Bare Polymer Research Articles

Green synthesised Mn3O4 and poly (o-phenylenediamine) for antimicrobial textile-based supercapacitor applications

The advancement of wearable supercapacitors (SCs) has recently garnered a lot of attention owing to their ease of fabrication into textiles, low cost, long cycle life, fast charging and discharging, high efficiency, and ability to bridge the energy and power gap between conventional capacitors and batteries. The present study focuses on the development of wearable textile-based SC electrodes using green-synthesised manganese oxide nanoparticles functionalised on poly(o-phenylenediamine) reinforced to a polymer nanocomposite. The prepared nanocomposite was characterized using spectroscopic techniques such as UV-visible spectroscopy, Fourier transform infrared spectroscopy, x-ray diffraction studies, and scanning electron microscopy to validate the incorporation of metal oxide nanoparticles into the polymer matrix. The thermal properties were studied using thermogravimetric analysis and differential scanning calorimetry. The electrochemical performance of the bare polymer and the nanocomposite was evaluated using cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy techniques. An impressive specific capacitance of 213 Fg-1was achieved at a current density of 1 Ag-1for the polymer nanocomposite and even after 1000 cycles a capacitance retention of 89% was observed. Enhanced antimicrobial activity was also observed for the nanocomposite against both gram-negative and gram-positive bacteria. Based on these attributes, the fabricated device can be used as an efficient antimicrobial wearable SC.

Electrochemical performances and antibacterial activity of green synthesized cobalt oxide nanoparticles and poly (o‐Phenylenediamine) based textile supercapacitor

AbstractThe demands for electric automotive and regenerative energy storage applications in various fields have brought the attention of researchers towards supercapacitors due to their high specific power, long cycle life, and their ability to bridge the power/energy gap between conventional capacitors and batteries/fuel cells. The incorporation of metal oxide nanoparticles into the functionalized polymer matrix enhances the efficiency of supercapacitor. UV, FT‐IR, TGA, XRD, and SEM analyses validates the incorporation of metal oxide into the polymer matrix to form polymer nanocomposite. A specific capacitance of 186.4 Fg−1 was observed for PoPD‐1 nanocomposite‐based device at a charge density of 1 A/g. The bare polymer and the nanocomposite also exhibited good antimicrobial efficacy and can be used as textiles for therapeutic applications.

Flexible carbon‐based fluoropolymer composites for effective EMI shielding and heat dissipation

AbstractContemporary applications require protection against overheating and electromagnetic radiation interference, preferably with reduced mass and enhanced basic performance, such as flammability or chemical or UV resistance and often also low or non‐electrically conductive. Materials exhibiting all these functions can be designed, but there is usually not just one but several different materials with advanced processing requirements; therefore, a simple manufacturing method providing percolation path formation involving powder mixing and hot pressing of providing excellent flexibility terpolymer comprising tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride monomeric units (THV)‐based nanocomposites is presented here. The addition of the graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) significantly improves the EMI shielding effectiveness, up to SETOT = 23 dB for the GNP filler, SETOT = 17 dB for the MWCNT/GNP filler per 1 mm samples thickness and enhances almost 900% the thermal conductivity to almost 2 W/mK per GNP filler. Besides this improvement, the electrical conductivity remains at a low level, not surpassing 1.5 S/cm, which is, as mentioned above, beneficial in many applications, especially thermal management. Moreover, the proposed material is an excellent alternative to flexible foam or sponges.Highlights Structural, electrical, EMI shielding, and thermal properties of flexible THV/GNP, THV/MWCNT, and THV/MWCNT/GNP nanocomposites are shown here. The oriented, long as over 1 mm filler paths are observed. The GNP filler provides the best thermal conductivity enhancement of over 800% compared to bare polymer. The EMI shielding effectiveness is dominated by absorption for all THV‐based nanocomposites. The electrical conductivity follows the power law, reaching σ = 1.49 S/cm for GNP‐filled nanocomposites.

Experimental and numerical investigations of VO2‐UHMWPE polymer composite plates across phase change temperature

AbstractIn the present study, experimental and numerical investigations are carried out on Vanadium dioxide (VO2)‐UHMWPE composite plates while considering the temperature across phase change. VO2 is known for semiconducting to metallic transition along with structural changes from monoclinic to tetragonal during heating above 68°C, which enhances structural stiffness. For the experimentation, VO2‐UHMWPE composite samples are fabricated by employing the Hot‐Press method. These samples are further utilized to perform the compression test in order to find Young's moduli at room temperature (RT) and 75°C (temperature across phase change) using a Universal Testing Machine (UTM). Based on the experimentally computed Young's moduli, the numerical investigations in terms of free vibration and bending analyses, are performed. For structural kinematics, a C0‐continuous higher‐order shear deformation theory (HSDT) is employed, and the governing equations are derived using the Lagrange model. The numerical results, that is, natural frequencies and center deflection, are assessed using the finite element method (FEM). The convergence and comparison studies are accomplished to ensure the performance and competence of the present numerical model within the framework of MATLAB and ABAQUS. The influence of temperature, thickness ratio, boundary conditions, etc. on the frequency and deflection of the bare UHMWPE polymer and VO2‐UHMWPE plates, is discussed in detail. Based on the results, it can be concluded that the VO2 reinforcement to the UHMWPE polymer improves structural stiffness at a temperature of 75°C. Moreover, VO2‐UHMWPE composite can be utilized for structural applications, wherein lightweight and high‐temperature resistive material is desired.Highlights The fabrication of the VO2‐UHMWPE composite samples is accomplished through the Hot‐Press method. Young's moduli of the VO2‐UHMWPE composites at RT and 75°C are assessed utilizing UTM. The finite element method is employed to analyze the behavior of the bare UHMWPE polymer and VO2‐UHMWPE plates in free vibration and bending. The effect of influencing parameters such as temperature, thickness ratio, boundary conditions, etc., on natural frequency and deflection of the plates are explored.

Tuning acceptor content and molecular structure in linear donor–acceptor polymeric photocatalysts for ultrahigh-performance visible-light-driven hydrogen evolution

A series of linear conjugated polymers were synthesized by tuning the dibenzothiophene-S,S-dioxide (DBTO) content and varying their molecular structures, and applied to study the light-driven hydrogen generation from water. We found that the photocatalytic hydrogen evolution rate (HER) under visible light irradiation improved upon increasing the content of DBTO segment in donor–acceptor (D–A) structural polymers. Benefiting from the D–A structure and the high content of active centers of DBTO group, the polymer DB-Th displayed an unprecedentedly high HER of 334.50 mmol g−1h−1 under visible-light-driven and cocatalyst-free conditions (one of the most effective bare polymer photocatalysts that has been reported), which is 1.38-fold as that of the 2D–A type polymer with the lower DBTO content and 255-fold as that of the D–D structural polymer without DBTO segment, demonstrating the significance of acceptor content in D–A structures for achieving ultrahigh photocatalytic hydrogen evolution activity under visible light.

Molecular Engineering in D-π-A-A-Type Conjugated Microporous Polymers for Boosting Photocatalytic Hydrogen Evolution.

Conjugated microporous polymer (CMP) photocatalysts with donor-π-acceptor (D-π-A) or donor-acceptor (D-A) structures have garnered great attention for solar-driven hydrogen generation because of their inherent charge separation nature and high surface area. Herein, we design a series of D-π-A-A-type CMP photocatalysts to uncover the influence of the content of the dibenzo[b,d]thiophene-S-S-dioxide (BTDO) acceptor on the photocatalytic activity. The results demonstrate that the acceptor content in the D-π-A-A-type CMP photocatalysts affects the electronic structure, the availability of reaction sites, and the separation between light-generated electrons and holes, which mainly determine the photocatalytic performance for H2 release. Benefiting from the synergy of light absorption, hydrophilicity, and active sites, the bare polymer PyT-BTDO-2 with an optimized BTDO content exhibits a high H2 production rate of 230.06 mmol h-1 g-1 under simulated sunlight, manifesting that the strategy of D-π-A-A structural design is efficacious for boosting the photocatalytic performance of CMP photocatalysts.

Dimensional effect of ZnO-g-C3N4 heterostructures on hydrophilic and anti-fouling properties of the PVDF/PAN composite membrane: Dye rejection

Bare polymer membranes face several limitations, including high fouling, low hydrophilicity, and high fouling resistance parameters. To overcome these challenges, modification methods such as adding polymer, monomer, inorganic, and other materials as additives are used. On the other hand, the type, gender, and morphology of additives are vital, owing to control of shape and size of pores, control of hydrophilicity, amount of dispersion in the membrane matrix, and overall improvement of membrane performance. In this research, ZnO-g-C3N4 heterostructures with different morphologies of ZnO were synthesized and added to the polymer membrane matrix. Several analyses confirmed the successful fabrication of membranes. The effect of the dimension (morphology) of the ZnO-g-C3N4 heterostructures on the dye removal and hydrophilic and anti-fouling properties of bare Polyvinylidene fluoride (PVDF)/Polyacrylonitrile (PAN) membrane was investigated. The 3 dimensional/2 dimensional (3D/2D) 18 wt% PVDF/PAN composite membrane with contact angle= 55.06º has pure water flux 95.8 L/m2 h, Bovine serum albumin (BSA) flux 39.4 L/m2 h, low resistance indexes, flux recovery ratio 87%, and rejection 95.3%, and 78.4%, for BSA and dye, respectively. Accordingly, 3D/2D 18 wt% PVDF/PAN composite membrane had better performance than other membranes owing to more hydrophilic properties, uniform and interconnected pores, and less surface roughness.

A Flexible Lithium-Ion-Conducting Membrane with Highly Loaded Titanium Oxide Nanoparticles to Promote Charge Transfer for Lithium-Air Battery.

In this research, we aim to investigate a flexible composite lithium-ion-conducting membrane (FC-LICM) consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and titanium dioxide (TiO2) nanoparticles with a TiO2-rich configuration. PVDF-HFP was selected as the host polymer owing to its chemically compatible nature with lithium metal. TiO2 (40-60 wt%) was incorporated into the polymer matrix, and the FC-LICM charge transfer resistance values (Rct) were reduced by two-thirds (from 1609 Ω to 420 Ω) at the 50 wt% TiO2 loading compared with the pristine PVDF-HFP. This improvement may be attributed to the electron transport properties enabled by the incorporation of semiconductive TiO2. After being immersed in an electrolyte, the FC-LICM also exhibited a Rct that was lower by 45% (from 141 to 76 Ω), suggesting enhanced ionic transfer upon the addition of TiO2. The TiO2 nanoparticles in the FC-LICM facilitated charge transfers for both electron transfer and ionic transport. The FC-LICM incorporated at an optimal load of 50 wt% TiO2 was assembled into a hybrid electrolyte Li-air battery (HELAB). This battery was operated for 70 h with a cut-off capacity of 500 mAh g-1 in a passive air-breathing mode under an atmosphere with high humidity. A 33% reduction in the overpotential of the HELAB was observed in comparison with using the bare polymer. The present work provides a simple FC-LICM approach for use in HELABs.

Galactose-functionalized methacrylate polymers as affinity sorbents for extraction of food allergen lectins

In this study, glycidyl methacrylate (GMA)-based materials functionalized with different galactose derivatives were prepared to be used as affinity sorbents for solid-phase extraction (SPE) of several food allergen lectins (such as phytohemagglutinin (PHA)). First, GMA-based polymers were synthesized and then galactose derivatives were immobilized onto the GMA surface using two different synthetic routes. In the first approach, the bare polymer was modified with ethylenediamine and glutaraldehyde, and subsequently two galactose derivatives were immobilized. In the second strategy, the starting polymer was modified with cystamine and gold nanoparticles (AuNPs), on which a thiolated galactose derivative was subsequently anchored. The resulting materials were characterized by scanning electron microscopy and used as SPE sorbents for the isolation of PHA (as probe protein) from food matrices. Different SPE parameters (sample pH, eluent solution composition, binding capacity, sample volume, selectivity and reusability) were evaluated. The material that provided the best PHA recovery (98%) was the one obtained in the second approach, being this material successfully applied to the selective extraction of PHA and other similar lectins from different foods (red and lima dried beans, fresh soybeans and biscuits containing soybean protein traces as indicated in their label). After SDS-PAGE of eluates, all samples only exhibited the characteristic PHA band around 30 kDa, suggesting the high potential of the developed material for application in food allergy field.

Fabrication and characterization of different polymer doped CNT nanocomposites for creatinine detection

In this paper, conducting, and natural polymers like polyaniline, polypyrrole and chitosan are doped with carboxylic acid (COOH) functionalized multiwalled carbon nanotubes (MWCNT) for the fabrication of bio-sensitive membrane of CNT based Bio-FET for label free and reliable detection of creatinine. The aim of this paper is to report a facile fabrication method comprising of chemical solution method which is cost effective, requires no sophisticated instrument and is therefore independent. Creatinine deiminase (CD) enzyme is immobilized on the developed bio-sensitive membrane by crosslinking technique. The physical characterization of the fabricated layer is performed by using X-ray Diffraction (XRD), Scanning electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) imaging technique. The electrochemical characterization of the fabricated layer is performed by Cyclic Voltammetry (CV). The respective bare polymer doped carbon nanocomposites and enzyme crosslinked polymer doped carbon nanocomposites are coated on ITO coated glass substrate with the help of spin coating technique and thereafter are used for electrochemical characterization. The XRD results illustrates the enforcement of crystalline behavior in the polymers and increase of electrical conductivity of the bio-sensitive membrane. The SEM results indicate uniform and compact crosslinking of CD with the respective polymers and COOH-MWCNTs composites. The FT-IR results describes the chemical composition and the bonding behavior of the enzyme with the respective polymers and the nanocomposites. The CV results illustrates a satisfactory electrochemical compatibility of the enzyme and the bare polymer nanocomposites. This describes the efficient bonding of the polymers and the enzyme on the large surface area of the nanocomposites. The obtained redox peaks justify the improvement of electrochemical conductivity of the enzyme and the polymers due to doping with COOH-MWCNT.

Sustainable valorization of asphaltenes via flash joule heating.

The refining process of petroleum crude oil generates asphaltenes, which poses complicated problems during the production of cleaner fuels. Following refining, asphaltenes are typically combusted for reuse as fuel or discarded into tailing ponds and landfills, leading to economic and environmental disruption. Here, we show that low-value asphaltenes can be converted into a high-value carbon allotrope, asphaltene-derived flash graphene (AFG), via the flash joule heating (FJH) process. After successful conversion, we develop nanocomposites by dispersing AFG into a polymer effectively, which have superior mechanical, thermal, and corrosion-resistant properties compared to the bare polymer. In addition, the life cycle and technoeconomic analysis show that the FJH process leads to reduced environmental impact compared to the traditional processing of asphaltene and lower production cost compared to other FJH precursors. Thus, our work suggests an alternative pathway to the existing asphaltene processing that directs toward a higher value stream while sequestering downstream emissions from the processing.

Polyaniline-tin(IV) molybdophosphate composite exchanger: Photocatalytic behavior and antibacterial activitiy

ABSTRACT. Polyaniline-tin(IV)molybdophosphate composite exchanger was prepared using sol–gel method by mixing polyaniline gel into the inorganic precipitates of tin(IV)molybdophosphate. The composite ion exchanger was characterized by various techniques such as XRD, UV-Vis, FTIR, SEM-EDX, and PL. Photocatalytic activities and antibacterial efficiencies of the bare polymer polyaniline (PANI), the inorganic exchanger tin(IV)molybdophosphate (TMP) and the composite polyaniline-tin(IV)molybdophosphate (PANI-TMP) were evaluated using methylene blue (MB) dye as a model organic pollutant and Gram negative and Gram positive bacteria as test microbes, respectively. Photocatalytic and antibacterial activities of polyaniline[1]tin(IV)molybdophosphate composite was found to be higher than that of organic (polyaniline) and inorganic (tin(IV)molybdophosphate) counterparts. The results obtained indicated the degradation efficiency of approximately 73% in 180 min exposure time. Effect of scavengers study evidenced the most important species in the degradation process to be (·O2 - ) and (·OH). Highest photocatalytic degradation efficiency for the composite exchanger studied was obtained at initial concentration of 10 mg/L MB, 100 mg/L of catalyst load and a pH of 8. Antibacterial efficiency of the exchanger over both Gram negative and Gram positive bacteria was found to be higher than the single counterparts.
 KEY WORDS: Ion exchangers, Antimicrobial activity, Composites, Photocatalysis, Polyaniline
 Bull. Chem. Soc. Ethiop. 2023, 37(1), 59-76. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i1.6 

Optimization of MIL-178(Fe) and Pebax® 3533 loading in mixed matrix membranes for CO2 capture

Global warming is considered as a consequence of extensive use of fossil fuels. Post combustion CO2 capture is an interesting and alternative solution where mixed matrix membranes (MMMs) can be an exciting candidate. This research focuses on the optimization of MMM composition consisting of Pebax® 3533 as the polymer matrix and porous coordination polymer (PCP) MIL-178(Fe) as a filler for gas separation application. MIL-178(Fe) characterized with SEM, TEM and TGA were applied to compare bare polymer and MMM. Optimum composition of the MMM obtained was 5 wt.% MIL-178(Fe) in Pebax® 3533. Average thickness of the optimized dense MMM was 116 ± 8 µm. Such MMM showed CO2 permeability and CO2/N2 selectivity of 312 ± 5 Barrer and 25.0 ± 0.5, respectively, 12% and 25% improved regarding the bare membrane. Additionally, optimum MMM was applied for CO2/CH4 separation and successfully compared in terms of improved CO2 permeability and CO2/CH4 selectivity.

Synthesis, properties, and material hybridization of bare aromatic polymers enabled by dendrimer support

Aromatic polymers are the first-choice platform for current organic materials due to their distinct optical, electronic, and mechanical properties as well as their biocompatibility. However, bare aromatic polymer backbones tend to strongly aggregate, rendering them essentially insoluble in organic solvent. While the typical solution is to install many solubilizing substituents on the backbones, this often provokes undesired property changes. Herein, we report the synthesis of bare aromatic polymers enabled by a dendrimer support. An initiator arene containing a diterpenoid-based dendrimer undergoes Pd-catalyzed polymerization with monomers bearing no solubilizing substituents to furnish bare aromatic polymers such as polythiophenes and poly(para-phenylene)s. The high solubility of dendrimer-ligated polymers allows not only the unveiling of the properties of unsubstituted π-conjugated backbone, but also mild release of dendrimer-free aromatic polymers and even transfer of aromatic polymers to other materials, such as silica gel and protein, which may accelerate the creation of hybrid materials nowadays challenging to access.

Novel fast ionic conductor ceramic composite separator for high-performance safe Li-ion power batteries

The ceramic composite separators coated with silica or alumina particles have been used in power batteries due to their better electrolyte wettability and better thermal stability compared with bare polymer separators. However, these oxide ceramics are Li+ ion insulators, which increase internal resistance and hinder the improvement of rate capability of batteries. Herein, we report a strategy to further improving the performance of lithium-ion batteries (LIBs) by using fast ionic conductor ceramic composite separator as an alternative to traditional ceramic coated separators. Lithium lanthanum titanate (LLTO), a fast ionic conductor with excellent room temperature bulk conductivity, are coated on the common polyethylene (PE) separators. Our results demonstrate that such a novel LLTO-coated separator possess excellent electrolyte wettability and thermal stability; and the assembled NCM523/graphite lithium-ion pouch cells with LLTO-coated separator show better rate capability and cyclic performance with 88.7% capacity retention after 1000 cycles at room temperature compared with the pouch cells with Al2O3-coated separators. The fast ionic conductor ceramic composite separators will be a potential competitor to the next-generation novel separators for high-performance Li-ion power batteries.

Polymer electrolytes based on magnesium triflate for quasi-solid-state magnesium-sulfur batteries

Herein, magnesium-ion conducting polymer electrolytes (PE) based on polyvinylidene fluoride (PVDF), tetraethylene glycol dimethyl ether (TEGDME), succinonitrile (SN), and different concentrations of magnesium triflate salt ((CF3SO3)2Mg) were fabricated. The structural, optical, electrical, and electrochemical properties were investigated. The conductivity increases to about 10−5 S.cm−1 with increasing the concentration of (CF3SO3)2Mg up to 33 wt%, at room temperature. The ionic transference number for the matrix containing 33 wt% of (CF3SO3)2Mg increases from ( = 0.4) to () with increasing the temperature comparatively from room temperature to 55 °C. Also, the cell with 33 wt% of (CF3SO3)2Mg shows low overpotential and steady Mg stripping/plating during the initial cycles at 55 °C. Polymer and dual electrolytes, as well as bare and modified Mg surface electrodes, are used to create Mg/S cells. The cell with a modified Mg surface electrode and dual electrolyte exhibit lower interfacial impedance, higher energy density, and charge-discharge capacity than the cell with a bare Mg electrode and polymer electrolyte.

Influence of Fused Deposition Modelling Nozzle Temperature on the Rheology and Mechanical Properties of 3D Printed β-Tricalcium Phosphate (TCP)/Polylactic Acid (PLA) Composite.

The primary goal of this study is to develop and analyze 3D printed structures based on a well-known composite known as β-Tricalcium Phosphate (TCP)– polylactic acid (PLA). There are some interesting aspects of this study. First, we developed 3D printable TCP–PLA composite filaments in-house, with high reproducibility, by a one-step process method using a single screw extruder. Second, we explored the physicochemical properties of the developed TCP–PLA composite filaments. Third, we investigated the effect of an FDM-based nozzle temperature of 190 °C, 200 °C, 210 °C, and 220 °C on the composite’s crystallinity and rheological and mechanical properties. Results confirmed the successful development of constant-diameter TCP–PLA composite filaments with a homogeneous distribution of TCP particles in the PLA matrix. We observed that a higher nozzle temperature in the FDM process increased the crystallinity of the printed PLA and TCP–PLA structures. As a result, it also helped to enhance the mechanical properties of the printed structures. The rheological studies were performed in the same temperature range used in the actual FDM process, and results showed an improvement in rheological properties at higher nozzle temperatures. The bare polymer and the composite polymer-ceramic melts exhibited lower viscosity and less rigidity at higher nozzle temperatures, which resulted in enhancing the polymer melt flowability and interlayer bonding between the printed layers. Overall, our results confirmed that 3D printable TCP–PLA filaments could be made in-house, and optimization of the nozzle temperature is essential to developing 3D printed composite parts with favorable mechanical properties.

Selective reflection enhancement by controlling of surface-layering structure of inorganic nanoparticles on polymer microspheres

Polymeric materials generally transmit or absorb UV light while weakly reflecting visible light. Treating the surface of a polymer material can increase reflectivity in the visible region. Inorganic nanoparticles, including silica and alumina, exhibit high reflectivity and light scattering at visible and UV wavelengths. Therefore, the possibility exists to absorb UV light and selectively reflect visible light by immobilizing a single layer of inorganic nanoparticles on the surface of polymer microspheres. Core-shell microspheres containing a layered shell of inorganic nanoparticles were prepared by a modified suspension polymerization method. The surface morphology of the microspheres was altered by changing the type, size, and amount of inorganic nanoparticles. The reflectivity of the microspheres was investigated via UV-Vis-NIR spectrophotometry. The packing density of the shell layer was controlled by changing the quantity of nanoparticles added. UV–visible spectroscopy indicates that the core-shell microspheres absorb UV light at wavelengths less than 380 nm and selectively reflect visible light at wavelengths greater than 400 nm. The reflectance of visible light is enhanced by changing the type and concentration of inorganic nanoparticles, and reflectance is increased by 26% relative to bare polymer microspheres. Thus, the core-shell microspheres absorb UV light and selectively reflect visible light.

Electrochemical Characterization of Modified Glassy Carbon Electrodes for Non-Enzymatic Glucose Sensors.

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers—cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OHads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.

Enhancement in pool boiling heat transfer of ethanol and nanofluid on novel supersonic nanoblown nanofiber textured surface

ABSTRACT Pool boiling of ethanol and Cu-nanofluid was investigated on bare and novel supersonic nanoblown polymer nanofiber nanotextured copper surface. Significant improvement in early ONB (2°C reduction), CHF (23.5%), and BHTC (~2–2.5 times) were achieved in nanotextured surface than bare one. Boiling of nanofluids led to the degradation of ONB and BHTC, with an increase in CHF by 16.7%. Synergistic effect of nanofluid boiling on nanotextured surface led to remarkable enhancement of CHF (44%), BHTC (>2.5 times), and ONB (3°C reduction). The nanofluid and nanotexture aided in ONB and CHF via enhancing nucleation sites, liquid overheating, bubble chopping, and surface wettability.