Polymer Matrix Research Articles

Optical properties of polyvinyl alcohol-glass waste powder composites

This study investigates the effect of glass waste powder content on the UV–Vis spectroscopy of polyvinyl alcohol (PVA). The glass powder was obtained from the waste of fluorescent tubes. The solution casting method was utilized to prepare PVA- glass composite films by adding glass powder with 10, 20, 30, and 40 wt. %. UV–Vis absorption spectra of PVA- glass samples were recorded in the range 220–1100 nm. The optical parameters were calculated as follow: absorbance, absorption coefficient, transmittance, refractive index, extinction coefficient, dielectric constant, and imaginary dielectric constant. Based on the XRD results, it is revealed that the PVA become more amorphous with increasing amount of glass waste. UV–Vis spectroscopy studies demonstrated that, for all samples, the absorbance, absorption coefficient, extinction coefficient, and Ei increases with the increase in the amount of glass waste. On the other hand, transmittance decreases with increasing amount of glass waste. The change of the studied properties with wavelength depends strongly on the amount of glass waste powder. At visible region, the transmittance is stable with increasing wavelength for samples containing 20, 30 and 40%. Glass waste, while the pure sample and the sample containing 10% glass waste, the transmittance increases with the wavelength. On the other hand, the absorbance and absorption coefficient for all samples decreases rapidly up to a specific wavelength and then the change is very slight at longer wavelengths. Also, the increase of extinction coefficient and imaginary dielectric constant with wavelength is related to the amount of glass powder added. The change of dielectric constant and refractive index with wavelength depends on the amount of the filler, where the pure and the sample filled with 10% glass powder show normal dispersion, while the other samples show anomalous dispersion. Finally, the pure sample had the highest energy gap (5.7 eV) while the sample containing 30% glass powder had the lowest value (4.8 eV). Through this study, it become possible to change the optical properties of PVA by adding glass waste powder, which allows the possibility of benefiting from the new composites to be used in different applications according to their response to different wavelengths. From an economic and environmental point of view, these wastes can be utilized instead of being thrown away by reusing them as polymer fillers, taking into consideration the change in the optical properties of the matrix polymer.

Development of Vitamin C-Enriched Oral Disintegration Films Using Chia Mucilage

Oral disintegration films (ODFs) offer a convenient alternative for administering active compounds with quick absorption, no need for water, customizable formulation, and promising pharmaceutical applications. This study aimed to develop chia mucilage films as a new polymer to carry vitamin C. Chia mucilage was extracted using the method of immersing the seeds in water, separated by vacuum filtration and using a sieve to remove the mucilaginous gel, then centrifuged and finally freeze-dried, with the mucilage obtained being used to produce films using the casting technique. The formulations included a control and a 1% vitamin C variant, with glycerol as a plasticizer. The produced films showed high solubility, pH close to the oral and a disintegration time of 53.17 s for the formulation with 1% vitamin C. The presence of vitamin C in the polymer matrix, as well as the interactions between them, were confirmed by DSC and FTIR spectra. On the first day of storage, after 1 min of reaction at 30 °C, the vitamin C concentration obtained was 477.50 mg/g, while at 40 °C was 411.28 mg/g. After 35 days of storage, the films showed a reduction in vitamin C concentration. Chia mucilage proved to be a promising polymer in the production of ODFs carrying vitamin C.

Whole-Cell Thermal Sensor for the Detection of P. falciparum-Infected Erythrocytes: Imprinted Polymers as Synthetic Receptors for the Detection of Malaria.

Malaria is a major public healthcare concern worldwide, representing a leading cause of death in specific regions. The gold standard for diagnosis is microscopic analysis, but this requires a laboratory setting, trained staff, and infrastructure and is therefore typically slow and dependent on the experience of the technician. This study introduces, for the first time, a biomimetic sensing platform for the direct detection of the disease. The heart of the sensor consists of a synthetic receptor created by surface imprinting Plasmodium falciparum-infected erythrocytes in a polymeric matrix. This receptor layer is coupled to a low-cost and fast thermal transducer platform, allowing for real time detection of the infection. The artificial receptor is a composite of poly(dimethylsiloxane) and graphene oxide that, in combination with the thermal readout, exhibited a limit of detection below 0.5% parasitemia in erythrocyte samples. This value is relevant for the diagnosis of infection in patients with low parasitemia levels. This study proves that biomimetic sensors could be further explored for the development of point-of-care technologies for the management of the disease.

The influence of the molecular weight of hyaluronic acid on the mangiferin release kinetics from the polymer matrix

Introduction. Currently, the use of natural biologically active agents (BAA) as effective antibacterial drugs for both external and internal use is becoming widespread. Polyphenol mangiferin, extracted from the leaves of the Mangifera indica plant, is the most attractive BAA. Despite high antimicrobial activity against gram-positive and gram-negative strains of bacteria, the use of mangiferin is limited by its low aqueous solubility. To increase solubility and, accordingly, bioavailability, various approaches are used, in particular, encapsulation in polymer and biopolymer matrices. One of the promising biopolymers for the encapsulation of biologically active substances is hyaluronic acid, which is completely biocompatible with the tissues of a living organism and is capable of complete biodegradation under the influence of enzymes (hyaluronidases).Aim. Study of the release kinetics of the biologically active agent (mangiferin) from a polymer matrix based on hyaluronic acid with different molecular weights.Materials and methods. Polymer films obtained by casting method from 1.5 wt.% forming solutions of hyaluronic acid with a molecular weight of 1.30 and 2.48 MDa with different contents of mangiferin were used as the objects of the study. The weight ratio of hyaluronic acid to mangiferin varied from 5 to 25. Released mangiferin was measured by UV/Vis spectrophotometry at a wavelength of 237 nm. A phosphate buffered saline with pH 7.4 was used as a model medium. The mangiferin release kinetic was assessed using various mathematical models.Results and discussion. Mangiferin release kinetic from a polymer matrix based on hyaluronic acid has a release sigmoidal pattern. The release mechanism has a complex nature of the Super Case II transport type, with the exception of a sample with a low content of mangiferin and hyaluronic acid with molecular weight equal to 1.3 MDa, for which an abnormal release pattern is detected (non-Fickian diffusion), due to the hydrophilic nature of hyaluronic acid, the rapid swelling of the polymer matrix, as well as a significant leading in the diffusion of mangiferin compared to the relaxation rate of the polymer. The most suitable model is the Weibull model, which describes the mangiferin release kinetics with greater accuracy compared to other mathematical models.Conclusion. The results obtained indicate the potential possibility of using the developed polymer films as biomedical materials for external use, which provide transdermal delivery of pharmaceutical agents. The authors of the study are planning to develop a methodology for prolonged and controlled release of a loaded biologically active agent, including by various cross-linking agents.

Design and Characterization of Aceclofenac-Loaded Microballoons using Eudragit with Hydroxypropyl Methylcellulose

Background: Drug delivery systems based on microballoons are one of the promising approaches for gastric retention, especially useful for drugs with site-specific absorption in the stomach. The microballoons are hollow, spherical particles under 200 micrometers, designed to float in the gastric environment. The Aceclofenac formulation of an NSAID is helpful with a half-life of 4–4.3 hours; this delivery form gives a sustained release and maintains constant plasma levels with enhanced bioavailability and decrease in dosing frequency. Methodology: Microballoons of Aceclofenac were prepared using Eudragit RS 100 and Hydroxy Propyl Methyl Cellulose as polymers from the emulsion–solvent diffusion method. In this, the polymers impart stability along with a profile of controlled release. Here, the microballoons was evaluated for physical parameter and the release profile regarding average particle size, floatation percentage, entrapment efficiency, true tapped density, and percentage yield, and FTIR will be carried out on complexes of drug and polymer. Results and Discussion: The prepared microballoons exhibit excellent floating properties and uniformity in size, which aided in long gastric retention. High entrapment efficiency with controlled and sustained release of the drug for an extended period was obtained. FTIR studies indicated that Aceclofenac remained stable in the polymer matrix with no considerable chemical interaction between the drug and the polymers. Conclusion: This research shows promise in microballoons-based delivery systems that could maintain the release for a longer duration from the delivery device with respect to Aceclofenac, which enhances bioavailability and reduces dosing frequencies. Keywords: Aceclofenac, Microballoons, NSAID, Sustain Release Medication, Eudragit RS100, HPMC

Carbon nanotube/bentonite @ polyvinylidene fluoride tri-flouro ethylene nanocomposite matrix for surpior elimination of carcinogenic dye from wastewater

Abstract This study examines the sorption behavior of Congo Red (CR) dye from water-based solutions using a synergistic nanocomposite made of Bentonite (BT), multi-walled carbon nanotubes (MWCNTs), and a Poly (vinylidene fluoride tri-flouroethylene) (P(VDF-TRFE)) polymer matrix with exceptional adsorption capacity for the selective removal of Congo red dye from aqueous solutions. This is done in order to address the urgent concerns surrounding the health and environmental implications of CR dye. Utilizing modern analytical technique such as FTIR, XRD, SEM, TEM, and TGA, the adsorption physicochemical interaction and nanocomposite manufacturing were carefully investigated, offering thorough insights into the composite's general properties. Nanocomposite structures of between 31 and 37 nm in diameter were discovered by TEM examination. The adsorption process was pH dependent, reaching a peak removal effectiveness of 94.5% at pH 3.0. The correlation coefficients obtained from kinetic modeling using pseudo-first-order and pseudo-second-order equations were 0.97389 and 0.96802, respectively, suggesting that the adsorption mechanism adhered to first-order rate kinetics. Thermodynamic investigation revealed an exothermic and spontaneous reaction, with a negative ΔG value between − 7.45 and − 7.95 J/mol. The nanocomposite outperformed the capacities reported for individual components in earlier investigations, with an impressive monolayer sorption capacity (qmax) of 143.88 mg/g. As a result, there is great potential for this innovative nanocomposite to be a very successful adsorbent for treating industrial wastewater. Graphical Abstract

Active Polylactide-poly(ethylene glycol) Films Loaded with Olive Leaf Extract for Food Packaging—Antibacterial Activity, Surface, Thermal and Mechanical Evaluation

As the demand for sustainable and innovative solutions in food packaging continues to grow, this study endeavors to introduce a comprehensive exploration of novel active materials. Specifically, we focus on characterizing polylactide-poly(ethylene glycol) (PLA/PEG) films filled with olive leaf extract (OLE; Olea europaea) obtained via solvent evaporation. Examined properties include surface structure, thermal degradation and mechanical attributes, as well as antibacterial activity. The results indicated a significant impact of the incorporation of OLE into this polymeric matrix, increasing hydrophobicity, decreasing surface free energy, and enhancing surface roughness, albeit with slight reductions in mechanical properties. Notably, these modified materials exhibited significant bacteriostatic, bactericidal and anti-adhesive activity against both Staphylococcus aureus and Escherichia coli. Consequently, PLA/PEG/OLE films demonstrated considerable potential for advanced food packaging, facilitating interactions between products and their environment. This capability ensures the preservation and extension of food shelf life, safeguards against microbial contamination, and maintains the overall quality, safety, and integrity of the packaged food. These findings suggest potential pathways for developing more sustainable and effective food packaging films.

Silicone Composites with Electrically Oriented Boron Nitride Platelets and Carbon Microfibers for Thermal Management of Electronics

This study investigated silicone composites with distributed boron nitride platelets and carbon microfibers that are oriented electrically. The process involved homogenizing and dispersing nano/microparticles in the liquid polymer, aligning the particles with DC and AC electric fields, and curing the composite with IR radiation to trap particles within chains. This innovative concept utilized two fields to align particles, improving the even distribution of carbon microfibers among BN in the chains. Based on SEM images, the chains are uniformly distributed on the surface of the sample, fully formed and mature, but their architecture critically depends on composition. The physical and electrical characteristics of composites were extensively studied with regard to the composition and orientation of particles. The higher the concentration of BN platelets, the greater the enhancement of dielectric permittivity, but the effect decreases gradually after reaching a concentration of 15%. The impact of incorporating carbon microfibers into the dielectric permittivity of composites is clearly beneficial, especially when the BN content surpasses 12%. Thermal conductivity showed a significant improvement in all samples with aligned particles, regardless of their composition. For homogeneous materials, the thermal conductivity is significantly enhanced by the inclusion of carbon microfibers, particularly when the boron nitride content exceeds 12%. The biggest increase happened when carbon microfibers were added at a rate of 2%, while the BN content surpassed 15.5%. The thermal conductivity of composites is greatly improved by adding carbon microfibers when oriented particles are present, even at BN content over 12%. When the BN content surpasses 15.5%, the effect diminishes as the fibers within chains are only partly vertically oriented, with BN platelets prioritizing vertical alignment. The outcomes of this study showed improved results for composites with BN platelets and carbon microfibers compared to prior findings in the literature, all while utilizing a more straightforward approach for processing the polymer matrix and aligning particles. In contrast to current technologies, utilizing homologous materials with uniformly dispersed particles, the presented technology reduces ingredient consumption by 5–10 times due to the arrangement in chains, which enhances heat transfer efficiency in the desired direction. The present technology can be used in a variety of industrial settings, accommodating different ingredients and film thicknesses, and can be customized for various applications in electronics thermal management.

Unravelling Lithium Interactions in Non-Flammable Gel Polymer Electrolytes: A Density Functional Theory and Molecular Dynamics Study

Lithium metal batteries (LiMBs) have emerged as extremely viable options for next-generation energy storage owing to their elevated energy density and improved theoretical specific capacity relative to traditional lithium batteries. However, safety concerns, such as the flammability of organic liquid electrolytes, have limited their extensive application. In the present study, we utilize molecular dynamics and Density Functional Theory based simulations to investigate the Li interactions in gel polymer electrolytes (GPEs), composed of a 3D cross-linked polymer matrix combined with two different non-flammable electrolytes: 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in trimethyl phosphate (TMP) solvents. The findings derived from radial distribution functions, coordination numbers, and interaction energy calculations indicate that Li⁺ exhibits an affinity with solvent molecules and counter-anions over the functional groups on the polymer matrix, highlighting the preeminent influence of electrolyte components in Li⁺ solvation and transport. Furthermore, the second electrolyte demonstrated enhanced binding energies, implying greater ionic stability and conductivity relative to the first system. These findings offer insights into the Li+ transport mechanism at the molecular scale in the GPE by suggesting that lithium-ion transport does not occur by hopping between polymer functional groups but by diffusion into the solvent/counter anion system. The information provided in the work allows for the improvement of the design of electrolytes in LiMBs to augment both safety and efficiency.

Poly Lactic Co-glycolic Acid d-α-tocopheryl Polyethylene Glycol 1000 Succinate Fabricated Polyethylene Glycol Hybrid Nanoparticles of Imatinib Mesylate for the Treatment of Glioblastoma Multiforme.

This study aimed to develop Imatinib Mesylate (IMT)-loaded Poly Lactic-co-Glycolic Acid (PLGA)-D-α-tocopheryl polyethylene glycol succinate (TPGS)- Polyethylene glycol (PEG) hybrid nanoparticles (CSLHNPs) with optimized physicochemical properties for targeted delivery to glioblastoma multiforme. Glioblastoma multiforme (GBM) is the most destructive type of brain tumor with several complications. Currently, most treatments for drug delivery for this disease face challenges due to the poor blood-brain barrier (BBB) and lack of site-specific delivery. Imatinib Mesylate (IMT) is one of the most effective drugs for GBM, but its primary issue is low bioavailability. Therefore, nanotechnology presents a promising solution for targeted IMT delivery to GBM. This article primarily explores the fabrication of IMT-loaded core-shell lipid-polymer hybrid nanoparticles (CSLHNPs) to achieve enhanced brain delivery with therapeutic efficacy. The primary objective of this study is to develop optimized, stable IMT-loaded hybrid nanoparticles with an encapsulated polymer matrix and to evaluate these nanoparticles using sophisticated instruments such as SEM and TEM to achieve smooth, spherical nanoparticles in a monodispersed phase. The enhanced stable formulation yielded a notable increase in entrapment efficiency, reaching 58.89 ± 0.5%. The physical stability analysis of nanoparticles was assessed over 30 days under conditions of 25 ± 2°C and 60 ± 5% relative humidity. Hemolytic assays affirmed the biocompatibility and safety profile of the nanoparticles. in vitro drug release kinetics revealed a sustained IMT release over 48 hours. The formulated CSLHNPs achieved a narrow size distribution with a mean vesicle diameter of 155.03 ± 2.41 nm and a low polydispersity index (PDI) of 0.23 ± 0.4, indicating monodispersity. A high negative zeta potential of -23.89 ± 3.47 mV ensured excellent colloidal stability in physiological conditions. XRD analysis confirmed the successful encapsulation of IMT within the nanoparticle matrix, with the drug transitioning to an amorphous state for enhanced dissolution. During Cell-Cell viability assays on LN229, glioblastoma cells were treated with IMT-loaded nanoparticles and showed a significantly enhanced inhibitory effect compared to free IMT. These hybrid nanoparticles demonstrated potential in reducing oxidative stress-induced cellular damage by mitigating reactive oxygen species (ROS). Thus, the prepared IMT hybrid nanoparticles showed higher cellular uptake and superior cytotoxicity compared to the plain drug. This study posits the IMT-PLGA-TPGS-DSPE PEG 2000-CSPLHNPs as a formidable and innovative drug delivery system for Glioblastoma Multiforme (GBM) treatment, warranting further exploration into their clinical application potential. Future work could involve conducting in vivo studies to evaluate the pharmacokinetics, biodistribution, and therapeutic efficacy of the IMT-PLGA-TPGS-DSPE PEG 2000-CSPLHNPs in animal models of Glioblastoma Multiforme (GBM). Additionally, further research may focus on optimizing the nanoparticle formulation for enhanced targeting capabilities, investigating long-term stability under varied storage conditions, exploring potential combination therapies to synergize with the nanoparticles, and assessing the scalability and manufacturability of the developed drug delivery system for potential clinical translation. Integration of advanced imaging techniques for real- time tracking and visualization of nanoparticle distribution within tumours could also be a promising direction for future investigations.

Polymer matrix composites from high-temperature cyanate ester resins and boron nitride nanotube-seeded electrospun fibers

Polymer matrix composites from high-temperature cyanate ester resins and boron nitride nanotube-seeded electrospun fibers

Design magneto‐dielectric elastomer composites for flexible electric/magnetic field response multi‐mode sensors

AbstractWith the increasing complexity of flexible sensor application scenarios, in order to achieve their use in electric and magnetic fields, this paper introduces a core‐shell structure with Ni‐doped cobalt ferrites as the magnetic core and barium titanate as the dielectric layer, filling it into a polymer matrix to prepare flexible magneto‐dielectric elastomer composites. Taking advantages of this design, the targets including the establishment of multi‐functionalization and the retention of fine mechanical properties have been simultaneously achieved. The synthesized elastomer composites exhibit fine flexibility and excellent magneto‐electric response. An optimum magnetic‐induced deformation angle achieves to 55° under an external magnetic field of 8000 Oe, and a maximum electric‐induced deformation approaches to about 8.29% under an applied electric field of 5 kV/mm. Besides that, with Ni‐doping, the magnetization behaviors of composite fillings could be tuned, resulting a controllable magnetic field response of the synthesized magneto‐dielectric rubber composites. This work provides a novel way to design multi‐functionalized flexible composites, which is significant for exploring multi‐mode flexible sensors.Highlights Magneto‐dielectric elastomers were prepared with using core‐shell filling. The elastomer composites exhibit fine magnetic and electric field response. The composites maintained good flexible mechanical properties.

Immobilization of Enzymes in Polymeric Materials Based on Polyamide: A Review

The immobilization of enzymes in polyamide-based polymeric materials through covalent bonding is an established technique to stabilize and reuse biocatalysts in industrial processes. Traditionally, enzymes are immobilized using crosslinking agents that activate functional groups on both the support and the enzyme, creating strong bonds that securely anchor the enzyme to the surface. While effective for maintaining enzyme activity over multiple cycles, this method can reduce catalytic efficiency due to rigid binding and involves complex activation steps. Recently, in situ immobilization approaches have emerged as promising alternatives. In this method, enzymes are directly entrapped within the polymer matrix during the synthesis of the polyamide support, such as nylon, simplifying the process and offering enhanced control over enzyme distribution. For instance, studies have demonstrated that in situ immobilization can improve enzyme stability by protecting it within the polymeric network, while reducing production costs and waste. This review explores the ability of polyamide as a support material for immobilization of enzymes, analyzing key techniques, performance across applications, and future strategies to optimize polymer-enzyme interactions for industrial use.

New Molecular Photoswitch Based on the Conformational Transition of Phenothiazine Derivatives and Corresponding Triplet Emission Properties.

Molecular photoswitch research has drawn much attention in the last century owing to its great potential in the development of smart materials. However, photoswitches suitable for constructing light-responsive luminescent materials remain limited, especially those involving triplet-state phosphorescence. Herein, we designed a novel molecular photoswitch based on the conformation transition of phenothiazine derivatives, minimizing steric hindrance (-CH3 > -Cl > -F) to regulate the conformation transition process while introducing a cyanobenzene acceptor to promote phosphorescence emission potential. When they were doped into a polymer matrix, varying photoswitch rates were achieved by incorporating different steric hindrance groups into phenothiazine or cyanobenzene groups, accompanied by photoresponsive room-temperature phosphorescence. This study is expected to greatly expand the diversity and applications of organic photoswitch molecules.

Synthesis of Metalopolymer Structure by Potentiostatic Deposition Method

The initial fundamental aspect examined in this study pertained to the chemical treatment of a silicon electrode in an acidic environment. The objective was to facilitate the deposition of organic or inorganic substances using electrochemical methods. Moreover, this study focused on investigating the nucleation process of poly(azacyclopenta-2,4-diene) on semiconductor substrates and exploring the incorporation of copper particles within the resulting film. The deposition of the polymer film onto the silicon electrode surface occurred through electrochemical oxidation of the monomer in a Na2SO4/H2O solution. The introduction of copper particles into the polymer film was achieved through electrochemical reduction in aqueous solutions, leading to the dispersion of metallic particles within the polymer matrix. Notably, the surface morphology of the poly(azacyclopenta- 2,4-diene)-metal composite films exhibited a coarser and more compact structural appearance compared to pure poly(azacyclopenta-2,4-diene) films. To gain further insights into the surface characteristics of the poly(azacyclopenta-2,4-diene) films, EDX analysis confirmed the successful incorporation of copper into the composite films.

Hammerhead Shark‐Inspired Microvillus‐Structured Ionic Elastomers for Wet Gas Sensing Based on Solvated Ion Transport

AbstractWater molecules are ubiquitous disruptors of conventional gas sensing materials, often leading to diminished sensing performance in materials that are reliant on electronic signal transmission. This creates the pressing need for efficient gas sensing materials with anti‐humidity interference properties. Here, a hammerhead shark‐inspired microvillus‐structured ionic elastomer based on ionic signal transmission in nanoconfined space is constructed by incorporating ionic liquids into a polymer matrix. The ionic elastomers with optimized microvillus structure demonstrated a 1.68‐fold higher response than that of the flat ones, short response time (9 s) toward 30 ppm triethylamine (TEA), excellent selectivity and low limit of detection (LOD) (104.56 ppb). Such sensing performance serves as a proof‐of‐concept for effectively combining solvated ion transport in nanoconfined space with microvillus structure design to develop advanced sensing systems. With such sensing materials, an evident response (23.52%), a similar response time (12 s), low LOD (498.05 ppb), and long‐term stability (at least 30 days) are achieved at the relative humidity of 70%. Mechanistic investigations revealed that effective transport of solvated ions is facilitated after sequential water and TEA surroundings while the microvillus structure significantly enhanced gas transport. Furthermore, the utility of such a sensing system is demonstrated in shrimp decay monitoring under wet conditions.

Processing of reactive acrylic thermoplastic resin at elevated temperatures for rapid composite and fiber metal laminate manufacturing

Thermoplastic polymers are increasingly being used as matrix materials for composites because they offer the advantage of recyclability and joinability over thermoset matrix systems. The polymerization kinetics and gas formation of different precursor mixtures of the liquid acrylic matrix system Elium® were investigated with different initiator contents and at different temperatures for accelerated processing of composites and fiber metal laminates. The mechanical and thermal properties of the resulting polymers showed no significant difference between the investigated parameters. However, the polymerization time was successfully reduced to under 15 minutes with higher temperatures and initiator contents in laminates with 1 mm thickness. In bulk polymerization and thicker laminates, the right parameters must be chosen to balance polymerization time and matrix heating to avoid gas formation leading to voids in the matrix. A combination of 75 wt% Elium® 130 and 25 wt% Elium® 190 with 1.25 wt% peroxide initiator at 50 °C was found to be optimal for reducing gas formation while simultaneously accelerating the polymerization reaction in 3-5 mm thick layers.

Influence of Fiber Direction on the Tribological Behavior of Carbon-Reinforced PEEK at Elevated Temperature for Application in Gas Turbine Engines

Abstract The aerospace industry aims for net-zero greenhouse gas emissions by 2050, requiring gas turbine engines to reduce CO2 emissions. This will impact engine material selection due to harsher operating conditions, limiting traditional metal/alloy use. While fiber-reinforced polymer (FRP) composites are commonly used in the aerospace industry, their use in gas turbine engines is often restricted by the lower operating temperatures of the polymer matrix. However, many studies have demonstrated the tribological potential of FRP in the fan section of the engines, but little attention has been given to the potential of orienting the fibers in the normal (i.e., out-of-plane) direction relative to the wear surface to leverage the anisotropic properties of FRP composites. This study investigates the impact of fiber orientation on the tribological properties of carbon fiber/polyetheretherketone (PEEK) (CF-PEEK) at elevated temperatures. Three CF-PEEK samples with different fiber orientations were selected for this study (parallel, antiparallel, and normal directions), as well as a fourth sample of pure PEEK. Tribological tests were conducted using a ball-on-disk tribometer at an elevated temperature of 200 °C to evaluate wear and friction behavior. The worn surfaces and counterfaces were analyzed using confocal laser scanning microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The findings reveal that CF-PEEK with fibers oriented in the normal direction demonstrates significantly enhanced tribological performance at elevated temperatures, achieving a 95% reduction in the friction coefficient and a 92% decrease in the wear-rate compared to pure PEEK. A wear mechanism has been proposed to explain the superior wear resistance of normally oriented fibers in CF-PEEK, linking it to the development of a fiber-based interface during the run-in phase and the formation of a uniform transfer film.

Highly Efficient Luminescent Solar Concentrators Based on Capped Carbon Quantum Dots with Unity Quantum Yield

AbstractLuminescent solar concentrators (LSCs) can convert sunlight to clean energy by serving as large‐area collectors of sunlight. Benefiting from their large‐area, semi‐transparency, and lightweight characteristics, LSCs have gained a great of attention. However, their optical efficiency is limited by the low quantum yield (QY) and small Stokes shift of conventional photoluminescent materials. Carbon quantum dots (C‐dots) are promising alternatives, yet achieving both high QY and large Stokes shift has proven challenging. Here, a simple, controllable vacuum heating method is introduced to synthesize highly efficient C‐dots using a citric acid‐urea‐cyanuric acid‐CaCl2 system. The cyanuric acid‐capped C‐dots exhibit outstanding properties, including a QY of 94.3% in solution and 100% in a polymer matrix, a large Stokes shift of 0.64 eV, and exceptional photostability, making them ideal for LSC applications. Ultrafast transient absorption spectroscopy provides insights into their exciton dynamics. An LSC (25 cm2) based on these C‐dots achieves an optical efficiency of 13.82% ± 0.30%, while its attached photovoltaic cell attains a power conversion efficiency of 4.82% ± 0.10% under natural sunlight (80 mW cm−2), marking the highest performance reported for C‐dot‐based LSCs. These results highlight the potential of cyanuric acid‐capped C‐dots for advanced solid‐state lighting and energy conversion technologies.

Exploring the Impact of Minor Water Content on Polymer Electrolytes with Molecular Dynamics.

Solid-state polymer electrolytes (SPEs) are increasingly favored over liquid electrolytes for emerging energy storage devices due to their safety features, enhanced stability, and multifunctionality. Minor solvents (such as water) are often introduced unintentionally or intentionally into SPEs. Although it can significantly affect SPEs' electrochemical and mechanical properties, the fundamental role of such solvent content has rarely been studied. Here, we investigate the effects of minor water content on two representative SPEs through molecular dynamics simulations. Focusing on SPEs composed of different base polymers, namely, poly(ethylene oxide) (PEO) and poly(lactic acid) (PLA), and the same salt, lithium perchlorate (LiClO4), our simulations reveal that slight hydration facilitates an increase in ionic conductivity while preserving the mechanical integrity of the SPEs. Notably, these water contents appear to affect ionic conductivity more effectively in certain systems than others, which is attributed to the unique interactions among ions, water, and the polymer matrix. Moreover, small amounts of water can maintain the stiffness of SPEs rather than reducing it. Such results suggest a facile approach to developing SPEs with balanced ionic conductivity and mechanical properties, suitable for a range of energy storage applications.