共查询到20条相似文献,搜索用时 15 毫秒
1.
《Current Applied Physics》2009,9(3):581-587
Efficient utilization of inherently conducting polymers in nano technological applications faces the challenge to assemble them into highly ordered structures which may yield novel properties. The present study reports for the first time the synthesis and characterization of nanostructured poly (1-naphthylamine) (PNA) dispersed polyvinyl alcohol (PVA) composites. The composites were prepared by loading PNA from 2 wt% to 10 wt% in PVA in aqueous as well as nonaqueous media. The composites were characterized by UV–visible spectroscopy, TEM, stress–strain studies, electrical conductivity measurements and moisture absorption studies under controlled humidity. A discrete but uniform distribution of nanoparticles was obtained in PNA/PVA composites synthesized in water having particle size between 5 and 30 nm. A self assembled network of nanostructured PNA particles was obtained in case of PNA/PVA composites synthesized in N-methylpyrolidone (NMP) with particle sizes between 10 and 65 nm. The variation in the nanostructured morphology of PNA particles in PVA matrix in the two cases resulted from the pronounced interaction of PVA with NMP through hydrogen bonding. This leads to the formation of a homogeneous matrix that facilitates the formation of a self assembled network of PNA nano particles. In case of PNA/PVA composites synthesized in water, lower affinity of PVA towards water was responsible for a discrete, agglomerate free distribution of PNA particles. We have found that the PNA/PVA nano composite synthesized in water exhibited good mechanical properties and electrical conductivity (8.1 × 10−1 S/cm) as well as lowest moisture absorption (4 wt%) which holds potential for use in semiconductor and biomedical devices. 相似文献
2.
Sung Hwan Koo Dong Jun Li Taeyeong Yun Dong Sung Choi Kyung Eun Lee Gil Yong Lee Youngtak Oh Joonwon Lim Suchithra Padmajan Sasikala Ho Jin Lee In Ho Kim Hong Ju Jung Rishabh Jain Sang Ouk Kim 《Particle & Particle Systems Characterization》2019,36(7)
Efficient water electrolysis catalyst is highly demanded for the production of hydrogen as a sustainable energy fuel. It is reported that cobalt derived nanoparticle (CoS2, CoP, CoS|P) decorated reduced graphene oxide (rGO) composite aerogel catalysts for highly active and reliable hydrogen evolution reaction electrocatalysts. 7 nm level cobalt derived nanoparticles are synthesized over graphene aerogel surfaces with excellent surface coverage and maximal expose of active sites. CoS|P/rGO hybrid aerogel composites show an excellent catalytic activity with overpotential of ≈169 mV at a current density of ≈10 mA cm?2. Accordingly, efficient charge transfer is attained with Tafel slope of ≈52 mV dec?1 and a charge transfer resistance (Rct) of ≈12 Ω. This work suggests a viable route toward ultrasmall, uniform nanoparticles decorated graphene surfaces with well‐controlled chemical compositions, which can be generally useful for various applications commonly requiring large exposure of active surface area as well as robust interparticle charger transfer. 相似文献
3.
Sidsel Ø. Andreasen Siow‐Feng Chong Mille B. L. Kryger Bettina E. B. Jensen Almar Postma Marie‐Helene Alves Brigitte Städler Kenneth N. Goldie Alexander N. Zelikin 《Particle & Particle Systems Characterization》2013,30(6):514-522
The assembly, cellular internalization, and cytotoxicity of nanoparticles based on physical hydrogels of poly(vinyl alcohol) (PVA) are reported. PVA nanoparticles are assembled using a liposomal templating technique followed by removal of the lipids using isopropanol, a process that requires the presence of a custom‐made block copolymer, poly(vinyl alcohol‐b‐vinyl pyrrolidone), to avoid aggregation of the nanoparticles. Polymer hydrogelation is induced via incubation in aqueous isopropyl alcohol solution, which results in PVA hydrogel nanoparticles (PVA HNP) with excellent colloidal stability and stability towards disintegration over at least 24 h. Pristine PVA HNP are found to be remarkably stealth‐like and exhibit negligible cellular internalization. This feature is likely inherent with the low fouling nature of PVA and makes PVA HNP attractive for targeted drug delivery with a low level of association with non‐targeted cells and tissues. Blending PVA with varied amounts of collagen results in colloidal hydrogel particles with a well pronounced tendency towards association with mammalian cells, specifically hepatocytes and endothelial cells. The association of PVA HNP elicits minimal changes in cellular proliferation, making these novel hydrogel particles convenient tools for drug delivery applications and creation of implantable artificial organelles and sensors. 相似文献
4.
《Composite Interfaces》2013,20(7):425-432
Abstract ZnS nanoparticles and Mn2+-doped ZnS nanoparticles were prepared by a reverse micelle reaction system. In addition, ZnS and Mn2+-doped ZnS nanoparticles were modified with poly(vinyl alcohol) (PVA) and 1-dodecanethiol (C12H25SH). The average particle size of the ZnS sample is determined around 2.3 nm by using the well-known Scherrer equation, which is in accordance with the results obtained from UV–vis and TEM analysis. Fluorescence intensity of the Mn2+-doped ZnS nanoparticles increases with increasing Mn2+ content compared with undoped ZnS nanoparticles, and coating PVA can also make fluorescence intensity increase. Different Zn2+/S2- or C12H25SH/Zn2+ can affect intensity of PL emission peak and its position, which is discussed in this paper. 相似文献
5.
T. Beuvier J.‐F. Bardeau B. Calvignac G. Corbel F. Hindr J.‐M. Grenche F. Boury A. Gibaud 《Journal of Raman spectroscopy : JRS》2013,44(3):489-495
Calcium carbonate (CaCO3)/iron oxide composites were synthesized through a simple one‐step impregnation procedure by mixing iron oxide nanoparticles (γ‐Fe2O3 and Fe3O4) of about 6 nm in size and CaCO3 microparticles (Φ = 2 µm–8 µm, vaterite phase). The morphology and structural properties of CaCO3, iron oxide nanoparticles and CaCO3/iron oxide composites were characterized as a function of low iron content (0 %w to 3.2 %w) by scanning electron microscopy and transmission electron microscopy, X‐ray diffraction and 57Fe Mössbauer spectrometry. The phase transformations induced by thermal treatment and laser irradiation were investigated in situ by X‐ray thermodiffraction (XRTD) and Raman spectroscopy. We have shown that the phase transformations observed by XRTD are also observed under laser irradiation as a consequence of the absorption of the laser irradiation by iron oxide nanoparticles. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
6.
Dextran‐Coated Antiferromagnetic MnO Nanoparticles for a T1‐MRI Contrast Agent with High Colloidal Stability
下载免费PDF全文
![点击此处可从《Particle & Particle Systems Characterization》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Herbert R. Neves Rafael A. Bini Jeam H. O. Barbosa Carlos E. G. Salmon Laudemir C. Varanda 《Particle & Particle Systems Characterization》2016,33(3):167-176
A simple approach to synthesize carboxymethyl dextran‐coated MnO nanoparticles (CMDex‐MnONPs) with high colloidal stability in physiological saline solutions is described here for potential applications as a magnetic resonance imaging (MRI) T1 contrast agent. The thermal decomposition methodology is used to produce uniform MnONPs with an average size of around 20 nm, and its hydrophobic surface is modified with CMDex molecules, conferring hydrophilic properties. After CMDex coating, the nanoparticle presents high colloidal stability in concentrations ranging from 10 to 50 μg mL?1, average hydrodynamic size (Z‐average) of 130 nm, polydispersity degree of ≈12%, and negative surface charge in both simulated body fluid solutions and pure water with zeta‐potential of –20 and –40 mV, respectively. The CMDex‐MnONPs with 20 nm show antiferromagnetic behavior at room temperature, and the magnetic properties are found to be strongly dependent of the nanoparticle size, increasing the contribution of the ferromagnetic Mn3O4 phase with decreasing size for nanoparticles about 3 nm. Cytotoxicity evaluation in cancerous and noncancerous cells in the range of 5.0–50.0 μg mL?1 shows low toxicity for cancerous cells and lack of the same for healthy cells lines. Related to the magnetic properties, CMDex‐MnONP presents significant r1 relaxivity and low r2/r1 relaxivity ratio. The results suggest that these nanoparticles display characteristics for potential applications as an MRI T1 contrast agent. 相似文献
7.
Guanghui Xu Qiang Zhang Weiping Zhou Jiaqi Huang Fei Wei 《Applied Physics A: Materials Science & Processing》2008,92(3):531-539
This study sought to produce carbon nanotube (CNT) pulp out of extremely long, vertically aligned CNT arrays as raw materials.
After high-speed shearing and mixing nitric acid and sulfuric acid, which served as the treatment, the researchers produced
the desired pulp, which was further transformed into CNT paper by a common filtration process. The paper’s tensile strength,
Young’s modulus and electrical conductivity were 7.5 MPa, 785 MPa and 1.0×104 S/m, respectively, when the temperature of the acid treatment was at 110°C. Apart from this, the researchers also improved
the mechanical property of CNT paper by polymers. The CNT paper was soaked in polyethylene oxide, polyvinyl pyrrolidone, and
polyvinyl alcohol (PVA) solution, eventually making the CNT/PVA film show its mechanical properties, which increased, while
its electrical conductivity decreased. To diffuse the polymer into the CNT paper thoroughly, the researchers used vacuum filtration
to fabricate a CNT/PVA film by penetrating PVA into the CNT paper. After a ten-hour filtration, the tensile strength and Young’s
modulus of CNT/PVA film were 96.1 MPa and 6.23 GPa, respectively, which show an increase by factors of 12 and 7, respectively,
although the material’s electrical conductivity was lowered to 0.16×104 S/m. 相似文献
8.
The I–V characteristics of the sliding contact of metallic composites of grade 45 steel without a lubricant are presented. Steel-based
composites are shown to increase the actual electric-contact area due to the appearance of electric discharges, which provide
the main passage of an electric current with a density up to 300 A/cm2. Copper-based composites cannot initiate electric-discharge conduction because of the fracture of the contact zone material
at a current density higher than 50 A/cm2. The electrical resistivity of the contact layer of metallic composites is calculated. It is found that, during friction
with a high current density, the electrical resistivity of the contact layer approaches the electrical resistivity of graphite.
It is experimentally shown that the actual electric-contact area can be increased by the introduction of a Pb-Sn melt into
the friction zone and reaching a current density higher than 300 A/cm2 in the contact. 相似文献
9.
Magnetically‐Confined Fe‐Mn Bimetallic Oxide Encapsulation as an Efficient and Recoverable Adsorbent for Arsenic(III) Removal
下载免费PDF全文
![点击此处可从《Particle & Particle Systems Characterization》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Li Yu Huijuan Liu Chunlei Liu Huachun Lan Jiuhui Qu 《Particle & Particle Systems Characterization》2016,33(6):323-331
Synthesis of bimetallic‐oxide‐encapsulated magnetic nanoparticles is still significantly challenging and has rarely been attempted previously, due to the effects of lattice mismatch, weak chemical interactions and variances in growth rates between different components, as well as the difficulty in process control for uniform co‐deposition. In the present work, Fe‐Mn bimetallic oxide (FMBO) nanoplatelet encapsulated magnetic nanoparticles (Mag‐FeMn) are prepared by controlled engineering of the interparticle coupling of Fe3O4 and FMBO, with its multifunctional capabilities highlighted in terms of the potentially superior As(III) sequestration and convenient recoverability. Multiple characterization techniques are employed to examine the derived morphologies and to accurately resolve both compositionally and magnetically the hierarchical structure in detail. The synthesized magnetic composites retain highly porous structure with the main components of Fe2O3, FeOOH, Fe3O4, and Mn3O4. Mag‐FeMn exhibits a quite competitive high capacity for As(III) capture (56.1 mg g–1), whereby As(III) oxidation coupled with synchronous sorption contributes to the improved performance. The unique heterostructure of FMBO encapsulation with an embedded magnetic core would be applicable to help with rational synthesis of other bimetallic oxide encapsulated magnetic nanoparticles, and definitely shows promise for the development of new nanotechnology enabled approaches for adsorption‐based water purification. 相似文献
10.
Jayaraman Jayabharathi Annadurai Prabhakaran Chockalingam Karunakaran Venugopal Thanikachalam Munusamy Sundharesan 《Journal of Physical Organic Chemistry》2017,30(2)
Interaction of sol–gel synthesized Ce–Ag‐codoped ZnO (CSZO) nanocrystals with (E)‐1‐(naphthalen‐1‐yl)‐2‐styryl‐1H‐phenanthro[9,10‐d]imidazole has been analysed. The synthesized nanocrystals and their composites with naphthyl styryl phenanthrimidazole have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X‐ray spectroscopy, X‐ray diffractometry, X‐ray photoelectron spectroscopy (XPS) lifetime and Fourier transform infrared spectroscopy and cyclic voltammetry. XPS shows doped silver and cerium in Ag0 and Ce4+ states, respectively. SEM and TEM images of CSZO nanoparticles show that they appear to be 3D trapezoid and cocoon‐like shape. The selected area electron diffraction pattern supports the nanocrystalline character of the synthesized material. The percentages of doping of cerium and silver in CSZO are 0.54 (at.) and 0.34 (at.), respectively. From the energy levels of the materials used in the imidazole–CSZO composite, the dominant CT direction has been analysed. Theoretical investigation shows that the binding energy and energy gap of the imidazole composites are highly dependent on the nature of the silver oxide cluster and that charge transfer in the imidazole–Ag4O4 composite is faster than the same in other composites. Molecular docking technique has also been carried out to understand the imidazole–DNA interactions. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
11.
T. Badapanda V. Senthil S. Anwar L.S. Cavalcante N.C. Batista E. Longo 《Current Applied Physics》2013,13(7):1490-1495
The polyvinyl alcohol (PVA)/barium zirconium titanate Ba[Zr0.1Ti0.9]O3 (BZT) polymer–ceramic composites with different volume percentage are obtained from solution mixing and hot-pressing method. Their structural and electrical properties are characterized by X-ray diffraction (XRD), Rietveld refinement, cluster modeling, scanning electron microscope and dielectric study. XRD patterns of PVA/BZT polymer–ceramics composite (with 50% volume fractions) indicate no obvious differences than the XRD patterns of pure BZT which shows that the crystal structure is still stable in the composite. The scanning electron micrograph indicates that the BZT ceramic is dispersed homogeneously in the polymer matrix without agglomeration. The dielectric permittivity (εr) and the dielectric loss (tan δ) of the composites increase with the increase of the volume fraction of BZT ceramic. Theoretical models are employed to rationalize the dielectric behavior of the polymer composites. The dielectric properties of the composites display good stability within a wide range of temperature and frequency. The excellent dielectric properties of these polymer–ceramic composites indicate that the BZT/PVA composites can be a candidate for embedded capacitors. 相似文献
12.
Ahmad I. Ayesh Mahmoud A. Mohsin Mohammad Y. Haik Yousef Haik 《Current Applied Physics》2012,12(4):1223-1228
Thin films of poly(vinyl alcohol) (PVA) that are 100–500 μm thick were prepared by solution casting method. Various ratios of 1-methyl-3-n-decyl-imidazolium bromide ionic liquid [MDIM](+)Br(?), were used as dopants (plasticizers) to control the conductivity of the PVA thin films. Fourier transform infrared spectroscopy (FTIR) was used to indicate the detailed interaction of PVA with proton of the dopant in the blends. Ac impedance spectroscopy was used to investigate the impedance of the films within a frequency range of 10–106 Hz as a function of temperature between 298 and 425 K. Each film with a precise doping concentration was sandwiched between two stainless–steel electrodes. The results showed that the electrical conductivity can be engineered by controlling the [MDIM](+)Br(?) doping concentration. Therefore, those films have potential to be used in flexible and cheap organic device applications. 相似文献
13.
《Composite Interfaces》2013,20(2-3):103-111
Semiconductor–polymer nanocomposites, with good control over the nanoparticle size and their dispersion within the polymer matrix, can have applications in many optical and luminescent display devices. Cadmium sulphide (CdS) is the most popular semiconductor nanoparticle exhibiting size dependent properties due to its large exciton binding energy and its suitability for large scale production. The nanoparticles need to be passivated against aggregation with suitable capping agents, without sacrificing the desirable properties like transparency and flexibility of the polymer. Cadmium sulphide nanoparticles capped with polyvinyl pyrrolidone (PVP) are synthesized using cadmium nitrate (Cd(NO3)2) and hydrogen sulphide (H2S) as Cd2+ and S2– sources, respectively. CdS particles with sizes in the range of 5–6 nm are prepared in methanol and the solvent is removed using a rotary evaporator. CdS powder is dispersed in polyvinyl alcohol (PVA) solution with dimethyl formamide (DMF) as solvent to get (PVP–CdS)–PVA nanocomposite film of about 0.2 mm thickness. This has been characterized by powder X-ray diffraction (XRD), optical absorption studies, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and photoluminescence (PL). Particle size does not change due to incorporation in the polymer matrix and the polymer retains its transparency and flexibility. The nanocomposite shows good photoluminescence property with stronger band edge emission than defect related emission. The latter could be quenched completely by optimizing the PVP content. Irradiation of the nanocomposite with 8 MeV electrons at a dose of 100 kGy could effectively quench the defect related emission. 相似文献
14.
XAS analysis of iron and palladium bonded to a polysaccharide produced anaerobically by a strain of Klebsiella oxytoca
下载免费PDF全文
![点击此处可从《Journal of synchrotron radiation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Iztok Arčon Stefano Paganelli Oreste Piccolo Michele Gallo Katarina Vogel‐Mikuš Franco Baldi 《Journal of synchrotron radiation》2015,22(5):1215-1226
Klebsiella oxytoca BAS‐10 ferments citrate to acetic acid and CO2, and secretes a specific exopolysaccharide (EPS), which is able to bind different metallic species. These biomaterials may be used for different biotechnological purposes, including applications as innovative green biogenerated catalysts. In production of biogenerated Pd species, the Fe(III) as ferric citrate is added to anaerobic culture of K. oxytoca BAS‐10, in the presence of palladium species, to increase the EPS secretion and improve Pd‐EPS yield. In this process, bi‐metallic (FePd‐EPS) biomaterials were produced for the first time. The morphology of bi‐metallic EPS, and the chemical state of the two metals in the FePd‐EPS, are investigated by transmission electron microscopy, Fourier transform infra‐red spectroscopy, micro‐X‐ray fluorescence, and X‐ray absorption spectroscopy methods (XANES and EXAFS), and compared with mono‐metallic Pd‐EPS and Fe‐EPS complexes. Iron in FePd‐EPS is in the mineralized form of iron oxides/hydroxides, predominantly in the form of Fe3+, with a small amount of Fe2+ in the structure, most probably a mixture of different nano‐crystalline iron oxides and hydroxides, as in mono‐metallic Fe‐EPS. Palladium is found as Pd(0) in the form of metallic nanoparticles with face‐centred cubic structure in both bi‐metallic (FePd‐EPS) and mono‐metallic (Pd‐EPS) species. In bi‐metallic species, Pd and Fe nanoparticles agglomerate in larger clusters, but they remain spatially separated. The catalytic ability of bi‐metallic species (FePd‐EPS) in a hydrodechlorination reaction is improved in comparison with mono‐metallic Pd‐EPS. 相似文献
15.
M. Madani Nabila A. Maziad Rasha M. Khafagy 《Journal of Macromolecular Science: Physics》2013,52(6):1191-1203
Thermally stimulated depolarization current (TSDC) and thermal analysis studies of gamma irradiated LiOH/PVA blends were done. To study the mechanisms of conduction and TSDC in poly(vinyl alcohol) (PVA) and LiOH/PVA blends, short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm?1 have been analyzed in the temperature range 300–410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly‐blend system. The temperature dependence, 300–408 K, of the current density (J) for pure PVA and its blended samples has been studied. It was observed that J values increase dramatically with increasing temperature (in the low temperature region from 300–340 K) owing to the formation of local ordered regions in the otherwise disordered amorphous matrix of PVA. Further increase in the temperature caused a marginal increase in J values. The temperature dependence of the specific heat for all samples was measured. A linear increase of C p was observed with an increase in temperature, which is ascribed to the increase in lattice vibration of linear macromolecules and consequently, increases in the number of internal degree of freedom of phonons. 相似文献
16.
Thermal properties of polymeric nanosolids, obtained by condensing the corresponding nanofluids, are investigated using photothermal techniques. The heat transport properties of two sets of polyvinyl alcohol (PVA) based nanosolids, TiO2/PVA and Cu/PVA, prepared by condensing the respective nanofluids, which are prepared by dispersing nanoparticles of TiO2 and metallic copper in liquid PVA, are reported. Two photothermal techniques, the photoacoustic and the photopyroelectric techniques, have been employed for measuring thermal diffusivity, thermal conductivity and specific heat capacity of these nanosolids. The experimental results indicate that thermal conduction in these polymer composites is controlled by heat diffusion through the embedded particles and interfacial scattering at matrix–particle boundaries. These two mechanisms are combined to arrive at an expression for their effective thermal conductivity. Analysis of the results reveals the possibility to tune the thermal conductivity of such nanosolids over a wide range using the right types of nanoparticles and right concentration. 相似文献
17.
Very promising nanoparticles for biomedical applications or in medical drug targeting are superparamagnetic nanoparticles based on a core consisting of iron oxides (SPION) that can be targeted through external magnets. Polyvinyl alcohol (PVA) is a unique synthetic biocompatible polymer that can be chemically cross-linked to form a gel. Biotechnology applications of magnetic gels include biosensors, targeted drug delivery, artificial muscles and magnetic buckles. These gels are produced by incorporating magnetic materials in the polymer composites. In this paper we report the synthesis of an aqueous ferrofluid and the preparation of a biocompatible magnetic gel with polyvinyl alcohol and glutharaldehyde (GTA). HClO4 was used to induce the peptization since this kind of ferrofluid does not have surfactant. The magnetic gel was dried to generate a biocompatible film. 相似文献
18.
Synthesis and characterization of CdS/PVA nanocomposite films 总被引:1,自引:0,他引:1
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 Cd2+-dispersed poly vinyl-alcohol (PVA) with H2S. 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 CdS 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. 相似文献
19.
Khaled M. Amin Abir M. Partila Hassan A. Abd El-Rehim Noha M. Deghiedy 《Particle & Particle Systems Characterization》2020,37(4):2000006
Today, plastic waste has been highlighted as one of the greatest threats to the environment. These environmental concerns and the increased necessity for safe food packaging have inspired scientists to focus on the development of active biodegradable materials. Herein, a novel poly(vinyl alcohol)/pluronic/ZnO nanocomposite film (PVA/PLUR/ZnO) is introduced as an active packaging material with enhanced antimicrobial activity. Gamma irradiation is used as a “green” route to prepare ZnO nanoparticles via a polymer pyrolysis method. The as-prepared ecofriendly ZnO nanoparticles are characterized and incorporated into the PVA/PLUR matrix in different concentrations. Transmission electron microscopy and dynamic light scattering measurements prove that ZnO nanoparticles have a mean particle size of 30 nm with a spherical-like morphology. Morphological and structural characterization confirm the successful incorporation of ZnO into the PVA/PLUR matrix, which in turn enhances the thermal and barrier properties of PVA/PLUR/ZnO nanocomposite films. On the other hand, the opacity of blends is increased. The PVA/PLUR/ZnO composites exhibit broad-spectrum antimicrobial activity against Gram-positive, Gram-negative bacterial pathogens, and fungi, and the activity increases with increasing concentrations of ZnO nanoparticles. These results introduce PVA/PLUR/ZnO films as effective antimicrobial materials for active food-packaging applications. 相似文献
20.
B. Doherty B. G. Brunetti A. Sgamellotti C. Miliani 《Journal of Raman spectroscopy : JRS》2011,42(11):1932-1938
The design and synthesis of a tailor‐made surface‐enhanced Raman scattering (SERS) active film that is fabricated to be removable from the surface of an artwork under study following effective measurements is detailed. It is shown that silver nanoparticles prepared by green chemical reduction with glucose can be effectively doped into a methylcellulose (MC) matrix for the formation of a gel, which can be subsequently applied to a minute area (ca 1–1.5 mm) of an artwork without posing a threat to its integrity. Studies have been aimed at characterizing this film's chemical and physical properties, with regard to the stability of the nanoparticles dispersed within the MC, the ease of application of the viscous gel, its speed of drying and the transparency of the dry film for SERS measurements. Importantly, results have led to reproducible SERS enhancements of the order 103–104 for studies carried out on reference laboratory dye components and unvarnished mock‐paintings. Techniques including optical and scanning electron microscopy were used to monitor the drying of the film and its resulting morphology, as well as to map the distribution of silver nanoparticles in the film so as to account for any visual modification to the underlying surface upon film removal. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献