2016-06-07

In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactivemore » growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron microscopy observations but also provide additional information on the large scale size and shape distribution of the nanostructured components.« less

Green synthesis of colloid silver nanoparticles and resulting biodegradable starch/silver nanocomposites.

PubMed

Cheviron, Perrine; Gouanvé, Fabrice; Espuche, Eliane

2014-08-08

Environmentally friendly silver nanocomposite films were prepared by an ex situ method consisting firstly in the preparation of colloidal silver dispersions and secondly in the dispersion of the as-prepared nanoparticles in a potato starch/glycerol matrix, keeping a green chemistry process all along the synthesis steps. In the first step concerned with the preparation of the colloidal silver dispersions, water, glucose and soluble starch were used as solvent, reducing agent and stabilizing agent, respectively. The influences of the glucose amount and reaction time were investigated on the size and size distribution of the silver nanoparticles. Two distinct silver nanoparticle populations in size (diameter around 5 nm size for the first one and from 20 to 50 nm for the second one) were distinguished and still highlighted in the potato starch/glycerol based nanocomposite films. It was remarkable that lower nanoparticle mean sizes were evidenced by both TEM and UV-vis analyses in the nanocomposites in comparison to the respective colloidal silver dispersions. A dispersion mechanism based on the potential interactions developed between the nanoparticles and the polymer matrix and on the polymer chain lengths was proposed to explain this morphology. These nanocomposite film series can be viewed as a promising candidate for many applications in antimicrobial packaging, biomedicines and sensors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Surface modification of a polyethylene film for anticoagulant and anti-microbial catheter

PubMed Central

Zheng, Yingying; Miao, Jianjun; Zhang, Fuming; Cai, Chao; Koh, Amanda; Simmons, Trevor J.; Mousa, Shaker A.; Linhardt, Robert J.

2016-01-01

A functional anticoagulant and anti-bacterial coating for polyethylene (PE) films is described. The stepwise preparation of this nanocomposite surface coating involves O2 plasma etching of PE film, carbodiimide coupling of cysteamine to the etched PE film, binding of Ag to sulfhydryl groups of cysteamine, and assembly of heparin capped AgNPs on the PE film. The nanocomposite film and its components were characterized by 1H-nuclear magnetic resonance spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and field emission-scanning electron microscopy. The resulting PE films demonstrate anticoagulant activity using a hemoglobin whole blood clotting assay, and anti-bacterial activity against Bacillus cereus 3551 (Gram-positive) and Escherichia coli BL21 (Gram-negative) bacteria. The hydrophilicity of the heparin coated PE was determined by contact angle measurements; and the stability of the nanocomposite film, with respect to Ag leaching, was assessed by atomic absorption spectroscopy. PMID:26900340

Graphene-sulfur nanocomposites for rechargeable lithium-sulfur battery electrodes

DOEpatents

Liu, Jun; Lemmon, John P; Yang, Zhenguo; Cao, Yuiliang; Li, Xiaolin

2014-06-17

Rechargeable lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter less than 50 nm..

Enhanced physicochemical properties of chitosan/whey protein isolate composite film by sodium laurate-modified TiO2 nanoparticles.

PubMed

Zhang, Wei; Chen, Jiwang; Chen, Yue; Xia, Wenshui; Xiong, Youling L; Wang, Hongxun

2016-03-15

Chitosan/whey protein isolate film incorporated with sodium laurate-modified TiO2 nanoparticles was developed. The nanocomposite film was characterized by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry, and investigated in physicochemical properties as color, tensile strength, elongation at break, water vapor permeability and water adsorption isotherm. Our results showed that the nanoparticles improved the compatibility of whey protein isolate and chitosan. Addition of nanoparticles increased the whiteness of chitosan/whey protein isolate film, but decreased its transparency. Compared with binary film, the tensile strength and elongation at break of nanocomposite film were increased by 11.51% and 12.01%, respectively, and water vapor permeability was decreased by 7.60%. The equilibrium moisture of nanocomposite film was lower than binary film, and its water sorption isotherm of the nanocomposite film fitted well to Guggenheim-Anderson-deBoer model. The findings contributed to the development of novel food packaging materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Positron Annihilation Spectroscopy as a Novel Interfacial Probe for Thin Polymeric Films and Nano-Composites

NASA Astrophysics Data System (ADS)

Awad, Somia; Chen, Hongmin; Maina, Grace; Lee, L. James; Gu, Xiaohong; Jean, Y. C.

2010-03-01

Positron annihilation spectroscopy (PAS) has been developed as a novel probe to characterize the sub-nanometer defect, free volume, profile from the surface, interfaces, and to the bulk in polymeric materials when a variable mono-energy slow positron beam is used. Free-volume hole sizes, fractions, and distributions are measurable as a function of depth at the high precision. PAS has been successfully used to study the interfacial properties of polymeric nanocomposites at different chemical bonding. In nano-scale thin polymeric films, such as in PS/SiO2, and PU/ZnO, significant variations of Tg as a function of depth and of wt% oxide are observed. Variations of Tg are dependent on strong or weak interactions between polymers and nano-scale oxides surfaces.

Diamond-like nanocomposite: a novel promising carbon based thin film as antireflection and passivation coating for silicon solar cell

NASA Astrophysics Data System (ADS)

Jana, Sukhendu; Das, Sayan; De, Debasish; Mondal, Anup; Gangopadhyay, Utpal

2018-02-01

Presently, silicon nitride (SiN x ) is widely used as antireflection coating (ARC) on p-type silicon solar cell. But, two highly toxic gasses ammonia and silane are used. In the present study, the ARC and passivation properties of diamond-like nanocomposite (DLN) thin film on silicon solar cell have been investigated. The DLN thin film has been deposited by rf-PACVD process using liquid precursor HMDSO in argon plasma. The film has been characterized by FESEM, HRTEM, FTIR, and Raman spectroscopy. The optical properties have been estimated by UV-vis-NIR spectroscopy. The minimum reflection has been achieved to 0.75% at 630 nm. Both the short circuit current density and open circuit voltage has been increased significantly from 28.6 mA cm-2 to 35.5 mA cm-2 and 0.551 V to 0.613 V respectively. The field effect passivation has been confirmed by dark IV characterization of c-Si /DLN heterojunction structure. All these lead to enhancement of efficiency by almost 4% absolute, which is comparable to SiN x . The ammonia and silane free deposited DLN thin film has a great potential to use as ARC for silicon based solar cell.

Structural, optical and thermal characterization of PVC/SnO2 nanocomposites

NASA Astrophysics Data System (ADS)

Taha, T. A.; Ismail, Z.; Elhawary, M. M.

2018-04-01

The structural, optical, and thermal properties of PVC/SnO2 nanocomposites were investigated. XRD patterns were used to explore the structures of these prepared samples. Optical UV-Vis measurements were analyzed to calculate the spectroscopic optical constants of the prepared PVC/SnO2 nanocomposites. Both direct and indirect optical band gaps decreased with increasing SnO2 content. The refractive index, high frequency dielectric constant, plasma frequency, and optical conductivity values increased with SnO2. The single oscillator energy increased from 5.64 to 10.97 eV and the dispersion energy increased from 6.35 to 19.80 eV with the addition of SnO2. The other optical parameters such as optical moments, single oscillator strength, volume energy loss, and surface energy loss were calculated for different SnO2 concentrations. Raman spectra of the PVC/SnO2 nanocomposite films revealed the characteristic vibrational modes of PVC and surface phonon modes of SnO2. The thermal stability of PVC/SnO2 nanocomposite films was studied using DTA and thermogravimetric analysis. The glass transition ( T g) values abruptly changed from 46 °C for PVC to an average value of 59 °C for the polymer films doped with 2.0, 4.0, and 6.0 wt% SnO2. The weight loss decreased as the SnO2 concentration increased in the temperature range of 350-500 °C, corresponding to enhanced thermal stability.

Ternary graphene/amorphous carbon/nickel nanocomposite film for outstanding superhydrophobicity

NASA Astrophysics Data System (ADS)

Zhu, Xiaobo; Zhou, Shengguo; Yan, Qingqing

2018-04-01

A novel superhydrophobic ternary graphene/amorphous carbon/nickel (G-Ni/a-C:H) carbon-based film was fabricated by a green approach of high-voltage electrochemical deposition without using aqueous solution, which was systematically investigated including the structure and relating applications on self-cleaning and corrosion resistance. Graphene and nickel nano-particle inserts were effective to tailor the feature of nanocrystallite/amorphous microstructure as well as micro-nanoscale hierarchical rose-petal-like surface for G-Ni/a-C:H carbon-based film. Surprisingly, this deposit could present outstanding superhydrophobicity with the contact angle of 158.98 deg and sliding angle of 2.75 deg without any further surface modification meanwhile it could possess fairly well adhesion. Furthermore, the superhydrophobic G-Ni/a-C:H carbon-based film could exhibit excellent corrosion resistance and self-cleaning performances compared to no graphene incorporated deposit. The procedure of fabricating deposit might be simple, scalable, and environmental friendly, indicating a promising prospect for industrial applications in the field of anti-fouling, anti-corrosion and drag resistance.

Carbon nanotube macrofilm-based nanocomposite electrodes for energy applications

NASA Astrophysics Data System (ADS)

Cao, Zeyuan

, Ni)) with CNT macofilms as high performance anodes for rechargeable lithium-ion batteries and as catalysts for oxygen reduction/evolution (ORR/OER). All MxOy-CNT macrofilm nanocomposites inherit the high specific capacity and cycling stability for lithium-ion batteries. NiO/SWNT and Co3O4/SWNT (200 °C) have their specialized high catalytic activities for ORR and OER in alkaline solutions, respectively. NiO/SWNT also exhibits an excellent electrochemical performance in asymmetric supercapacitors with a high power and energy density. Experimental measurements on electrochemical kinetics such as potentiostatic/galvanostatic intermittent titration techniques (PITT/GITT) are depended to understand the underlying improved Li+ diffusion behavior of nanocomposites. Critical effects of the film thickness have been identified. The CNT macrofilm with a thickness that is comparable to the characteristic diffusion length of 300~500 nm enables the nanocomposite with the highest Li+ chemical diffusion coefficient and thus an optimal electrochemical performance. The adhesive characteristic of CNT macrofilms is noticed for the first time after fragmentation by ultrasound that origins from irregular structures of laterally 2-D distributed CNT segments. The fragmented CNT macrofilms (FCNT) as "bifunctional" adhesive conductors promote a general approach to construct nanocomposite electrodes with both cathode and anode materials for lithium-ion batteries. An in-situ tribology method combining the wear track imaging and force measurement is employed to evaluate the adhesion strength of the adhesive FCNT conductors. The results show that the FCNT macrofilms have a higher adhesion strength than the conventional polymer binder polyvinylidene fluoride (PVDF). It is confirmed that the fabricated nanocomposite electrodes exhibit high rate and retention capabilities, superior to the electrodes using PVDF and carbon black. Thus, FCNT is recognized to be a competent substitute for polymer