Polyacrylonitrile Research Articles

Laser-Controlled Information Releasing and Hiding Based on Perovskite Phosphors.

Laser-active interference with high confidentiality and convenience opens up a cutting-edge path for releasing and hiding key targets; however, its development still faces enormous challenges owing to the difficulty of concealing objects. Herein, a novel conceptual design for laser-controlled information release and hiding (LIRH) is proposed and successfully realized. Cs2NaInCl6:Er3+, Yb3+ (CNIC:Er, Yb) perovskite microcrystal is adopted as a carrier for LIRH implementation, exhibiting excellent up-conversion (UC) emission under NIR (980 and 1530 nm) irradiation due to its ultralow phonon energy. The fluorescence intensity crossover and outstanding photon output capacity are revealed in comparison with Er3+/Yb3+ codoped and Er3+ single-doped CNIC phosphors under different laser sources, and the obvious difference in quantum yields (QY) under 980 and 1530 nm excitation provides theoretical possibility for LIRH. More importantly, the obtained LIRH features high stability at temperatures up to 413 K, showing good adaptability in various potential scenarios. Moreover, CNIC:Er, Yb is further combined with polyacrylonitrile (PAN) polymer to form fluorescent fibers with exceptional crystal stability and composite flexibility, thus making the LIRH code a reality based on perovskite composite phosphors. The laser-active invisibility offers an innovative idea for LIRH, further extending the application of LIRH in the field of information encryption, which has promising prospects in information safety, advanced anticounterfeiting, and smart responsive materials.

Interlayer-Functionalized Graphene with Phosphorus–Silicon-Containing Elements for Improving Thermal Stability and Flame Retardance of Polyacrylonitrile

Highly-effective non-halogenated flame retardants have received widespread attention because they are environmentally friendly, with low toxicity and low smoke density. In this work, interlayer-functionalized graphene (fRGO) containing silicon and phosphorus elements was synthesized via hydrolytic condensation with 3-(methacryloyloxy)propyltrimethoxysilane and addition reaction with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Interlayer spacing and oxygen-containing groups of reduced graphene oxide (RGO) were regulated by controlling the hydrazine hydrate dosage. Then, phosphorus–silicon-containing organic molecules were inserted into RGO interlayers; this was verified by FTIR, XPS, TEM, etc. The fRGO was added to a polyacrylonitrile (PAN) matrix using a solution blending method to prepare polyacrylonitrile (PAN) composites. The fRGO addition caused the significant decrease in cyclization heat and the considerable increase in char residues, indicating improved thermal stability. Importantly, PAN composites exhibited outstanding flame-retardant properties, with the peak heat release rate reduced by 45%, which is ascribed to the dense graphitic carbon layers induced by phosphorus–silicon-containing organics and the 2D barrier effect of RGO layers to prevent the heat and mass transfer.

Step‐wise non‐solvent induced phase separation of polyacrylonitrile/thermoplastic polyurethane self‐supportive filtration membranes

AbstractThis study investigated the fabrication of polyacrylonitrile (PAN) membranes using non‐solvent induced phase separation methods, with the addition of thermoplastic polyurethane (TPU) as an additive. The incorporation of TPU and the utilization of stepwise induced phase separation techniques resulted in notable improvements in membrane structure and water filtration performance. Scanning electron microscopy revealed that membranes with TPU exhibited a denser pore network and finer primary channels, leading to enhanced water flux and protein rejection rates. Mechanical testing indicated that TPU addition improved the membrane's mechanical properties, particularly its elongation at break and tensile strength, especially under wet conditions. Additionally, optimization of the coagulation bath involved methanol spraying followed by water immersion, resulting in membranes with further enhanced flux and rejection properties. Compared with neat PAN membranes, the membranes with TPU exhibited increased water flux from 405 to 539 L/m2 h, as well as improved elongation at break and tensile strength in both dry and wet conditions. Furthermore, the combination of stepwise induced phase separation significantly enhanced the water flux from 342.7 to 483.0 L/m2 h, while also improving the retention rate of ovalbumin from 25.7% to 31.5%.

Electrospun nanofibers membranes of La(OH)3/PAN as a versatile adsorbent for fluoride remediation: Performance and mechanisms

Abstract Excessive existence of fluoride in water resources can lead to harmful impacts on ecosystems and organisms. Electrospun polyacrylonitrile (PAN) nanofiber membranes loaded with La(OH)3 nanorods composites (La(OH)3/PAN electrospun nanofiber membranes [ENFMs]) are fabricated and used as an efficient fluoride scavenger. Adsorbent fabricate protocols, pH, initial F− concentration, adsorbent dosage, and adsorption time, in addition to coexisting anions, were systematically evaluated. The investigation unveils that a pH of 3.0 is optimal for F− remediation. The adsorption kinetics and isotherm of La(OH)3/PAN ENFMs are well described by the pseudo-second-order model (R 2 > 0.997) with characteristics of chemisorption and Langmuir isotherm (R 2 > 0.999) with the feature of single-layer coverage. The existence of Cl−, SO4 2−, NO3 −, and CO3 2− does not significantly hinder fluoride removal by La(OH)3/PAN ENFMs with the exception of PO4 3−. Calculations of ΔH, ΔG, and ΔS reveal that the nature of F− adsorption onto La(OH)3/PAN ENFMs is endothermic and favorable at a higher temperature.

Effects of Moisture Content and Heat Treatment on the Viscoelasticity and Gelation of Polyacrylonitrile/Dimethylsulfoxide Solutions

Polyacrylonitrile (PAN) gels create significant obstacles in industrial fiber spinning by forming insoluble networks that compromise solution stability and uniformity. This study investigates the rheological properties of PAN/dimethyl sulfoxide (DMSO) solutions, examining how aging time, moisture content, and polymer concentration affect gelation behavior. Dynamic rheological analysis revealed that both physical and chemical crosslinks play crucial roles in gel formation, with gelation accelerating markedly when moisture content exceeds 3% and aging progresses. Under heat treatment at 80 °C, samples with increased moisture content demonstrated rapid transitions to solid-like states, indicating a critical moisture threshold for enhanced gelation kinetics. Additionally, reductions in polymer concentration disrupted physical crosslink density, thereby mitigating gel formation. These results underscore the importance of precisely controlling moisture and concentration parameters in PAN solutions to stabilize solution properties and minimize gel formation, thus enhancing process efficiency and quality in PAN-based carbon fiber production.

Highly Effective Polyacrylonitrile-Rich Artificial Solid-Electrolyte-Interphase for Dendrite-Free Li-Metal/Solid-State Battery.

Lithium metal anode batteries have attracted significant attention as a promising energy storage technology, offering a high theoretical specific capacity and a low electrochemical potential. Utilizing lithium metal as the anode material can substantially increase energy density compared with conventional lithium-ion batteries. However, the practical application of lithium metal anodes has encountered notable challenges, primarily due to the formation of dendritic structures during cycling. These dendrites pose safety risks and degrade battery performance. Addressing these challenges necessitates the development of a reliable and effective protection layer for lithium metal. This study presents a cost-effective and convenient method to spontaneously produce lithium metal protective layers by creating polymeric layers by using acrylonitrile (AN). This method remarkably extends 6× of the lifetime of lithium metal anodes under high current density (1 mA/cm2) cycling conditions. While the cycle life of bare lithium metal is approximately 150 h under high current cycling conditions, AN-treated lithium metal anodes exhibit an impressive longevity of over 900 h. The AN-treated lithium metal anodes are further integrated and tested with sulfide-based Li10GeP2S12 (LGPS) solid-state electrolytes to evaluate its interfacial stability at a solid-solid interface. The formation of the polyacrylonitrile (PAN)-rich ASEI, due to AN-treatment, effectively reduces and stabilizes the cell overpotential to only one-tenth of that with the interface without treatment. This strategy paves a route to enable a highly efficient and highly stable Li/LGPS solid-state battery interface.

Anion‐Anchored Polymer‐in‐Salt Solid Electrolyte for High‐Performance Zinc Batteries

AbstractSolid polymer electrolytes hold promise for addressing key challenges in rechargeable zinc batteries (ZBs) utilizing aqueous electrolytes. However, achieving simultaneous high ionic conductivity, excellent mechanical strength, and a high cation transference number while effectively suppressing Zn dendrites remains challenging. Herein, we design a novel polymer‐in‐salt solid electrolyte (PISSE) composed of polyacrylonitrile (PAN), zinc chloride (ZnCl2), and niobium pentoxide with oxygen vacancies (Nb2O5‐x) with high ionic conductivity. PAN polymer matrix provides the electrolyte good mechanical properties and solubility of Zn salt. The high concentration of ZnCl2 effectively decouples the Zn2+ from polymer chain segments and provides more ionic conduction amorphous region. Moreover, incorporating Nb2O5‐x filler accelerates Zn2+ desolvation by anchoring (ZnxCly)2x–y clusters and enhances the system's mechanical properties, achieving a superior Zn2+ transference number (~0.93) and interfacial stability. Consequently, the optimized PISSE demonstrates exceptional stability during prolonged cycling periods, wide temperature range operation (−40 °C to 60 °C), remarkable flexibility, and compatibility with diverse electrode materials. This study provides valuable insights into the design of solid‐state electrolytes based on ZBs and elucidates their multifunctional prospects.

An Increase in the Rigidity of the Environment Favors MLCT over the MC State in [Ru(bpy)2(Nicotine)2](Cl)2: A Case Study of Photolabile Ligands.

Ru(II)-complexes with photolabile ligands find a wide range of applications, e.g., in drug release and in the design of light-responsive interfaces. While light-driven ligand loss has been studied mechanistically in detail for complexes in solution, comparably few studies are present that investigate the process in a material context, i.e., in a rigid environment and in the absence of solvent. This paper adds to this underrepresented perspective by studying the excited-state dynamics of [Ru(bpy)2(nicotine)2] (Cl)2 (Ru-nico) as a model system in poly(methyl methacrylate) (PMMA) and polyacrylonitrile (PAN) matrices. Femtosecond transient absorption spectroscopy and time-resolved emission spectroscopy are employed to monitor the photodissociation of labile nicotine ligands in polymer environments. Photoexcitation within the metal-to-ligand charge transfer (MLCT) band leads to transient dissociation of the nicotine ligand when the complex is dissolved in water. However, optical excitation of the 1MLCT transition of the complexes embedded in polymer matrices does not result in photodissociation, likely due to the rigidity of the environment, which cannot solvate the undercoordinated complex after ligand dissociation and the dissociated ligand. These insights shed light on the role of the local environment when considering the photophysics of ligand loss from Ru(II)-polypyridyl complexes and, hence, their use in the light-activation of reactive molecular components in materials.

MOF nanoflowers-based flexible portable NO sensors for human airway inflammation detection

The concentration of nitric oxide (NO) in exhaled breath is linked to respiratory diseases, requiring precise detection. Traditional two-dimensional (2D) carbon-based materials used in chemiresistive gas sensors suffer from high detection limits due to a lack of functional sites, while metal oxide sensors are limited by poor selectivity and high operating temperatures, restricting their development. Recently, metal–organic frameworks (MOFs) have emerged as an effective material for NO monitoring due to their superior selectivity; however, their inherent insulating properties hinder practical use. In this study, we synthesized Ni, Co-MOF-74-Carbon Nanotube (CNT) heterostructured nanoflowers, leveraging their bimetallic active sites and large specific surface area to enhance NO adsorption. This composite material, integrated with breathable nanofibrous membranes through physical deposition, exhibits high selection to NO, achieving a linear response range of 30 to 1000 ppb at room temperature and a limit of detection (LOD) of 18.6 ppb. This sensor can accurately detect NO levels in the exhaled breath of both healthy and diseased individuals, confirming its potential for respiratory disease diagnosis. Additionally, we developed a portable device integrating the Ni, Co-MOF-74-CNT- polyacrylonitrile (PAN) membrane, a microcontroller unit (MCU), and a Bluetooth module for real-time NO detection. The systematic design and successful validation of this portable gas sensor pave the way for future home-based real-time monitoring of airway inflammation.

Electrospun hydrophilic PAN/CO/TA composite nanofibrous membrane for adsorbing Cu(II) in water

In this paper, a novel polyacrylonitrile (PAN)/collagen (CO)/tannic acid (TA) composite nanofiber membrane for the adsorption of Cu(II) in water was prepared. The nanofibrous membranes were characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric (TG), and water contact angle (WCA) techniques, and their adsorption performance on Cu(II) in water was tested. The results showed that incorporating CO improved the hydrophilic performance of the membranes, and the contact angle of PAN/CO decreased from 60.57° to 39.16° with the increase of CO content, which exhibited good hydrophilicity. Moreover, CO effectively crosslinked TA, so that TA was well fixed on the surface of the fiber membrane, and the resulting PAN/CO/TA composite nanofiber membrane had good fiber morphology, uniform fiber diameter distribution, with an average diameter of 292.22 nm, and good adsorption performance for Cu(II), up to 133.26 mg/g. The adsorption kinetics fitting showed that the adsorption mechanism was mainly electrostatic adsorption and chelation of Cu(II) by phenoxy anion. PAN/CO/TA and PAN/CO/TA/Cu nanofiber membranes showed bacteriostatic effects on E. coli and S. aureus, with PAN/CO/TA/Cu nanofiber membranes being particularly effective, with the average inhibition bands for E. coli and S. aureus being 7.50 mm and 10.05 mm, respectively. The distribution of the electric field during the spinning process was also simulated by finite element analysis in this study. Since TA is a natural polymer of plant origin and CO is of animal origin, it provides an environmentally friendly and cost-effective method to remove Cu(II) from water.

A Novel method of controlling the molecular weight of PAN-Lignin copolymer - synthesis and characterization

Polyacrylonitrile-lignin copolymer (PLC) has been successfully prepared via solution polymerization technique by a three step synthesis procedure. The main aim of this research is to control the molecular weight of the PLC by varying the initiator, monomer or solvent concentration in the reaction. The loading of lignin was kept constant which is 20 wt % in the PLC. The Polyacrylonitrile (PAN) homopolymer synthesized in the first step and the final copolymer PLC were characterized by various techniques such as FTIR, NMR, DSC, UV etc. The chemical bonding of lignin with the PAN backbone has been ascertained by these characterisation methods. This study explores a promising way to control the molecular weight of PLC copolymer which can be further used in the production of precursor fibre for carbon fibre.

Synthesis and thermal behavior of acrylonitrile/guanidine crotonate copolymer for carbon fiber precursor

AbstractThe thermal oxidation stabilization of polyacrylonitrile (PAN) copolymer is a highly exothermic process. It significantly impacts the quality of the finished PAN‐based carbon fiber, which is often addressed by adding appropriate comonomers. This paper synthesized guanidine crotonate (GCA) as a comonomer and copolymerized with acrylonitrile (AN) to prepare P(AN‐GCA). DSC analysis revealed that when compared to PAN and P(AN‐CA) copolymers, the initial exothermic temperature, maximum exothermic heat flux, and heat flux of P(AN‐GCA) copolymer were greatly reduced. FT‐IR spectroscopy showed that the degree of pre‐oxidation increased with the increasing comonomer GCA content, indicating that the addition of comonomer GCA could promote PAN pre‐oxidation cyclization and improve the copolymer's degree of pre‐oxidation. The activation energies of PAN and P(AN‐GCA) were 160 and 126 KJ/mol, respectively. It was shown that the addition of GCA could effectively reduce the activation energy of the cyclization reaction of the polymer while simultaneously promoting it. TGA analysis shows that the introduction of GCA improves the copolymer's thermal stability, and the yield at 800°C is more than 54%, which is at least 19% higher than PAN homopolymer. P(AN‐GCA) has the potential to be carbon fiber precursor.

Influence of Silicon Carbide Incorporation on Thermal and Ablation Properties of Carbon Fabric-Phenolic Resin Composites

To shield re-entry spacecraft from the extreme heat experienced during hypersonic flight through a planet's or the earth's atmosphere, thermal protection systems (TPS) were developed. This work involved the fabrication of composites using a polyacrylonitrile (PAN) based carbon fabric (Cf)-phenolic resin matrix (PR) modified with different weight percentages (wt.%) of silicon carbide (SiC), namely 0 wt.% (Cf/PR), 1wt.%, 3wt.%, and 5wt.%. The composites were prepared using the hydraulic hot press method. The manufactured composites were analyzed for their thermal conductivity and resistance to ablation using an oxyacetylene torch test. Furthermore, the ablated composites underwent X-ray diffraction (XRD), revealing a SiO2 compound layer on the ablated composite surface. The experimental results demonstrated that the Cf/PR composites modified with 3wt.% of SiC exhibited superior characteristics. The composites consist of 3wt.% Cf/PR-SiC exhibited a thermal conductivity value of 0.57 W/m K. Additionally, these composites showed a noticeable decrease in the mass ablation rate (MAR) at 0.0052 mm/sec and linear ablation rates (LAR) at 0.025061 gm/sec. This study proposed an effective way to improve the thermal and ablation characteristics of TPS materials.

In Situ Constructing Robust Interface by Deep Eutectic Polymeric Electrolyte Enables High Performance Lithium Metal Batteries with High-Loading Cathode.

The low Li+ transport and poor interface have consistently been two major impediments to practical applications of Polyacrylonitrile (PAN)-based composite solid-state electrolytes (PCPE). In this work, a polymerizable deep eutectic electrolyte is meticulously designed with high fluidity which consists of Poly (Ethylene Glycol) Diacrylate (PEGDA), Fluoroethylene Carbonate (FEC), Succinonitrile (SN) and dual salts (LiTFSI/LiDFOB) to promote Li+ transport and ameliorate the interface of PCPE. Inclusion of PEGDA monomers and FEC alters the crystallinity of SN, enhancing the wettability of thick electrode, and formation of polymeric 3D network from polymerization of PEGDA can anchor SN and suppress the side reactions between SN and lithium metal. Consequently, the modified PCPE exhibit an enhanced conductivity of 4.47×10-4Scm-1 with Li-ion transference number of 0.60, and show an excellent lithium stability. LiCoO2(LCO)/SP-PCPE/Li batteries with higher loading (3-4.4V, 6mgcm-2) can work for over 300 cycles at 0.5 C. Even with an ultra-high loading of 16mgcm-2, LCO/SP-PCPE/Li batteries achieve an excellent cycling performance. This work provides new insights into how to construct a robust interface for solid-state batteries with high-loading cathode.

Thermal stability and anti-ablation performance of plasma spray coated-YSZ on Al2TiO5 modified novel ablative carbon-phenolic composites

Abstract Despite ongoing challenges, ablative thermal protection systems are among the most promising methods for safeguarding spacecraft during re-entry thermal protection systems (TPS). A novel aluminium titanate (Al2TiO5/AT) and a highly efficient thermal barrier of coating (TB/TBCs) made from yttria-stabilized zirconia (YSZ), powder, but deposited using the plasma spray technique on polyacrylonitrile (PAN)-based carbon fiber fabric(C)-reinforced with resorcinol phenol formaldehyde resin (RF) composites (C-RF)) would be a potential candidate for TPS applications. This study investigates the composites with varying wt.% of AT that were developed, namely 0 wt.% (YSZ-C-RF), 1 wt.%, 3 wt.%, and 5 wt.% (YSZ-AT-C-RF) by utilizing a hot press moulding machine. Thermal stability and ablation performance of unmodified C-RF with modified YSZ-C-RF and YSZ-AT-C-RF composites are examined through thermogravimetric analysis (TGA) and oxyacetylene torch test/OAT (4.0 MW/m2 for 60 sec). Also, the phase composition and microstructure of the ablated surface are determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The TBC of YSZ has an obvious influence on the residual weight ratios at high temperatures in C-RF and also plays a positive role in increasing thermal stability under nitrogen atmosphere for enhancing ablation resistance concerning YSZ-C-RF. The mass and linear ablation rates (MAR and LAR) of the composites after modifying the surface by YSZ-coated particles are reduced by 82.98% and 15.65%, respectively. Similarly, the introduction of AT particles and TBC of YSZ results in evidence of improving the thermal stability and the ablation resistance in varying wt.% of YSZ-AT-C-RF composites. The primary optimum AT weight loading for enhancing ablation resistance in YSZ-C-RF composites is 1wt.%. The modification of 1wt.% AT particles and YSZ-Coated particles reduce MAR and LAR by 54.79% and 61.94%, respectively. This work offers a meaningful method to remarkably enhance the ablation performance of the modified C-RF and YSZ-AT-C-RF composites.

High-Energy-Density Lithium–Sulfur Battery Based on a Lithium Polysulfide Catholyte and Carbon Nanofiber Cathode

Li–S batteries are promising large-scale energy storage systems but currently suffer from performance issues; a major reason is the dissolution of polysulfides in electrolytes. To this end, we report a high-energy-density Lithium–Sulfur (Li–S) battery that combines a catholyte and a sulfur-free carbon nanofiber (CNF) cathode. The cathode was synthesized by carbonizing binder-free polyacrylonitrile (PAN) nanofibers, affording a high surface area. In the catholyte, added polysulfides acted as both conductive Li salts and active materials. Investigating the electrochemical performance of this concept in both Swagelok- and pouch-type cells afforded energy densities exceeding 3 mAh cm−2 at a discharge rate of 0.1 C. This combination could also be utilized in high-capacity pouch cells with capacities of up to 250 mAh g−1. Both cell types exhibited good cycle performance. Adding LiNO3 to the electrolyte suppressed the redox shuttle reactions. Moreover, the cathode being binder-free increased the energy density and simplified cathode fabrication. Characterizing the cathode before and after cycling revealed that deposition was reversible, and that cell reactions at least partially formed sulfur as the end product, resulting in high sulfur amounts in the cell. We expect our concept to greatly aid in the development of practically applicable Li–S cells.

Ultrafast and Highly Selective Sequestration of Radioactive Barium Ions by a Layered Thiostannate.

As a simulant of hazardous 226Ra2+, the simultaneously selective and rapid elimination of radioactive 133Ba2+ ions from geothermal water is necessary but still challenging. In this paper, we demonstrated the usability of a layered thiostannate with facile synthesis and inexpensive cost, namely, K2xSn4-xS8-x (KTS-3, x = 0.65-1), for the remediation of radioactive 133Ba2+ in multiple conditions, including sorption isotherm, kinetics, and the influences of competitive inorganic/organic ions, pH values, and dosages. KTS-3 has a strong barium uptake ability (171.3 mg/g) and an ultrafast adsorption kinetics (about 2 min). Impressively, it can achieve a high preference for barium regardless of the excessive interference ions (Na+, K+, Mg2+, Ca2+, and humic acid) and acidic/alkaline environments, with the largest distribution coefficient Kd value reaching 6.89 × 105 mL/g. Also, the Ba2+-laden products can be easily eluted by a concentrated KCl solution, and its adsorption performances for barium resist well even after five consecutive cycles. In addition, owing to the regular appearance and excellent mechanical strength, the prepared KTS-3/PAN (PAN = polyacrylonitrile) granule displays a good removal efficiency in the flowing ion-exchange column. These advantages mentioned above render it very promising for the effective and efficient cleanup of radioactive 133Ba2+-contaminated wastewater.

Delaying cyclization of polyacrylonitrile by boric acid for sulfurized poly(acrylonitrile) cathode materials

Sulfurized poly(acrylonitrile) (SPAN) has become one of the most promising cathode materials in rechargeable Lithium-Sulfur (Li-S) batteries due to their inhibited polysulfide dissolution, high sulfur utilization and excellent electrochemical performance via unique solid–solid conversion mechanism. However, the sulfur content of SPAN (<50 %) is still one of the significant reasons that restrict the electrochemical performance and practical applicability. In this paper, a small amount of boric acid (HBO) was introduced into the precursor of SPAN cathode materials easily before heat-treating, to increase the sulfur content and improve the electrochemical performance. Meanwhile, the results of first principles calculation suggested that the increase of sulfur content of SPAN was derived from the delayed cyclization of polyacrylonitrile (PAN) by HBO. We also discovered when the additive amount of HBO was 1.5 % of PAN mass, the SPAN cathode material possessed high sulfur content up to 54.24 wt%, and delivered prominent reversible electrochemical performances of 714 mAh/g at 0.2C and 734 mAh/g at 0.1C with high Coulombic efficiency. In summary, we proposed a simple and easy method to improve sulfur content and introduced a new strategy for the design of high-sulfur content and high-performance SPAN cathode materials.

Room temperature in situ growth of fluorinated covalent organic framework on electrospun nanofibers for efficient detection of benzoylurea insecticide residue in water samples

The accurate detection of benzoylurea insecticides (BUs) residues is vital for the environment and human health. In this work, a room-temperature synthesis strategy was developed to fabricate the covalent organic framework (COF)–polyacrylonitrile (PAN) nanofibers composite by an electrospinning technique. The COF was functionalized on PAN nanofibers via in situ polymerization of 1,3,5-tris(4-aminophenyl)triazine (TAPT) and 2,3,5,6-tetrafluoroterephthaldehyde (TFTA). The obtained TAPT-TFTA@PAN nanofibers showed a porous structure, high surface area, good crystallinity and excellent extraction efficiency to BUs. A sensitive method combining dispersive solid-phase extraction (DSPE) using TAPT-TFTA@PAN nanofibers as an adsorbent with liquid chromatography–ultraviolet detector was developed for trace analysis of four BUs in environment water samples. This method achieved a wide linear range of 0.5–200 ng·mL−1 for triflumuron and hexaflumuron, and of 0.5–150 ng·mL−1 for teflubenzuron and fluazuron. The limits of detection (S/N = 3) for four BUs ranged from 0.11 to 0.42 ng·mL−1. The accuracy of the proposed method was validated by measuring trace BUs in the spiked water samples with recoveries in the range of 98.3 %∼125.3 %. The results demonstrated that the TAPT-TFTA@PAN nanofibers have great potential as an extractant for effective enrichment of benzoylurea insecticide from complex water samples.

Thermal hysteresis enhancement and dispersion thermal stability in paraffin actuators: Comparison of pan-nanofibers vs metal oxide nanoparticles use

In this research, the possibility of thermal property enhancement of paraffin actuators with nanofiber and metal oxide nanoparticle addition was experimentally evaluated. Besides pure paraffin compound, paraffin mixed with the CuO, Fe3O4, ZnO, Al2O3, and electrospun polyacrylonitrile (PAN) nanofiber nanoparticles were used, and a significant hysteresis improvement at first-level measurement was observed as 24.6, 26.2, 20.0, 29.2, and 30.8 % sequentially for the samples respectively compared with pure paraffin. Thermal dispersion stability of the nanocomposites was comprehended via computer tomographic (CT) investigation. The excessive precipitation of CuO, Fe3O4, and ZnO particles in the paraffin nanocomposite was observed. Precipitation of PAN Nanofiber- and Al2O3-Paraffin nanocomposite was not visually detectable via CT throughputs. The effect of thermal dispersion stability on the hysteresis performance of the nanocomposites was also investigated to ensure long-term consistent hysteresis performance advantages in paraffin actuators. Thermal dispersion stability effect on hysteresis performance of paraffin actuators with CuO, Fe3O4, ZnO, Al2O3, and PAN nanofiber nanocomposite paraffin compounds showed losses as 14.3, 14.6, 5.8, 4.3 and 2.2 % sequentially for the samples respectively.