DCIMIQ - CIMIQ - MCPI - Artículos de Revistas

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Immobilized Ni on TMEDA@βiO2@aSiO2@Fe3O4: as a novel magnetic nanocatalyst for preparation of pyrido[2,3-d:6,5-d']dipyrimidines
(Royal Society of Chemistry, 2023-04-14) Almajidi, Yasir Qasim; Ubaidullah, Mohd; Pandit, Bidhan; Kareem, A. K.; Romero Parra, Rosario Mireya; Bobirjon, Adizov; Kadhum, Wesam R.; Al-Erjan, Amran M.; Abosaooda, Munther; Mahmoud, Aisha Kamal
In the current body of research, a very quick and effectual procedure for the synthesis of pyrido[2,3-d:6,5-d']dipyrimidines has been developed. This method is accomplished through the one-pot multi-component reaction of 2-thiobarbituric acid, NH4OAc and aldehydes utilizing Ni-TMEDA@βSiO2@αSiO2@Fe3O4 as a novel mesoporous nanomagnetic catalyst at room temperature. This protocol is one of the few reports of the preparation of these derivatives without the use of conventional heating as well as energies such as microwave and ultrasound radiation. The characterization of the prepared catalyst was well accomplished by different techniques such as FT-IR, ICP-OES, SEM, TEM, BET, XRD, VSM, TGA, EDX and Elemental mapping. This organometallic catalyst was reusable for seven times with negligible decrement in its catalytic performance. In addition, all of the products were produced with high TON and TOF values, which demonstrates that our catalyst has a very high level of activity in the preparation of pyrido[2,3-d:6,5-d']dipyrimidines.
S-scheme N-doped carbon dots anchored g-C3N4/Fe2O3 shell/core composite for photoelectrocatalytic trimethoprim degradation and water splitting
(Elsevier, 2023-01-01) Dang, Van Dien; Annadurai, Thamilselvan; Khedulkar, Akhil Pradiprao; Lin, Jui-Yen; Adorna, Joemer; Yu, Wan Ju; Pandit, Bidhan; Huynh, Trung Viet; Doong, Ruey-An
Photoelectrocatalysis is a promising technique for energy conversion and environmental treatment. This study describes the photoelectrochemical (PEC) degradation of trimethoprim and hydrogen evolution using a photoanode prepared by N-doped carbon dots (NCD) incorporated g-C3N4/α-Fe2O3 (CNFO) shell/core nanocomposite. The electrochemical analysis reveals that the photocurrent density of NCD@CNFO photoanode reached 3.07 mA cm−2 at 1.6 V vs. NHE, which is 4 and 15 times greater than that of CNFO and intact α-Fe2O3, respectively. In the presence of peroxymonosulfate (PMS), the NCD@CNFO photoanode enabled 95 % and 90 % of trimethoprim (TMP) degradation in aqueous solution and lake water, respectively. Hydrogen generation coupled with TMP degradation was also observed in the PEC system, where the H2 generation rate was 550 µmol cm−2 h−1. Both superoxide (•O2−) and hydroxyl (•OH) radicals played a significant role in the degradation of TMP. The achievements could be assigned to the excellent photoabsorption and electron transfer properties of NCD, which enhanced the PEC activity of CNFO by enabling the S-scheme heterojunction to reduce electron-hole recombination. Moreover, PMS served as a cathodic electron acceptor to improve the catalytic properties of NCD@CNFO photoanode, demonstrating its contribution to both water treatment and hydrogen production. Such superior efficiency offers great potential to develop a PEC system using carbon dots/semiconductor hybrid catalysts for antibiotic degradation and synchronous photocatalytic H2 evolution from wastewater, providing an alternative solution to environmental pollution and energy crisis issues.
Preparation of cellulose acetate film with dual hydrophobic-hydrophilic properties using solution blow spinning
(Elsevier, 2023-03-01) Kramar, Ana; González Benito, Francisco Javier; European Commission; Universidad Carlos III de Madrid; Agencia Estatal de Investigación (España)
Solution blow spinning (SBS), a processing method alternative to electrospinning, where pressured air is used instead of an electric field, was used in this work for the preparation of cellulose acetate (CA) materials. The sequential use of SBS to produce a double-layered film is also investigated. Mixtures of acetone with acetic acid or N,N-dimethylformamide (DMF) were studied as systems for polymer solution preparation. The type of produced material (flat film or multi-structured membranes constituted from submicrometric fibers with beads), its thermal properties, crystallinity, and morphology are more dependent on the solvent system than other SBS processing parameters. Roughness and porosity of differently produced materials influence wettability measured by the contact angle, which ranges in this work from approx. 69.8 degrees ± 3 degrees for a flat film to 104 degrees ± 5 degrees for fibrous material. Finally, a double-layered film, prepared by sequential SBS of individual layers different in terms of wettability, renders a standalone film of dual wettability, with one side hydrophobic and the other hydrophilic.
Regulated electrochemical performance of manganese oxide cathode for potassium-ion batteries: A combined experimental and first-principles density functional theory (DFT) investigation
(Elsevier, 2023-03) Pandit, Bidhan; Rondiya, Sachin R.; Shaikh, Shoyebmohamad F.; Ubaidullah, Mohd; Amaral, Ricardo; Dzade, Nelson Y.; Goda, Emad S.; Rana, Abu Ul Hassan Sarwar; Gill, Harjot Singh; Ahmad, Tokeer; European Commission
Potassium-ion batteries (KIBs) are promising energy storage devices owing to their low cost, environmental-friendly, and excellent K+ diffusion properties as a consequence of the small Stoke's radius. The evaluation of cathode materials for KIBs, which are perhaps the most favorable substitutes to lithium-ion batteries, is of exceptional importance. Manganese dioxide (alfa-MnO2) is distinguished by its tunnel structures and plenty of electroactive sites, which can host cations without causing fundamental structural breakdown. As a result of the satisfactory redox kinetics and diffusion pathways of K+ in the structure, alfa-MnO2 nanorods cathode prepared through hydrothermal method, reversibly stores K+ at a fast rate with a high capacity and stability. It has a first discharge capacity of 142 mAh/g at C/20, excellent rate execution up to 5C, and a long cycling performance with a demonstration of moderate capacity retention up to 100 cycles. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) simulations confirm that the K+ intercalation/deintercalation occurs through 0.46 K movement between MnIV/MnIII redox pairs. First-principles density functional theory (DFT) calculations predict a diffusion barrier of 0.31 eV for K+ through the 1D tunnel of alfa-MnO2 electrode, which is low enough to promote faster electrochemical kinetics. The nanorod structure of alfa-MnO2 facilitates electron conductive connection and provides a strong electrode–electrolyte interface for the cathode, resulting in a very consistent and prevalent execution cathode material for KIBs.
Facile Green Preparation of Reduced Graphene Oxide Using Citrus Limetta-Decorated rGO/TiO2 Nanostructures for Glucose Sensing
(MDPI, 2023-01-06) Gijare, Medha; Chaudhari, Sharmila; Ekar, Satish; Shaikh, Shoyebmohamad F.; Mane, Rajaram S.; Pandit, Bidhan; Siddiqui, Muhammad Usman Hassan; Garje, Anil
The important electrochemical measurements of reduced graphene oxide-titanium oxide (rGO)/TiO2) electrodes for the application of a glucose sensor are reported in the proposed work. Investigating the sensitivity, stability, and reproducibility of sensor electrodes that were made and used to evaluate the concentration of glucose in the serum is one of the novel aspects of this work. This study presents the use of citrus limetta (sweet lime) fruit peel waste to synthesize a green reduction of graphene oxide (rGO). The rGO/TiO2 composite obtained using the microwave heating method is applied for measuring the structural and morphological properties by various means. A conducting fluorine-tin oxide substrate is used to modify the enzymeless glucose sensor electrode. The electrochemical measurements of rGO/TiO2 sensor electrodes are carried out using the technique of cyclic voltammetry. The rGO/TiO2 sensor electrode exhibits a high sensitivity of 1425 µA/mM cm2 towards glucose concentration in the range of 0.1 to 12 mM. The sensor was found to be extremely stable and repeatable with a response time of 5 s along with a minimum detection limit of 0.32 muM of glucose. The rGO/TiO2 sensor shows relative standard deviation (RSD) of 1.14%, 1.34%, and 1.3% which reveals its excellent stability, repeatability, and reproducibility respectively. The sensor was used for glucose level detection in natural blood serum and shows an RSD of 1.88%. which is in good agreement with the commercial glucose sensor values.
Airbrushed PSF/ZnO composite coatings as a novel approach for the consolidation of historical bones
(MDPI, 2023-02-02) Moradienayat, Monireh; González Benito, Francisco Javier; Olmos Díaz, Dania; Comunidad de Madrid; Ministerio de Economía y Competitividad (España); Universidad Carlos III de Madrid
In this work, the preparation and characterization of films based on polysulfone (PSF) filled with zinc oxide, ZnO, nanoparticles (NPs) are conducted. The novelty of this research mainly relies on two points: (i) the use of a commercial airbrush to prepare or modify materials, and (ii) the design of new materials (nanocomposites) for the consolidation and restoration of historical bones. To accomplish these objectives, free-standing thin films and ancient bone coatings of PSF/ZnO nanocomposites with different particle contents (0%, 1%, 2%, 5% and 10%, % wt) are prepared using a commercial airbrush. Mechanical characterization is carried out to correlate properties between free-standing thin films and coatings, thus understanding the final performance of the coatings as consolidants for ancient bones. Thin films of PSF/ZnO show that the elastic modulus (E) increases with particle content. The mechanical behavior of the surfaces of the treated and untreated bones is studied locally using Martens hardness measurements. Maximum values of Martens hardness are obtained for the bone samples treated with polysulfone filled with 1% ZnO nanoparticles (HM = 850 N·mm-2) or 2% ZnO (HM = 625 N·mm-2) compared to those treated just with neat PSF (HM = 282 N·mm-2) or untreated bone (HM = 140 N·mm-2), indicating there is a correspondence between rigidity of free-standing films and hardness of the corresponding coatings. In terms of mechanical performance, it is demonstrated the existence of a balance between nanoparticle concentration and probability of nanoparticle aggregation, which allows better material design for ancient bones consolidation.
Obtaining medical textiles based on viscose and chitosan/zinc nanoparticles with improved antibacterial properties by using a dielectric barrier discharge
(MDPI, 2022-10-01) Korica, Matea D.; Kramar, Ana; Peršin Fratnik, Zdenka; Obradović , Bratislav; Kuraica, Milorad M.; Dojčinović , Biljana; Zemljič, Lidija Fras; Kostić, Mirjana
This study aimed to obtain functional viscose textiles based on chitosan coatings with improved antibacterial properties and washing durability. For that reason, before functionalization with chitosan/zinc nanoparticles (NCH+Zn), the viscose fabric was modified by nonthermal gas plasma of dielectric barrier discharge (DBD) to introduce into its structure functional groups suitable for attachment of NCH+Zn. NCH+Zn were characterized by measurements of hydrodynamic diameter and zeta potential and AFM. DBD-plasma-modified and NCH+Zn-functionalized fabrics were characterized by zeta potential measurements, ATR-FTIR spectroscopy, the calcium acetate method (determination of content of carboxyl and aldehyde groups), SEM, breaking-strength measurements, elemental analysis, and ICP-OES. Their antibacterial activity was determined under dynamic contact conditions. In addition to SEM, the NCH+Zn distributions on viscose fabrics were also indirectly characterized by measuring their absorbent capacities before and after functionalization with NCH+Zn. Washing durability was monitored through changes in the zeta potential, chitosan and zinc content, and antibacterial activity after 1, 3, and 5 washing cycles. The obtained results showed that DBD plasma modification contributed to the simultaneous improvement of NCH+Zn sorption and antibacterial properties of the viscose fabric functionalized with NCH+Zn, and its washing durability, making it suitable for the production of high-value-added medical textiles.
Nonwoven mats based on segmented biopolyurethanes filled with MWCNT prepared by solution blow spinning
(MDPI, 2022-10-01) Ramos, Pablo; Calvo-Correas, Tamara; Eceiza, Arantxa; González Benito, Francisco Javier; Ministerio de Ciencia, Innovación y Universidades (España); Universidad Carlos III de Madrid
To prepare nonwoven mats constituted by submicrometric fibers of thermally responsive biopolyurethanes (TPU) modified with multiwalled carbon nanotubes (MWCNT), solution blow spinning (SBS) was used. The TPU was the product of synthesis using poly(butylene sebacate)diol, PBSD, ethyl ester L-lysine diisocyanate (LDI), and 1,3-propanediol (PD) (PBSe:LDI:PD) as reactants. TPU was modified by adding different amounts of MWCNT (0, 0.5, 1, 2, and 3 wt.%). The effect of the presence and amount of MWCNT on the morphology and structure of the materials was studied using field-emission scanning electron microscopy (FESEM) and Fourier-transform infrared spectroscopy (FTIR), respectively, while their influence on the thermal and electric behaviors was studied using differential scanning calorimetry (DSC) and capacitance measurements, respectively. The addition of MWCNT by SBS induced morphological changes in the fibrous materials, affecting the relative amount and size of submicrometric fibers and, therefore, the porosity. As the MWCNT content increased, the diameter of the fibers increased and their relative amount with respect to all morphological microfeatures increased, leading to a more compact microstructure with lower porosity. The highly porous fibrous morphology of TPU-based materials achieved by SBS allowed turning a hydrophilic material to a highly hydrophobic one. Percolation of MWCNT was attained between 2 and 3 wt.%, affecting not only the electric properties of the materials but also their thermal behavior.
Improved optoelectronic properties of nanostructured Eu doped Bi2S3 thin films for the detection of UV light
(MDPI, 2022-10) Shkir, Mohd; Ben Gouider Trabelsi, Amira; Alkallas, Fatemah H.; Alfaify, Salem; Pandit, Bidhan; Ubaidullah, Mohd
Due to a suitable band gap and high light absorption behavior, Bi2S3 is showing major success in photo-to-current conversion applications. In this current work, the authors used a low-cost nebulizer spray pyrolysis method to create nano-sized pure and unique Eu contents (1-5 wt.%)-loaded Bi2S3 thin layers by taking bismuth nitrate and thiourea as the source materials. The parent and Eu doped Bi2S3 thin films, deposited on a well-cleaned glass substrate at 350 °C, were analyzed using a variety of characterization approaches, including FESEM, EDS, XRD, PL, UV-Vis, and I-V, to describe the morphologies, compositions, crystallinity, defect states, band gap, and photodetection capability, respectively. The X-ray diffraction outcomes confirmed an orthorhombic polycrystalline structure for all Eu concentrations, and they were highly oriented along the (130) plane. Incorporation of Eu into the host matrix improves the intensity of all the peaks, and the crystallite size (25 nm) was found to be highest for the 3% Eu doped Bi2S3 thin film. The formation of a nanowire-like morphology was confirmed thorough field emission electron microscopy analysis, which is preferred for photo detectors. Upon excitation at 325 nm, grown pure and Eu doped Bi2S3 thin films indicated five emission peaks at 387, 418, 439, 480, and 523 nm, respectively. All the films showed significant absorption in the UV region, and importantly, a narrowing of the band gap is seen from 2.29 to 2.17 eV. Finally, the current-voltage characteristics of the pure and Eu doped Bi2S3 thin films were tested using silver contacts as electrodes. The results showed that the 3% Eu doped Bi2S3 sample showed a higher UV photocurrent characteristic, with high specific detectivity (1.82 × 1010 Jones), photoresponsivity (3.88 × 10-1 AW-1), external quantum efficiency (125%), and rapid photo response, as well as a recovery speed of 0.3 s and 0.4 s, due to the effective light absorption and photocarrier generation. We believe that our study may provide a cost-effective approach for UV photosensor applications.
Electrospun nickel nanoparticles@poly(vinylidene fluoride-hexafluoropropylene) nanofibers as effective and reusable catalyst for H2 generation from sodium borohydride
(Elsevier, 2022-11) Al Enizi, Abdullah M.; El Halwany, M. M.; Shaikh, Shoyebmohamad F.; Pandit, Bidhan; Yousef, Ayman
Nickel nanoparticles (Ni NPs) supported on Poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers (PVDF-HFP NFs) were successfully synthesized through electrospinning and in-situ reduction of Ni2+ salts into the surface of PVDF-HFP NFs to form metallic Ni NPs@PVDF-HFP NFs. Different percentages of nickel acetate tetrahydrate (NiAc) (10 %, 20 %, 30 %, 40 % wt.) based PVDF-HFP. The formation of tiny metallic Ni NPs @PVDF-HFP membrane NFs was demonstrated using standard physiochemical techniques. Nanofibers membranes have demonstrated good catalytic activity in H2 production from sodium borohydride (NaBH4). The sample composed of 40 %wt Ni showed the highest catalytic activity compared to the other formulations. Whereas 103 mL of H2, from the hydrolysis of 1.34 mmol NaBH4, was produced using 40 wt% NiAc compared to 68 mL, 81 mL, and 93 mL for 10 wt%, 20 wt%, and 30 wt% NiAc, respectively, in 60 min at 25 °C. The hydrogen generation has been enhanced with an increase in the Nanofibers membrane amount and reaction temperature. The latter results in a low activation energy (23.52 kJ mol−1). The kinetics study revealed that the reaction was pseudo-first-order in sodium borohydride concentration and catalyst amount. Furthermore, the catalyst exhibits satisfactory stability in the hydrolysis process for ten cycles. Because of its easy recyclability, the introduced catalyst has a wide range of potential applications in the generation of H2 from sodium borohydride hydrolysis.
Vanadium oxide anchored MWCNTs nanostructure for superior symmetric electrochemical supercapacitors
(Elsevier, 2019-11-15) Pande, Shilpa A.; Pandit, Bidhan; Sankapal, Babasaheb R.
Proper selection of electrode material with sensible scheme is definitely significant to dodge commercial obstacles of supercapacitors. This challenge has been addressed by engineering prototype symmetric supercapacitor (SSC) device fabricated with enhanced supercapacitive vanadium (V) oxide integrated multi-walled carbon nanotubes (MWCNTs) composite as electrode material with Li-ion associating LiClO4 electrolyte. The V2O5/MWCNTs composite with nanoscale architecture has been synthesized with inexpensive and simple chemical bath deposition (CBD) method. The cyclic voltammetry of SSC device has exhibited the involvement of electrochemically active reversible redox process in the composite. The specific capacitance of 569.7 F/g at scan rate of 2 mV/s including excellent electrochemical stability of 89.2% at 4000 CV cycles have been achieved with operating potential window of 2 V. Furthermore, the device exhibits excellent energy density of 62 Wh/kg and exceptional power density of 11.5 kW/kg. The low resistive factors have driven the device towards the potential application as glowing of red LED for 10 s.
Novel chemical route for CeO2/MWCNTs composite towards highly bendable solid-state supercapacitor device
(Nature Research, 2019-04-10) Pandit, Bidhan; Sankapal, Babasaheb R.; Koinkar, Pankaj M.
Electrode materials having high capacitance with outstanding stability are the critical issues for the development of flexible supercapacitors (SCs), which have recently received increasing attention. To meet these demands, coating of CeO2 nanoparticles have been performed onto MWCNTs by using facile chemical bath deposition (CBD) method. The formed CeO2/MWCNTs nanocomposite exhibits excellent electrochemical specific capacitance of 1215.7 F/g with 92.3% remarkable cyclic stability at 10000 cycles. Light-weight flexible symmetric solid-state supercapacitor (FSSC) device have been engineered by sandwiching PVA-LiClO4 gel between two CeO2/MWCNTs electrodes which exhibit an excellent supercapacitive performance owing to the integration of pseudocapacitive CeO2 nanoparticles onto electrochemical double layer capacitance (EDLC) behaved MWCNTs complex web-like structure. Remarkable specific capacitance of 486.5 F/g with much higher energy density of 85.7 Wh/kg shows the inherent potential of the fabricated device. Moreover, the low internal resistance adds exceptional stability along with unperturbed behavior even under high mechanical stress which can explore its applicability towards high-performance flexible supercapacitor for advanced portable electronic devices.
The electrochemical kinetics of cerium selenide nano-pebbles: The design of a device-grade symmetric configured wide-potential flexible solid-state supercapacitor
(Royal Society of Chemistry, 2021-02-21) Pandit, Bidhan; Agarwal, Akanksha; Patel, Priyanka; Sankapal, Babasaheb R.
Next-generation portable flexible electronic appliances require liquid-free energy storage supercapacitor devices to eliminate leakage and to support mechanical bending that is compatible with roll-to-roll technologies. Hence, a state-of-the-art process is presented to design a solid-state, wide-potential and flexible supercapacitor through the use of nano-pebbles of cerium selenide via a simple successive ionic layer adsorption and reaction (SILAR) method that could allow an industry scalable route. We strongly believe that this is the first approach amongst physical and chemical routes not only for synthesizing cerium selenide in thin-film form but also using it for device-grade supercapacitor applications. The designed solid-state symmetric supercapacitor assembled from cerium selenide electrodes sandwiched by PVA–LiClO4 gel electrolyte attains a wide potential window of 1.8 V with capacitance of 48.8 F g−1 at 2 mV s−1 and reveals excellent power density of 4.89 kW kg−1 at an energy density of 11.63 W h kg−1. The formed device is capable of 87% capacitive retention even at a mechanical bending angle of 175°. Lighting up a strip of 21 parallel connected red LEDs clearly demonstrates the practical use of the designed symmetric solid-state supercapacitor, aiming towards the commercialization of the product in the future.
Reinforcement-matrix interactions and their consequences on the mechanical behavior of basalt fibers-cement composites
(2021-11-22) Iorio, Morena; Marra, F.; Santarelli, M. L.; González Benito, Francisco Javier; Ministerio de Economía y Competitividad (España); Universidad Carlos III de Madrid
In order to prepare basalt fibers-reinforced cement-based mortars with higher compatibility between reinforcement and matrix, basalt fibers with new surface treatments (sizing) were studied looking for enhanced interaction at the interphase between basalt fibers and cement matrix. As-received, calcinated, activated and silanized (by three silane aqueous solutions: i) aminopropyltriethoxysilane, APTES; ii) ¿-aminopropylmethyldiethoxysilane, APDES and iii) a mixture APTES APDES 50% by weight) basalt fibers were dispersed in Portland cement matrix. Performances of the composites were evaluated by mechanical tests. Final correlation between the fibers surface characteristics and mechanical performance was carried out considering the induced microstructural changes and adhesion at the interface. Fractographic analysis by SEM and laser and optical profilometry were performed. A clear improvement in mechanical properties was obtained when basalt fibers were dispersed in cement matrix. Results suggest that better behavior is achieved when basalt fibers modified with a complex mixture of silanes are dispersed in cement matrix.
Cellulose-Based Nanofibers Processing Techniques and Methods Based on Bottom-Up Approach-A Review
(MDPI AG, 2022-01-11) Kramar, Ana; González Benito, Francisco Javier; European Commission; Ministerio de Ciencia e Innovación (España); Universidad Carlos III de Madrid
In the past decades, cellulose (one of the most important natural polymers), in the form of nanofibers, has received special attention. The nanofibrous morphology may provide exceptional properties to materials due to the high aspect ratio and dimensions in the nanometer range of the nanofibers. The first feature may lead to important consequences in mechanical behavior if there exists a particular orientation of fibers. On the other hand, nano-sizes provide a high surface-tovolume ratio, which can have important consequences on many properties, such as the wettability. There are two basic approaches for cellulose nanofibers preparation. The top-down approach implies the isolation/extraction of cellulose nanofibrils (CNFs) and nanocrystals (CNCs) from a variety of natural resources, whereby dimensions of isolates are limited by the source of cellulose and extraction procedures. The bottom-up approach can be considered in this context as the production of nanofibers using various spinning techniques, resulting in nonwoven mats or filaments. During the spinning, depending on the method and processing conditions, good control of the resulting nanofibers dimensions and, consequently, the properties of the produced materials, is possible. Pulp, cotton, and already isolated CNFs/CNCs may be used as precursors for spinning, alongside cellulose derivatives, namely esters and ethers. This review focuses on various spinning techniques to produce submicrometric fibers comprised of cellulose and cellulose derivatives. The spinning of cellulose requires the preparation of spinning solutions; therefore, an overview of various solvents is presented showing their influence on spinnability and resulting properties of nanofibers. In addition, it is shown how bottom-up spinning techniques can be used for recycling cellulose waste into new materials with added value. The application of produced cellulose fibers in various fields is also highlighted, ranging from drug delivery systems, high-strength nonwovens and filaments, filtration membranes, to biomedical scaffolds.
Airbrushed Polysulfone (PSF)/Hydroxyapatite (HA) Nanocomposites: Effect of the Presence of Nanoparticles on Mechanical Behavior
(MDPI AG, 2022-02-15) Moradienayat, Monireh; Olmos Díaz, Dania; González Benito, Francisco Javier; Comunidad de Madrid; Universidad Carlos III de Madrid
Nanocomposite films of polysulfone (PSF)—hydroxyapatite (HA) were prepared with a commercial airbrush. Structural, thermal, and mechanical characterization allows obtaining new information to understand the role of the nanofiller–polymer matrix interphase in the final performance of these materials in relation to its possible applications in the restoration of bones. Fourier-transform infrared spectroscopy shows that there are hardly any structural changes in the polymer when adding HA particles. From thermal analysis (differential scanning calorimetry and thermogravimetry), it can be highlighted that the presence of HA does not significantly affect the glass transition temperature of the PSF but decelerates its thermal degradation. All this information points out that any change in the PSF performance because of the addition of HA particles cannot be due to specific interactions between the filler and the polymer. Results obtained from uniaxial tensile tests indicate that the addition of small amounts of HA particles (1% wt) leads to elastic moduli higher than the upper bound predicted by the rule of mixtures suggesting there must be a high contribution of the interphase. A simple model of the nanocomposite is proposed for which three contributions must be considered, particles, interphase and matrix, in such a way that interphases arising from different particles can interact by combining with each other thus leading to a decrease in its global contribution when the amount of particles is high enough. The mechanical behavior can be explained considering a balance between the contribution of the interphase and the number of particles. Finally, a particular mechanism is proposed to explain why in certain nanocomposites relatively high concentrations of nanoparticles may substantially increase the strain to failure.
Preparation, Properties and Water Dissolution Behavior of Polyethylene Oxide Mats Prepared by Solution Blow Spinning
(MDPI AG, 2022-04) Lorente Fernández, Miguel Ángel; González Gaitano, Gustavo; González Benito, Francisco Javier; Ministerio de Ciencia, Innovación y Universidades (España); Universidad Carlos III de Madrid
The relationship between processing conditions, structure and morphology are key issues to understanding the final properties of materials. For instance, in the case of polymers to be used as scaffolds in tissue engineering, wound dressings and membranes, morphology tuning is essential to control mechanical and wettability behaviors. In this work, the relationship between the processing conditions of the solution blow spinning process (SBS) used to prepare nonwoven mats of polyethylene oxide (PEO), and the structure and morphology of the resulting materials are studied systematically, to account for the thermal and mechanical behaviors and dissolution in water. After finding the optimal SBS processing conditions (air pressure, feed rate, working distance and polymer concentration), the effect of the solvent composition has been considered. The structure and morphology of the blow spun fibers are studied as well as their thermal, mechanical behaviors and dissolution in water. We demonstrate that the morphology of the fibers (size and porosity) changes with the solvent composition, which is reflected in different thermal and mechanical responses and in the dissolution rates of the materials in water.
High Stability and Long Cycle Life of Rechargeable Sodium-Ion Battery Using Manganese Oxide Cathode: A Combined Density Functional Theory (DFT) and Experimental Study
(ACS Publications, 2021-03-10) Pandit, Bidhan; Rondiya, Sachin R.; Dzade, Nelson Y.; Shaikh, Shoyebmohamad F.; Kumar, Nitish; Goda, Emad S.; Al Kahtan, Abdullah A.; Mane, Rajaram S.; Mathur, Sanjay; Salunkhe, Rahul R.
Sodium-ion batteries (SIBs) can develop cost-effective and safe energy storage technology for substantial energy storage demands. In this work, we have developed manganese oxide (α-MnO2) nanorods for SIB applications. The crystal structure, which is crucial for high-performance energy storage, is examined systematically for the metal oxide cathode. The intercalation of sodium into the α-MnO2 matrix was studied using the theoretical density functional theory (DFT) studies. The DFT studies predict Na ions’ facile diffusion kinetics through the MnO2 lattice with an attractively low diffusion barrier (0.21 eV). When employed as a cathode material for SIBs, MnO2 showed a moderate capacity (109 mAh·g–1 at C/20 current rate) and superior life cyclability (58.6% after 800 cycles) in NaPF6/EC+DMC (5% FEC) electrolyte. It shows a much higher capacity of 181 mAh·g–1 (C/20 current rate) in NaClO4/PC (5% FEC) electrolyte, though it suffers fast capacity fading (11.5% after 800 cycles). Our findings show that high crystallinity and hierarchical nanorod morphology of the MnO2 are responsible for better cycling performance in conjunction with fast and sustained charge-discharge behaviors.
Polymeric materials with antibacterial activity: A review
(MDPI, 2021-02-18) Olmos Díaz, Dania; González Benito, Francisco Javier; Comunidad de Madrid
Infections caused by bacteria are one of the main causes of mortality in hospitals all over the world. Bacteria can grow on many different surfaces and when this occurs, and bacteria colonize a surface, biofilms are formed. In this context, one of the main concerns is biofilm formation on medical devices such as urinary catheters, cardiac valves, pacemakers or prothesis. The development of bacteria also occurs on materials used for food packaging, wearable electronics or the textile industry. In all these applications polymeric materials are usually present. Research and development of polymer-based antibacterial materials is crucial to avoid the proliferation of bacteria. In this paper, we present a review about polymeric materials with antibacterial materials. The main strategies to produce materials with antibacterial properties are presented, for instance, the incorporation of inorganic particles, micro or nanostructuration of the surfaces and antifouling strategies are considered. The antibacterial mechanism exerted in each case is discussed. Methods of materials preparation are examined, presenting the main advantages or disadvantages of each one based on their potential uses. Finally, a review of the main characterization techniques and methods used to study polymer based antibacterial materials is carried out, including the use of single force cell spectroscopy, contact angle measurements and surface roughness to evaluate the role of the physicochemical properties and the micro or nanostructure in antibacterial behavior of the materials.
Effect of a silica nanofiller on the structure, dynamics and thermostability of LDPE in LDPE/silica nanocomposites
(Royal Society of Chemistry, 2015) Olmos Díaz, Dania; Gonzalez Gaitano, Gustavo; González Benito, Francisco Javier; Ministerio de Ciencia e Innovación (España); Ministerio de Educación, Cultura y Deporte (España)
The effect of the presence of silica nanoparticles on the structure, thermal stability and dynamics of low density polyethylene, LDPE, has been studied. Different loads of nanoparticles were dispersed within a LDPE matrix using high energy ball milling (HEBM) as a preliminary processing step to ensure a uniform dispersion of nanofiller to obtain nanocomposites in the form of films by hot pressing. The monitoring of the FTIR-ATR spectra of the samples as a function of the temperature has proven as a convenient method to study the interactions at a molecular scale between the polyethylene chains and the nanofiller. Band splitting observed in the bending and rocking modes of the ethylene groups indicated formation of crystalline phases whereas the analysis of absorbance band ratios from the stretching vibrations of PE accounted for the behavior of the polymer bulk. No evidence of strong polymer–filler interactions were found with the exception of a thermal relaxation process observed at 55 °C. Structural, morphological and thermal characterization of the nanocomposites did not reveal remarkable changes at low loads of filler, indicating that in the case of LDPE–silica nanocomposites, where weak interactions between the polymer and filler occur, the volume fraction of nanoparticles must be relatively high in order to produce changes in the bulk properties.

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