Conducting Polymer Polypyrrole Research Articles

UV‐Curable 3D‐Printable Microwave‐Absorbing Material with a Sword‐Sheath Structure Based on Multiwalled Carbon Nanotube/Polypyrrole Nanotube/Fe3O4 Composites

Multiwalled carbon nanotube (MWCNT)/polypyrrole nanotube (PPyNT)/triiron tetraoxide (Fe3O4) composites with a sword‐sheath structure are added to a UV‐curable resin to form a unique highly microwave‐absorbing material with a low absorbent content. Specifically tailored for high‐precision stereolithography three‐dimensional (3D) printers, the low absorbent content ensures an efficient curing and molding of the photosensitive resin. The conducting polymer polypyrrole is coated on the MWCNTs via free‐radical polymerization, forming a sheath structure. The initiator of the free‐radical polymerization, FeCl3, is converted into Fe3O4 and loaded onto the sheath structure. This ternary composite material is uniformly dispersed in the photosensitive resin with interconnected sword‐sheath structures, ensuring a favorable dielectric loss performance even at a low absorbent content. Importantly, the material exhibits both dielectric loss and magnetic loss properties. Using a UV‐cured microwave‐absorbing material with an absorbent content of 0.5 wt%, an electromagnetic loss of −22.5 dB can be achieved with a thickness of 1 mm. This UV‐cured microwave‐absorbing material facilitates the high‐precision 3D printing of microwave structures with various intricate shapes, broadening the application scope of microwave‐absorbing materials.

Conductive polypyrrole: synthesis, characterization, thermal, and electrical properties for different applications

Pyrrole monomer (mPPy) in an aqueous solution was used to create the conductive polymer polypyrrole (a homo-PPy) using a chemical oxidative polymerization process over a period of several hours at room temperature. Ferric chloride (FeCl3) oxidant was used, and sodium dodecyl sulphate (C12H25NaO4S), a surfactant. The produced PPy samples were characterized using a variety of methods, including X-ray diffraction (XRD), the Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), Differential Thermal analysis (DTA), Thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). SEM images revealed that nanoparticles of a homo-PPy with radii of 60–90 nm were well evenly distributed in the structure. The thermal stability and electrical conductivity of homo-PPy nanoparticles were observed to rise with a solvent ethylene glycol. As temperature rises, the conductivity of homo-PPy samples is significantly raised, and electrical conductivities ranging from.0.44 to 2.2 (Ω.m)−1. Results from FTIR and XRD analysis confirmed the structural formation of a homo-polypyrrole during synthesis from pyrrole monomer. Because of their improved electrical conductivity and thermal stability, homo-PPy nanoparticles have potential applications in energy storage, adsorption and contamination elimination, electromagnetic protection, and resistance to corrosion.

Controllable Fabrication of Polypyrrole Nanopillar/Hair Arrays by Oxygen Plasma Treatment and Their Applications as Antibacterial Flexible pH Sensors

AbstractFlexible pH sensors have attracted a great deal of attention in numerous applications, such as wearable healthcare devices, smart wound bandages, and other pH monitor sensors for chemical and bioprocess control. Herein, a facile approach to fabricate conducting polymer polypyrrole nanopillar arrays is proposed, and its potential as an advanced pH sensing interface is shown. Using oxygen plasma treatment as the etching tool, polypyrrole nanopillar/hair arrays can be prepared after etching 3D polypyrrole network structures. Conductive polypyrrole nanopillar arrays possessed unique advantages in sensing: their featured nanopillars has enhanced antibacterial properties; their structures showed excellent hydrophilicity and are favorable for interaction with analytes in small‐volume liquids. A flexible polypyrrole nanopillar array‐based potentiometric pH sensor integrated with a solid‐state reference electrode is further designed and fabricated. Superior performance with a near‐Nernstian response of 60.1±1.0 mV pH−1, excellent repeatability, high stability, and reproducibility is verified in the physiological pH range. The reliabilities of flexible and small‐volume sample testing, as well as the applicability for artificial sweat sample pH sensing, are examined. Provided with the advantages of antibacterial properties and hydrophilicity, the proposed flexible pH sensor is promising for trace analysis in biological, medical, and healthcare applications.

Tuning low frequency dielectric properties of flexible ternary polymer blend film reinforced with bio- ionic liquid for the application in green electronics

Biofriendly conducting polymeric blends and composites exhibiting high dielectric constant and dielectric loss are promising for applications as sensors, actuators, microwave absorbing materials, fuel cells and biomedical applications. A great deal of work is reported on using fillers such as conductive nanomaterials, bio ceramics, carbon nanotubes, graphene etc in blends of Polyvinylchloride, Polyvinylpyrrolidone, Polymethylmethacrylate, Polyvinyl alcohol with conducting polymer Polypyrrole, Polyaniline for enhancing their conductivities, tailoring dielectric and electrical, thermal and surface properties of such polymeric materials. However, appropriate dispersion of such fillers in polymeric matrices remains technically challenging. In this regard, bio-ionic liquids have emerged as a novel class of materials and their combination with specific polymer blends opens the possibility to develop smart novel materials with different morphologies. Present work aims to explore the low frequency dielectric properties exhibited by free standing, flexible, biofriendly/biodegradable ternary polymer blend film of Polyvinylchloride-Polyvinylpyrrolidone-Polypyrrole reinforced with choline acetate. The detailed analysis of low frequency dielectric properties authenticates that addition of choline acetate result in modifying the dielectric properties of ternary polymer blend film.. The harmlessness of these films was confirmed from disk diffusion test indicating their benign nature towards (Escherichia coli) (CFT073) and (Bacillus subtilis). Therefore, the developed films can potentially be used for various scale multifunctional dielectric and electrical applications working in close contact with living matter, green electronics and various health monitoring systems.

Novel ternary PPy–ZnFe2O4/fly ash-cenosphere photocatalysts for photodegradation of methyl orange under UV light

In this study, fly ash cenospheres (FACs), characterized by their floating properties and inherent photocatalytic activity, were used as a carrier to support ZnFe2O4 material and doped with conductive polymer polypyrrole (PPy) to prepare a novel ternary PPy–ZnFe2O4/FACs (PPy–ZF) composite catalyst. X-ray diffraction, Fourier transform infrared spectroscopy, TEM, and scanning electron microscopy were used to characterize the structure, morphology, and optical properties of the samples prepared. In particular, a 20 mg/L methyl orange (MO) solution at pH 4 was given 0.075 g of PPy–ZF catalyst to add, and after 30 min of dark adsorption, followed by irradiation for 180 min, 98.54% of the MO was removed. The material was also shown to have good stability and reusability through three cycles of use. Additionally, the material exhibited good photocatalytic activity for other dyes. The results of photocatalytic experiments showed their significantly enhanced photocatalytic activity toward MO, which was mainly attributed to the synergistic effect of PPy and ZnFe2O4 on the surface of FACs, leading to a high separation efficiency and a low rate of photogenerated charge complexation. In addition, cyclic tests demonstrated the stability and reusability of the composite. The leading role in the photocatalytic degradation of MO was demonstrated by the radical trapping experiment, which showed ·O2 − and h+. The present study can significantly improve the photocatalytic performance of the floating materials of ZnFe2O4/FACs, which is beneficial to solve the current energy crisis and environmental pollution problems. It has certain reference significance to solve the problems of environmental pollution, waste recycling, and catalyst recycling in the future.

Electro-Chemo-Mechanical Coupling in Hierarchical Nanoporous Gold-Polypyrrole-Water Hybrids

Nanoporous (np) metals made by dealloying is a novel class of nanostructured materials that offers numerous functionalities, ranging from sensing, energy storage, to (electro-)catalysis and beyond. A substantial amount of research in np materials has been focused on np gold due to its excellent structural and chemical stability, adjustable pore size, high conductivity, biocompatibility, and easy fabrication process via free corrosion or electrochemical dealloying. A considerable number of studies have been conducted to investigate np gold infiltrated with an aqueous electrolyte [1]. In that way, the material is considered as a hybrid so that one can reversibly tune the gold surface state by manipulating the superficial charge densities or adsorbate coverages via the applied electric potential [1]. The above-mentioned approach results in a number of intriguing properties of np Au revealed upon electrode potential variation in aqueous electrolytes such as actuation [2, 3], sensing [4], tunable strength [5] and elastic modulus [6]. The behavior is well-studied in case of weak ion adsorption and surface oxidation.One of the promising methods towards further improvement of functional and mechanical properties of np metals was implemented by Roschning and Weissmueller [7]. It was shown that the actuation strain of np Au can be enhanced via electrodeposition of a conductive polymer polypyrrole (PPy) on the gold surfaces. The actuation strain of the np Au-PPy hybrids strongly scales with the PPy phase fraction. Moreover, Li et al. [8] observed variations of effective elastic modulus in np Au-PPy-water hybrids. Thus, introducing the conductive polymer into a pore space of the np metal yields a hybrid actuator with a significantly improved actuation amplitude and yield strength.Here, we employ PPy for surface functionalization of hierarchical (hc) np Au (Figure 1) to explore the impact of the conductive polymer coating on the functional behavior of the hierarchically structured np metals. Np metals with structural hierarchy made by dealloying [9] open up new opportunities for multifunctional hard-soft hybrids. The larger pores at the higher hierarchical level (characterized by diameters around 120 nm) can promote fast mass exchange, while nanopores at the lower hierarchy level (below 30 nm) provide a large surface area and high chemical activity. Actuation behavior of the hybrid materials was analyzed in situ in a dilatometer upon potential cycling in a 1 M HClO4 aqueous electrolyte. The elastic response was examined in situ in a dynamic mechanical analyzer in the same electrolyte. We revealed pronounced changes of the macroscopic length and Young’s modulus in response to the voltage-induced redox reactions of the polymer films at the np electrodes. In the contribution, we discuss the origin of the electro-chemo-mechanical coupling phenomena.[1] Shao et al., in Nanoporous Gold: From an ancient technology to a high-tech material. RSC (2012).[2] Kramer et al. Nano Lett., 4(5) 793 (2004).[3] Jin et al. Nano Lett., 10(1) 187 (2010).[4] Stenner et al., Adv. Funct. Mater. 26 (28), 5174 (2016).[5] Jin et al., Science 332, 1179 (2011.)[6] Mameka et al., Acta Mater. 76, 272 (2014).[7] Roschning et al., Adv. Mater. Interfaces, 2001415 (2020).[8] Li et al., Acta Mater., 212 (1), 116852 (2021).[9] Shi et al., Science 371, 1026 (2021).Figure 1. Scanning electron micrograph of hierarchical nanoporous Au-PPy hybrid microstructure. Figure 1

A flexible supercapacitor with high energy density and wide range of temperature tolerance using a high-concentration aqueous gel electrolyte

As the demand for a wide range of wearable devices increases, extensive effort is devoted to developing high-performance flexible energy storage devices such as batteries and supercapacitors. Of particular interest, flexible supercapacitors using aqueous electrolytes have high application potential owing to their many advantages including low cost, harmlessness to the human, and environmental safety compared to others using electrolytes such as ionic liquids and organic electrolytes. However, poor temperature tolerance and narrow operation voltage window have hindered the practical application of aqueous supercapacitors. In this study, we report on a wide temperature-tolerant flexible aqueous supercapacitor featuring high electrochemical performance designed by a deliberate selection of electrode materials and electrolytes. As a flexible electrode, three-dimensional microporous graphene foam coated with conducting polymer Polypyrrole (PPy) is used to enhance capacitance up -to 90.0 F/g by increasing the surface area and inducing the pseudo-capacitance of PPy. As a gel-type electrolyte, a high-concentration NaClO4 is mixed with Polyvinyl alcohol to enlarge the voltage window to 1.8 V and a stable temperature range from -25 to 80°C, even under repetitive bending deformation. The fabricated supercapacitor exhibits a superior energy density of 37.4 Wh kg−1 and maintains 92.0% of initial capacitance at room temperature after three repeated cycles of cooling/heating across a wide temperature range over 100°C. This work suggests a high potential application of the fabricated supercapacitor as an eco-friendly and stable energy storage system for powering diverse wearable devices under various conditions.

A Free-Standing Polymer Polypyrrole/Cellulose Composite Film via Spatial-Confined Interfacial Electrodeposition for Flexible Supercapacitors.

As a kind of energy storage device, a flexible supercapacitor has the characteristics of high capacity, fast charge/discharge rate, good stability, portability and softness. Conductive polymer polypyrrole (PPy) can be used as an electrode material for supercapacitors due to its environmental friendliness, simple synthesis process, good conductivity and potential for large-scale production. However, pristine PPy inevitably suffers from structural rupture due to repeated doping/de-doping during charge and discharge processes, which in turn impairs its cycle stability. In general, compounding with flexible substrates like soft carbon materials, cellulose or nylon fabric, is a good strategy to weaken the inner stress and restrain the structure pulverization of PPy. Herein, cellulose is utilized as a soft substrate to compound with PPy based on the electrochemical oxidation of polypyrrole. The interfacial electrodeposition method can successfully obtain a smooth, uniform and flexible PPy/cellulose composite film, which shows good conductivity. The assembled symmetric supercapacitor with PPy/cellulose film has an optimized specific capacitance of 256.1 mF cm-2, even after 10,000 cycles at a current density of 1 mA cm-2. Furthermore, there is no significant capacitance loss even after 180° bending of the device. This work provides a new means to prepare flexible, low-cost, environmentally friendly and high-performance electrode materials for energy conversion and storage systems.

Development and Analytical Evaluation of a Point-of-Care Electrochemical Biosensor for Rapid and Accurate SARS-CoV-2 Detection.

The COVID-19 pandemic has underscored the critical need for rapid and accurate screening and diagnostic methods for potential respiratory viruses. Existing COVID-19 diagnostic approaches face limitations either in terms of turnaround time or accuracy. In this study, we present an electrochemical biosensor that offers nearly instantaneous and precise SARS-CoV-2 detection, suitable for point-of-care and environmental monitoring applications. The biosensor employs a stapled hACE-2 N-terminal alpha helix peptide to functionalize an in situ grown polypyrrole conductive polymer on a nitrocellulose membrane backbone through a chemical process. We assessed the biosensor's analytical performance using heat-inactivated omicron and delta variants of the SARS-CoV-2 virus in artificial saliva (AS) and nasal swab (NS) samples diluted in a strong ionic solution, as well as clinical specimens with known Ct values. Virus identification was achieved through electrochemical impedance spectroscopy (EIS) and frequency analyses. The assay demonstrated a limit of detection (LoD) of 40 TCID50/mL, with 95% sensitivity and 100% specificity. Notably, the biosensor exhibited no cross-reactivity when tested against the influenza virus. The entire testing process using the biosensor takes less than a minute. In summary, our biosensor exhibits promising potential in the battle against pandemic respiratory viruses, offering a platform for the development of rapid, compact, portable, and point-of-care devices capable of multiplexing various viruses. The biosensor has the capacity to significantly bolster our readiness and response to future viral outbreaks.

Polypyrrole- and Polyaniline-Coated Cotton Fabrics as Efficient Adsorbents for the Pharmaceutical Water Contaminants Diclofenac and Salicylic Acid.

The emerging pharmaceutical contaminants diclofenac (DCF) and salicylic acid (SA) pose potential hazards to humans and living organisms due to their persistence in water environments. In this work, the conductive polymers polypyrrole (PPY) and polyaniline (PANI) were successfully coated on cotton fabrics, as confirmed by FTIR and SEM measurements. The coated fabrics efficiently removed DCF at pH 5.3 and SA at pH 4, with removal efficiencies that exceeded 90% and 70%, respectively. Adsorption was rapid for most of the tested contaminant-fabric systems and reached equilibrium within 20-30 min. The best adsorption performance for both contaminants was shown on the PPY-coated fabrics, which yielded adsorption capacities of about 65 and 21 mg/g for DCF and SA, respectively. This could be explained by molecular modeling simulations, which mostly estimated higher total cohesive energy densities for adsorption on the PPY-coated fabrics than on the PANI-coated ones. The adsorption mechanism involved both coulombic electrostatic attractions and non-coulombic van der Waals and π-π stacking. The fabrics could be reused for three adsorption-desorption cycles. Immobilization of the conductive polymers on cotton fabrics provides a facile method for their handling and collection during adsorption and regeneration cycles while maintaining their multi-functionality in adsorbing different contaminants.

Preparation and study of Nanocomposite material CAFe-PPy

Carbon aerogel (CA) is a new type of lightweight porous material with many excellent properties. Here, CAFe-PPy was prepared via iron and conductive polymer polypyrrole (PPy) on carbon aerogel. The physical properties of CA and CAFe-ppy were compared. Iron, nitrogen and oxygen were successfully loaded onto CAFe-PPy. PPy can increase the conductivity of CAFe-PPy, but it also blocks some holes.

BiOI/PPy/cotton photocatalytic fabric for efficient organic dye contaminant degradation and self-cleaning application

Water pollution caused by industrial organic dyes poses a serious threat to human health and the ecological environment. Natural cellulose fibers functionalized with photocatalysts are regarded as promising materials for removing organic dyes. However, the immobilized photocatalysts usually exhibit a high recombination rate of photo-generated charge carriers, which seriously reduces the photocatalytic efficiency. Herein, a photocatalytic functional cotton fabric was prepared by a two-step process, including in-situ gas-phase polymerization of pyrrole and layer-by-layer self-assembly process of bismuth oxyiodide. The conjugated molecular structure of polypyrrole (PPy) conductive polymer could effectively facilitate the separation of photo-generated electron-hole pairs of bismuth oxyiodide photocatalyst on the fiber surface. The ability of composite fabrics to absorb visible light was greatly enhanced. The photocatalytic functional fabric exhibited a high photocatalytic degradation efficiency towards organic dye contaminants. On the other hand, the PPy nano-layers on cotton fibers induced bismuth oxyiodide nanosheets to self-assemble a more dense porous structure, which trapped a large amount of tiny air. The prepared fabric exhibited an obvious superhydrophobicity with a water contact angle above 150° and an excellent self-cleaning ability toward liquid/solid contaminants. This work provides a new insight into water treatment through the development of efficient photocatalytic textiles.

Inductive Coupling of Bipolar Signals with a Conjugate Coil Pair for an Analog Passive ECG Sensor Using a PPy-Coated pvCNT Dry Electrodes.

The wireless capture of analog differential signals from fully passive (battery-less) sensors is technically challenging but it can allow for the seamless capture of differential biosignals such as an electrocardiogram (ECG). This paper presents a novel design for the wireless capture of analog differential signals using a novel conjugate coil pair for a wireless resistive analog passive (WRAP) ECG sensor. Furthermore, we integrate this sensor with a new type of dry electrode, namely conductive polymer polypyrrole (PPy)-coated patterned vertical carbon nanotube (pvCNT) electrodes. The proposed circuit uses dual-gate depletion-mode MOSFETs to convert the differential biopotential signals to correlated drain-source resistance changes and the conjugate coil wirelessly transmits the differences of the two input signals. The circuit rejects (17.24 dB) common mode signals and passing only differential signals. We have integrated this novel design with our previously reported PPy-coated pvCNT dry ECG electrodes, fabricated on a stainless steel substrate with a diameter of 10 mm, which provided a zero-power (battery-less) ECG capture system for long duration monitoring. The scanner transmits an RF carrier signal at 8.37 MHz. The proposed ECG WRAP sensor uses only two complementary biopotential amplifier circuits, each of which has a single-depletion MOSFET. The amplitude-modulated RF signal is envelope-detected, filtered, amplified, and transmitted to a computer for signal processing. ECG signals are collected using this WRAP sensor and compared with a commercial counterpart. Due to the battery-less nature of the ECG WRAP sensor, it has the potential to be a body-worn electronic circuit patch with dry pvCNT electrodes that stably operate for a long period of time.

Electrochemical control of bone microstructure on electroactive surfaces for modulation of stem cells and bone tissue engineering

ABSTRACT Controlling stem cell behavior at the material interface is crucial for the development of novel technologies in stem cell biology and regenerative medicine. The composition and presentation of bio-factors on a surface strongly influence the activity of stem cells. Herein, we designed an electroactive surface that mimics the initial process of trabecular bone formation, by immobilizing chondrocyte-derived plasma membrane nanofragments (PMNFs) on its surface for rapid mineralization within 2 days. Moreover, the electroactive surface was based on the conducting polymer polypyrrole (PPy), which enabled dynamic control of the presentation of PMNFs on the surface via electrochemical redox switching, further resulting in the formation of bone minerals with different morphologies. Furthermore, bone minerals with contrasting surface morphologies had differential effects on the differentiation of human bone marrow-derived stem cells (hBMSCs) cultured on the surface. Together, this electroactive surface showed multifunctional characteristics, not only allowing dynamic control of PMNF presentation but also promoting the formation of bone minerals with different morphologies within 2 days. This electroactive substrate could be valuable for more precise control of stem cell growth and differentiation, and further development of more suitable microenvironments containing bone apatite for housing a bone marrow stem cell niche, such as biochips/bone-on-chips.

Convenient construction of porous dendritic Cu-doped Ni@PPy/stainless steel mesh electrode for oxidation of methanol and urea

In multifunctional catalysts, Ni-based alloys and compounds can be used for methanol oxidation reaction (MOR) and urea oxidation reaction (UOR). Herein, the porous dendritic NiCu@PPy/316L stainless steel mesh (SSM) electrode is prepared by dynamic hydrogen bubble template electrodeposition, followed by cyclic voltammetry electrodeposition of polypyrrole (PPy) conductive polymer on the electrode surface. Among them, dynamic hydrogen bubbles successfully assisted the formation of porous structures in the Ni-based deposition layer. In addition, the morphology of the resulting Ni-based layer further evolves from particle stacking to dendritic with high specific surface area with Cu doping. Eventually, 2-NiCu/SSM achieves current densities of 294.5 mA·cm−2 (MOR) and 278.6 mA·cm−2 (UOR) at 0.8 V, respectively. The PPy coating prevents the agglomeration of NiCu particles in the catalytic layer and further improves the persistence of the electrochemical performance. After 2000 cycles, the current densities of 2-NiCu @PPy/SSM in the new electrolyte are maintained at 89.1% (MOR) and 94.8% (UOR) of the original value, with a 10% increase for MOR and a 7% increase for UOR compared to the sample without PPy coating (2-NiCu /SSM).

具有协同吸附-催化效应的莫特-肖特基异质结构修 饰隔膜助力锂硫电池

The low sulfur usage, strong shuttle effect, and dilatory redox processes limit the practical application of lithium-sulfur batteries (LSBs). The method of separator modification with a unique Mott-Schottky heterostructure used in this work significantly alleviates these issues. This unique structure is synthesized by in situ polymerizing the conductive polymer polypyrrole (PPy) on the surface of Bi2MoO6 nanosheets to form Bi2MoO6-PPy nanosheets. This unique heterostructure can minimize the redox energy barrier on polysulfides due to the strong adsorption effect, high catalytic activity, and built-in electric field of Bi2MoO6-PPy nanosheets. The battery demonstrates good cycling stability when assembled with the functional separator modified by Bi2MoO6-PPy nanosheets, with an ultralow capacity decay of 0.045% per cycle over 500 cycles at 2 C. Furthermore, even with a high sulfur loading (7.5 mg cm−2), the battery retains an areal capacity of 6.3 mA h cm−2 at 0.2 C after 80 cycles. As a result, the suggested Mott-Schottky heterostructure-based Bi2MoO6-PPy nanosheets-modified separator (Bi2MoO6-PPy@PP separator) successfully suppresses the shuttle effect, providing an effective strategy for deploying efficient LSB.

Construction of Polypyrrole-Coated CoSe2 Composite Material for Lithium-Sulfur Battery.

Lithium-sulfur batteries with high theoretical energy density and cheap cost can meet people's need for efficient energy storage, and have become a focus of the research on lithium-ion batteries. However, owing to their poor conductivity and "shuttle effect", lithium-sulfur batteries are difficult to commercialize. In order to solve this problem, herein a polyhedral hollow structure of cobalt selenide (CoSe2) was synthesized by a simple one-step carbonization and selenization method using metal-organic bone MOFs (ZIF-67) as template and precursor. CoSe2 is coated with conductive polymer polypyrrole (PPy) to settle the matter of poor electroconductibility of the composite and limit the outflow of polysulfide compounds. The prepared CoSe2@PPy-S composite cathode shows reversible capacities of 341 mAh g-1 at 3 C, and good cycle stability with a small capacity attenuation rate of 0.072% per cycle. The structure of CoSe2 can have certain adsorption and conversion effects on polysulfide compounds, increase the conductivity after coating PPy, and further enhance the electrochemical property of lithium-sulfur cathode material.

In Situ Gas-Phase Polymerization of Polypyrrole-Coated Lithium-Rich Nanotubes for High-Performance Lithium-Ion Batteries

Conductive polymer polypyrrole (PPy)-coated lithium-rich manganese-based Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) nanotube cathode materials were synthesized by electrospinning and subsequently subjected to low-temperature vapor-phase polymerization. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) results confirm that the successful coating of the PPy layer (~2 nm) on the surface of LMNCO nanotubes did not destroy their morphologies or structures. Electrochemical tests indicate that the electrochemical performance of PPy-coated LMNCO nanotubes has been significantly enhanced. At a rate of 1 C, the discharge capacity of the PPy-coated LMNCO cell is 200.1 mAh g−1, and the capacity retention is 99% after 120 cycles. This excellent stability is attributed to the inhibition of side reactions and the protective function of the tubular structure due to the PPy coating layer. Additionally, the rate capability is also improved at a high current density due to the higher electronic and ionic conductivity.

Al/SnO2 Nanothermite ESD Desensitization by Means of the Elaboration of Tailored SnO2-Polypyrrole Composites.

Incidents can occur when handling energetic materials (EMs) due to their sensitivity to external stimuli. Mechanical (friction, impact) and electrical (electrostatic discharge (ESD)) stimuli can trigger involuntary ignition of EMs. Nanothermites, defined as highly reactive mixtures of a metal and a metal oxide, show interesting reactive properties (high temperature/amount of heat). However, their extreme sensitivity to ESD is a significant drawback in their development. With a sensitivity threshold of lower than a millijoule and considering the human body capacity discharge is a few tens of millijoules, the handling of such energetic mixtures is extremely hazardous. ESD desensitization is therefore of crucial importance for the use of these materials. To achieve this goal, polypyrrole (PPy) conductive polymer was used as an additive within an Al/SnO2 energetic formulation. This polymer is able to easily conduct the electrostatic charges, which is useful to avoid an ignition after a spark stimulus. PPy was added to the nanothermite through the elaboration of SnO2-PPy composites. Delaying the SnO2 introduction time during pyrrole's polymerization (t = 0, 1, 24 h) changed the microstructures of the composites. The various SnO2-PPy composites highlighted that the additive's distribution within the composite is a key component for the modulation of ESD sensitivity. For example, this threshold is higher for a nanothermite formulated with the composite elaborated at t = 0 h (96.5 mJ with 7.5 vol % of polymer) than a composition based on the composite at t = 24 h (16.9 mJ with 8.2 vol % of polymer). Meanwhile, the reactive properties are decreased. The loss of reactivity (e.g. combustion speed) was explained by the thermal insulating property of the additive. Overall, the aim of this study is to help in the understanding of ESD desensitization of nanothermites in order to make them safer for operators and adapted to the required applications.

Application of Polypyrrole-Based Electrochemical Biosensor for the Early Diagnosis of Colorectal Cancer

Although colorectal cancer (CRC) is easy to treat surgically and can be combined with postoperative chemotherapy, its five-year survival rate is still not optimistic. Therefore, developing sensitive, efficient, and compliant detection technology is essential to diagnose CRC at an early stage, providing more opportunities for effective treatment and intervention. Currently, the widely used clinical CRC detection methods include endoscopy, stool examination, imaging modalities, and tumor biomarker detection; among them, blood biomarkers, a noninvasive strategy for CRC screening, have shown significant potential for early diagnosis, prediction, prognosis, and staging of cancer. As shown by recent studies, electrochemical biosensors have attracted extensive attention for the detection of blood biomarkers because of their advantages of being cost-effective and having sound sensitivity, good versatility, high selectivity, and a fast response. Among these, nano-conductive polymer materials, especially the conductive polymer polypyrrole (PPy), have been broadly applied to improve sensing performance due to their excellent electrical properties and the flexibility of their surface properties, as well as their easy preparation and functionalization and good biocompatibility. This review mainly discusses the characteristics of PPy-based biosensors, their synthetic methods, and their application for the detection of CRC biomarkers. Finally, the opportunities and challenges related to the use of PPy-based sensors for diagnosing CRC are also discussed.