Ultraviolet-visible Spectroscopy Research Articles

Supramolecular phosphorescent assemblies based on cucurbit[8]uril and bromophenylpyridine derivatives for dazomet recognition.

A bromophenylpyridine derivative (N1) was designed, synthesized, and the molecule was incorporated into the cavity of the cucurbit[8]uril (Q[8]) as a guest to form a 2:1 host-guest complex. This complex demonstrates good room temperature phosphorescence (RTP) properties in aqueous solution. The host-guest interaction and optical properties of N1@Q[8] in aqueous solution were studied by means of 1H NMR, ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, phosphorescence spectroscopy, scanning electron microscopy and inverted fluorescence microscopy. The results show that the bromophenyl part of the guest molecule enters the cavity of Q[8], while the other part of N1 remains outside the cavity, resulting in a 2:1 supramolecular structure. This assembly exhibits specific recognition of dazomet on the phosphorescence spectrum with a detection limit of 8.8329×10-7mol·L-1. Collectively, this finding opens up a new possibility for the potential application of room temperature phosphorescent materials in analytical detection.

An experimental investigation into malachite green degradation using highly active NiFe2O4/Bi4O5I2 photocatalyst under visible light

In this study, a highly efficient NiFe2O4/Bi4O5I2 (NFO/BOI) photocatalyst has been successfully synthesized through the two-step hydrothermal method. Various characterization techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and Mott-Schottky (M-S) analysis were employed to scrutinize the physical, chemical, optical, and electrical characteristics of the as-synthesized photocatalyst. The photocatalytic performance of NFO/BOI was assessed through the degradation of malachite green (MG). The findings revealed that both the weight percent of NiFe2O4 loaded and catalyst loading significantly influenced the degradation efficiency of NFO/BOI on MG. Under 1 hour of visible light irradiation, MG achieved an impressive removal rate of 95.04% using NFO/BOI as the catalyst. Radical trapping experiment confirmed that superoxide anion radical plays a pivotal role in the MG degradation progress. This work introduces a novel direction for designing efficient catalysts for the treatment of water pollution using visible light.

Photocatalytic degradation of antibiotic enrofloxacin under solar light using ZnO and Bi2MoO6 materials

Enrofloxacin (ENR) as one of the most commonly used veterinary antibiotic in the aquaculture industry has led to serious water pollution due to its extensive use. In this study, ZnO catalysts were synthesized using a facile precipitation method, while the Bi2MoO6 catalysts were prepared via a solvothermal method. The resulting materials underwent comprehensive characterization using techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), and photoluminescence spectroscopy (PL) to investigate their physical, chemical, and optical properties. Subsequently, the devised catalysts were scrutinized for degradation of ENR under simulated solar light irradiation. The degradation efficiency of ENR by Bi2MoO6 nanosheets reached 69.08%, which greatly exceeded that of ZnO 38.30%.

Fabrication and comprehensive characterization of HPMC/PVA/CMC-MoO₃ bio-nanocomposites: Enhanced mechanical, electrical, and antibacterial properties for food packaging applications.

This study explores the synthesis and characterization of bio-nanocomposite films composed of HPMC/PVA/CMC blends with molybdenum trioxide (MoO₃) nanofillers at varying concentrations. X-ray diffraction (XRD) analysis confirms the structural integrity of the polymer matrix, with MoO₃ enhancing crystallinity as its concentration increases. Fourier-transform infrared spectroscopy (FTIR) reveals strong hydrogen bonding between MoO₃ and the polymer matrix, leading to improved interfacial compatibility. Ultraviolet-Visible (UV-Vis) spectroscopy indicates enhanced optical properties, with increased UV absorption correlating with higher MoO₃ content. As the MoO₃ concentration increased, the indirect energy gap decreased from 3.96 eV to 2.94 eV. Mechanical testing demonstrates significant improvements in tensile properties, including Young's modulus, ultimate tensile strength, and toughness, attributed to MoO₃'s electrostatic and hydrogen bonding effects on the polymer network. Electrical and dielectric analyses further show that higher MoO₃ levels boost conductivity, interfacial polarization, and charge storage, particularly at low frequencies. Additionally, the addition of MoO₃ reduces the contact angle, enhancing hydrophilicity, and significantly increases cell viability, achieving a peak value of 93.33 ± 1.73 % at 2.0 % MoO₃ loading. Antibacterial assays confirm strong inhibition of both gram-positive and gram-negative bacterial growth, with greater efficacy observed against gram-positive strains. These results underscore the potential of HPMC/PVA/CMC-MoO₃ nanocomposites for applications in bio-compatible, mechanically robust, and antibacterial materials.

Biosynthesis of Zr-doped WO3 Nanoparticles: Evaluation of Antibacterial, Antioxidant, and Enzymatic Activities

Herein, biocompatible pure tungsten oxide (WO3) and zirconium-doped tungsten oxide (Zr-doped WO3) nanoparticles (NPs) were prepared via a green approach from moringa plants with different doping concentrations (3, 5, and 7%). The as-synthesized materials were morphologically and optically characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR spectra clearly showed that two distinguishing bands at 603 and 674 cm-1 of WO3 were shifted to a higher wavenumber upon doping with zirconium. EDX analysis confirmed the successful synthesis of pure WO3 and Zr-doped WO3 by the green approach. The UV-Vis study exhibited that the bandgap of pure WO3 is blue-shifted upon Zr doping due to the Burstein-Moss effect. The XRD pattern revealed that the crystalline nature of WO3 is increased by increasing the Zr content. Further, the as-synthesized materials were evaluated for enzymatic, antibacterial, and antioxidant activities. The enzymatic results showed that 7% of Zr-doped WO3 NPs have a higher activity for the α-amylase enzyme. Additionally, 7% Zr-doped WO3 also showed better antioxidant activity, up to 85% for free radical scavenging. The antibacterial performance of 7% Zr-doped WO3 is higher as compared to other corresponding samples for different strains of bacteria. These results demonstrated that this facile and novel synthetic route will open a new door for designing an efficient nanomaterial for biomedical applications.

Exploring the effect of natural deep eutectic solvents on zein: Structural and functional properties.

This study evaluated the effects of chemical modification, including ethanol, acetic acid, and natural deep eutectic solvents (NADES), on the secondary and tertiary structures, hydrophobicity, free amine content, protein-protein interactions, and functional properties of zein. The NADES used included choline chloride: oxalic acid, choline chloride: urea, choline chloride: glycerol, and glucose: citric acid. The results reveal that the NADES system significantly altered zein's structures, as evidenced by Fourier transform infrared spectroscopy, fluorescence, and Ultraviolet-Visible Spectroscopy analysis. Circular dichroism spectroscopy analysis indicated significant conformational change in modified zein, with decreased α-helix and increased random coil content. Notably, the NADES system leads to greater disruption of hydrogen bonds and facilitates the exposure of hydrophobic regions compared to water, ethanol, and acetic acid systems. This resulted in enhanced solubility, surface hydrophobicity, and free amine content in zein, indicating a more significant change in protein structure. In contrast, water and acetic acid solvents maintained more stable disulfide bonds within zein, which correlates with lower solubility and less unfolding. The NADES system promoted interactions between zein and its solvent components, improving emulsifying properties. Water, ethanol, and acetic acid systems had higher solubility in urea, thiourea, and dithiothreitol than the NADES system, revealing disruption of both covalent and noncovalent bonds in zein modified by NADES. Overall, this study highlights the superior ability of the NADES system to modify zein's structure and functionality compared to conventional solvents, suggesting its potential for enhancing protein applications in the industrial production of foods.

One new polyketide and four new sesquiterpenes derivatives from the fungicolous fungi aspergillus nidulans LZ8 of Ganoderma lingzhi.

One new polyketide asperfuranone D (1), four new sesquiterpenes derivatives aspergillone C-F (2-5) and three known compounds (6-8) were successfully isolated from Aspergillus nidulans LZ8, a fungicolous fungi from the macrofungal Ganoderma lingzhi. The structures of these compounds were elucidated by extensive spectroscopic analyses including ultraviolet-visible spectroscopy (UV), mass spectrometry (MS), nuclear magnetic resonance (NMR), and electronic circular dichroism (ECD) calculation. In addition, the anti-inflammatory activities of the new compounds were evaluated using LPS-induced RAW 264.7 cells. The results revealed that compound 5 showed moderate nitric oxide (NO) inhibitory activity with the IC50 value of 13.19 ± 1.05 μM, while the IC50 value of the positive control L-NMMA was 41.88 ± 0.91 μM.

PRODUCTION AND CHARACTERIZATION OF ANTI-DIABETIC GOLD NANOPARTICLES USING THE LEAF EXTRACT OF MANGIFERA INDICA

Diabetes has continued to affect the well-being of millions of individuals all over the world. More than seventy percent of Africans have undiagnosed diabetes mellitus, with Nigeria among the list of the African countries recording most undiagnosed cases. Biologically synthesized gold nanoparticles using the extracts of plants have continued to gain grounds in the treatment of diabetes. In the present research, a straightforward green method was used to form gold nanoparticles (AuNPs) from Mangifera indica leaf extract. Transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), and selected area electron diffraction (SAED) were used to characterize the nanoparticles. Using XRD and SAED, the AuNPs' crystallinity was ascertained. The TEM revealed particles of various morphologies, and the UV-Vis revealed a surface plasmon resonance (SPR) at 539 nm. The stability of the colloidal suspension was implied by the DLS measurement, which revealed a hydrodynamic size of 31.74 nm and a zeta potential of -23.7 mV. With percentage inhibitions that were about equivalent to that of acarbose, the conventional medication, the AuNPs demonstrated strong antidiabetic efficacy against the alpha-glucosidase and alpha-amylase enzymes. The research revealed the potential of Mangifera indica leaf extract-mediated gold nanoparticles in treatment of diabetes.

Structural, Morphological and Electrochemical Studies of Synthesized BaCuTiO3 Doped NiTiO3 Nanocomposites for Energy Storage Application

This research explores the development of Ba0.8Cu0.2TiO3 and NiTiO3 nanocomposites for use in high-performance flexible piezoelectric energy harvesters (FPEHs). This study aims to address the brittleness of traditional piezoceramics by developing flexible nanocomposites that are compatible with wearable electronics. The nanocomposites were synthesized and characterized using various techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), photoluminescence (PL), vibrating sample magnetometry (VSM) and X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (C-V) measurements were employed to evaluate the electrical properties, while piezoelectric modeling and various circuit designs were explored to optimize energy efficiency. The results demonstrate that the addition of NiTiO3 to Ba0.8Cu0.2TiO3 alters the electrical and magnetic properties of the composite, enhancing its suitability for energy storage applications. The energy storage applications of the nanocomposites were evaluated by measuring output voltage, stored energy, open-circuit voltage and short-circuit current. These findings indicated that Ba0.8Cu0.2TiO3-NiTiO3 nanocomposites are the promising materials for flexible piezoelectric energy harvesters, offering improved mechanical flexibility, energy conversion efficiency and environmental stability. This work contributes to the advancement of sustainable energy solutions for powering low-power electronics and portable devices.

Theoretical Study of the Structural and Electronic Properties of NIPAM Polymer Dosimetry Gel

Background: Gel dosimeters consist of two types: Frick and Polymer, with compounds that are highly reactive to radiation. Objective: The difference in energy between the Highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was investigated. Methods: An examination of the structure of a dosimetry gel polymer of type N- sopropylacrylamide (NIPAM) was carried out with the assistance of the Gaussian 09 software, the Fourier Transform Infrared Spectrometer (FTIR), the proton and carbon nuclear magnetic resonance (H NMR-C NMR), and the ultraviolet-visible spectroscopy (UV-vis) approach were used. The molecular geometry was determined using density functional theory (DFT) (B3LYP) and computational means. Subsequently, this molecule’s vibrational frequencies and electrical characteristics were examined, with the ground state represented by the 6-31G basis. The computations of the structure, as well as the vibrational frequencies and chemical shift, demonstrated a satisfactory theoretical approximation. Results: Based on the findings, it has been shown that NIPAM has a high-water solubility and is of great assistance in the process of introducing a powerful polar amide group into a hydrophobic polymer via the use of suspension or emulsion polymerization, and strong coupling effect (interaction of magnetic fields) between the hydrogen atoms and the deformation. Conclusions: The atoms within the structure, the molecule is highly reactive, the computed results demonstrated the accuracy of the theoretical approximation despite these discrepancies.

Electro-optical and thermal characterization of cadmium doped copper tartrate crystals grown in silica gel

Cadmium doped copper tartrate crystals were grown by Gel Growth technique by single diffusion. Silica gel of optimum specific gravity was set with tartaric acid at optimum pH and aging period for crystal growth. Band gap of cadmium doped copper tartrate crystal is determined using Ultraviolet-Visible Spectroscopy is 5.780 eV. Blue Color of cadmium Copper tartrate crystal and transparency is confirmed using Photoluminescence spectroscopy. Emission originates from Cu2+ vacancy-related defects or their complexes. Dimensions of crystals are found from Powder X-Ray Diffraction data. The edge lengths of unit cell calculated from indexing of PXRD data are, a = 5.47 Å, b =11.76 Å, c =9.20Å and volume of unit cell is, 621.02208 Å3.

Design and fabrication of nanocomposite adsorbents for dairy industry wastewater treatment

The dairy industry produces a significant volume of effluents that contain various pollutants, which causes environmental issues. In this study, the fabrication and performance of nanocomposite adsorbents incorporating activated carbon (AC), calcium alginate (CA), and nanosilica, as a simple, cost-effective, and eco-friendly approach to treat dairy wastewater, aiming to enhance food processing sustainability by reducing water consumption, minimizing wastewater, and supporting the Water-Food-Environment Nexus. The nanoparticles were synthesized using sand extraction in an environmentally friendly approach with a size of 30–45 nm. Several techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–VIS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to characterize the materials. Furthermore, the nanocomposite adsorbent performance and efficiency in removing chemical oxygen demand (COD) were assessed through batch experiments. The nanocomposite adsorbents’ optimal conditions were investigated through batch experiments, achieving a 99.7% COD removal in dairy wastewater treatment. The best results were obtained with a 4-h contact time, pH of 2, and nanosilica dosage of 10%, demonstrating the adsorbent’s high efficiency in organic pollutant removal. However, the adsorption isotherm, kinetic, and thermodynamic studies were carried out and the best-fitted models of isotherm, and kinetic models were Langmuir, and pseudo-second-order reaction, respectively. The thermodynamic reaction of this study is related to being endothermic.

Anti-Inflammatory Activities of New Compounds Isolated from the Fruits of Foeniculum Vulgare Mill.

Forty-nine compounds, including six previously unknown together with forty-three known ones, were isolated from the fruits of Foeniculum vulgare Mill. Their structures were elucidated using high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV), nuclear magnetic resonance (NMR), and electronic circular dichroism (ECD) methods. All isolates were evaluated their anti-inflammatory activity. The results indicated that compounds 1 and 6 inhibit lipopolysaccharide (LPS)-induced nitric oxide production in RAW 264.7 macrophages with IC50 values of 41.77±1.80, 46.72±1.75 μmol/L, respectively. Moreover, the potential targets of the four active ingredients were explored through network pharmacology, revealing that SRC, TP53, AKT1, and PIK3CA may serve as key anti-inflammatory targets. Additionally, the anti-inflammatory activities of compounds 1-6 were first observed in this experiment.

Scots Pine Bark Extracts as Co-Hardeners of Epoxy Resins.

Extracts from natural waste like bark or leaves are great sources of phytochemicals, which contain functional groups (hydroxyl, carboxylic, vinyl, allyl) attractive in terms of polymer synthesis. In this study, the synthesis of epoxy with an extract of Scots pine bark as a natural co-hardener was evaluated. Ultraviolet-visible (UV-Vis) spectroscopy was used for the identification of phytochemicals with conjugated dienes and quantification of TPC. Also, the total solid content (TSC) of representative extracts was calculated. The best extract in terms of total phenolic content (TPC) value was selected as a co-hardener and investigated using differential scanning calorimetry (DSC) for thermal effects and attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) for reactions between functional groups. Also, the mechanical properties (flexural modulus, flexural strength, impact strength, Shore D hardness) and density of composition were obtained for extract-based epoxy and compared to reference sample values. Results were discussed in terms of future research and improvement of compositions. Also, potential applications were proposed.

Green synthesis of silver nanoparticles from endophytic fungus Colletotrichum sp. with special emphasis on antibacterial, antioxidant and plant growth promoting potential

The creation of "microbial nanotechnology" for quick and large-scale manufacturing of nanoparticles would be possible with an effective biosynthesis method. Plumbago zeylanica L. is a medicinal plant from which the endophytic fungus Colletotrichum sp. was isolated and identified by 18S rDNA sequencing and microscopic studies. Cell filtrate of Colletotrichum sp. was employed to produce biological silver nanoparticles which acted as a reducing and stabilising agent during this process. The brown colour proved that silver nanoparticles (AgNPs) are being produced. In characterization of AgNPs, ultraviolet-visible spectroscopy revealed maximum absorption at 425 nm. From transmission electron microscopy and field emission scanning electron microscopic study the shape of the silver nanoparticle was found spherical with 10–30 nm diameters. The existence of elemental silver (peak) was verified by the silver signal in the energy-dispersive X?ray spectroscopy. Fourier-transform infrared analysis showed some major and minor shifts in the peaks of some chemical bonding. Synthesised AgNP had strong antibacterial action against pathogenic bacterial strains in 200 g/mL concentration and against Pseudomonas aeruginosa MTCC 741, it showed the highest inhibition. The AgNP concentration of 150 g/mL demonstrated the highest competency for antioxidant capabilities while ascorbic acid was used as the reference. Also, AgNP exhibited plant growth-promoting ability as in 40 mg/L concentration; it significantly enhanced the shoot and root growth, total soluble protein, sugar, and indole acetic acid content of P. zeylanica L. This AgNP can be useful in pharmaceutical industries and agriculture as nano fertilizers for all these purposes.

Comparative photocatalytic performance of iron nanoparticles biosynthesized from aqueous extracts of potato, potato peels, and leaves.

This study presents an eco-friendly, cost-effective approach for synthesizing highly efficient nanocatalysts with the help of organic waste. Iron nanoparticles (INPs) were synthesized from aqueous extracts of potato, potato peel, and potato leaf and were evaluated for their photocatalytic efficiency for the degradation of methylene blue dye. X-ray Diffraction (XRD) confirmed Fe3O4 nanoparticles cubic crystal structure with the smallest crystallite size (9.52 nm) with potato peel, and Brunauer-Emmett-Teller (BET) analysis also showed the highest surface area (61.2 m2/g) for the same material. At the same time, other characterizations such as Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Ultraviolet-Visible Spectroscopy (UV-Vis) for these nanoparticles were also performed, which provided insights into the chemical and physical composition and photoactivity. Photocatalytic tests demonstrated efficient methylene blue (MB) degradation under sunlight for all iron nanoparticles. The iron nanoparticle prepared using potato peel extracts achieved the highest degradation efficiency of 99 % in 120 min, with the highest first-order kinetics K = 0.0426 min-1, attributed to its smallest crystallite size, highest surface area, and suitable band gap.

A Novel Dual Cross-linking Reagent for Dentin Bonding Interface Stability.

The cross-linking reagent has been proposed as a means of modifying dentin collagen, inhibiting matrix metalloproteinase activities, and enhancing bond durability during dentin bonding procedures. This study aimed to synthesize an operation-friendly dual cross-linking reagent-3-(4-formyphenoxy)-2-hydroxypropyl methacrylate (FPA)-to assess its ability to cross-link dentin collagen and reduce enzymatic activity at the bonding interface. Cytotoxicity was evaluated by a cell counting kit-8 test and calcein AM/propidium iodide assay. Attenuated total reflection-Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and molecular docking of FPA-collagen showed that FPA can mediate covalent bonding and hydrogen bonding. The hydroxyproline release test and thermogravimetric analysis demonstrated that FPA-collagen can resist exogenous proteases and thermolysis. The gelatin zymography and in situ zymography indicated that FPA can reduce enzymatic activity at the bonding interface. The bonded samples were subjected to microtensile bond strength analysis after 24 h and thermocycling. The bonding interface quality was evaluated by the water contact angle, confocal laser scanning microscope, field emission scanning electron microscopy, and nanoleakage assessment. This study demonstrated the effectiveness and significant clinical potential of the dual cross-linking reagent FPA in that it increases the longevity of resin-dentin bonds and reduces dentin matrix metalloproteinase activities at the bonding interface.

Characterization of Rice Husk for Graphene Extraction and Metallization

Rice husk, an underutilized agricultural waste product, serves as a potential precursor for graphene synthesis. This study focuses on synthesizing and characterizing graphene through the chemical exfoliation method, employing advanced analytical techniques to explore its potential applications in metallization. Graphene was produced by chemically activating rice husk ash (RHA) with potassium hydroxide (KOH) at 800 ºC. The extracted graphene underwent analysis using various techniques. X-ray Diffraction (XRD) confirmed the material's crystalline nature and graphitic structure. Fourier-Transform Infrared Spectroscopy (FTIR) identified typical functional groups present in the synthesized graphene. Raman Spectroscopy revealed significant defects and confirmed that the graphene consists of single or few-layer thin sheets. Transmission Electron Microscopy (TEM) showed the presence of thin graphene sheets and nanoparticles with sizes ranging from 1.47 nm to 5.80 nm. Ultraviolet-Visible Spectroscopy (UV-Vis) confirmed electronic structure and optical properties, essential for metallization. X-ray Fluorescence (XRF) confirmed the purity of the graphene, while Brunauer-Emmett-Teller (BET) analysis revealed a high specific surface area, making the material suitable for surface-based applications. Electrical conductivity tests demonstrated good conductivity in the lower to moderate current range. The study underscores the potential of rice husk-derived graphene for metallization, offering a cost-effective and eco-friendly synthesis method for industrial and commercial applications.

Identifying Crystal Structure of Halides of Strontium and Barium Perovskite Compounds with EXPO2014 Software.

The synthesis of ethylamine-based perovskites has emerged to attempt to replace the lead in lead-based perovskites for the alkaline earth elements barium and strontium, introducing chloride halide to prepare the perovskites in solar cell technology. X-ray diffraction studies were conducted, and EXPO2014 software was utilized to resolve the structure. Chemical characterization was performed using Fourier transform infrared spectroscopy, photophysical properties were analyzed through ultraviolet-visible spectroscopy, and photoluminescence properties were determined to confirm the perovskite characteristics. The software employed can determine new crystal structures, as follows: orthorhombic for barium perovskite CH3CH2NH3BaCl3 and tetragonal for strontium perovskite CH3CH2NH3SrCl3. The ultraviolet-visible spectroscopy data demonstrated that a temperature increase (90-110 °C) contributed to reducing the band gap from 3.93 eV to 3.67 eV for barium perovskite and from 4.05 eV to 3.84 eV for strontium perovskite. The results exhibited that new materials can be obtained through gentle chemistry and specialized software like EXPO2014, both of which are capable of conducting reciprocal and direct space analyses for identifying crystal structures using powder X-ray diffraction.

Untangling the Efficient Boron-Initialized Hydroxyl-Terminated Polybutadiene Combustion for High Energetic Solid Propulsion Systems.

Highly energetic boron (B) particles embedded in hydroxyl-terminated polybutadiene (HTPB) thermosetting polymers represent stable solid-state fuel. Laser-heating of levitated B/HTPB and pure HTPB particles in a controlled atmosphere revealed spontaneous ignition of B/HTPB in air, allowing for examination of the exclusive roles of boron. These ignition events are probed in situ via simultaneous spectroscopic diagnostics: Raman and infrared spectroscopy, temporally resolved high-speed optical and infrared cameras, and ultraviolet-visible (UV-vis) spectroscopy. The emission spectra unravel two stages of the B/HTPB ignition─the exoergic ignition of boron followed by HTPB combustion. It was found that HTPB readily absorbs the energy from the irradiating carbon dioxide (CO2) laser but efficiently transfers that thermal energy to the densely arranged boron particles due to the lower heat capacity of the latter. This transferred energy causes a surge in temperature for the boron particles, leading to ignition (in an oxygen environment) in B/HTPB, unlike the case with HTPB alone. The accumulated energy from the second stage of boron ignition triggers the decomposition of HTPB in conjunction with hydrogen abstraction to produce radical precursors via boron oxides (BO and BO2)─the key emitting intermediates detected. Along with conventional combustion products such as carbon dioxide (CO2) and water (H2O), the formation of partially oxidized gaseous products such as methanol (CH3OH) and methyl vinyl ether have also been detected as a tracer of diverse oxidation events, suggesting a complex oxidation chemistry within HTPB and overall depict crucial insights for its use as a solid rocket fuel.