Polyvinylpyrrolidone Research Articles

Biomimetic heat-localized and solar absorption-enhanced hollow structural nanofibrous membrane for clean water production from saline water and dye wastewater

The rational design of material structures can be an effective approach to enhance the performance of solar-driven clean water production. In this study, a hollow structural nanofibrous membrane was developed by mimicking the hollow structure of polar bear hair using coaxial electrospinning. The shell layer consisted of carbon nanoparticles (C NPs) decorated CuO nanosheets (C@CuO), that exhibited photothermal conversion capacity. Meanwhile, the core layer containing hydrophilic polyvinylpyrrolidone (PVP) was eliminated to generate the hollow structure. The C NPs enhanced the membrane’s light absorption to increase thermal energy harvesting, while the CuO nanosheets improved the membrane’s wettability enhancing the water supply. Furthermore, the hollow structure limited air convection, prevented heat conduction, and minimized heat radiation, enabling heat localization to be achieved inside the membrane to suppress heat loss during evaporation. For 3.5 wt% saline water and actual dye wastewater, the C@CuO nanofibrous membrane achieved high evaporation rates of 1.36 kg·m−2·h−1 and 1.31 kg·m−2·h−1, respectively, under 1 sun illumination. Moreover, even after continuous 6-h evaporation tests, the evaporation rate of the C@CuO membrane remained virtually unchanged, highlighting its long-term stability with regard to salt resistance in real-world applications. Additionally, the remarkable flexibility of the C@CuO membrane offers convenience during operation and guarantees dimensional stability when it is subjected to external stresses. These discoveries should inspire subsequent research on developing delicate architectural materials and exploring their potential applications in various fields, including energy generation, clean water production, and thermal insulation.

Multi-Stimuli-Responsive Carbon Dots with Intrinsic Photochromism and In Situ Radical Afterglow.

The combination of advanced photoluminescence characteristics to photochromism is highly attractive in preparing high-performance multifunctional photo-responsive materials for optoelectronic applications. However, this is rather challenging in material design owing to the limited mechanism understanding and construction principles. Here, an effective strategy to integrate photochromism and afterglow emission in carbon dots (CDs) is proposed through embedding naphthaleneimide (NI) structure in CDs followed by polyvinylpyrrolidone (PVP) encapsulation. The NI-structured CDs-PVP shows intrinsic photochromism owing to the in situ formation of NI-radical anions and controllable multi-stimuli-responsive afterglow behaviors related to the oxygen-trigged triplet exciton quenching and Förster resonance energy transfer (FRET) from the pristine CDs to the photoactivated CDs radicals. Notably, a wide range of appearance colors from colorless to brown, luminescence color transition from blue to yellow, and much elongated afterglow lifetime up to 253ms are observed. With the extraordinary stimuli-chromic and stimuli-luminescent CDs-PVP film dynamically responsive to multiple external stimuli, reversible secure snapchat, data encryption/decryption and synaptic imaging recognition are realized. These findings demonstrate a fundamental principle to design multi-stimuli-responsive photochromic CDs with afterglow, providing important understandings on the synergic mechanism of dynamic photochromism and emission behaviors and thereby expanding their applications in advanced information anti-counterfeiting and artificial intelligence.

Double-layer dissolving microneedles for delivery of mesenchymal stem cell Secretome: Formulation, characterisation and skin irritation study

Regenerative therapy based on stem cells have been developed, focusing on either stem cell or secretome delivery. Most marketed cellular and gene therapy products are available as injectable dosage forms, leading to several limitations requiring alternative routes, such as the intradermal route. Microneedles, capable of penetratingthe stratum corneumbarrier, offer a potential alternative for intradermal delivery. This present study aimed to develop double-layer dissolving microneedles (DMN) for the delivery of freeze-dried mesenchymal stem cell secretome. DMNs were fabricated using a two-step casting method and composed of two polymer combinations: poly(vinyl pyrrolidone) (PVP) with poly(vinyl alcohol) (PVA) or PVP with sodium hyaluronate (SH). The manufactured DMNs underwent assessments for morphology, mechanical strength, in skin dissolution, protein content, in vitro permeation, in vivo skin irritation, and physical stability. Based on evaluations of morphology and mechanical strength, two formulas (F5 and F12) met acceptance criteria. Evaluation of protein content revealed that F12 (PVP-SH combination) had a higher protein content than F5 (PVP-PVA combination), 99.02 ± 3.24 μg and 78.36 ± 3.75 μg respectively. In vitro permeation studies showed that F5 delivered secretome protein by 100.84 ± 0.88%, while F12 delivered 99.63 ± 9.21% in 24 h. After four days of observation onSprague-Dawleyrat’s skin, no signs of irritation, such as oedema and redness, was observed after applying both formulations. The safety of using PVP-PVA and PVP-SH combinations as excipients for DMN secretome delivery has been confirmed, promising significant advancements in biotherapeutic development in the future.

Formation of CdTe core and CdTe@ZnTe core-shell quantum dots via hydrothermal approach using dual capping agents: deciphering the food dye sensing and protein binding applications.

Excessive use of food coloring agents in the food industry to make the food more attractive or improve the taste has caused various health and ecological problems. Therefore, it is necessary to develop a reliable, sensitive, and selective sensing probe to detect food dyes in different food products for future industrial processing and biosafety. In recent decades, surface-functionalized quantum dots (QDs), owing to their unique optical properties, have gained tremendous interest for a wide range of applications, including biomedical, bioimaging and sensing applications. Herein, we have reported the synthesis of excellent colloidal stable and highly luminescent CdTe core and CdTe@ZnTe core-shell QDs using dual functionalizing agents, polyvinyl pyrrolidone and vitamin C. The synthesized QDs were explored as excellent sensing probes for the food dyes carmoisine, Ponceau 4R and tartrazine with limit of detection (LOD) values of 0.097 ± 0.006, 0.147 ± 0.001 and 0.044 ± 0.001 μM for CdTe-PVP QDs and 0.079 ± 0.001, 0.114 ± 0.002 and 0.042 ± 0.001 μM for CdTe@ZnTe-PVP QDs, respectively. The sensitivity of the synthesized QDs for the food dyes was also investigated in real samples (soft drinks and medications). Moreover, considering the potential effects of QDs as therapeutics or nano-drug carriers, the interactions between the synthesized QDs and carrier protein human serum albumin (HSA) were investigated. The binding affinity was observed to be in the order of 104 M-1. QDs were found to quench the intrinsic fluorescence of HSA, and both types of quenching (static and dynamic) occur via electrostatic interactions in association with hydrophobic forces without any significant alteration in the protein structure.

Enhancing UV light sensitivity of PVP polymer by doping chromium trioxide via the electrospun solutions

Herein, chromium trioxide (Cr2O3) doped Polyvinylpyrrolidone(PVP) nanofibers with high crystallinity and UV light sensitivity are successfully grown onto the glass substrates by electrospun deposition at room temperature. The effect of Cr2O3 concentration on the morphology, structure, and photoluminescence properties of the as-fabricated PVP nanofibers is examined. With the increase in doping concentration of Cr2O3 (i.e., 1, 2 and 3 %), the direct band gap of PVP nanofibers is reduced to 4.05, 4.01, and 3.85 eV, respectively. XRD and FE-SEM results manifest that the crystallinity and diameter of the nanofibers are dependent upon Cr2O3 concentration, i.e., the mean diameter decreases from 600 to 200 nm. Photoluminescence spectra indicate higher UV emission upon the addition of Cr2O3, with greater emission near the band edge for thinner nanofibers. A possible mechanism for the formation of PVP/Cr2O3 nanofibers is addressed in detail. Furthermore, it is found that the sensitivity of the as-fabricated PVP/Cr2O3 detector to UV-light emission strongly depends on Cr2O3 concentration, i.e., good responsivity (2.257 A/W) and specific detectives (9.8 × 1012 cm Hz1/2/W) at a Cr2O3 concentration of 2 % are achieved at a wavelength of 454.1 nm, besides recording the lowest rise and fall times.

Encapsulation of Phenolic Compounds Extracted from Beet By-Products: Analysis of Physical and Chemical Properties.

Beet is a nutritious and health-promoting food with important bioactive compounds in its industrial by-products. The encapsulation of antioxidants from beet by-products has been proposed for valorization. For this, an ethanol-water extract was mixed with polyvinylpyrrolidone (PVP) (used as a carrier agent) and then encapsulated. The encapsulation was performed by spray drying, where the effects of temperature (140-160 °C), extract input flow rate (10-30%), and extraction solvent (ethanol-water 50/50 v/v and ethanol) were evaluated for the total phenol content and the spray-drying yield. The yields obtained were between 60 and 89%, and total phenols were between 136 and 1026 mg gallic acid equivalents/g of encapsulated product. Both responses were affected (p < 0.05) by the extraction solvent. The optimal spray-drying conditions were determined by response surface methodology (RSM). The encapsulated product obtained at optimal conditions was characterized by infrared spectrometry, X-ray fluorescence, Ultra-High Performance Liquid Chromatography, and scanning electron microscopy analysis. The results show that the encapsulated product has a high content of total phenols and compounds such as betanin, isobetanin, and neobetanin. Considering the results of physicochemical properties and the bioactive compounds, the optimized encapsulated product could be applied in the food industry as a bioactive ingredient or natural colorant. However, the further investigation of alternative carrier agents needs to be performed to reduce caking.

Double-Fluorescent Response Spiropyran-Functionalized Graphitic Carbon Nitride Solvent Decoder and Nanofiber Mat-Based Visual Colorimetric Sensor for Humidity Detection within Grain Heaps.

Spiropyran-functionalized graphitic carbon nitride (MCH@g-C3N4) in acidic conditions was prepared for the first time. MCH@g-C3N4 exhibited dual-wavelength fluorescence emission with two distant bands and distinct solvatochromic behavior owing to the different molecular structures of spiropyran. A three-dimensional organic solvent decoder was fabricated for solvent identification based on the emission wavelength and fluorescence quantum yield of MCH@g-C3N4 in different polar solvents. The ratiometric fluorescence sensing of the water content in organic solvent was realized using water to induce the structural change of spiropyran. A solid-phase MCH@g-C3N4/polyvinylpyrrolidone (PVP) nanofiber mat-based sensor was prepared via cospinning MCH@g-C3N4 with hydrophilic PVP. A fluorescent humidity sensor was fabricated using a commercial syringe equipped with a stainless-steel needle (catcher) to obtain the air inside the grain heap, which enabled the accurate location of the sampling spot. The space between the syringe and piston was used as an enclosed sensing space. Thus, a simple, accurate, and intuitive visual colorimetric method for the internal humidity of a grain heap was realized by analyzing the recorded images.

High-Performance Polyamidoxime Porous Membrane Prepared by the In Situ Modification/Nonsolvent-Induced Phase Separation Strategy for Uranium Extraction from Seawater.

The abundance of uranium (U(VI)) reserves in seawater makes it crucial to develop economically efficient methods for uranium extraction from seawater. In this work, an enhanced polyamidoxime porous membrane (PAOM) was fabricated by pre-in situ amidoxime modification combined with nonsolvent-induced phase separation (NIPS). The strategy of in situ modification of the polyacrylonitrile (PAN) solution served to enhance the homogeneity of the reaction and avoid the destruction of the membrane matrix and pore structure. Compared with the control sample (AOPM), PAOM possessed better mechanical strength and hydrophilicity. The introduction of polyvinylpyrrolidone (PVP) formed a porous structure in PAOM, improving spatial accessibility and facilitating the diffusion transport and capture of UO22+ inside the membrane. The more uniform and abundant distribution of amidoxime groups in PAOM gave it ultrahigh adsorption capacity and selectivity. The equilibrium adsorption capacity and Kd value of PAOM were 1.72 and 5.51 times higher than those of AOPM. Meanwhile, PAOM also demonstrated good recyclability, with only a 6.15% decrease in adsorption capacity after seven cycles. Additionally, PAOM exhibited excellent dynamic adsorption performance, and after 14 days of continuous filtration and adsorption, PAOM could extract 2.03 mg·g-1 U(VI) from natural seawater.

Chemical and green synthesized Co/Ni-doped hematite nanoparticles for enhancing the photocatalytic and antioxidant properties

This research focuses on developing environmentally friendly and economically viable Co/Ni-doped hematite nanoparticles (HNPs) through both chemical and green synthesis methods and evaluated their potential for biomedical and environmental applications. The chemical synthesis employs polyvinylpyrrolidone (PVP), while the green approach utilizes Azadirachta indica (A. indica) leaf extract as a stabilizing agent. Co/Ni-doped HNPs are crystalline size ranging from 14 to 21 nm, morphology analysis revealed that the NPs exhibited a quasi-spherical, with an average particle size ranging from 15.98 to 25.91 nm, and dopants confirmed to contain by the XPS spectra. VSM study explains magnetic parameters, coactivity, residual magnetism, and magnetization. A. indica plants contain quinones, saponins, glycosides, alkaloids, and flavonoids. Characterization of the nanoparticles reveals optimized Co/Ni-doped HNPs with enhanced photocatalytic activity. These nanoparticles exhibit a remarkable 93%–95% degradation of UV-reactive dyes (methyl orange and methylene blue) within 90 min, attributed to structural and surface modifications that improve light absorption and enhance charge separation. The study concludes that green-synthesized Co/Ni-doped HNPs outperform chemically synthesized counterparts as superior photocatalysts. Additionally, antioxidant evaluations using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) assays suggest significant antioxidant capabilities. A high scavenging activity percentage, ranging from 83% to 88%, was observed, which increased with higher concentrations of the synthesized Co/Ni-doped HNPs making these nanoparticles suitable for biomedical and environmental applications that require a magnetic system. In this study, the IC50 values for the antioxidant activity of chemically and green synthesized Co/Ni-doped hematite nanoparticles against the DPPH/NO assay were calculated to be 18.33 μg ml−1 and 16.09 μg ml−1, respectively. The research highlights the multifunctional properties of Co/Ni-doped HNPs, addressing the demand for tailored inorganic magnetic nanoparticles with minimal ecological impact.

Preparation of silver nanowires with controlled parameters for conductive transparent electrodes

Silver nanowires (AgNWs) have excellent flexibility, unique optical transmittance and high conductivity. The polyol process is appropriate for preparing AgNWs due to its simplicity, effectiveness, low cost, and high yield. This work aims to investigate the effect of preparation parameters of the polyol process on the silver nanowires properties. The parameters include the controlling agent, molecular weight of the polyvinylpyrrolidone (PVP), the temperature, and the reducing agent. The amount of silver nanoparticles formed during preparation was used to determine the optimum preparation conditions. The transmission electron microscope (TEM) images showed minimal amount of Ag nanoparticles when using mixed molecular weight of PVP-40K, and PVP-1.3M at 150 °C with the assistance of copper chloride as a controlling agent. The prepared AgNWs had an average length of 3.7 µm and aspect ratio of 15.3. The fabricated electrodes were characterized using a scanning electron microscope (SEM) and four probe resistivity measurements. The electrical measurement of the AgNWs electrodes indicated that the surfactant thickness is a critical parameter in having low sheet resistance electrodes. Also, the optical transmission was affected by the amount of nanoparticles. The prepared electrode with high concentration of AgNWs and a minimal amount of nanoparticles exhibited 80% optical transmission.

Complex formation and stabilization of Z‐isomer‐enriched astaxanthin esters derived from Haematococcus lacustris with water‐soluble carriers via spray drying

AbstractTo enhance the water solubility and bioavailability of astaxanthin esters, inclusion complexes of Z‐isomer‐enriched astaxanthin esters with water‐soluble carriers were prepared using a spray drying technique. A food‐grade Haematococcus alga extract was used as the source of astaxanthin esters, and the Z‐isomerization was performed via direct heating of the extract. Polyvinylpyrrolidone (PVP) and hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) were used as water‐soluble carriers. The effects of spray drying conditions on the encapsulation efficiency of astaxanthin esters in the carriers and the total Z‐isomer ratio of encapsulated astaxanthin esters were investigated, and the physical properties and storage stability of the resulting composites were evaluated. Under optimum spray drying conditions, efficient production of highly water‐soluble Z‐isomer‐rich astaxanthin esters was achieved in both carriers: &gt;95% encapsulation efficiency and &gt;55% total Z‐isomer ratio. The physical properties, such as surface morphology and particle size distributions, of the resulting particles differed significantly between PVP and HP‐β‐CD. Storage tests demonstrated that the formulated Z‐isomer‐rich astaxanthin esters were highly stable. Our findings will contribute to the practical applications of Z‐isomer‐rich astaxanthin materials.Practical Applications: The formulation technology developed in this study has the potential to address the industrial challenges of using astaxanthin, that is, low water solubility and low bioavailability. Furthermore, the low storage stability of astaxanthin Z‐isomers, which hinders their industrial use, can be solved simultaneously. The resulting Z‐isomer‐rich astaxanthin powders are expected to be used in a wide range of applications, including nutraceuticals, cosmetics, and animal feeds.

Anthelmintic efficacy of Fenbendazole and Niclosamide suspensions obtained by liquid phase mechano-chemical treatment

The purpose of the research is to study the anthelmintic efficacy of suspensions based on a combined solid dispersion of Fenbendazole and Niclosamide.Materials and methods. Mechanochemistry methods were used to prepare suspensions of Fenbendazole (FBZ) and Niclosamide (NSM) substances, in particular, liquid phase grinding of substances with additives (licorice extract, polyvinylpyrrolidone (PVP)) in water or in aqueous sodium carboxymethylcellulose (NaCMC) solution. The grinding was conducted in LE-101 roller mill at energy intensity of 1 g for 1 hour at a roll rotation speed of 60–70 rpm. The resulting suspension samples of combined FBZ and NSM dispersions were studied for cestodocidal activity on a laboratory model of hymenolepiosis of white mice that were infected at a dose of 200 infective Hymenolepis nana eggs per animal.Results and discussion. The 100% efficacy of a combined NaCMC-based drug suspension containing FBZ 13 mg and NSM 130 mg in 1 g of suspension was achieved at a dose of 20 mg/kg of NSM and 2 mg/kg of FBZ. The suspension based on licorice extract, NaCMC, and dioctyl sulfosuccinate sodium salt containing FBZ 18.6 mg and NSM 186 mg in 1 g of suspension at the same dose, i.e. 20 mg/kg of NSM and 2 mg/kg of FBZ showed 71.43% efficacy against H. nana. The suspension based on licorice extract and NaCMC containing FBZ 24.6 mg and NSM 246 mg in 1 g of suspension at the same dose showed a 62.0% effect against H. nana. The activity of the basic drug, the FBZ and NSM suspension was 28.58% at this dose without using mechano-chemical treatment.

Flexible inner surface of polysulfone membranes prevents platelet adhesive protein adsorption and improves antithrombogenicity in vitro.

We investigated whether the condition of the inner surface of hollow fibers affects the blood compatibility of hemodialyzers. We used scanning probe microscope/atomic force microscopy (SPM/AFM) to investigate the height of the swelling and flexible layers (thickness and softness) on the inner surfaces of the hollow fibers. Next, we tested the blood compatibility between dialyzers comprising a hollow fiber membrane, in which the other dialyzers, except for PVP, were additionally coated using PS membranes coated with other materials. After blood was injected into the dialyzer and plugged, dynamic stimulation was performed by slightly rotating the dialyzer for 4 h, although there was no blood circulation. The vitamin E-coated polysulfone (PS) membrane showed a higher thickness and softness of the flexible layer than the asymmetric cellulose triacetate membrane without polyvinylpyrrolidone (PVP) and the PS membranes with PVP. We found that the dialyzer with vitamin E coating significantly suppressed the decrease in platelets, increase in β-TG, and increase in PF4 compared to those coated with NV polymer. Additionally, as the adsorbed protein on the inner surface, the total protein, fibronectin, and vWF levels were significantly lower in the vitamin E-coated dialyzer. The thickness and softness of the flexible layer of the inner surface of the hollow fiber membrane in vitro affect differences in blood coagulation performance in clinical research. Future clinical trials are required to confirm our results.

Polyvinylpyrrolidone mediated electrospun ZnO-ZnFe2O4 composite nanofibers for removing malachite green from water

This study explores the application of ZnO-ZnFe2O4 composite nanofibers for the adsorption of Malachite Green (MG) dye from water. The composite nanofibers were fabricated using simple polyvinylpyrrolidone (PVP) mediated electrospinning method by changing zinc and iron precursor weight ratio named as Zn–Fe (1-1), Zn–Fe (2–1) and Zn–Fe (1–2). The diameter of 1D nanofibers was found to be 40–60 nm. The formation of hexagonal wurtzite structure of ZnO and cubic spinel structure of ZnFe2O4 was confirmed by XRD and HRTEM analysis. The effects of various parameters such as pH, contact time and initial concentration on the adsorption process were investigated. The Zn–Fe (1-1) nanofibers showed higher adsorption efficiency than other two. The adsorption results demonstrated excellent adsorption performance, with a maximum adsorption capacity of 146.77 mg/g at pH = 7 for Zn–Fe (1-1). Furthermore, the adsorption kinetics and isotherms were analyzed to understand the adsorption mechanism and equilibrium behaviour. It was found that the nanofibers material can be recycled and reused up to five cycles.

Optimization of precursor structure by dispersants to promote nitrogen reduction process to prepare high-quality VN

In this study, three dispersants of polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG) and citric acid (CA) are used to optimize the structure of the precursor in order to prepare high quality VN. Under optimum condition, the VN with nitrogen content of 17.94 % is prepared by adding 5 % PVP. The sequence of phase evolution from the precursor to VN is: APV → V2O5 → V6O13 → V7O13 → VO2 → V3O5 → V2O3 → (VC) → VN. The precursors of adding 5 % PVP have lower Ea of 0.17 kJ mol−1, 20.51 kJ mol−1 and 62.70 kJ mol−1 during reduction and nitration process, which is easier to be reduced and nitridated. PVP not only promotes the uniform dispersion of the carbon powders in the vanadium rich solution but also enhance the hydrogen bonding of APV ions to promote their nucleation and growth. The precursor with uniform and concentrated particle size distribution, complete and stable encapsulation of shell of APV and core of carbon powder, and uniform and moderate thickness of APV shell is successfully prepared by adding PVP. The precursor has a larger phase reaction interface and more reactive sites during the nitriding reduction process, which results in a faster reduction and nitriding rate. In comparison with the current process, the nitriding reaction temperature has been reduced from 1400 ∼ 1500 °C to 1150 ∼ 1200 °C, the reaction time has been shortened by 75 %, and the N2 consumption has been reduced by 40 %.

One-step solvothermal synthesis of nitrogen-doped carbon dots with efficient red emission from conjugated perylene for multiple applications

Despite its significance for applications related to plant growth, the development of carbon dots (CDs) with bright red emissions still faces multiple obstacles. Herein, red emission hydrophobic carbon dots (RH-CDs) featuring one emission peak centered at 594 nm and a shoulder emission peak at 630 nm with a quantum yield of 34 % and a wide full width at half maximum (FWHM) of 100 nm (580 nm–680 nm) were synthesized by adopting large conjugated perylene anhydride and aromatic amine precursors under solvothermal conditions. Density functional theory calculations support the method of using larger conjugated systems and higher graphite N doping to increase red emissions from CDs. With a post-surface functionalization strategy, polyvinylpyrrolidone (PVP)-modified RH-CDs (QY = 12 %) were utilized as an anti-counterfeiting ink for information printing. Moreover, both blue-red light-emitting diodes (LEDs) and light conversion poly (methyl methacrylate) (PMMA)-CDs film were fabricated with emission spectra that are consistent with the absorption spectra of plants, suggesting that the prepared RH-CDs may have widespread application potential as a stable fluorescent material in plant growth.

Coprecipitation of nicotinic acid in PVP by gas antisolvent technique using Box-Behnken design

Nicotinic acid is a water-soluble compound recognized in the medical field for its ability to decrease low-density lipoprotein cholesterol levels. Additionally, nicotinic acid is used to alleviate the effects of heat stress in ruminant animals. The supercritical gas antisolvent technique was employed using carbon dioxide to encapsulate nicotinic acid in polyvinylpyrrolidone (PVP) using ethanol + acetone. Encapsulation efficiency, process yield and crystallite size data were evaluated using the Box-Behnken design. Gas chromatography-mass spectrometry quantified the encapsulation efficiency at (13.1 to 66.9)%, and the same technique was used to determine that the encapsulation of nicotinic acid increased the dissolution rate compared to the pure compound. A residual solvent level was quantified at least 33 times lower than the maximum permitted level. The encapsulation was shown to protect the active ingredient in thermal degradation tests in a climatic chamber. XRPD showed the stability of the crystalline structure of niacin after encapsulation, and the effects on its microstructure were evaluated using Rietveld analysis. Spectroscopic analysis showed evidence of intermolecular bonding between nicotinic acid particles and PVP. An average particle size of (80.4 to 238.9) µm was obtained by SEM analysis.

Enhanced engineering and biocidal polypropylene filaments enabling melt reduction of AgNO3 through PVP agent: A scalable process for the defense industry with MEX additive manufacturing

This study focused on the production of polypropylene (PP)/silver (Ag) composites via additive manufacturing. This study aimed to enhance the quality of medical-grade PP in material extrusion (MEX) three-dimensional printing (3DP) by improving its mechanical properties while simultaneously adding antibacterial properties. The latter can find extremely important and versatile properties that are applicable in defense and security domains. PP/Ag nanocomposites were prepared using a novel method based on a reaction occurring while mixing appropriate quantities of the starting polymers and additives, namely polyvinylpyrrolidone (PVP) as the matrix material and silver nitrate (AgNO3) as the filler. This process produced three-dimensional (3D) printed filaments, which were then used to create specimens for a series of standardized tests. It was found that the mechanical properties of the nanocomposites were enhanced in relation to pristine PP, especially for the PP matrix with various loadings of AgNO3 and PVP, such as 5.0 wt% and 2.5 wt%, respectively. The voids, inclusions, and actual-to-nominal dimensions also showed improved results. The 3DP specimens exhibited a more effective biocidal performance against Staphylococcus aureus than Escherichia coli, which developed an inhibition zone only in the case of PP with filler loading percentages of AgNO3 and PVP at 10.0 wt% and 5.0 wt%, respectively Compounds possessing such properties can be beneficial for various applications requiring increased mechanical properties and biocidal capabilities, such as in the Defence or medical industries.

Study on the catalytic performance of Fe in-situ modified small crystallite Silicalite-1 zeolite in Chichibabin condensation reaction

Pyridine and its derivatives, collectively referred to as pyridine bases, are widely used in industries such as pesticides and pharmaceuticals, serving as crucial intermediates in the chemical industry. In recent years, with the development of the pesticide and pharmaceutical industries, the demand for pyridine bases has rapidly increased. The Chichibabin condensation reaction is the most commonly route for industrial production of pyridine bases. Currently, the most used ZSM-5 zeolite catalyst is limited by the instability of its silicon-aluminum framework structure, resulting in a short active reaction cycle (5 h). To address this limitation, this study selected the thermally stable and hydrothermally stable Silicalite-1 zeolite. Polyvinylpyrrolidone (PVP) was employed as a colloidal dispersant and Fe was introduced into the MFI framework through in-situ modification during the hydrothermal synthesis of zeolite. The influence of PVP dosage, template agent dosage, and other crystallization conditions on the crystallinity, pore structure, and acidity of Silicalite-1 zeolite products was investigated using XRD, SEM, TG, and N2 adsorption-desorption measurement. The acidity of Fe-modified Silicalite-1 zeolites was characterized using NH3-TPD, Py-FTIR, FT-IR, and XPS. These results indicated that the introduction of seed crystals effectively reduced the particle size of the zeolite to about 200 nm. Fe-modified Silicalite-1 displayed a disk-like morphology with excellent crystal dispersion. The highest relative crystallinity of the zeolite reached 103% with 15% seed crystal input and 3.75% PVP addition. The Fe-modified Silicalite-1 possessed a significantly enhanced abundance of both Lewis (L) and Brønsted (B) acid sites, resulting in an increase in the initial activity from 66% to 85% for the pyridine bases synthesis through the Chichibabin condensation. Compared to ZSM-5, Fe-modified Silicalite-1 exhibited superior catalytic stability, maintaining the total carbon conversion and pyridine bases yield above 66% and 40%, respectively, over a 15 h reaction period. Furthermore, the strategy proposed in this study, employing polyvinylpyrrolidone as a colloidal stabilizer to modify Silicalite-1 zeolite, could significantly broadened the application prospects of weakly acidic pure silica zeolites in the field of acid catalysis. This approach has demonstrated significant scientific value and industrial potential.

Preparation, mechanical analysis and investigation of swelling behavior of boron nitride reinforced hydrogel polymer composite films

AbstractThis study presents the preparation, hydrogel kinetics, and mechanical analysis of Boron Nitride (BN) reinforced PVA/PVP/PEO‐BN hydrogel composite films using Polyvinyl alcohol (PVA), Polyvinyl pyrrolidone (PVP), and Polyethylene oxide (PEO) commercial polymers. Dynamic mechanical analysis tests reveal that PVA90PEO5PVP5‐BN composite films exhibit plastic‐viscoelastic behavior under a maximum force of 18 N. The Young's Modulus values for PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20 are 0.22, 0.32, and 0.44 MPa, respectively. The highest % Strain value is observed in PVA90PEO5PVP5‐BN%20, reaching 279.80%. In the hydrogel kinetics study, Schott's and Fickian models are utilized. The regression from the Fickian model is quite low, with exponential diffusion index, n, values lower than 0.5, indicating a classical Fickian water diffusion mechanism. Schott's model provides graphs with significantly higher regression compared to the Fickian model. The results indicate compatibility with the other model and confirm the presence of water‐based diffusion. Equilibrium swelling values (Se, g H2O/g gel) are 6.71, 7.03, and 7.91 for PVA90PEO5PVP5, PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20, respectively. Differential Scanning Calorimetry (DSC) analysis results show that the glass transition temperatures, Tg, are 52.37, 60.20, and 63.05°C for PVA90PEO5PVP5, PVA90PEO5PVP5‐BN%10, and PVA90PEO5PVP5‐BN%20, respectively.