Polymer Fibers Research Articles

Influence of Mixed Solvent in the Morphology and Hydrophobicity of Electrospun Polystyrene Porous Fibers.

Electrospun polystyrene (PS) fibers are produced using a mixed solvent of chloroform and n,n-dimethylformamide (DMF) to investigate the influence of the solvent ratio on the fiber surface morphology and contact angle of the obtained mats. Electrospinning is a simple processing technique for producing fibers with diameters in the range of nanometers to a few micrometers. When using the different solvent ratios for this process, porous PS membranes are created due to nonsolvent and thermally induced phase separation (N-TIPS). The morphology of the fibers is analyzed through scanning electron microscopy (SEM), which showed that fibers have diameters between 200nm and 6µm. SEM also revealed that the pores present on the surface of the fibers vary from densely compacted and well-formed nanopores with diameters in the range of 20-50nm to larger pores with sizes of ≈100-200nm. The pore size varied with different solvent ratios. The surface area is analyzed using the Brunauer-Emmett-Teller (BET) method and found that the polymeric fibers have a high surface area (≈35 m2g-1). The fibers with such morphology are highly hydrophobic, with a contact angle higher than 143°. These materials are excellent candidates for applications in textiles, filtration, and biomedical fields.

Fatigue and wear performance of bioepoxy vacuum-infused and autoclave-cured E-glass fiber reinforced polymer composite gears in mesh with a steel pinion

Polymer composite gears are under investigation as a promising solution to mitigate the performance gap between polymer and metal gears. The study presented in this paper evaluates the fatigue and wear performance of E-glass fiber reinforced polymer composite gears. The E-glass fibers are vacuum infused with bioepoxy, followed by autoclave curing. High-speed milling is utilized to fabricate the gears, which are then subjected to testing at torques ranging from 0.5 to 0.8 Nm. Gear failure modes predominantly include wear combined with tooth edge intra-bundle fiber delamination due to fatigue, followed by extensive inter-ply delamination just prior to failure. Gear tooth wear volume demonstrates a nearly linear correlation with the number of cycles, with accelerated wear rates observed at higher torques. E-glass fiber polymer composite gears exhibit a shorter service life and a higher wear coefficient compared to our previously developed carbon fiber reinforced polymer composite gears. However, their performance remains fair, with a service life between that of PA6 GF30 and PA66 GF30 glass fiber reinforced gears.

Catechin as a functional additive in electrospun PCL/gelatin/nHA nanocomposite fibers for tissue engineering applications

AbstractThe promise of polymeric nanocomposite fibers in the biomedical field is well‐documented due to their adjustable properties and versatility. Electrospun fiber mats, which mimic the extracellular matrix, are particularly noted for their potential in tissue regeneration and repair. In this study, we investigate the role of catechin, a flavonoid, in enhancing cellular response to electrospun nanocomposite fibers of polycaprolactone (PCL), gelatin, and nanohydroxyapatite (nHA). Nanocomposite fibers were fabricated with varying concentrations of catechin and comprehensive analyses of the composite fibers were performed to evaluate their structural and chemical properties. In vitro, assays were performed to examine cell viability and ascertain the influence of catechin on cellular responses to these nanocomposite fibers. Simultaneously, in vivo studies assessed tissue responses to these materials. The findings revealed that incorporating catechin into PCL/gelatin/nHA nanocomposite fibers improved cellular responses in vitro as demonstrated by enhanced cell viability. Furthermore, in vivo investigations displayed positive tissue responses with these fibers, indicating their capacity to enhance cell growth and accelerate tissue regeneration. This study elucidates the potential of catechin as an integral component in designing polymeric nanocomposite fibers, potentially broadening the scope of their biomedical applications.

Tailoring the size and shape of PbWO4 particles in highly filled polymer fibers for γ‐rays shielding

AbstractHighly filled polymer fibers offer huge promise for radiation protection safety and wear comfort of personal protective equipment (PPE) in radiation environments. However, it usually sacrifices mechanical properties that directly related to practical usability. Here, as high as 75 wt% PbWO4 (PWO) particles have been filled in polyvinyl alcohol (PVA) fiber via tailoring their size and shape for enhanced γ‐rays shielding and good mechanical properties. Clearly shown that 0 dimensional (0‐D) PWO exhibits better dispersion and compatibility between the interfaces than 1‐D PWO in highly filled PVA fibers. In addition, 70 wt% 0‐D PWO/PVA fibers display better mechanical properties than 70 wt% 1‐D PWO/PVA fibers. Note that 75 wt% 0‐D PWO/PVA fibers show 1.02 cN/dtex of tensile strength. However, 75 wt% 1‐D PWO/PVA fibers fail to be fabricated smoothly. Importantly, the overlapped fabrics with 75 wt% 0‐D PWO/PVA fibers display 43.05% of γ‐ray shielding (105 keV) meanwhile it offers good air and water vapor permeability for wear comfort. The superior γ‐ray shielding ascribes the polymer fibers with the higher filling in comparison with its counterpart, which provides a practical means to design radiation protection safety and wear comfort of articles.Highlights This work breaks the upper limit of filling in polymer fibers Filler structure can weigh the integrated properties of polymer fibers. 0‐D PWO particles promote interfacial compatibility in highly filled fibers. Radiation protection safety and wear comfort of articles tend to be designed.

Ceramic Nanotubes—Conducting Polymer Assemblies with Potential Application as Chemosensors for Breath Ammonia Detection in Chronic Kidney Disease

This paper describes the process of producing chemosensors based on hybrid nanostructures obtained from Al2O3, as well as ZnO ceramic nanotubes and the following conducting polymers: poly(3-hexylthiophene), polyaniline emeraldine-base (PANI-EB), and poly(3, 4-ethylenedioxythiophene)-polystyrene sulfonate. The process for creating ceramic nanotubes involves three steps: creating polymer fiber nets using poly(methyl methacrylate), depositing ceramic films onto the nanofiber nets using magnetron deposition, and heating the nanotubes to 600 °C to burn off the polymer support completely. The technology for obtaining hybrid nanostructures from ceramic nanotubes and conducting polymers is drop-casting. AFM analysis emphasized a higher roughness, mainly in the case of PANI-EB, for both nanotube types, with a much larger grain size dimension of over 5 μm. The values of the parameter Rku were close or slightly above 3, indicating, in all cases, the formation of layers predominantly characterized by peaks and not by depressions, with a Gaussian distribution. An ink-jet printer was used to generate chemiresistors from ceramic nanotubes and PANI-EB structures, and the metallization was made with commercial copper ink for printed electronics. Calibration curves were experimentally generated for both sensing structures across a wider range of NH3 concentrations in air, reaching up to 5 ppm. A 0.5 ppm detection limit was established. The curve for the ZnO:PANI-EB structure presented high linearity and lower resistance values. The sensor could be used in medical diagnosis for the analysis of breath ammonia and biomarkers for predicting CKD in stages higher than 1. The threshold value of 1 ppm represents a feasible value for the presented sensor, which can be defined as a simple, low-value and robust device for individual use, beneficial at the patient level.

Photo-induced time-dependent controllable wettability of dual-responsive multi-functional electrospun MXene/polymer fibers

Switchable wettability potential in smart fibers is of paramount importance in various applications. Light-induced controllable changes in surface wettability have a significant role in this area. Herein, smart waterborne homopolymer, functional copolymer with different polarity and flexibility, and multi-functional terpolymer particles containing a time-dependent dual-responsive acrylated spiropyran, as a polymerizable monomer, were successfully synthesized through eco-friendly single-step emulsifier-free emulsion polymerization. Presence of 10 wt% of butyl acrylate and dimethylaminoethyl methacrylate relative to methylmethacrylate as functional comonomers decreased the Tg of the samples almost 20 ℃ and increased their polarity. The optical properties of the particles were investigated, and the UV–vis and fluorescence spectroscopy results showed that not only polarity and flexibility of the polymer chains may have a positive effect on improving the optical properties, but also the simultaneous presence of functional groups has a synergistic effect. The smart polymer particles with flexibility and polarity features exhibited higher absorption and emission compared to other samples. Inspired by these findings, multi-functional smart polymer fibers were prepared using the electrospinning method. The smart multi-functional electrospun fibers containing few-layer Ti3C2 MXenes were synthesized to improve the fibers’ properties and change the surface wettability due to the hydrophilic functional groups of MXene. Field-emission scanning electron microscopy images displayed the successful preparation of few-layer MXenes. Smooth and bead-free fibers with bright red fluorescence emission under UV irradiation were shown using fluorescence microscopy. The study on the surface wettability of fibers revealed that UV and visible light irradiation induced reversible time-dependent changes in the wettability of the smart multi-functional MXene/polymer electrospun fibers from hydrophobic to hydrophilic, reaching a water contact angle of 10° from an initial water contact angle of 100° under UV light and also changing to superhydrophilic state with passing time. Upon visible light exposure, the fibers returned to their original state. Furthermore, the fibers demonstrated a high stability over five alternating cycles of UV and visible light irradiation. This study shows that the fabrication of time-dependent smart fibers, utilizing the flexibility and polarity in the presence of MXenes, significantly improves and controls surface wettability changes. The outstanding dynamically photo-switchable wettability of these fibers may offer exciting opportunities in various applications, especially in the separation of oil from water contaminants.

Superelastic and strong microfibrous sponges prepared by solution blow spinning for high-efficiency warmth retention

We report a facile strategy for preparing ultralight, mechanically robust, and washable heat-retaining materials via solution blow spinning technology and thermal crosslinking. Fluffy microfibrous assemblies with nonwoven structure were fabricated by blending fibers of stiff and soft polymers and creating a bonding architecture among them. The premise of this design is that polystyrene, which is stiff, can endow materials with rigidity, while thermoplastic polyurethane, which is soft, can absorb energy during mechanical deformation. Moreover, the stability of the sponge was improved by using tris (2-methyl-1-aziridine propionate; TTMA) as a crosslinking agent. The optimized microfibrous sponges present excellent mechanical properties with a large breaking elongation of 42.1% and outstanding resilience in resisting 100 cyclic compressions at 40% strain. Furthermore, the microfibrous sponges exhibit a low volume density of 33.32 mg/cm3, effective heat-preservation ability (low thermal conductivity: 23.1 mW/m·K) and excellent washability. The preparation of microfibrous sponges via solution blow spinning can be a novel route for developing ultralight and superelastic heat retention materials.

Fabrication and Customization of Highly Porous PLGA Membranes Utilizing Near‐Field Electrospinning, Thermal Transitions, and Multilayer Strategies

Polymer porous membranes are crucial in various applications, including water filtration, tissue engineering, and drug administration. Conventional far‐field electrospinning (FFES) is widely used for producing polymeric membranes due to its cost‐effectiveness, scalability, and flexibility in using many polymers. However, FFES has limitations in controlling pore form and size, as it produces randomly oriented fibers that lead to inconsistent and noncustomizable pore sizes. To address these limitations, this work combines near‐field electrospinning (NFES) with thermal treatment of polymer fibers and membranes. NFES offers more precise control over fiber placement and alignment, producing well‐defined fiber patterns with consistent and customizable pore sizes without compromising the thickness of membranes. By exploring the interplay between polymer behavior, thermal effects, and capillary action, the differences in pore area under various temperatures and fiber spacings are characterized. Additionally, this study investigates the influence of multilayer infusion on pore size and geometric arrangement by examining multilayer configurations stacked at various angles. The results indicate that increasing the number of layers leads to decreased pore size, while the alignment of infused fibers affects pore shape. This integrated approach enhances control over membrane characteristics, improving the performance and consistency of polymer porous membrane fabrication across various applications.

Fabrication of conductive polyimide/metal composite fibers for high temperature EMI shielding

Surface metallization of high-performance polymer fibers via electroless plating represents a significant advancement in producing lightweight, flexible and durable electromagnetic interference (EMI) shielding fabrics. The conventional process for metallization of polyimide (PI) fibers faces challenges, including complex procedures and insufficient interfacial adhesion between the metal layer and fiber matrix. Herein, carboxylate-containing PI (PIC) fibers were developed to mitigate the mechanical degradation caused by traditional alkaline etching. Conductive composite fibers (PIC/Cu) were successfully produced through a continuous electroless copper plating process. The robust PIC/Cu interfacial bonding achieved based on nanoscale mechanical interlocking through Ni nanoparticles imparts excellent flexibility and durability, evidenced by only a 4 % increase in electrical resistance after 5000 bending cycles. The dense, uniform copper layer provides high conductivity (1.3 × 104 S/cm), resulting in an optimal EMI shielding efficiency of 63.4 dB for the corresponding fabric. Moreover, PIC/Cu-Ni fibers prepared by further electroless plating of nickel layer on the surface of PIC/Cu fibers demonstrate remarkable electrical stability across temperatures ranging from 50 to 350°C, with only a 1.2 % reduction in conductivity after exposure to 350°C for 1 h. These findings advance the development of high-performance conductive PI fibers for applications in aerospace vehicles and high-temperature environments.

The feasibility of using epoxy resin reinforced with sugar cane bagasse residue for a high performance coatings: a cost of goods sold and blue ocean analysis

The natural and biodegradable characteristics of sugarcane bagasse (SCB) make it a promising ingredient for composite materials. Researchers have explored ecological and low-cost materials, identifying SCB as a green option with low pollution levels. This study investigates the strategic position for SCB and epoxy composite when applied as high-performance coatings. Epoxy resin is valued for its adhesion, strength and durability. Integrating sustainable, cost-effective reinforcements is vital for enhancing these properties and reducing environmental impact. SCB, a sugar industry waste, has favorable characteristics like fibrous structure and polymer compatibility. In this research, SCB residue was processed and incorporated into epoxy resin. Both analisys the Cost of Goods Solds (COGS) and a Blue Ocean Strategy analysis identified new market opportunities, positioning this composite as a sustainable, high-performance solution in coatings. It´s relevant to point that SCB could offer substantial improves on corrosion resistance, offering a sustainable alternative with competitive performance and cost.

Enhancement of mechanical and structural characteristics through the hybridization of carbon fiber with Cordia‐dichotoma/polyester composite

AbstractSingle fiber polymer composites containing either natural or artificial fibers may not deliver the desired characteristics. The current study used the hand‐layup technique to make a hybrid composite by incorporating the natural fiber, Cordia‐dichotoma (CD) and artificial fiber, carbon fibers (CF) in a polyester matrix and compressing the mixture for the desired size. The current study investigates the influence of carbon fiber loading (0, 5, 10, and 15 wt%) on the mechanical, structural, and crystalline properties of CD/polyester composites keeping the total fiber loading at 20 wt%. Mechanical properties are investigated with a universal testing machine, and impact strength using Izod impact apparatus. Better mechanical properties (tensile strength‐457.38 MPa; flexural strength‐290.09 MPa and impact strength‐346.46 J/m) were obtained for the pure carbon fiber composite arranged in four layers (CF/CF/CF/CF), followed by hybrid composite (CF/CD/CD/CF) (tensile strength‐319.24 MPa; flexural strength‐253.03 MPa and impact strength‐291.34 J/m) whereas pure CD fiber (CD/CD/CD/CD) composite yielded the lowest values (tensile strength‐117.96 MPa; flexural strength‐164.99 MPa and impact strength‐118.11 J/m). Composites undergo hybridization, which improves their mechanical properties, lowers their cost, and makes them more environmentally friendly. The characteristics of the specimens were examined using Fourier Transform Infrared Spectroscopy (FTIR), X‐ray Diffraction Analysis (XRD), Atomic Force Microscope (AFM), and Scanning Electron Microscopy (SEM). According to findings, crystallinity index is increased from 77.94% for CD/CD/CD/CD composite and increased to 78.21% for CF/CD/CD/CF composite. Highest crystallinity index of 82.46% was obtained for CF/CF/CF/CF composite. These hybrid composites may be used for applications involving medium loads.Highlights In this study, Cordia‐dichotoma natural fibers are extracted and treated with alkali (NaOH) to reduce the biodegradability. To lower the cost and enhance mechanical and biodegradable properties Carbon and cordia‐dichotoma fibers have been hybridized. Mechanical Properties such as tensile, flexural and impact properties are evaluated for the prepared hybrid composites. Hybrid composites were analyzed using FTIR, AFM, XRD, and SEM to assess their suitability to various applications.

Impact of concentration polarization on the performance of membrane gas separation processes: application to biogas upgrading

Through the illustrative application of biogas treatment, this paper investigates the impact of concentration polarization on the separation performance of emerging inorganic membranes in membrane gas separation processes. The results show that polarization may significantly reduce the biogas purification rate, although its effects on methane recovery remain moderate. Contrary to previous assumptions, the impact of polarization does not monotonously increase with increasing permeance to CO2 and selectivity. Material selectivity is shown to not significantly influence the polarization intensity, and the CO2 permeance at which peak polarization conditions occur is not constant but varies depending on the operating and geometric conditions considered. The impact of polarization impact intensifies with increasing fiber diameter and operating pressure, preventing taking full advantage of the exceptional permeances of inorganic membranes, and therefore, constitutes a major obstacle to their use as an alternative to conventional polymeric fibers.

A Versatile In Situ Precipitation Assisted Direct-Write-3D Printing Strategy for Skinless Hierarchical Porous Polymeric Scaffolds.

Skinless, hierarchical porous 3D polymer scaffolds are of critical importance in tissue engineering, enabling improved cell infiltration, nutrient, metabolite and energy exchange, and biomimetic structures, crucial for regenerative medicine, drug delivery, and advanced material applications. However, it is still a great challenge to construct this kind of material with traditional 3D printing techniques. Herein, a novel simple, and versatile in situ precipitation-assisted direct-write-3D printing strategy for skinless, hierarchical porous 3D scaffolds is reported. Homogenous ink containing molecularly dissolved fructose (soluble porogen molecule) and polymer (whether it is hydrophilic, hydrophobic or amphiphilic) is directly extruded into a nonsolvent bath, where simultaneously solidification of the polymer and in situ precipitation of the porogen molecules both on the exterior surface and inside the separated polymer fibers happen. Subsequently, by simply leaching the in situ formed porogen particles, skinless hierarchical porous polymeric 3D scaffolds can be obtained. It is believed that 3D printing, polymer/macromolecule-based scaffolds, especially the skinless hierarchical porous biomaterials, and the tissue engineering market can benefit tremendously from this simple and versatile approach.

The effect of nanocellulose and silica filler on the mechanical properties of natural fiber polymer matrix composites

Natural fiber-reinforced polymer matrix composites recently got great attention in biomedical applications due to their inherent characteristics such as biocompatibility, lightweight, and biodegradability. However, natural fiber composites suffer from poor mechanical properties and weak interfacial adhesion. It is well documented that the addition of nanofiller has improved the mechanical properties of different synthetic fibers such as glass and carbon composites. The main objective of this paper is to study nanofillers' effect on the mechanical properties of unidirectional false banana fibers reinforced polymer composites. The filler materials, crystalline nanocellulose fibrils, and crystalline nanosilica particles were extracted from sugarcane bagasse and its byproducts. The composite samples were fabricated by adding the nanofillers in unidirectional natural fibers arranged in four fiber orientations (0°, 0o/90o ±45o, and quasi-isotropic), and their tensile, flexural, compression strength, thermal stability, and void content were measured following ASTM standards. The results revealed that adding nanofillers increased the tensile, flexural, and compressive strengths by 16 % (98.83 Mpa), 11 % (161.60 Mpa), and 23 % (114.62 Mpa), respectively. Similarly, at 0° orientation, the addition of nanoparticles enhances the tensile, bending, and compressive modulus by 30 % (15.43 Gpa), 12 % (13.52 Gpa), and 60 % (42.6 Gpa), respectively. On the other hand, the void content was reduced with the addition of nanofillers. The results also revealed that composites with crystalline nanosilica particle fillers had superior thermal stability compared to crystalline nanocellulose fibril fillers. The overall results of this research give the confidence that nano particle-filled natural fiber composites can be used for bio-based engineering applications, such as prosthetic sockets.

Comparative study on shape memory, mechanical, and thermomechanical properties of multi‐walled carbon nanotubes and graphene nanoplatelets modified bidirectional (twill) carbon fiber polymer composites

AbstractThe research conducts a comparative analysis of epoxy/bi‐directional (twill) carbon fiber three‐phase shape memory hybrid composites modified with MWCNT and GnP, examining their mechanical, thermomechanical, and shape memory properties. Fabrication involves preparing nanoparticle‐modified epoxy nanocomposites through ultrasonication followed by hand layup technique. The findings revealed that the modified composites achieved their optimal performance at a 0.6 wt% concentration of nanoparticle, with the tensile strength and modulus increasing by 33.59% and 23.47% for 0.6 wt% MWCNT composite and by 45.94% and 25.61% for 0.6 wt% GnP composite. GnP‐modified composites outperformed MWCNT ones due to GnP's sheet structure aligning parallel to the load and larger surface area facilitating enhanced interaction with the matrix. Despite polymer modification, the shape recovery ratio values remained high, with 98.92% for unmodified composite, 97.72% for 0.6 wt% MWCNT composites, and 97.12% for 0.6 wt% GnP modified composites, all exceeding 90%, indicating no compromise in performance.

Isolation and quantification of human urinary exosomes using a Tween-20 elution solvent from polyester, capillary-channeled polymer fiber columns

BackgroundExosomes, a subset of extracellular vesicles (EVs), are a type of membrane-secreted vesicle essential for intercellular communication. There is a great deal of interest in developing methods to isolate and quantify exosomes to study their role in intercellular processes and as potential therapeutic delivery systems. Polyester, capillary-channeled polymer fiber columns and spin-down tips are highly efficient, low-cost means of exosome isolation. As the methodology evolves, there remain questions as to the optimum elution solvent for specific end-uses of the recovered vesicles; fundamental biochemistry, clinical diagnostics, or therapeutic vectors. ResultsWhile both acetonitrile and glycerol have been proven highly successful in terms of EV recoveries in the hydrophobic interaction chromatography workflow, many biological studies entail the use of the non-ionic detergent, Tween-20, as a working solvent. Here we evaluate the use of Tween-20 as the elution solvent for the recovery of exosomes. A novel 10-min, two-step gradient elution method, employing 0.1 % v/v Tween-20, efficiently isolated EVs at a concentration of ∼1011 EV mL−1 from a 100 μL urine injection. Integration of absorbance and multi-angle light scattering detectors in standard HPLC instrumentation enables a comprehensive single-injection determination of eluted exosome concentration and sizes. Transmission electron microscopy verifies the retention of the vesicular structure of the exosomes. The micro-bicinchoninic acid protein quantification assay confirmed high-purity isolations of exosomes (∼99 % removal of background proteins) SignificanceThe effective use of Tween-20 as an elution solvent for exosome isolation/purification using capillary-channeled polymer fiber columns adds greater versatility to the portfolio of the approach. The proposed method holds promise for a wide range of fundamental biochemistry, clinical diagnostics, and therapeutic applications, marking a significant advancement in EV-based methodologies.

Influence of Alkanolamine Plasmas on Poly(Ethylene Terephthalate) Fibro-Porous Biomaterial Constructs.

The development of fibrous polymer scaffolds is highly valuable for applications in tissue engineering. Furthermore, there is an extensive body of literature for chemical methods to produce scaffolds that release nitric oxide. However, these methods often use harsh chemistries and leave behind bulk waste. Alkanolamine low-temperature plasma (LTP) is unexplored and single-step processing to form nitric oxide (NO) releasing constructs is highly desirable. The major question addressed is whether it is possible to achieve single-step processing of spun polyester with alkanolamine plasma to achieve nitric oxide releasing capabilities. Herein we report the experiments, processes, and data that support the claim that it is indeed possible to produce such a bio-functional material for potential biomedical applications, especially in cardiovascular implants. Among the tested alkanolamines, monoethylamine (MEA) plasma treated biomaterial outperformed in comparison with diethanolamine (DEA) and triethanolamine (TEA) in terms of NO release and cellular response.

Research on CdSe/ZnS Quantum Dots-Doped Polymer Fibers and Their Gain Characteristics.

Polymer fibers are considered ideal transmission media for all-optical networks, but their high intrinsic loss significantly limits their practical use. Quantum dot-doped polymer fiber amplifiers are emerging as a promising solution to this issue and are becoming a significant focus of research in both academia and industry. Based on the properties of CdSe/ZnS quantum dots and PMMA material, this study experimentally explores three fabrication methods for CdSe/ZnS quantum dots-doped PMMA fibers: hollow fiber filling, melt-drawing, and melt extrusion. The advantages and disadvantages of each method and key issues in fiber fabrication are analyzed. Utilizing the CdSe/ZnS quantum dots-doped PMMA fibers that were fabricated, we theoretically analyzed the key factors affecting gain performance, including fiber length, quantum dots doping concentration, and signal light intensity. Under the conditions of 1.5 W power and 445 nm laser pumping, a maximum on-off gain of 16.2 dB was experimentally achieved at 635 nm. Additionally, using a white light LED as the signal source, a broadband on-off gain with a bandwidth exceeding 70 nm and a maximum gain of 12.4 dB was observed in the 580-650 nm range. This research will contribute to the development of quantum dots-doped fiber devices and broadband optical communication technology, providing more efficient solutions for future optical communication networks.

Exploring the Cutting Process of Coaxial Phase Change Fibers under Optical Characterization Tests

Urban heat islands (UHI) are a growing issue due to urbanization, causing citizens to suffer from the inadequate thermal properties of building materials. Therefore, the need for climate-resistant infrastructure is crucial for quality of life. Phase change materials (PCMs) offer a solution by being incorporated into construction materials for thermoregulation. PCMs store and release heat as latent heat, adjusting temperatures through phase changes. Polymeric phase change fibers (PCFs) are an innovative technology for encapsulating PCMs and preventing leaks. This study produced PCFs via wet-spinning, using commercial cellulose acetate (CA, Mn 50,000) as the sheath and polyethylene glycol (PEG 2000) as the core. The PCFs were cut using a hot-cutting method at three different temperatures and washed with distilled water. Morphological analysis was conducted with a bright-field microscope, and chemical analysis was performed using Fourier transform infrared spectroscopy (FTIR) before and after controlled washing. Additionally, the washing baths were analyzed by UV-visible spectroscopy to detect PEG. The PCFs displayed a well-defined core-shell structure. Although some PEG 2000 leakage occurred in unsuccessful cuts, cuts at 50 °C showed sealed ends and less material in the baths, making it viable for civil engineering materials.

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants.

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.