Efficiently Fabricated Core-Sheath Piezoelectric Sensor Based on PVDF Microfibrillar Bundle.

With the rapid development of information technology (e.g., Internet of Things (IoT) and artificial intelligence (AI)), piezoelectric sensor (i.e., piezoelectric nanogenerator, PENG) receives an increasing number attention in the field of self-powered wearable devices. Taking piezoelectric fiber as an example, it shows promising application for wearable devices owing to its light weight and high flexibility compared with block electronic devices. However, it still remains a challenge to fabricate low-cost and high-performance piezoelectric fiber via a large-scale but efficient method. In this study, via extrusion molding and leaching, a core-sheath piezoelectric sensor is facilely fabricated, whose core and sheath layer are respectively slender steel wire (i.e., electrode) and PVDF microfibrillar bundle (PMB) (i.e., piezoelectric layer). Such piezoelectric sensor shows decent output performance in both pressing (12.3 V) and bending (0.32 V) mode. Meanwhile, it possesses sensitive stress responsiveness when serving for self-powered sensing. Furthermore, such piezoelectric sensors can realize wearable signal transmission and human motion monitoring, showing promising potential for wearable devices in the future. This work proposes a large-scale but efficient method for fabricating high-performance PVDF microfibril based piezoelectric fiber, opening a new pathway to develop self-powered sensors following the concept of polymer "structuring" processing.

Long-Cycling Cellulose-Based Gel Polymer Electrolyte Utilizing Nanohydrotalcite as a Li+ Transport Redistributor.

The hydroxyl groups on the surface of the cellulose-based gel polymer electrolyte lead to poor interfacial compatibility due to side reactions with lithium sheets. In this paper, a novel cellulose-based gel polymer electrolyte was prepared by uniformly coating the surface of a cellulose membrane with a nanohydrotalcite/PVDF-HFP composite using electrospinning technology. This cellulose-based gel polymer electrolyte exhibits good interfacial compatibility and excellent cycling stability (91.7% specific capacity retention after 500 cycles at 0.5C). Theory and experiments have shown that nanohydrotalcite on the surface of cellulose membrane can effectively prevent the contact of hydroxyl groups with lithium sheets to reduce the side reactions. In addition, nanohydrotalcite can also act as a Li+ transport redistributor to facilitate the uniform deposition of Li+ and reduce the formation of lithium dendrites to extend the cycle life.

Double-Layer Electronegative Structure-Based Triboelectric Nanogenerator for Enhanced Performance Using Combined Effect of Enhanced Charge Generation and Improved Charge Trapping.

The performance of a triboelectric nanogenerator (TENG) device depends on the amount of generated surface charges during triboelectrification and the retention of surface charges. Here, we present the fabrication of a double-layer nanocomposite structure for the electronegative layer in a TENG, which resulted in the enhanced generation of surface charges and retention of generated charges. The double-layer structure is a stack of two different nanocomposite layers, in which the top layer is a nanocomposite of PVDF and MXene and the bottom layer is a nanocomposite layer of PDMS and NaNbO3 nanoparticles. The use of the double-layer structure for the electronegative layer enhanced the generated voltage to 150 V and the current to 4.3 µA, resulting in an output power density of 134 µW/cm2, which is ∼5.8 times higher compared to the performance of a TENG with a single PVDF electronegative layer. Through systematic Kelvin probe force microscopy measurements, it is shown that the introduction of a highly electronegative MXene in the PVDF matrix improved the electron affinity of the friction layer, resulting in enhanced charge generation during contact electrification. The introduction of NaNbO3 ferroelectric nanoparticles in the PDMS matrix is shown to result in enhanced internal polarization and increased trap sites, resulting in the retention of generated surface charges for longer durations. The combined effect of the two layers resulted in a substantial improvement in TENG performance. The application of the TENG device in wireless communication for signal transfer is also presented.

Composite Nanoarchitectonics of Electrospun Piezoelectric PVDF/AgNPs for Biomedical Applications, Including Breast Cancer Treatment.

This study focused on preparing composite nanomats by incorporating silver nanoparticles (AgNPs) in polyvinylidene fluoride (PVDF) nanofibers through the electrospinning process. A short review of piezoelectric PVDF-related research is presented. PVDF is known for its biocompatibility and piezoelectric properties. Since electrical signals in biological tissues have been shown to be relevant for therapeutic applications, the influence of the addition of AgNPs to PVDF on its piezoelectricity is studied, due to the ability of AgNPs to increase the piezoelectric signal, along with providing antibacterial properties. The prepared samples were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. In addition, the biological activity of composites was examined using a cytotoxicity assay and an assessment of the antibacterial activity. The obtained results show that the incorporation of AgNPs into PVDF nanofibers further enhances the piezoelectricity (crystalline ß-phase fraction), already improved by the electrospinning process, compared to solution-casted samples, but only with a AgNPs/PVDF concentration of up to 0.3%; a further increase in the nanoparticles led to a ß-phase reduction. The cytotoxicity assay showed a promising effect of PVDF/AgNPs nanofibers on the MDA-MB-231 breast cancer cell line, following the non-toxicity displayed in regard to the healthy MRC-5 cell line. The antibacterial effect of PVDF/AgNPs nanofibers showed promising antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus, as a result of the Ag content. The anticancer activity, combined with the electrical properties of nanofibers, presents new possibilities for smart, multifunctional materials for cancer treatment development.

Advancements in Flexible Nanogenerators: Polyvinylidene Fluoride-Based Nanofiber Utilizing Electrospinning.

With the gradual miniaturization of electronic devices and the increasing interest in wearable devices, flexible microelectronics is being actively studied. Owing to the limitations of existing battery systems corresponding to miniaturization, there is a need for flexible alternative power sources. Accordingly, energy harvesting from surrounding environmental systems using fluorinated polymers with piezoelectric properties has received significant attention. Among them, polyvinylidene fluoride (PVDF) and PVDF co-polymers have been researched as representative organo-piezoelectric materials because of their excellent piezoelectric properties, mechanical flexibility, thermal stability, and light weight. Electrospinning is an effective method for fabricating nanofibrous meshes with superior surface-to-volume ratios from polymer solutions. During electrospinning, the polymer solution is subjected to mechanical stretching and in situ poling, corresponding to an external strong electric field. Consequently, the fraction of the piezoelectric ß-phase in PVDF can be improved by the electrospinning process, and enhanced harvesting output can be realized. An overview of electrospun piezoelectric fibrous meshes composed of PVDF or PVDF co-polymers to be utilized is presented, and the recent progress in enhancement methods for harvesting output, such as fiber alignment, doping with various nanofillers, and coaxial fibers, is discussed. Additionally, other applications of these meshes as sensors are reviewed.

Hybridization of Polymer-Encapsulated MoS2-ZnO Nanostructures as Organic-Inorganic Polymer Films for Sonocatalytic-Induced Dye Degradation.

The development of environmentally friendly technology is vital to effectively address the issues related to environmental deterioration. This work integrates ZnO-decorated MoS2 (MZ) to create a high-performing PVDF-based PVDF/MoS2-ZnO (PMZ) hybrid polymer composite film for sonocatalytic organic pollutant degradation. An efficient synergistic combination of MZ was identified by altering the ratio, and its influence on PVDF was assessed using diverse structural, morphological, and sonocatalytic performances. The PMZ film demonstrated very effective sonocatalytic characteristics by degrading rhodamine B (RhB) dye with a degradation efficiency of 97.23%, whereas PVDF only degraded 17.7%. Combining MoS2 and ZnO reduces electron-hole recombination and increases the sonocatalytic degradation performance. Moreover, an ideal piezoelectric PVDF polymer with MZ enhances polarization to improve redox processes and dye degradation, ultimately increasing the degradation efficiency. The degradation efficiency of RhB was seen to decrease while employing isopropanol (IPA) and p-benzoquinone (BQ) due to the presence of reactive oxygen species. This suggests that the active species •O2- and •OH are primarily responsible for the degradation of RhB utilizing PMZ2 film. The PMZ film exhibited improved reusability without substantially decreasing its catalytic activity. The superior embellishment of ZnO onto MoS2 and effective integration of MZ into the PVDF polymer film results in improved degrading performance.

Repair of parastomal hernias with the intraperitoneal funnel meshes IPST-R and IPST.

The treatment of parastomal hernias (PSH) represents a major challenge in hernia surgery. Various techniques have been reported with different outcomes in terms of complication and recurrence rates. The aim of this study is to share our initial experience with the implantation of the DynaMesh-IPST-R and -IPST, intraperitoneal funnel meshes made of polyvinylidene fluoride (PVDF). This is a retrospective observational cohort study of patients treated for PSH between March 2019 and April 2023 using the chimney technique with the intraperitoneal funnel meshes IPST-R or IPST. The primary outcome was recurrence and the secondary outcomes were intraoperative and postoperative complications, the latter assessed using the Clavien-Dindo classification. A total of 21 consecutive patients were treated with intraperitoneal PVDF funnel meshes, 17 with IPST-R and 4 with IPST. There were no intraoperative complications. Overall, no complications occurred in 61.9% (n = 12) of the patients. Major postoperative complications (defined as Clavien-Dindo ≥ 3b) were noted in four cases (19.0%). During the mean follow-up period of 21.6 (range 4.8-37.5) months, one patient (4.8%) had a recurrence. In conclusion, for the treatment of parastomal hernias, the implantation of IPST-R or IPST mesh has proven to be efficient, easy to handle, and very safe. In particular, the low recurrence rate of 4.8%, which is in line with the current literature, is convincing. However, a larger number of patients would improve the validity of the results.

Ultraviolet Grafting of Bismuth Oxide Enhances the Photocatalytic Performance of PVDF Membrane and Improves the Problem of Membrane Fouling.

Photocatalytic membranes are crucial in addressing membrane fouling issues. However, the grafting amount of the catalyst on the membrane often becomes a key factor in restricting the membrane's self-cleaning capability. To address the challenge, this manuscript proposes a method for solving membrane fouling, featuring high grafting rates of bismuth oxide (Bi2O3) and acrylic acid (AA), significant contaminant degradation capability, and reusability. A highly photocatalytic self-cleaning microfiltration membrane made of polyvinylidene fluoride bismuth oxide and acrylic acid (PVDF-g-BA) was prepared by attaching nano Bi2O3 and acrylic acid onto the polyvinylidene fluoride membrane through adsorption/deposition and UV grafting polymerization. Compared with pure membranes and pure acrylic grafted membranes (PVDF-g-AA), the modified membrane grafted with 0.5% bismuth oxide not only improves the grafting rate and filtration performance, but also has higher self-cleaning ability. Furthermore, the degradation effect of this membrane on the organic dye methyl violet 2B under visible light irradiation is very significant, with a degradation rate reaching 90% and almost complete degradation after 12 h. Finally, after repeated filtration and photocatalysis, the membrane can still significantly degrade contaminants and can be reused.

Electrospun Polyvinylidene Fluoride Membranes: Waterproofing and Acoustic Performance for Air and Acoustic Vents in Electronics.

Advancements in electronic devices demand materials capable of exceptional performance in various challenging environments. This study presents polyvinylidene fluoride (PVDF) nonwoven membranes with controlled porosity, created using an air-guided electrospinning method, followed by a calendaring process. These membranes exhibit a combination of water-repellent properties and sound transmission capabilities, making them ideal candidates for use in air and acoustic vents in electronic systems. A key feature of our membrane is the three-dimensional nanostructured pores, ranging from 0.20 to 0.76 µm, with a mean pore size of 0.51 µm, achieved through the formation of randomly arranged long nanofibers. By employing both experimental and theoretical methods, we achieved impressive performance metrics: air permeability of 0.86 cm3/cm2/s, water contact angles up to 139.3°, and breakthrough pressure as low as 0.27 MPa. Our PVDF nonwoven membranes maintain an optimal balance of stiffness, density, and air permeability, leading to exceptionally low sound transmission loss values ranging between -10 and -40 dBV/Pa, all while preserving their structural integrity. These findings contribute to the development of next-generation waterproof and acoustically permeable membranes, offering enhanced performance capabilities in demanding operational scenarios. This work advances the field of nanomaterials, environmental engineering, and acoustic technologies, with the potential to influence the design of future electronic devices.

Core-Shell Composite Nanofibers with High Temperature Resistance, Hydrophobicity and Breathability for Efficient Daytime Passive Radiative Cooling.

Radiative cooling technology, which is renowned for its ability to dissipate heat without energy consumption, has garnered immense interest. However, achieving high performance, multifunctionality, and smart integration while addressing challenges such as film thickness and enhancing anisotropic light reflection remains challenging. In this study, a core-shell composite nanofiber, PVDF@PEI, is introduced and designed primarily from a symmetry-breaking perspective to develop highly efficient radiative cooling materials. Using a combination of solvent-induced phase separation (EIPS) inverse spinning and (aggregation) self-assembly methods (EISA or EIAA) and coaxial electrostatic spinning (ES), superconformal surface anisotropic porous nanofiber membranes are fabricated. These membranes exhibit exceptional thermal stability (up to 210 °C), high hydrophobicity (contact angle of 126°), robust UV protection (exceeding 99%), a fluorescence multiplication effect (with a 0.6% increase in fluorescence quantum efficiency), and good breathability. These properties enable the material to excel in a wide range of application scenarios. Moreover, this material achieved a remarkable daytime cooling temperature of 8 °C. The development of this fiber membrane offers significant advancements in the field of wearables and the multifunctionality of materials, paving new paths for future research and innovation.

Quasi-Gel Polymer Electrolyte Interfaced with Electrodes through Solvent-Swollen Poly(ethylene oxide) for High-Performance Lithium/Lithium-Ion Batteries.

Solid polymer electrolytes (SPEs) are regarded as a superior alternative to traditional liquid electrolytes of lithium-ion batteries (LIBs) due to their improved safety features. The practical implementation of SPEs faces challenges, such as low ionic conductivity at room temperature (RT) and inadequate interfacial contact, leading to high interfacial resistance across the electrode and electrolyte interfaces. In this study, we addressed these issues by designing a quasi-gel polymer electrolyte (QGPE), a blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(ethylene oxide) (PEO), and succinonitrile (SN), with the desired mechanical strength, ionic conductivity, and interfacial stability through a simple solution casting technique. The QGPE features a thin solvated PEO layer on its surface, which wets the electrode, reducing the interfacial resistance and ensuring a homogeneous Li-ion flux across the interface. The optimized QGPE exhibits a good lithium-ion conductivity of 1.14 × 10-3 S cm-1 with a superior lithium-ion transference number of 0.7 at 25 °C. The Li/QGPE/Li symmetric cell exhibits a highly reversible lithium plating/stripping process for over 1300 h with minimal voltage polarization of ∼20 mV. The Li/QGPE/LiFePO4 full cell demonstrates good rate capability and excellent long-term cycling performance at a 0.1 C rate at 25 °C, maintaining a specific discharge capacity of 148 mAh g-1 over 200 cycles. The effectiveness of QGPE for LIBs is proven using a graphite/QGPE/LiFePO4 4 × 4 cm pouch cell, showcasing outstanding flexibility and tolerance against intentional abuse.

Enhancing Thermoelectric and Cooling Performance of Bi0.5Sb1.5Te3 through Ferroelectric Polarization in Flexible Ag/PZT/PVDF/Bi0.5Sb1.5Te3 Film.

Bi2Te3-based thin films are gaining recognition for their remarkable room temperature thermoelectric performance. Beyond the conventional "process-composition-performance" paradigm, it is highly desirable to explore new methods to enhance their performance further. Here, we designed a sandwich-structured Ag/PZT/PVDF/Bi0.5Sb1.5Te3(BST) thin film device and effectively regulated the performance of the BST film by controlling the polarization state of the PZT/PVDF layers. Results indicate that polarization induces interlayer charge redistribution and charge transfer between PZT/PVDF and BST, thereby achieving the continuous modulation of the electrical transport characteristics of BST films. Finally, following polarization at a saturation voltage of 3 kV, the power factor of the BST film increased by 13% compared to the unpolarized condition, reaching 20.8 µW cm-1 K-2. Furthermore, a device with 7 pairs of P-N legs was fabricated, achieving a cooling temperature difference of 11.0 K and a net cooling temperature difference of 2.4 K at a current of 10 mA after the saturation polarization of the PZT/PVDF layer. This work reveals the critical effect of introducing ferroelectric layer polarization to achieve excellent thermoelectric performance of the BST film.

ZIF-67@polyvinylidene fluoride mixed matrix membranes towards improved hydrogen separation performance.

This work is primarily focused on overcoming the limitations of polymeric membranes in achieving the balance between permeability and selectivity of the separation performance. The filler, Zeolitic imidazole framework -67 (ZIF-67) nanoparticles were synthesised in cubical morphology using hexadecyltrimethylammonium bromide (CTAB) as a surfactant via the wet-chemical method. The uniform particles with particle sizes ranging between 120-180 nm were incorporated into the polyvinylidene fluoride (PVDF) matrix to fabricate mixed matrix membranes via the phase inversion method. These mixed matrix membranes were systematically characterised to confirm the chemical, structural and morphological properties of the materials and membranes. Furthermore, the membranes showed a 56.5% improvement in their mechanical properties. The results confirm that 5 wt.% ZIF-67/PVDF membrane showed the best separation results compared to its pure counterpart. The permeability of H2 gas was reported to be 1,094,511 Barrer, with selectivities of 3.03 for H2/CO2 and 3.06 for H2/N2. This represents a 210.6% increase in the permeability of H2 gas. These results demonstrate the influence of ZIF-67 loading in the PVDF polymer matrix along with the potential of ZIF-67/PVDF mixed matrix membranes in the field of hydrogen separation and purification.

AC/DC Magnetic Field Sensing Based on a Piezoelectric Polymer and a Fully Printed Planar Spiral Coil.

Additive manufacturing (AM) is emerging as an eco-friendly method for minimizing waste, as the demand for responsive materials in IoT and Industry 4.0 is on the rise. Magnetoactive composites, which are manufactured through AM, facilitate nonintrusive remote sensing and actuation. Printed magnetoelectric composites are an innovative method that utilizes the synergies between magnetic and electric properties. The study of magnetoelectric effects, including the recently validated piezoinductive effect, demonstrates the generation of electric voltage through external AC and DC magnetic fields. This shift in magnetic sensors, utilizing piezoinductive effect of the piezoelectric polymer poly(vinylidene fluoride), PVDF, eliminates the need for magnetic fillers in printed devices, aligning with sustainability principles, essential for the deployment of IoT and Industry 4.0. The achieved sensitivity surpasses other studies by 100 times, showcasing linear outputs for both applied AC and DC magnetic fields. Additionally, the sensor capitalizes on the linear phase shift of the generated signal with an applied DC magnetic field, an unprecedented effect. Thus, this work introduces a remarkable magnetoactive device with a sensitivity of ST = 95.1 ± 0.9 µV Oe-1 mT-1, a significantly improved performance compared to magnetoelectric devices using polymer composites. As a functional proof of concept of the developed system, a magnetic position sensor has been demonstrated.

Lithium-Rich Porous Aromatic Framework Doped Quasi-Solid Polymer Electrolyte for Lithium Battery with High Cycling Stability.

Lithium-ion batteries (LIBs) have revolutionized the energy storage landscape and are the preferred power source for various applications, ranging from portable electronics to electric vehicles. The constant drive and growth in battery research and development aim to enhance their performance, energy density, and safety. Advanced lithium batteries (LIBs) are considered to be the most promising electrochemical storage devices, which can provide high specific energy, volumetric energy density, and power density. However, the trade-off between ionic conductivity and cycling stability is still a major contradiction for SPEs. In this work, a novel hydroxylated PAF-1 was designed and synthesized through post-modification, and the lithium-rich single-ion porous aromatic framework PAF-1-OLi was thereafter prepared by lithiation, achieved with a specific surface area to be 155 m2 g-1 and a lithium content of 2.01 mmol g-1. PAF-1-OLi, lithium bis(trifluoromethanesulfony)limine (LiTFSI), and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) were compounded to obtain PAF-1-OLi/PVDF by solution casting, which had good mechanical, thermodynamic, and electrochemical properties. The ion conductivity of PAF-1-OLi/PVDF infiltrated with plasticizer was 2.93 × 10-4 S cm-1 at 25 °C. The tLi+ was 0.77, which was much higher than that of the traditional dual-ion polymer electrolytes. The electrochemical window of PAF-1-OLi/PVDF can reach 4.9 V. The Li//PAF-1-OLi/PVDF//LiFePO4 battery initial discharge specific capacity was 147 mAh g-1 and reached 134.9 mAh g-1 after 600 cycles with a capacity retention rate of 91.2%, demonstrating its good cycling stability. The anionic part of lithium salt was fixed on the framework of PAF-1 to increase the Li+ transfer number of PAF-1-OLi/PVDF. The lithium-rich PAF-1-OLi and the LiTFSI provided abundant Li+ sources to transfer, while PAF-1-OLi helped to form a continuous Li+ transport channel, effectively promoting the migration of Li+ in the PAF-1-OLi/PVDF and effectively improving the Li+ conductivity. This study afforded a novel polymer electrolyte based on lithium-rich PAF-1-OLi, which has excellent electrochemical performance, providing a new choice for the polymer electrolyte of lithium batteries.

Catechol-Fe(III) complexes modified PVDF membrane for hazardous pollutants separation and antifouling properties.

Organic pollutants, such as toluene and xylene, in industrial wastewater negatively impact the environment. Membrane treatment is one of the best methods to reduce impurities in wastewater. Existing membranes that coat the water surface with hydrophilic material only effectively resist the initial fouling, resulting in poor oil and water selectivity. Here we report a simple and efficient method to enhance the water flux and antifouling properties of polyvinylidene fluoride (PVDF) membranes. This method involves developing and applying Catechol-Fe(III) complexes with a rough surface to the PVDF surface. Forming Catechol-Fe(III) complexes on the surface better anchors them to the membrane than the dip-coating method. The PVDF membranes with rough Catechol-Fe(III) complexes are superoleophobic, with an oil contact angle of 152 ° and high permeability, with pure water flux of 10487 Lm-2h-1bar-1 and 1 wt% toluene in water emulsion flux of 4697 Lm-2h-1bar-1. Overall, the straightforward manufacturing process, increased permeability, and outstanding antifouling capabilities of the PVDF membrane incorporating rough nanoparticles offer promising prospects for designing and implementing suitable membranes for oil in water emulsion separation applications.

Establishment of a Mass Concrete Strength-Monitoring Method Using Barium Titanate-Bismuth Ferrite/Polyvinylidene Fluoride Nanocomposite Piezoelectric Sensors with Temperature Stability.

Mass concrete is widely used in large-scale projects, including metro upper cover structures, water conservancy dams, and heavy equipment foundations, among others, necessitating the process of health monitoring in mass concrete construction. The development of reliable and simple strength-monitoring methods for mass concrete is challenging because the inner temperature of mass concrete is high and changes a lot. This study proposes a strength-monitoring approach for mass concrete using barium titanate-bismuth ferrite/polyvinylidene fluoride (BT-BFO/PVDF) nanocomposite piezoelectric sensors, wherein the new sensors are embedded as actuators and sensors in mass concrete. The stress wave generated by the BT-BFO/PVDF piezoelectric sensors is used to monitor the specimen's strength for 28 days. The piezoelectric voltage received by the sensors in mass concrete is analyzed. The experimental results indicate that the signal received by the BT-BFO/PVDF sensors is not easily affected by the internal temperature of mass concrete compared with that of the traditional PVDF piezoelectric sensors. The signal parameters sensitive to concrete strength variation and the change trend of concrete strength are closely related to the piezoelectric voltage. Therefore, the proposed approach using BT-BFO/PVDF nanocomposite piezoelectric sensors is efficient (error < 10%) in mass concrete monitoring. Moreover, the monitoring results do not need temperature compensation. The physical meaning of the obtained strength prediction formula is proposed. An experimental system based on PVDF dynamic strain-sensing characteristics is established.

Influence of photothermal nanomaterials localization within the electrospun membrane structure on purification of saline oily wastewater based on photothermal vacuum membrane distillation.

Today, synergistic combination of special nanomaterials (NMs) and electrospinning technique has emerged as a promising strategy to address both water scarcity and energy concerns through the development of photothermal membranes for wastewater purification and desalination. This work was organized to provide a new perspective on membrane design for photothermal vacuum membrane distillation (PVMD) through optimizing membrane performance by varying the localization of photothermal NMs. Poly(vinylidene fluoride) omniphobic photothermal membranes were prepared by localizing graphene oxide nanosheets (GO NSh) (1) on the surface (0.2 wt%), (2) within the nanofibers structure (10 wt%) or (3) in both positions. Considering the case 1, after 7 min exposure to the 1 sun intensity light, the highest temperature (∼93.5 °C) was recorded, which is assigned to the accessibility of GO NSh upon light exposure. The case 3 yielded to a small reduction in surface temperature (∼90.4 °C) compared to the case 1, indicating no need to localize NMs within the nanofibers structure when they are localized on the surface. The other extreme belonged to the case 2 with the lowest temperature of ∼71.3 °C, which is consistent with the less accessibility of GO NSh during irradiation. It was demonstrated that the accessibility of photothermal NMs plays more pronounced role in the membrane surface temperature compared to the light trapping. However, benefiting from higher surface temperature during PVMD due to enhanced accessibility of photothermal NMs is balanced out by decrease in the permeate flux (case 1: 1.51 kg/m2 h and case 2: 1.83 kg/m2 h) due to blocking some membrane surface pores by the binder. A trend similar to that for flux was also followed by the efficiency. Additionally, no change in rejection was observed for different GO NSh localizations.

Prediction of a Novel Electromechanical Response in Polar Polymers with Rigid Backbones: Contrasting Furan-Derived Nanothreads to Poly(Vinylidene Fluoride).

Syn furan nanothreads have all oxygen atoms arranged on one side of the thread backbone; these polar threads present intriguing opportunities in electromechanical response owing to their rigid ladder-like backbone. We retrained a C/H/O reactive force field to simulate their response to external electric field for both end-anchored individual threads and bulk nanothread crystals, contrasting the results to those for poly(vinylidene fluoride) (PVDF) polymer. Whereas the field induces a length-independent torque in PVDF through backbone rotation about σ bonds, furan-derived nanothreads generate a length-dependent torque by progressively twisting their rigid backbone. This mode of response couples the rotational history of the electric field to axial tension in the anchored thread. In simulations of densely packed syn furan nanothread crystals without anchors, the crystals pole in a field (∼3 GV/m at 300 K) similar to that seen in simulations of PVDF, suggesting that crystals of polar nanothreads can be ferroelectric.

Surface modification of PVDF ultrafiltration membranes using spacer arms and synthetic receptors for virus capturing and separation.

Although membrane technology has demonstrated outstanding pathogen removal capabilities, current commercial membranes are insufficient for removing small viruses at trace levels due to certain limitations. The theoretical and practical significance of developing a new form of hydrophilic, anti-fouling, and virus-specific ultra-purification membrane with high capturing and separation efficiency, stability, and throughput for water treatment is of the utmost importance. In this study, molecularly imprinted membranes (MIMs) were fabricated from polyvinylidene fluoride (PVDF) membranes utilizing novel surface hydrophilic modification techniques, followed by the immobilization of virus-specific molecularly imprinted nanoparticles (nanoMIPs) as synthetic receptors. Three distinct membrane functionalization strategies were established and optimized for the first time: membrane functionalization with (i) polyethyleneimine (PEI) and dopamine (DOP), (ii) PEI and 3-(chloropropyl)-trimethoxysilane (CTS), and (iii) chitosan (CS). Hydrophilicity was enhanced significantly as a result of these modification strategies. Additionally, the modifications enabled spacer arms between the membrane surface and the nanoMIPs to decrease steric hindrance. The surface chemistry, morphology, and membrane performance results from the characterization analysis of the MIMs demonstrated excellent hydrophilicity (e.g., the functionalized membrane presented 37.84° while the unmodified bare membrane exhibited 128.94° of water contact angle), higher permeation flux (145.96 L m-2 h-1 for the functionalized membrane), excellent uptake capacity (up to 99.99 % for PEI-DOP-MIM and CS-MIM), and recovery (more than 80 % for PEI-DOP-MIM). As proof of concept, the cutting-edge MIMs were able to eliminate the model adenoviruses up to 99.99 % from water. The findings indicate that the novel functionalized PVDF membranes hold promise for implementation in practical applications for virus capture and separation.