Morphological Stability Research Articles

Hydrothermal synthesis, response surface study, and interfacial tension evaluation of modified nanotube

Modification of pure Halloysite nanotube (pHNT) with organic and inorganic materials for various applications have been reported, but inadequately addressed in the area of enhanced oil recovery (EOR). This work for the first time employed Design-Expert Software tool to systematically modify the surface of the pHNT with Cerium and Silver nanoparticles to achieve optimum product yield; modified HNT (m-HNT). The influence of reactants on m-HNT yield were analysed via a Response Surface Methodology (RSM). Central composite design at 5-levels was deployed in determining the loading of the pHNT (1–5 g), Cerium Nitrate (Ce; 1–2 g) and Silver Nitrate (Ag; 0.5–2.5 g). The synthesis was accomplished by a Hydrothermal reflux method using a Teflon-lined Stainless-Steel Autoclave. The FTIR, FESEM, XRD and TGA were used to characterize the m-HNT. Subsequently, a spinning drop equipment was used to investigate the interfacial tension (IFT) reduction effect of the optimized m-HNT at different concentrations in comparison with the pHNT. Results have shown that the surface modification was successful after establishing improvements in terms of wave numbers, crystallography, morphology, and thermal stability in the m-HNT. In RSM analysis, the ANOVA demonstrates an adequate R2 of 99.5 %, signifying good data correlation. Thus, each of the pHNT, Ce and Ag is significant to the m-HNT yield (P < 0.05). At optimum conditions, experimental yield was found to be 92.4 % against the model predicted the yield of 94.7 %. Consequently, at this condition, the formulation of the m-HNT had reduced the IFT of the baseline brine/oil system from 9.2 ± 1.1 mN/m to a range of 0.043–0.052 mN/m at 100 to 500 ppm. Moreover, in comparison with the pHNT, about 17 to 41 % reduction effects were achieved by m-HNT at different concentrations. The study reveals that modifying the pHNT with Ce/Ag could improve its chemical properties and significantly offers good IFT reduction effect as parts of prerequisite conditions in enhanced oil recovery (EOR).

Adsorptive performance of a new magnetic hydrochar nanocomposite for highly efficient removal of cadmium ions from water: Mechanism, modeling, and reusability studies

In this study, a novel and effective magnetic watermelon seed hydrochar (MWSHC) was successfully synthesized via hydrothermal carbonization technique and in situ co-precipitation method. The prepared magnetic watermelon seed waste hydrochar has been utilized for the elimination of cadmium ions from the aqueous environment. The structural morphology, surface properties, and thermal stability of MWSHC adsorbent were characterized using FTIR, SEM, XRD, BET surface area, and TGA analysis, which demonstrated the successful synthesis of MWSHC. An extensive study of Cd(II) adsorption was conducted by assessing the influence of contact time, adsorbent mass, pH, initial Cd(II) concentration, temperature, and coexisting cations on the adsorption process of Cd(II). The results revealed that the removal efficiency of Cd(II) was 96.60% achieved at pH 7.0, time: 300 min, and dosage: 0.01 g, T: 298 K. Adsorption isotherm and kinetic parameters were estimated. The results indicated that the Cd(II) adsorption onto MWSHC followed the Freundlich and pseudo-second-order models. Based on the Langmuir equation, the MWSHC has a maximum adsorption capacity of 347.2 mg/g at 298 K. The reusability of magnetic hydrochar nanocomposite was studied, revealing that around 84.4% Cd(II) was still removed after four cycles. In conclusion, the newly- prepared MWSHC adsorbent has the advantages of high adsorption capacity, cost-effectiveness, and easy separation, thus having promising applications in effectively removing cadmium(II) from the aqueous environment.

Functions of local structural surrounding in activity of Ca-containing catalysts for vapor upgrading during biomass thermal decomposition

The catalytic activity of calcium-containing complex oxides with perovskite structure (CaTiO3), brownmillerite structure (Ca2Fe2O5 and Ca2FeAlO5), spinel structure (CaAl2O4), and pseudowollastonite structure (CaSiO3) was compared to CaO for the upgrading of Oakwood fast pyrolysis vapors. Initial catalyst particle sizes range between 0.61 and 3.21 μm, while the BET surface area is between 0.2 and 8.7 m2/g. In contrast to CaO, the complex oxides compounds demonstrated negligible CO2 and H2O chemisorption during catalytic fast pyrolysis, thereby a low deactivation of catalysts, good structural and morphological stability and thus high reusage feasibility. Due to their unique features, Ca-containing catalysts were found to promote specific reaction pathways, such as the conversion of guaiacol to 3-methyl phenol, 4-ethenyl-2-methoxyphenol to 4-ethyl-2-methoxyphenol, 1-(4-hydroxy-3,5-dimethoxyphenyl)ethanone to 3,5-dimethoxy acetophenone and long chain carboxylic acids to acetic acid through a multitude of reaction routes including demethylation/demethoxylation, hydrogenation and hydrodeoxygenation, oxidative cleavage, and dehydration reactions. CaO and Ca2Fe2O5 promoted the alkylation reactions within the methoxy phenolics, whilst CaSiO3 promoted hydrogenation reactions. The formation of acetic acid was promoted over Ca2FeAlO5, CaAl2O4, and CaSiO3, while acetone, 2-butanone, new cyclic C5 ketones were revealed over CaO. The resulting ketonic fraction was noticeably affected by the use of Ca2Fe2O5 and CaAl2O4 catalysts.

Migrating scour depth around a spur dike with downward seepage using multiscale characterizations

The current work uses an experimental method to analyse a multiscale statistical assessment of scour depth surrounding the spur dikes with downward seepage. The experiments used three T-shape spur dikes arranged in three series and provided outward from the channel's bank. A no-seepage condition and two distinct seepage velocities, VS1 = 0.09 mm/s and VS2 = 0.18 mm/s, were used in the experiments. Seepage from a channel affects the morphological behaviour and stability of the channel's bed, leading to changes in its hydrodynamic characteristics. In addition, downward seepage movement shifts the flow near the channel boundary and weakens the particles' stability. Thus, the streamwise velocity and Reynolds shear stress increase near the bed. As the seepage velocity increases, the local scour formation also rises relative to the channel's bed until the channel reaches a state of equilibrium. The celerity of scour depth for both time and length scales depends on the amount of downward seepage. Initially, higher seepage leads to faster changes in the scour depth, but over time, this rate decreases until it becomes constant. The bedform elevations' tails are thicker initially, but they become thinner and closer to the Gaussian distribution curve over time.

Influence of crosslinking effect on chemical and rheological properties of aged liquid bio-rubber composite SBS modified asphalt

The influence of the cross-linking effect between a liquid bio-rubber (LBR), a desulphurised crumb rubber formed via pyrolysis in bio-oil, SBS, a cross-linker, and asphalt on the chemical and rheological properties of aged LBR/SBS composite modified asphalt (LBR/SBSMA) was studied. Four types of modified asphalts were prepared by adding LBR, LBR+sulphur, LBR+SBS and LBR+SBS+sulphur to simulate cross-linking. FTIR and GPC were used to obtain oxidation, aromatisation and polymer degradation indexes and molecular weight. DSR and BBR were used to acquire rheological indexes. Sulphur was the key factor in achieving cross-linking, which promoted phase morphology stability, enhanced oxidation and aromatisation resistance and restrained polymer degradation. LBR could prevent the variation of |G*| and the change of δ in high frequency after ageing. The low-temperature performance of aged LBR asphalt was satisfactory. The cross-linking effect retained superior ageing resistance despite a slight impairment of low-temperature continuous grading temperature, producing a sustainable and high-performance modified asphalt.

Extraction of microfibrillated cellulose from elephant egesta and evaluating its reinforcing ability in pectin/alginate packaging films

AbstractPectin and sodium alginate (SA) composite films were prepared by adding various concentrations of microfibrillated cellulose (MFC) via solvent casting using glycerol as a plasticizer. Herein, elephant egesta was turned into cellulose fibers from which MFC was extracted. This paper aims to examine the reinforcing property of MFC on the pectin/SA matrix. Fibrous morphology, qualitative analysis, crystallinity, and thermal stability of MFC were confirmed through SEM, FT‐IR, XRD, and TGA‐DTA analysis, respectively. The impact of various compositions of MFC (0.5%, 1%, 2%, and 5%) on the biopolymeric blend was analyzed based on mechanical and optical properties, hygroscopicity, and hydrophilicity. The outcomes revealed that adding MFC to 5% enhances the film's tensile strength by 51%. The produced film also served as a successful barrier against UV–visible light. Moreover, it exhibits a tremendous increase in contact angle and a decrease in properties such as elongation at break, moisture content (MC) and water solubility (WS). Therefore, MFC can be an excellent reinforcing agent in biodegradable polymer composites, which finds application in the food packaging industry.Highlights Microfibrillated cellulose was successfully extracted from elephant egesta and characterized. Energy efficient method of extraction. Pectin/SA films were incorporated with the extracted MFC via solvent casting. Prepared films show enhanced tensile strength and UV–visible barrier property which makes them suitable for packaging purposes. Bio‐based polymers reduce environmental pollution.

Adsorption of Glucose Molecules on Stainless Steel Enables Ni‐Rich Passivation Film

AbstractStainless steel (SS) is well known for its remarkable versatility. Besides the importance of passivation film for durability and stability of SS, the composition and morphology of passive surface layer have to be precisely modified to create an alloy that is optimal for specific purposes. Herein, we report on the electrochemical preparation of nickel‐enriched passive film which is accomplished by the preferential adsorption of glucose on nickel species among constituents of SS. The presence of nickel‐rich surface and the exposure of nickel on the outmost surface layer participating in surface reactions are verified by monitoring redox couple of Ni2+/Ni3+ as well as elemental analyses (TEM‐Energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy). Reversible interchange of nickel‐rich into iron‐rich surface and vice versa is possible by adding or removing glucose. We find that molecules having more than tri‐dentate of hydroxy groups (e. g. glycerol) is required for the formation of Ni‐rich surface (chelate effect).

Acetylated rice starch nanocrystals improved the physical, mechanical, and structural properties of native rice starch based films

Rice starch nanocrystals (SNC) and acetylated rice starch nanocrystals (ASNC) with three different substitution degrees (DS) for 0.22 (ASNCa), 0.56 (ASNCb), and 0.83 (ASNCc), respectively, were synthesized. Starch nanocrystals (SNC, ASNCa, ASNCb and ASNCc) with varying concentrations (0–25 %) were used in the production of composite rice starch-based films plasticized with glycerol using the solvent casting technique. Films were compared concerning their morphology, moisture content and solubility, transmittance, tensile strength, elongation at break. The SNC and ASNC content and acetylated DS had a significant effect (p ≤ 0.05) on all the properties investigated when compared to the control film. The addition of ASNC resulted in less hydrophilic films and UV light barrier properties, and the addition of SNC and ASNC increased the rigidity of starch film. There was an increase of 156.7 % in tensile strength for 10 % ASNCc composite films and a reduction of 68.1 % in water vapor permeability for 20 % ASNCc composite films. The rice starch/ASNCb nanocomposite films with the addition of 5 % and 10 % ASNCb exhibited a compact, smooth, and flat surface structure. Therefore, these results showed that ASNC significantly improved the mechanical properties, surface morphology and thermal stability of the films.

Improvement in spectroscopic properties of Dy3+ doped Ba2Mg(PO4)2 phosphors through substitution strategy

In this work, we have synthesized Dy3+ activated Ba2Mg(PO4)2 phosphors by cationic/anionic substitution strategy. We have substituted Ca, Sr and VO4 in Ba2Mg(PO4)2 host lattice. These phosphors were synthesized by a high-temperature solid-state reaction method at 700 °C. The prepared samples' phase formation, thermal stability, photoluminescence properties and CIE coordinate were discovered in detail. The phase purity, morphology, functional groups and thermal stability of the prepared materials were investigated using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Fourier transform infrared (FT-IR) and Thermogravimetric – differential thermal analysis (TG-DTA) techniques. The Photoluminescence (PL) properties of Ba2Mg1−x(PO4)2:xDy3+, Ba2Mg1−x-ySry(PO4)2:xDy3+, Ba2Mg1−x-yCay(PO4)2:xDy3+ and Ba2Mg(1−x)(PO4)2−z(VO4)z:xDy3+ phosphors were studied in detailed. Under the different excitation wavelengths, the PL emission spectra show two characteristic peaks in the blue and yellow regions. In this study, the effect of cationic/anionic substitution has also been investigated. By co-doping (Sr2+, Ca2+, VO43-) ions, it was observed that the PL emission intensity increased significantly. The Commission Internationale de l′Elcairage (CIE) coordinates and color correlated temperature (CCT) of prepared samples were also calculated using ORSRAM SYLVANIA color calculator. The observed results revealed that Dy3+ activated Ba2Mg(PO4)2 phosphor and Sr2+, Ca2+, VO43- co-doped samples have potential applicability for detailed future studies in the field of lighting and display devices.

Nanosheet-assembled transition metal sulfides nanoflowers derived from CoMo-MOF for efficient oxygen evolution reaction

Oxygen evolution reaction (OER) is a multi-electron transfer process, whose intrinsic sluggish dynamic restricts the whole process of overall water splitting (OWS). To address this issue, a porous transition metal sulfide (TMS) catalyst with rich heterojunctions was prepared by vulcanization and trace Fe doping of CoMo-based metal–organic framework (MOF). In this work, the nanoflower composed of ultrathin 2D nanosheets anchored on a nickel foam presents a layered interface that contributes to the exposure of active regions. The resulting electrode denoted as Fe@CoMo2S4/Ni3S2/NF required a low overpotential (η10 = 167 mV @ 10 mA cm−2, η50 = 260 mV @ 50 mA cm−2) in 1.0 M KOH for OER and a small cell voltage (E = 1.513 V @ 10 mA cm−2) to power OWS when coupled with commercial Pt/C. It also exhibited splendid morphological and chemical stability with virtually invariant polarization curve and flower-like appearance after 1000 CV cycles, as well as long-term durability over 100 h with a constant current density of 10 mA cm−2. This work revealed the multi-anionic regulation mechanism in the surface reconstruction of sulfide electrocatalysts, and verified that Co/Mo/Ni-based oxysulfide was the true active substance of OER, which inspired the understanding and design of multi-anionic regulated electrocatalysts.

Dry Heat Treatment of Finger Millet Starch for Thin Films—Studies on Physicochemical, Mechanical, and Barrier Properties

AbstractThis research work aims to investigate the impact of dry heat treatment (DHT) on the morphological, structural, and physicochemical properties of native finger millet starch (FMS), with the goal of enhancing its applicability in thin films. The influence of DHT on FMS is examined through various parameters, including moisture content, amylose content, ash content, swelling power, and solubility. Subsequently, a sequential evaluation is conducted to assess the morphology, structural and thermal stability, film thickness, water vapor permeability, water solubility, and mechanical properties of thin films produced from both FMS and DHT‐modified FMS. Regarding the modification of FMS, the solubility of FMS exhibits improvement, while amylose content, swelling, ash, and moisture content exhibit a decline. Thin films fabricated using DHT‐modified FMS displays enhanced homogeneity and continuity, devoid of cracks and holes typically observed in native FMS‐based thin films. Furthermore, the mechanical properties, water solubility, and water vapor permeability of the films are also improved as a result of the DHT treatment.These results demonstrate that DHT can be useful for enhancing the physical and chemical properties of high amylose finger millet starch for its applications in edible films and coatings.

Electrochemical, optical and electrochromic properties of fused polydithienothiophene: A stable material with reversible doping

Fused-thiophene-based conjugated materials have received great importance due to their rigid and planar structure, enhancing the performance of electronic devices. We herein report the electrochemical synthesis of polydithieno[3,2-b:2′,3′-d]thiophene (PDTT) on different working electrodes (platinum, glassy carbon and ITO-coated glass) as well as on flexible ITO-coated PET electrode. We used both potentiodynamic and potentiostatic electropolymerization methods for the deposition of polymer films using TBAClO4/MeCN electrolyte-solvent system. The chemical and physical properties of the obtained polymer PDTT were characterized by FTIR, cyclic voltammetry, electrochemical impedance spectroscopy, UV–vis–NIR spectrophotometer and FESEM. The color of the film was red-orange in neutral form and transmission blue-grey in oxidized form. We explored the properties of PDTT in terms of electrochemical, optical and morphological stability, adhesion and chemical doping-dedoping. Further, the electrochromic behavior of the polymer films is presented at different wavelengths, and the coloration efficiency of 156.5 cm2C−1 and the maximum optical contrast of 26.4 % were recorded in the visible region. Finally, density functional theory (DFT) calculations on PDTT and its monomer were performed to understand the structure and energy levels and further compared with the experimental results.

Modified locally derived graphene nanoplatelets for enhanced rheological, filtration and lubricity characteristics of water-based drilling fluids

Drilling fluid rheology, filtration, and lubricity are fundamental parameters that influence the efficiency and ease of drilling operations. The drilling industry is constantly exploring different research areas for stabilizing and improving these parameters at high temperatures. The use of drilling fluid additives, especially synthetic polymers, poses a threat to the environment. Herein, rice husk char (RHC) was used to synthesize graphene Nanoplatelets (GNP) whose surface is modified with triton-X100 nonionic surfactant. Field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), Particle size distribution (PSD), Energy Dispersive X-Ray Analysis (EDX), and Zeta potential analysis are performed on the synthesized nanomaterials to verify their morphology, functional groups, particle size, elemental composition, and material stability. Synthesized GNP from RHC (GNP-RHC) along with surface-modified GNP-RHC (GNP-TXT) were examined critically and their properties compared using a water-based mud (WBM) formulation. The rheological and lubricity characteristics of all the mud samples were determined before and after hot rolling (AHR), and the filtration properties were determined under API and high pressure high temperature (HPHT) conditions. The TGA results indicate that GNP-TXT nanomaterial resists thermal degradation with 10% weight loss at 300 °C, while the zeta potential analysis indicates the materials are stable. Since the GNP-TXT particles are so well dispersed, the GNP-TXT-based muds worked better than the GNP-RHC-based muds and was more stable at controlling filtration and improving rheological properties. For example, at 1.5 g AHR, the plastic viscosity of GNP-TXT-based mud decreased by 22.2% from 9 to 7 cP, while that of GNP-RHC-based mud decreased from 17 to 7 cP by 59%. Also, the API and HPHT FL of WBM of 11 and 24.8 mL, respectively, were reduced by GNP-TXT-based muds to the range of 8.6 and 9.8 mL for API and 18.6 and 22.3 mL for HPHT. However, GNP-RHC-based drilling muds showed a lower fluid loss control of the WBM between 9.6 and 10.2 mL for API and between 19.6 and 23.6 mL for HPHT. Furthermore, the coefficient of friction of the WBM of 0.45 was decreased with GNP-RHC concentrations between 0.47 and 0.32, while GNP-TXT demonstrated a higher decrease between 0.26 and 0.20.

Preparation of Cellulose Nanofibers from Agricultural Waste Hemp by Mechanical Defibrillation

In this work, cellulose hemp fibers were extracted from agricultural waste via a pretreatment process using an alkaline solution followed by a bleaching process. The high-pressure homogenization by microfluidizer was conducted to defibrillate hemp fibers into cellulose nanofibers (CNFs). The obtained products in each step of the process, including hemp raw fibers, alkaline-treated fibers, bleached fibers, and CNFs, were analyzed in terms of morphology, chemical composition, chemical structure, crystallinity, and thermal stability. SEM images revealed the successful extraction and decreased diameter with the uniform nanofiber shape. The disappearance of lignin and hemicellulose-related peaks in FTIR analysis, a decrease in their content in the chemical composition results, and an increase in the thermal stability of purified fibers indicated the success of the chemical treatment in removing noncellulosic components.

Enhancement of luminescence properties of Ca2Al2SiO7: Eu3+ red phosphors by Li+, Na+, K+, Mg2+ charge compensators

Rare-earth doped Ca2Al2SiO7 (CAS) phosphors have been widely investigated due to their luminescent properties and low price. However, the luminescence intensity and thermal stability of CAS based phosphors are still not favorable due to rare-earth doping induced vacancies. In this study, to compensate the Ca2+ vacancies by charge unbalanced substitution of Eu3+ in Ca2Al2SiO7: 0.07Eu3+ phosphor, a series of Ca2Al2SiO7: 0.07R, 0.07Eu3+ (RLi+, Na+, K+, Mg2+) phosphors with charge compensators are prepared by sol-gel method. The effects of different charge compensators Li+, Na+, K+, Mg2+ on the phase purity, surface morphology, luminescence properties and thermal stability of the CAS: 0.07Eu3+ phosphors are investigated. It is found that the structures and microstructures of the phosphors are seldom influenced by the co-doped charge compensators R, while the photoluminescence properties are strongly reinforced. Compared with the uncompensated phosphor, all R co-doped samples exhibit remarkable enhancement on luminescence intensity. Among them, Mg2+ compensated phosphor demonstrates the largest enhancement effect with intensity up to 4 times of uncompensated sample. CAS: 0.07 Mg2+, 0.07Eu3+ exhibits a good color purity (87%) with chromaticity coordinates (0.6454, 0.3542), which is very close to the standard red light. Furthermore, the luminous intensity can maintain 76.1% of the initial intensity at 438 K, indicating its excellent thermal stability. These results indicate that charge compensated CAS: Eu3+ phosphors can be used as a candidate material for red phosphor in white LED.

Morphology, semiconductor properties, and chemical stability of AG(I) oxide anodically formed on silver and silver alloys

Morphology, semiconductor properties, and chemical stability of AG(I) oxide anodically formed on silver and silver alloys

ZnxCo(1−x) coatings from choline chloride-ethylene glycol deep eutectic solvent as electrocatalysts for hydrogen evolution reaction

Hydrogen has emerged as a clean and renewable energy and its production by water splitting is a promising production route. However, to meet the demand on a commercial scale, research focusing on more efficient electrocatalysts is necessary. In this work, new findings on Zn, Co and Zn-Co coatings produced in deep eutectic solvent based on choline chloride (ChCl) and ethylene glycol (EG) are reported. Varying the concentrations of Zn2+ and Co2+ ions in 1ChCl:2EG, crystalline electrodeposits with fine control of composition and morphology were obtained, and which present different reactivity to electrocatalyze the hydrogen evolution reaction (HER) in alkaline medium. The performance of metallic coatings is influenced by temperature, due to changes in viscosity, ionic diffusion coefficient and charge transport in the electrolyte. The results also revealed that increasing the Co content in the coatings, changes occur in the morphological organization, stability, and electrode area, which positively influence the hydrogen production. Among the different coatings tested (Zn, Co, Zn96-Co4 and Zn3-Co97), Zn3-Co97 was the most promising in terms of Tafel coefficient (108 mV dec–1), exchange current density (8.57 × 10−6 A cm−2) and overpotential estimated for HER (333 mV at 10 mA cm−2) in 1 mol L–1 KOH at 298.15 K, although the other materials also showed electrochemical advantages over the unmodified Cu substrate. The reported data also reiterate the great electrochemical potential of metallic coatings for water splitting and complement the growing energy demand for hydrogen gas.

Conjugated Nanohoop Polymers based on Antiaromatic Dibenzopentalenes for Charge Storage in Organic Batteries

AbstractWith their bent π‐systems, cyclic conjugation and inherent cavities, conjugated nanohoops are attractive for organic electronics applications. For ease of processing and morphological stability, an incorporation into polymers is desirable, but to date was hampered with few exceptions by synthetic difficulties. We herein present a unique strategy for the synthesis of conjugated nanohoop polymers using a dibenzo[a,e]pentalene (DBP) as central connector. We demonstrate this versatility by synthesizing three electronically diverse copolymers with dithienyldiketo(pyrrolopyrrol), fluorene and carbazole comonomers, and report the first donor‐acceptor nanohoop polymer. Optoelectronic investigations reveal the prevalence of cyclic or linear conjugation, depending on the comonomer unit, and ambipolar electrochemical properties through the antiaromatic character of the DBP units. As the first report on using conjugated nanohoops for charge storage as positive electrode materials, we show a significant improvement in battery performance in a nanohoop‐containing polymer compared to an equivalent nanohoop‐free reference polymer. We believe this study will pave the way for the synthesis of a diverse range of nanohoop polymers and further stimulate their exploration for charge storage in batteries.

Conjugated Nanohoop Polymers based on Antiaromatic Dibenzopentalenes for Charge Storage in Organic Batteries.

With their bent π-systems, cyclic conjugation and inherent cavities, conjugated nanohoops are attractive for organic electronics applications. For ease of processing and morphological stability, an incorporation into polymers is desirable, but to date was hampered with few exceptions by synthetic difficulties. We herein present a unique strategy for the synthesis of conjugated nanohoop polymers using a dibenzo[a,e]pentalene (DBP) as central connector. We demonstrate this versatility by synthesizing three electronically diverse copolymers with dithienyldiketo(pyrrolopyrrol), fluorene and carbazole comonomers, and report the first donor-acceptor nanohoop polymer. Optoelectronic investigations reveal the prevalence of cyclic or linear conjugation, depending on the comonomer unit, and ambipolar electrochemical properties through the antiaromatic character of the DBP units. As the first report on using conjugated nanohoops for charge storage as positive electrode materials, we show a significant improvement in battery performance in a nanohoop-containing polymer compared to an equivalent nanohoop-free reference polymer. We believe this study will pave the way for the synthesis of a diverse range of nanohoop polymers and further stimulate their exploration for charge storage in batteries.

Solution-processable poly(ether-ether-ketone) membranes for organic solvent nanofiltration: from dye separation to pharmaceutical purification

Through polymer engineering, the membrane properties can be considerably changed and its performance can be improved. Organic solvent nanofiltration (OSN) membranes require polymers with good solution processability to facilitate membrane preparation. However, the resultant membranes should have excellent solvent resistance. Poly(ether-ether-ketone) (PEEK) is a potential polymer for OSN applications because of its high thermal stability and excellent solvent resistance. However, commercial PEEK has limited solution processability, and its fabrication requires a harsh acidic environment. Herein, two customized PEEKs were synthesized by incorporating methyl (–CH3) and sulfonyl (SO2) groups into the polymer backbone. The membranes were prepared by phase inversion using N-methyl-2-pyrrolidone (NMP) and TamiSolve as a green alternative. The effects of the polymer structure, green solvent, and crosslinking on the membrane morphology, chemical and mechanical stability, as well as separation performance have been examined. The molecular interaction between organic solvents and PEEKs were investigated through molecular dynamic simulations and density functional theory. The molecular weight cutoff (MWCO) values of the membranes were 540–768 g mol−1, with a high corresponding permeance of 8.2–20 L m−2 h−1 bar−1 in acetone. The long-term stability of membranes was successfully demonstrated over two weeks through a continuous crossflow filtration using acetone under a pressure of 30 bar. The membranes demonstrated excellent active pharmaceutical ingredient purification through the removal a 2-methoxyethoxymethyl chloride (125 g mol−1) carcinogenic impurity from roxithromycin (837 g mol−1).