Acetate Matrix Research Articles

Probing the Kinetics of Crystallite Growth in Sol–Gel Derived Metal-Oxides Using Nanocalorimetry

In this work, we show that fast-scanning chip nanocalorimetry can be used to kinetically separate the heat flow contributions of crystallite growth and precursor decomposition that occur during the thermal decomposition of metal-oxide solgel precursors. We illustrate the technique using zinc acetate dihydrate, a common precursor used in the sol-gel synthesis of zinc oxide thin films. Through an appropriately defined heating sequence consisting of precursor decomposition, followed by rapid quenching and subsequent zinc oxide crystallite growth, it is shown that the exothermic peaks corresponding to the growth of zinc oxide crystals can be kinetically separated from the endothermic peaks associated with precursor decomposition. The kinetic separation of these processes enables an analysis to be performed on the crystallite growth kinetics of zinc oxide within a zinc acetate matrix, as it would naturally occur during a solgel process. Through a quantitative analysis, we estimate the activation energy of crystallite growth, confirming Johnson–Mehl–Avrami growth kinetics at low heating rates, and extract a time–temperature-transformation diagram to visualize and quantify isocrystalline surfaces. Such fundamental knowledge regarding the evolution of crystallinity as a function of heating conditions is useful in the much broader sense of application development, serving as a guide to direct the precise thermokinetic engineering of crystallinity in sol–gel derived metal-oxide films. In particular, we emphasize its significance for electronic (ideally, high crystallinity), optoelectronic, and thermoelectric (ideally, low crystallinity) applications.

Cellulose acetate/multi-wall carbon nanotube/Ag nanofiber composite for antibacterial applications.

Herein we propose cellulose acetate/carbon nanotube/silver nanoparticles (CA/CNT/Ag) nanofiber composite for antibacterial applications. The nanofiber composite are expected to avoid harmful effects of silver (i.e. argyria and argyrosis) owing to anchoring of silver nanoparticles on carbon nanotubes (CNTs) and embedding of the composite inside cellulose acetate (CA) matrix. The carbon nanotubes/silver nanoparticles (CNT/Ag) nanocomposite localized inside the CA polymer matrix allow minimal/no direct contact of silver nanoparticles with human cells and are expected to show reduced silver leaching. The cellulose acetate (CA) nanofibers loaded with silver nanoparticles anchored multiwall carbon nanotubes (CNT/Ag) were fabricated by electrospinning. The samples were studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR), tensile strength tests and antibacterial assays. Synthesis of the CNT/Ag nanocomposite was confirmed with XPS, XRD, EDS and TEM analysis. SEM images showed regular morphology of the CA/CNT/Ag nanofiber composites. TEM images depicted anchoring of silver nanoparticles on CNTs and embedding of CNT/Ag in the CA nanofiber matrix. The antibacterial test results demonstrated excellent antibacterial performance of the CA/CNT/Ag. The CA/CNT/Ag samples ensured effective bacterial growth inhibition on agar plates, in liquid medium (optical density, OD590nm) (for 48h) and in bactericidal assay (relative cell viability, %). Our results suggested CA/CNT/Ag composite nanofibers as potential candidate for safer antibacterial applications.

Determination of Bendiocarb Insecticide by Reverse Flow Injection Analysis Using a Solid-Phase Reactor Containing Micro PbO2, Nano PbO2 and Grafted SiO2 - PbO2 Immobilized

Bendiocarb (BEN) is an acutely toxic carbamate insecticide which used in public places and agriculture, it is also effective against a wide range of nuisance and disease vector insects. A new rapid and sensitive reverse flow injection spectrophotometric procedure coupled with on-line solid-phase reactor is designed in this article for the determination of BEN in its insecticidal formulations and water samples, by using three different solid-phase reactors containing bulk PbO2 (B-SPR), PbO2 nanoparticles (N-SPR) and grafted nanoparticles of SiO2-PbO2 (G-SPR) immobilized on cellulose acetate matrix (CA). This method of oxidative coupling is based on alkaline hydrolysis of the BEN pesticide, and then coupled with N,N dimethyl-p-phenylenediamine sulphate (DMPD) to give a blue color product which measured at λmax 675 nm. It worth to mentioned that under optimal conditions, Beer’s law is obeyed in the range of 1-175 μg mL-1 for B-SPR and 0.25-70 μg mL-1 of BEN for both N-SPR and G-SPR respectively within limit of detection (LOD) of 0.931, 0.234 and 0.210 μg mL-1 for B-SPR N-SPR and G-SPR respectively. The surface methodology of the solid phase was also investigated by using atomic force microscopy.

Determination of Bendiocarb Insecticide by Reverse Flow Injection Analysis Using a Solid-Phase Reactor Containing Micro PbO2, Nano PbO2 and Grafted SiO2 - PbO2 Immobilized

Bendiocarb (BEN) is an acutely toxic carbamate insecticide which used in public places and agriculture, it is also effective against a wide range of nuisance and disease vector insects. A new rapid and sensitive reverse flow injection spectrophotometric procedure coupled with on-line solid-phase reactor is designed in this article for the determination of BEN in its insecticidal formulations and water samples, by using three different solid-phase reactors containing bulk PbO2 (B-SPR), PbO2 nanoparticles (N-SPR) and grafted nanoparticles of SiO2-PbO2 (G-SPR) immobilized on cellulose acetate matrix (CA). This method of oxidative coupling is based on alkaline hydrolysis of the BEN pesticide, and then coupled with N,N dimethyl-p-phenylenediamine sulphate (DMPD) to give a blue color product which measured at λmax 675 nm. It worth to mentioned that under optimal conditions, Beer’s law is obeyed in the range of 1-175 μg mL-1 for B-SPR and 0.25-70 μg mL-1 of BEN for both N-SPR and G-SPR respectively within limit of detection (LOD) of 0.931, 0.234 and 0.210 μg mL-1 for B-SPR N-SPR and G-SPR respectively. The surface methodology of the solid phase was also investigated by using atomic force microscopy.

Mg-MOF-74/Polyvinyl acetate (PVAc) mixed matrix membranes for CO2 separation

In this study, Mg-MOF-74 crystals were synthesised in order to prepare polymer/Mg-MOF-74 mixed matrix membranes (MMMs) for CO2/CH4 separation. Activation temperature and time of the Mg-MOF-74 crystals were determined in order to enhance the performance of polymer/Mg-MOF-74 mixed matrix. The Mg-MOF-74 crystals were then incorporated into polyvinyl acetate (PVAc) matrix to form dense MMMs by a solvent-casting method. After the structural characterisation of the prepared membranes, their CO2/CH4 separation properties were determined by measuring mixed gas permeabilities at 6 and 15 bar with a Wilke-Kallenbach method at steady-state. SEM image of MMM showed there were no visible voids at the MOF/polymer interface. The highest BET area of Mg-MOF-74 crystals was measured when activiation was performed at 150 °C for 24 h under vacuum. Mixed gas permeability measurements of the membranes showed that both CO2 permeability and selectivity were improved with the increasing amount of MOF suggesting strong adsorption selectivity of Mg-MOF-74 for CO2. Activation time of Mg-MOF-74 crystals influenced the permeability and selectivity of MMMs. Incorporation of Mg-MOF-74 helped reducing the effect of plasticization.

An Effective Optical Dual Gas Sensor for Simultaneous Detection of Oxygen and Ammonia.

The development of a simple, low-cost sensor for the effective sensing of multiple gases in industrial or residential zones has been in high demand in recent days. In this article, we have proposed an optical sensor for the dual sensing of oxygen (O2) and ammonia (NH3) gases, which consists of oxygen and ammonia-sensitive fluorescent dyes coated individually on both sides of a glass substrate. An ethyl cellulose (EC) matrix doped with platinum (II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP) serves as the oxygen-sensing material, whereas the NH3-sensing material includes an eosin Y fluorescent indicator immobilized within a cellulose acetate (CA) matrix. Both the oxygen and ammonia-sensitive materials were excited by the same LED light source with a 405 nm peak wavelength, while the corresponding emissions were detected separately for the selective sensing of the gases under study. The dual gas sensor exhibits maximum sensitivities of around 60 and 20 for oxygen and ammonia gases, respectively. The high sensitivity and selectivity of the proposed optical dual sensor suggests the feasibility of the simultaneous sensing of oxygen and ammonia for practical applications.

Determining the Effect of pH on Iron Oxidation Kinetics in Aquatic Environments: Exploring a Fundamental Chemical Reaction To Grasp the Significant Ecosystem Implications of Iron Bioavailability

Understanding the controls of the oxidation rate of iron (Fe) in oxygenated aquatic systems is fundamental for students of the Earth and Environmental Sciences as it defines the bioavailability of Fe, a trace metal essential for life. The laboratory experiment presented here was successfully developed and used during a third-year undergraduate lab course at Imperial College London for several years. It employs ultraviolet–visible (UV–vis) spectroscopy calibrated externally with 0 to 50 μM Fe2+ standards created in a 492 μM ferrozine and 0.43 M acetate matrix. The students conducted the oxidation experiments in stirred batch reactors at equilibrium with atmospheric oxygen. The solution contained 40.5 μM initial Fe2+ concentration and a 5.1 mM imidazole buffer. The pH was adjusted to values between 7.22 and 7.77. The students observed a pseudo-first-order reaction with respect to Fe2+ concentration. Plotting the logarithms of the apparent rate constants (k′) at different pH values leads to a gradient of 2.2 ± 0.2 min–1 pH–1, indicating a second-order reaction with respect to OH– concentration, in agreement with published literature. The oxidation reaction occurred rapidly (tens of seconds to tens of minutes) indicating that in oxygenated aquatic systems, Fe3+ will be the dominant oxidation state, significantly reducing the bioavailability of Fe. The simple laboratory experiment presented here allows the students to learn about kinetic parameters for a fundamental chemical reaction. It allows the students to explore the significant implications this has for aquatic ecosystems.

Polyethylene/Ethylene Vinyl Acetate and Ethylene Octene Copolymer/Clay Nanocomposite Films: Different Processing Conditions and Their Effect on Properties

Polymer nanocomposites based on a layered clay used as nanofiller and copolymers ethylene and vinyl acetate matrix (EVA, the content of vinyl acetate (VA) component 19 wt% and 5 wt%) and ethylene octene copolymer (EOC, 17% and 45% of octene) were prepared. KO Buss kneader and double screw extruder were used. The MMT Na+ and four types of commercial products such as Nanofil N5 and N3000, Cloisite 93A and 30B were used as nanofillers—5 wt% in relation to the content of montmorillonite. The aim was to evaluate the influence of copolymer composition and processing on prepared nanocomposite properties. The morphology of samples was examined by means of X‐ray diffraction (XRD) and transmission electronic microscopy TEM. Furthermore, mechanical and especially barrier properties were observed. Despite the fact that the XRD and microscopy results have revealed that complete exfoliation did not take place in any case, mechanical properties as well as the permeability showed that used 5 wt% of clay was enough to achieve the improvement of properties. Cloisite 30B might be the most suitable for the polyethylene/EVA matrix. In case of EOC copolymer the nanofiller Nanofil N3000 and mainly Cloisite 93A seems to be more suitable. The better properties were achieved for the version of EVA with lower VA content and also for EOC 17, but not for each evaluated property. POLYM. ENG. SCI., 59:2514–2521, 2019. © 2019 Society of Plastics Engineers

High-Performance All-Organic DFB and DBR Waveguide Laser with Various Grating Height Fabricated by a Two-Photon Absorption DLW Method

Organic solid-state lasers (OSSLs) with distributed feedback (DFB) structures or distributed Bragg reflectors (DBRs) are promising for potential application in bio-sensing and hazardous materials detection. Here, the laser performances of the all-organic DFB waveguide lasers with various grating heights ranging from 0.4 to 4.7 μm were investigated. The grating structures used as the lasing cavity were fabricated using a two-photon absorption (TPA) direct laser writing (DLW) method with an SU-8 negative photoresist. The laser active layer consisted of a rhodamine 6G (R6G) laser dye and a cellulose acetate (CA) matrix. The R6G/CA solution was spin-coated onto the quartz substrate with the cavity (grating) structures to fabricate the DFB waveguide laser devices. The diffraction order of lasing ranged from m = 4 to 7. As the grating height was increased to 1.9 μm, the slope efficiency increased for all diffraction orders and the threshold decreases for each diffraction order. The dependence of the cavity (grating) length on the laser performances was investigated. The slope efficiency increased as the cavity length increased to 300 μm. The effect of the cavity (grating) position on the slope efficiency and the threshold position of the cavity (grating) was also studied. A maximum slope efficiency of 10.2% was achieved for the DFB waveguide laser device with a cavity (grating) length of 300 μm, a cavity position at 6 mm from the emission edge of the waveguide, and an aspect ratio ≈3 between the grating height of 1.74 μm and the grating width of 0.6 μm for the diffraction order m = 6 for lasing.

Influence of Natural Fillers on Thermal and Mechanical Properties and Surface Morphology of Cellulose Acetate-Based Biocomposites

In the present study, the influence of adding natural fillers to a cellulose acetate (CA) matrix, in order to develop biocomposites, on the properties of the achieved materials has been investigated. Extracted wood flour, holocellulose, and alpha cellulose were used as appropriate fillers. The results of the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the fillers and biocomposites suggested the importance of the degree of degradation of filler properties, induced by the chemical treatment necessary for the preparation of the fillers, with emphasis on the content of lignin and the degradation of cellulose. Scanning electron microscopy (SEM) and mechanical analysis revealed that the matrix-filler ratio had a major effect on the prepared CA-based biocomposites, since polarity differences between the two major components caused the reduction of attractive forces in the matrix-filler relation, subsequently altering the properties of the developed materials.

Ultrasonic dispersion and activation of TiO2 nanoparticles and its effect on bacterial inhibition in EVA films

By incorporating titanium dioxide (TiO2) nanoparticles, assisted by ultrasound, it was possible to confer antibacterial properties to an ethylene-co-vinyl acetate (EVA) matrix. A systematic study of the ultrasonic process was performed to determine whether or not the sonication parameters have a significant effect on the nanoparticles dispersion and therefore, on the composite antibacterial property. Scanning electron microscopy showed a significant difference in the TiO2 agglomerate size when sonication was applied instead of mechanical dispersion. In addition, the TiO2 nanoparticles efficiency to inhibit bacterial growth was demonstrated by comparing the measurements of colony forming units as a function of the dispersion treatment. It was found that the combination of 60% pulse and 60% amplitude were the best conditions to reduce Escherichia coli growth.

Fabrication and performance of PSf/CA ultrafiltration membranes: Effect of additives for fouling resistance and selective polyphenol removal from apple juice

This work focused on the addition of different pore formation-controlling agent to a polysulfone/cellulose acetate blend membrane via immersion precipitation using phase inversion technique to improve the fouling resistance and selective polyphenol removal of apple juice. The membranes were prepared by blending hydrophilic polyvinylpyrrolidone (PVP) and amphiphilic Pluronic F127 (Plu) with polysulfone/cellulose acetate matrix in N-methyl-2-pyrrolidone. The morphology, mechanical strength, flux permeation, flux recovery ratio, and polyphenol separation of these membranes were characterized. It was found that the fabricated membranes with addition of PVP and Plu were more effective than the membrane without a pore formation-controlling agent. The flux recovery of the membranes with combined pore formers after ultrafiltration of bovine serum albumin increased from 12.4% to 66.9%. The selectivity of polyphenols increased from 6% to 79% with an improved flux recovery of 79%, which shows the reduction of yellowish-brown pigment in apple juice.

EFFECTS OF THE PRESENCE OF CELLULOSE AND CURAUA FIBERS IN THE THERMAL AND MECHANICAL PROPERTIES OF ECO-COMPOSITES BASED ON CELLULOSE ACETATE

Eco-composite materials have gained the interest of academia and industry due to their environmentally friendly features. In this work, two groups of eco-composites of cellulose acetate matrix reinforced with cellulose and curaua fibers were prepared by extrusion and injection method. The first group of eco-composites, were prepared on laboratory scale, with curaua fibers, virgin and treated by two different methods; extraction with acetone and mercerized. A second group of materials was obtained on pilot scale, for which cellulose fibers and curaua fibers treated with acetone were used at different times of extraction. The acetone treatment was selected because in the first group, the materials with these fibers presented better mechanical properties, and mainly for their lower thermal conductivity (0.132 W m-1 K-1), compared to those from untreated fibers (0.178 W m-1 K-1) and treated with NaOH (0.255 W m-1 K-1). The eco-composites prepared on a pilot scale with curaua fibers previously treatment with acetone for 5 days presented a better balance of their thermal and mechanical properties, which could allow their use as thermal insulation with high mechanical performance (thermal conductivity = 0.097 W m-1 K-1 and modulus of elasticity = 2.2 GPa).

Novel insights into the properties of AgBiO3 photocatalyst and its application in immobilized state for 4-nitrophenol degradation and bacteria inactivation

This study focuses on the synthesis of novel AgBiO3 nanoparticles by the hydrothermal route and investigating its properties responsible for waste water treatment. The temperature and time of hydrothermal reaction was optimized to 150 °C and 24 h to obtain highly active crystalline nanoparticles, as determined by XRD. The oxidation state of each element in the material was determined from XPS analysis. The morphology and size of the nanoparticles was obtained from SEM and TEM analysis. The optical and electrochemical properties of the material were studied by UPS and Mott Schottky plot. AgBiO3 was found to have a low band gap that facilitates the absorption of higher wavelength range as confirmed by Tauc plots and UV–vis DRS analysis. The excellent photocatalytic activity of the immobilized material towards the degradation of 4-nitrophenol and inactivation of E. coli was confirmed from kinetic studies and stability tests. A maximum degradation of 90% was achieved for 4-NP and a 5-log reduction was observed for viable E. coli cells in 5 h and 1 h respectively. Scavenger studies were performed to identify that superoxide radicals were responsible for the photocatalytic activity of the material. To eliminate the cost of separation and ease the reusability of the material, the nanoparticles were immobilized on cellulose acetate. Leaching of Ag and Bi ions from immobilized as well as free AgBiO3 nanoparticles into water was obtained via ICP-MS analysis. The results indicated that the leaching of Ag and Bi was controlled to a considerable extent due to immobilization on cellulose acetate matrix.

Preparation of cellulose acetate blended with chitosan nanostructured membrane via electrospinning for Cd2+ adsorption in artificial wastewater

This study focused on using chitosan (CS) as the functional polymer in the cellulose acetate (CA) matrix to provide reactive ion exchange sites for heavy metal ions. Pure CA and CA/CS blends (wt % 95:5, 90:10 and 85:15) were electrospun to determine the most qualified blend for the adsorption experiment. The morphologies of the electrospun nanostructured membranes were investigated using Scanning Electron Microscopy. The average fiber diameter was found to decrease with increasing CS concentration. CA and CS interaction was confirmed using Fourier Transform Infrared Spectroscopy. Upon characterization, the blend with 15% CS had the best properties for the adsorption process. The adsorption capacities of pure CA and CA/CS blend at different membrane loading and initial concentration showed a significant increase from 67.25 mg Cd2+/g pure CA membrane to 110.48 mg/g CS doped membrane. The experiment revealed that the adsorption kinetics of pure CA and CA/CS blend for Cd2+ were described by the pseudo-second order reaction model. The adsorption isotherm data for Cd2+on the surface of pure CA and CA/CS blend best fit the Freundlich isotherm and can be used to describe adsorption of Cd2+. This study produced an innovative nanostructured membrane for the removal of Cd2+ in wastewater.

Magnesium Aluminium Layered Double Hydroxide Assisted Dispersion of Multiwalled Carbon Nanotubes for Enhanced Reinforcement of Ethylene-co-Vinyl Acetate Matrix

Successful utilization of natural anionic clays like montmorillonite and hectorite for the homogeneous dispersion of multiwalled carbon nanotubes (MWCNTs) in ethylene-co-vinyl acetate (EVA), motivated us to investigate the role of magnesium aluminium layered double hydroxide (MgAl-LDH) in a similar role. MWCNT/MgAl-LDH 3D hybrid filler (HML) was prepared from the unmodified constituents in 1:1 wt. ratio by simple dry grinding method. The dispersion of this hybrid filler with extraordinary stability was subsequently used in the preparation of EVA/HML nanocomposites by solution intercalation method. Analysis shows MWCNTs to be homogeneously dispersed in the polymer matrix in presence of LDH layers. Reinforcing efficiency of HML in EVA matrix was evaluated through detailed studies of the nanocomposites. Mechanical, thermal and dielectric properties of neat EVA are substantially improved with HML content. Maximum improvement observed in tensile strength, elongation at break and toughness are 182%, 87%, and 300% respectively at 4 wt% HML. However, best dielectric response with ~400 and ~89 times enhancement in AC conductivity and dielectric constant are observed 1 wt% HML content. Comparison of HML with previously reported MWCNT/montmorillonite (MMT) and MWCNT/hectorite 3D hybrid fillers confirms superior reinforcing efficiency of the former. Improvements in properties are attributed to homogeneous dispersion of fillers and improved polymer-filler interaction on account of synergy between MWCNTs and LDH.

Dye diazonium-modified multiwalled carbon nanotubes: Light harvesters for elastomeric optothermal actuators

Novel elastomer/modified carbon nanotube nanocomposites were prepared by melt mixing ethylene vinyl acetate (EVA) matrix with dye-grafted multiwalled carbon nanotubes (MWCNTs, CNTs in short). The latter were prepared by spontaneous reactions of diazotized Azure A (AA-N2+), Neutral Red (NR-N2+) and Congo Red (CR-N2+) dyes with CNTs in water at RT. The dispersion of the dye-modified CNTs was facilitated with cholesteryl 1-pyrenecarboxylate (PyChol) surfactant. The EVA/modified CNT nanocomposites were employed as optothermal actuators. The photo-actuation measurements were performed on the un-stretched as well as the stretched strips of pristine EVA and EVA/CNT-dye nanocomposites using a dynamic mechanical analyzer (DMA) equipped with a red light emitting diode (red LED) at a wavelength of 627 nm illuminated either 10 s or 30 s. The concentration of modified dyes, the use of PyChol surfactant and the applied pre-strain were the parameters investigated in this work.To sum up, the nanocomposites prepared so far could be regarded as promising optothermal actuators used for touch displays visually impaired people.

Influence of an Interfacial Effect on the Laser Performance of a Rhodamine 6G/Cellulose Acetate Waveguide on a Vinylidene Fluoride Copolymer Layer.

The fluorescent properties of dyes and fluorophores in condensed matter significantly affect the laser performance of organic dye lasers and fluorescent polymer lasers. Concentration quenching of fluorescence is commonly observed in condensed matter. Several approaches have been presented to suppress such quenching, such as the use of a dendrimer and the use of effective energy transfer in a guest-host system. The enhanced fluorescence of rhodamine 6G (R6G) dye on a vinylidene fluoride polymer is an alternative method for enhancing laser performance because of the roughness of the P(VDF-TrFE) surface and the interaction between polar β-crystals of P(VDF-TrFE) and R6G dye. In this paper, a significant improvement in slope efficiency (SE) is demonstrated without a significant depression in the lasing threshold for distributed feedback (DFB) and distributed Bragg reflector (DBR) lasers fabricated using an R6G-dispersed cellulose acetate (CA) matrix spin-coated onto a copolymer of vinylidene fluoride and trifluoroethylene P(VDF-TrFE) thin film. SEs of 3.4 and 1.3% were measured for DBR and DFB laser devices with CA/R6G on a P(VDF-TrFE) thin film, respectively, whereas an SE of less than 1.0% was measured for both corresponding laser devices without a P(VDF-TrFE) thin film. From the aspect of simple fabrication procedures, repeatability in device fabrication and performance, stability of the device, time for device fabrication, the present approach is the most preferable way for industrial applications, requiring only the additional step of spin-coating of a P(VDF-TrFE) thin film.

Efficient alternative of antimicrobial nanocomposites based on cellulose acetate/Cu-NPs

ABSTRACTThe current research presents an efficient, cheap, and safe antimicrobial material for widespread use based on copper nanoparticles (Cu-NPs) loaded on cellulose acetate (CA) matrix. A reduction process of CuSO4·5H2O has been performed to prepare Cu-NPs. The nanosized copper particles included oxidized Cu (15–20 nm). Two different loads of Cu-NPs were used in this study, 2% and 6% mol.%. The presence of Cu-NPs incorporated with CA films slightly affected the tensile index of the films, where low and high-loaded Cu-NPs enhanced the tensile index by small values ranged from 0.640 to 0.650 and 0.667, respectively. A study on the antibacterial activity of these nanocomposites was carried out for Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. It has been found that CA containing Cu-NPs (2%) exhibited the highest antimicrobial activity against all test microbes including S. aeureus (21 mm), P. aeruginosa (18 mm), C. albicans (19 mm), and Aspergillus niger (15 mm). Results also revealed that CA film with 6% exhibited lower activity than film with 2% Cu-NPs. The morphological properties of CA/Cu-NPs films were characterized by scanning electron microscopy and transmission electron microscope in addition to X-ray diffraction. Low-loaded Cu-NPs showed homogenous distribution through CA matrix while, the high-loaded Cu-NPs were agglomerated through CA matrix. Thermal properties illustrated the enhancement of thermal stability of the film with increasing the loaded Cu-NPs.

Dendrite-free Li metal deposition in all-solid-state lithium sulfur batteries with polymer-in-salt polysiloxane electrolyte

Replacement of solid polymer electrolyte (SPE) to routine liquid electrolyte is highly desirable for high-energy-density lithium sulfur batteries due to its low volatility, high safety and the ability to suppress shuttle effect. Herein, a polymer-in-salt polysiloxane SPE was fabricated with bi-grafted polysiloxane copolymer, lithium bis(trifluoromethanesulfonyl)imide and poly(vinylidene fluoride), which shows higher ionic conductivity (7.8 × 10-4 S cm-1 at 25 °C). To obtain the satisfactory ionic conductivity and high mechanical property of solid electrolyte simultaneously, cellulose acetate matrix was combined as a rigid substrate to prepare composite polymer electrolyte (CPE) that possesses high ionic conductivity (4.0 × 10-4 S cm-1), enhanced mechanical strength (6.8 MPa), wide electrochemical stability window (4.7 V vs. Li+/Li), and high ion transference number (0.52) at ambient temperature. In addition, the CPE effectively inhibits the growth of lithium dendrites and diffusion of polysulfides. The assembled lithium sulfur battery with CPE exhibits good room-temperature cycling performance at 1C, which indicates that such polymer-in-salt polysiloxane based composite electrolyte membranes can be applied to ambient temperature all-solid-state lithium sulfur batteries.