Spongy p-Toluenesulfonic Acid-doped Polypyrrole with Extraordinary Rate Performance as Durable Anodes of Sodium-Ion Batteries at Different Temperatures

Covalent Organic Nanosheets with a Tunable Electronic Structure to Achieve Unprecedented Stability and High-Performance in Sodium-Ion Batteries

This study develops a new type of fluorinated covalent organic nanosheets (CONs) as anode materials for sodium-ion batteries by incorporating an electron-withdrawing benzothiadiazole (BT) unit and F atom into the framework. These modifications lead to a reduced bandgap and electron density, generating strong permanent dipoles that increased Na+ accessible sites within the self-assembled solid-state structure. To elucidate the effect of these electronic changes, the Na+ storage performance of fluorinated D/A-CON-10-F is compared to that of nonfluorinated D/A-CON-10. The reduced electron density in D/A-CON-10-F weakens its interaction with Na+, yet enhances ion and charge carrier conductivities, leading to improved electrochemical performance. Notably, D/A-CON-10-F exhibits a reversible discharge capacity of ≈637 mA h g-1 at 100 mA g-1, maintaining structural stability over 5000 cycles with excellent rate capability. These results demonstrate that dipole engineering in CONs effectively enhances charge transport and long-term stability, offering a promising strategy for next-generation sodium-ion battery anodes.

Efficient template free polymerization of continuously porous hybrid conducting polymers for highly stable flexible micro pseudocapacitors

Developing high-performance microscale-energy storage devices is essential for next-generation smart electronics. Hybrid conducting polymers (HCPs) offer a promising solution to address the limitations of traditional conducting polymers, with poor cycling and mechanical stability. Here, we present a novel, template-free bicontinuous microemulsion (BME)-based method of fabricating highly cross-linked, continuously porous PPy-CoO electrodes for micro-pseudocapacitors (MPCs). The bicontinuous structure endows HCPs with tunable functionalities, mechanical flexibility, and efficient ion transport. The synergy between PPy's fast charge transfer and CoO's high charge-storage capacity boosts the electrochemical performance of device, with excellent areal capacitance of 30.58 mF cm-2, energy density of 4.22 µWh cm-2, and power density of 75.97 µW cm-2 at 0.2 mA cm-2. The device retains 106% capacitance under 180° bending and 83% capacitance retention after 10,000 cycles in a bent (180°) position. This study demonstrates the BME polymerization approach as a scalable, cost-effective, and versatile strategy for producing multifunctional 3D HCP composites for functional devices.

Biodegradable, robust, and conductive bacterial cellulose @PPy-P macrofibers as resistive strain sensors for smart textiles

Fiber-based resistive strain sensors have attracted significant interest in the development of smart wearable devices due to their portability, flexibility, and easy conformability. However, current fiber-based resistive strain sensors mainly composed of metals and nondegradable polymers are not environmentally friendly and have poor mechanical strength. In this work, we examined biodegradable, robust, and conductive macrofibers fabricated through the in situ polymerization of p-toluenesulfonic acid (P-TSA)-doped polypyrrole (PPy) in bacterial cellulose (BC) nanofibers using wet-stretching and wet-twisting methods. The BC/PPy-P macrofibers possessed excellent conductivity (~7.19 S/cm), with superior mechanical properties (~210 MPa tensile strength and 2 GPa Young's modulus). Importantly, the BC/PPy-P microfiber operating as a resistive strain sensor possessed fast response time (15 s) and long-term stability (up to 1000 cycles), which could be used to effectively detect human movements. Moreover, the matrix material BC of BC/PPy-P macrofibers could be completely degraded within 96 h in the cellulase solution, leaving only PPy-P particles that could be recycled for other use. Therefore, the prepared BC/PPy-P microfibers provided a promising strategy for developing green resistive strain sensing fibers, with great potential to design eco-friendly smart fabric for monitoring human movements.

Ultrasensitive Electrochemical Detection of Salmonella typhimurium in Food Matrices Using Surface-Modified Bacterial Cellulose with Immobilized Phage Particles

The rapid and sensitive detection of Salmonella typhimurium in food matrices is crucial for ensuring food safety. This study presents the development of an ultrasensitive electrochemical biosensor using surface-modified bacterial cellulose (BC) integrated with polypyrrole (Ppy) and reduced graphene oxide (RGO), further functionalized with immobilized S. typhimurium-specific phage particles. The BC substrate, with its ultra-fibrous and porous structure, was modified through in situ oxidative polymerization of Ppy and RGO, resulting in a highly conductive and flexible biointerface. The immobilization of phages onto this composite was facilitated by electrostatic interactions between the polycationic Ppy and the negatively charged phage capsid heads, optimizing phage orientation and enhancing bacterial capture efficiency. Morphological and chemical characterization confirmed the successful fabrication and phage immobilization. The biosensor demonstrated a detection limit of 1 CFU/mL for S. typhimurium in phosphate-buffered saline (PBS), with a linear detection range spanning 100 to 107 CFU/mL. In real samples, the sensor achieved detection limits of 5 CFU/mL in milk and 3 CFU/mL in chicken, with a linear detection range spanning 100 to 106 CFU/mL, maintaining high accuracy and reproducibility. The biosensor also effectively discriminated between live and dead bacterial cells, demonstrating its potential in real-world food safety applications. The biosensor performed excellently over a wide pH range (4-10) and remained stable for up to six weeks. Overall, the developed BC/Ppy/RGO-phage biosensor offers a promising tool for the rapid, sensitive, and selective detection of S. typhimurium, with robust performance across different food matrices.

Electrostatic Adsorption Behaviors of Polymer Plates to a Droplet

Electrostatic transfer and adsorption of electrically conductive polymer-coated poly(ethylene terephthalate) plates from a particle bed to a water droplet were studied, with the influence of plate thickness and shape observed. After synthesis and confirmation of the particles' properties using stereo and scanning electron microscopies, elemental microanalysis, and water contact angle measurement, the electric field strength and droplet-bed separation distance required for transfer were measured. An electrometer and high-speed video footage were used to measure the charge transferred by each particle, and its orientation and adsorption behavior during transfer and at the droplet interface. The use of plates of consistent square cross section allowed the impact of contact-area-dependent particle cohesion and gravity on the electrostatic transfer of particles to be decoupled for the first time. The electrostatic force required to extract a plate was directly proportional to the plate mass (thickness), a trend very different from that previously observed for spherical particles of varied diameter (mass). This reflected the different relationship between mass, surface area, and cohesive forces for spherical and plate-shaped particles of different sizes. Thicker plates transferred more charge to the droplet, probably due to their remaining at the bed at higher field strengths. The impact of plate cross-sectional geometry was also assessed. Differences in the ease of transfer of square, hexagonal, and circular plates seemed to depend only on their mass, while other aspects of their comparative behavior are attributed to the more concentrated charge distribution present on particles with sharper vertices.

Kinetic Study of the Effective Thermal Polymerization of a Prebiotic Monomer: Aminomalononitrile

Aminomalononitrile (AMN), the HCN formal trimer, is a molecule of interest in prebiotic chemistry, in fine organic synthesis, and, currently, in materials science, mainly for bio-applications. Herein, differential scanning calorimetry (DSC) measurements by means of non-isothermal experiments of the stable AMN p-toluenesulfonate salt (AMNS) showed successful bulk AMN polymerization. The results indicated that this thermally stimulated polymerization is initiated at relatively low temperatures, and an autocatalytic kinetic model can be used to appropriately describe, determining the kinetic triplet, including the activation energy, the pre-exponential factor, and the mechanism function (E_α, A and f(α)). A preliminary structural characterization, by means of Fourier transform infrared (FTIR) spectroscopy, supported the effective generation of HCN-derived polymers prepared from AMNS. This study demonstrated the autocatalytic, highly efficient, and straightforward character of AMN polymerization, and to the best of our knowledge, it describes, for the first time, a systematic and extended kinetic analysis for gaining mechanistic insights into this process. The latter was accomplished through the help of simultaneous thermogravimetry (TG)-DSC and the in situ mass spectrometry (MS) technique for investigating the gas products generated during these polymerizations. These analyses revealed that dehydrocyanation and deamination processes must be important elimination reactions involved in the complex AMN polymerization mechanism.