Intercalation Method Research Articles

Zwitterion Intercalated Manganese Dioxide Nanosheets as High-Performance Cathode Materials for Aqueous Zinc Ion Batteries.

In this study, a novel approach is introduced to address the challenges associated with structural instability and sluggish reaction kinetics of δ-MnO2 in aqueous zinc ion batteries. By leveraging zwitterionic betaine (Bet) for intercalation, a departure from traditional cation intercalation methods, Bet-intercalated MnO2 (MnO2-Bet) is synthesized. The positively charged quaternary ammonium groups in Bet form strong electrostatic interactions with the negatively charged oxygen atoms in the δ-MnO2 layers, enhancing structural stability and preventing layer collapse. Concurrently, the negatively charged carboxylate groups in Bet facilitate the rapid diffusion of H+/Zn2+ ions through their interactions, thus improving reaction kinetics. The resulting MnO2-Bet cathode demonstrates high specific capacity, excellent rate capability, fast reaction kinetics, and extended cycle life. This dual-function intercalation strategy significantly optimizes the electrochemical performance of δ-MnO2, establishing it as a promising cathode material for advanced aqueous zinc ion batteries.

Supramolecular chemistry for the incorporation of multi‐guest molecules into two‐dimensional metal hydroxide hosts

AbstractThe incorporation of functional molecules into the interlayer space of layered double hydroxide (LDH) has been extensively studied for its role in immobilization, stabilization, manipulation of the molecular configuration, and the release from the host. To create dramatically enhanced properties and achieve unexpectedly high performances, it is necessary to incorporate multi‐guests as well as control the guest‐guest interaction. In the present review, we have summarized the multi‐guest incorporation into LDH based on the supramolecular chemistry, which provides insights into non‐covalent molecular interaction through host‐guest chemistry. Four well‐known intercalation methods in LDH, that is, coprecipitation, ion exchange, reconstruction, and exfoliation‐reassembly, are generally applied to multi‐guest intercalation. Combinative methods, in which two different intercalation approaches are combined, are also summarized. The multi‐guest incorporation, despite the difficulty involved in its synthesis design, could provide fine‐tuned and enhanced properties that are useful for a variety of applications.

Novel poly(2-ethyl-2-oxazoline) and poly(diallyldimethylammonium chloride) polymer functionalized montmorillonite: Physicochemical aspects and near-IR study of hydration properties

The novel functionalized montmorillonites (Mts) with non-ionic poly(2-ethyl-2-oxazoline) (PEtOx) and cationic poly(diallyldimethylammonium) (PDDA) were created via an intercalation method with different loading ratio of both polymers. A comprehensive investigation into their physicochemical properties was conducted using Carbon analysis (CA), Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), Simultaneous thermal analysis (TGA/DSC) and BET-N2 adsorption analysis. The impact of hydration on PEtOx-Mts and PDDA-Mts was assessed through gravimetric analysis and near-infrared spectroscopy (NIR) spectroscopy. PXRD analysis revealed a significant increase in 001 diffraction of PDDA-Mt corresponding to a PDDA interlayer with a basal spacing ranging from 1.47 to 1.49 nm. Conversely, the basal spacing exceeding 2 nm for PEtOx suggested, that the PEtOx polymer was intercalated in a larger amount and packed in a less compact manner compared to PDDA. After modification of Na-Mt with PEtOx polymer, FTIR spectroscopy confirmed the presence of the carbonyl CO group (3265 and 1641 cm-1) and the stretching (2982, 2942 and 2883 cm-1) and bending (1480–1200 cm-1) vibrations of the CH2 and CH3 groups. The vibrations of CH groups were further verified following PDDA modification. NIR spectroscopy also confirmed the vibrational bands attributed to both modifiers after intercalation of PEtOx and PDDA. The results of BET-N2 adsorption revealed a significant decrease in the specific surface area (SSA) after intercalation with a non-ionic PEtOx polymer. On the contrary, in the case of saturation of Na-Mt with polycation PDDA, SSA increased slightly in two instances. TGA analysis confirmed greater weight loss for PEtOx-Mts compared to PDDA-Mts. Derivative thermogravimetry (DTG) revealed the release of physisorbed bound water around 100 °C, decomposition of the organic phase within the 250–550 °C range and dehydroxylation of OH groups around 550–800 °C in both cases. The results obtained from the gravimetry and NIR analysis indicated a greater hydrophobic nature for PEtOx-Mts compared to PDDA-Mts. These findings hold substantial potential for enhancing the properties of novel organo-montmorillonites, thereby facilitating their application as adsorbents for pollutants, surface coatings, biodegradable materials, fillers in polymer nanocomposites, drug carriers, anticancer agents and various other significant applications.

Honeycomb-like macroporous crosslinked chitosan assisted EDTA-intercalated Ca-Mg-Al layered hydrotalcite composite foams for efficient U(VI) biosorption

The biosorption is considered to be highly efficient for the separation of radionuclide from radioactive wastewater. Herein, the crosslinked chitosan assisted EDTA intercalated Ca-Mg-Al layered double hydroxides composite foam (CS-EDTA-LDH) was synthesized by combining EDTA intercalation and freeze-drying methods. The macroporous and ultralight properties of CS-EDTA-LDH facilitates its rapid adsorption and facile recovery, and the inorganic/organic incorporation can avoid pore collapse and provide numerous adsorption sites, while the EDTA intercalation can enhance the complex capture of U(VI). The CS-EDTA-LDH presents various functional groups (carboxyl, hydroxyl and amino groups) for U(VI) adsorption, and the adsorption capacity for U(VI) reached 272.3 mg/g at pH 5.0 and 298 K. The adsorption kinetics of U(VI) conformed to PSO equation, whereas the isotherms conformed to the Freundlich model, indicating heterogeneous adsorption with diffusion process as a rate-controlling step. The thermodynamic parameters indicate that U(VI) adsorption by CS-EDTA-LDH is endothermic and spontaneous in nature. The adsorption mechanism is related to the synergic complexation by multi-functional groups, ion exchange, and possible isomeric substitution. Overall, CS-EDTA-LDH could be a promising biosorbent for the cleanup of radioactive pollution due to its high performance for U(VI) adsorption and facile recovery.

Enhanced field emission performance of holey expanded graphite by heat treatment

Expanded graphite (EG) is a promising material in field emission due to its high conductivity, thermal stability, and low cost. In this paper, the field emission performance of EG is enhanced by introducing hole defects through partial air oxidation. First, EG was prepared using electrochemical intercalation and microwave-assisted expansion methods. Subsequently, holey expanded graphite (HEG) was obtained by air-heating treatment of EG at different temperatures. Finally, bulk HEG cathodes were prepared by the cold pressing method, and the holes' effect on field emission performance was investigated. The results showed that EG's conductivity and tensile properties significantly improved after heat treatment. Optimal conditions of heat treatment were established at 400 °C providing material with the best field emission performance. The turn-on field (at 1 mA/cm2) and threshold field (at 10 mA/cm2) are 3.01 V/μm and 3.42 V/μm, respectively, with a maximum current density of 1359.17 mA/cm2 (at 5.83 V/μm) and a maximum field enhancement factor of 2407. The voltage fluctuation is only 1.1 % over 24 h at 3 mA @ 440.33 mA/cm2, indicating good emission stability and operation life.

Electrochemical Lithium Intercalation & Exfoliation in 2D TMDs and Its in-Situ Studies

We developed a lithium ion battery intercalation & exfoliation method with detailed experimental procedures for the mass production of 11 two dimensional TMDs and inorganic nanosheets, such as MoS2, WS2, TiS2, TaS2, ZrS2, graphene, h-BN, NbSe2, WSe2, Sb2Se3 and Bi2Te3, among them 3 TMDs achieved mono- or double layer yield > 90%. This method involves the electrochemical intercalation of lithium ions into layered inorganic materials and a mild sonication process. The Li insertion can be monitored and finely controlled in the battery testing system, so that the galvanostatic discharge process is stopped at a proper Li content to avoid decomposition of the intercalated compounds. The intercalation strategy can also be used to tune 2D TMDs’ physical and chemical properties for various applications. For example, we developed a one-step covalent functionalization method on MoS2 nanosheets for membrane fabrication, which exhibited excellent water desalination performance. For lithium intercalation mechanism, the state-of-the-art In-Situ Liquid Phase TEM is an ideal technique for identifying the phase changes during intercalation process. With self-designed electrochemical liquid cell utilized, we can directly vapture the dynamic electrochemical lithiation and delithiation of electrode in a commercial LiPF6/EC/DEC electrolyte, such as LiF nanocrystal formation, lithium metal dendritic growth, electrolyte decomposition, and solid-electrolyte interface (SEI) formation. Combining with other in-situ techniques, such as in-situ XAS, XRD and Raman, etc, the underlying lithium intercalation mechanism in TMDs were further investigated, which render us a comprehensive understanding of the intrinsic correlation between the intercalation process and TMDs.

Elucidating the Interactions between Different Transition Metal Cations and Ti3C2Tx MXene through Intercalation Method for Electrochemical Applications

MXenes, are a family of two-dimensional (2D) transition metal carbides, nitrides and/ or carbonitrides.[1] The intercalation of different metal cations and organic molecules into MXene for tuning MXenes’ electronic and electrochemical properties have been widely reported.[2] [3] [4] However, transition metals (TMs) which have distinct electrochemical behaviors[5] [6] have not been explored in the literature of MXenes’ intercalation. Therefore, we herein compared the intercalation effects of different TM cations on Ti3C2Tx, for offering a general insight on the influences of multi-valent, redox-active TMs on MXenes. In particular, the changes on the physiochemical and electrochemical properties of MXenes were investigated using different in-situ and ex-situ methods, for a better understanding on the interfacial interactions of TM cations and MXenes in the confined environment of MXenes’ multilayer structures. This work serves as a foundation for the fine-tuning of MXenes’ properties by utilizing a variety of TM cations intercalation for different electrochemical systems.[1] B. Anasori, M. R. Lukatskaya, Y. Gogotsi, Nature Reviews Materials 2017, 2, 16098.[2] M. R. Lukatskaya, O. Mashtalir, E. Ren Chang, Y. Dall’Agnese, P. Rozier, L. Taberna Pierre, M. Naguib, P. Simon, M.W. Barsoum, Y. Gogotsi, Science 2013, 341, 1502-1505.[3] J. Li, H. Wang, X. Xiao, Energy & Environmental Materials 2020, 3, 306-322[4] M. Ghidiu, S. Kota, J. Halim, A. W. Sherwood, N. Nedfors, J. Rosen, V. N. Mochalin, M. W. Barsoum, Chemistry of Materials 2017, 29, 1099-1106.[5] D. Göhl, H. Rueß, M. Pander, A. R. Zeradjanin, K. J. J. Mayrhofer, J. M. Schneider, A. Erbe, M. Ledendecker, Journal of The Electrochemical Society 2020, 167, 021501.[6] M. Esmaeilirad, A. Baskin, A. Kondori, A. Sanz-Matias, J. Qian, B. Song, M. Tamadoni Saray, K. Kucuk, A. R. Belmonte, P. N. M. Delgado, J. Park, R. Azari, C. U. Segre, R. Shahbazian-Yassar, D. Prendergast, M. Asadi, Nature Communications 2021, 12, 5067.

Bilayered Vanadium Oxides Pillared by Strontium Ions and Water Molecules as Stable Cathodes for Rechargeable Zn-Metal Batteries.

Vanadium-based compounds have attracted significant attention as cathodes for aqueous zinc metal batteries (AZMBs) because of their remarkable advantages in specific capacities. However, their low diffusion coefficient for zinc ions and structural collapse problems lead to poor rate capability and cycle stability. In this work, bilayered Sr0.25V2O5·0.8H2O (SVOH) nanowires are first reported as a highly stable cathode material for rechargeable AZMBs. The synergistic pillaring effect of strontium ions and water molecules improves the structural stability and ion transport dynamics of vanadium-based compounds. Consequently, the SVOH cathode exhibits a high capacity of 325.6mAhg-1 at 50mAg-1, with a capacity retention rate of 72.6% relative to the maximum specific capacity at 3.0Ag-1 after 3000 cycles. Significantly, a unique single-nanowire device is utilized to demonstrate the excellent conductivity of the SVOH cathode directly. Additionally, the energy storage mechanism of zinc insertion and extraction is investigated using a variety of advanced in situ and ex situ analysis techniques. This method of ion intercalation to improve electrochemical performance will further promote the development of AZMBs in large-scale applications.

Intercalation-Induced Irreversible Lattice Distortion in Layered Double Hydroxides.

Inducing strain in the lattice effectively enhances the intrinsic activity of electrocatalysts by shifting the metal's d-band center and tuning the binding energy of reaction intermediates. NiFe-layered double hydroxides (NiFe LDHs) are promising electrocatalysts for the oxygen evolution reaction (OER) due to their cost-effectiveness and high catalytic activity. The distorted β-NiOOH phase produced by the Jahn-Teller effect under the oxidation polarization is known to exhibit superior catalytic activity, but it eventually transforms to the undistorted γ-NiOOH phase during the OER process. Such a reversible lattice distortion limits the OER activity. In this study, we propose a facile boron tungstate (BWO) anion intercalation method to induce irreversible lattice distortion in NiFe LDHs, leading to significantly enhanced OER activity. Strong interactions with BWO anions induce significant stress on the LDH's metal-hydroxide slab, leading to an expansion of metal-oxygen bonds and subsequent lattice distortion. In situ Raman spectroscopy revealed that lattice-distorted NiFe LDHs (D-NiFe LDHs) stabilize the β-NiOOH phase under the OER conditions. Consequently, D-NiFe LDHs exhibited low OER overpotentials (209 and 276 mV for 10 and 500 mA cm-2, respectively), along with a modest Tafel slope (33.4 mV dec-1). Moreover, D-NiFe LDHs demonstrated excellent stability at 500 mA cm-2 for 50 h, indicating that the lattice distortion of the LDHs is irreversible. The intercalation-induced lattice strain reported in this study can provide a general strategy to enhance the activity of electrocatalysts.

Effects of expanded graphite’s structural and elemental characteristics on its oil and heavy metal sorption properties

Expanded graphite has promising potential environmental applications due to its porous structure and oleophilic nature, which allow it to absorb large quantities of oil. The material is produced by intercalating graphite and applying heat to convert the intercalant into gas to cause expansion between the layers in the graphite. Using different intercalants and temperature conditions results in varying properties of expanded graphite. This work has proven that the sorption properties of commercial expanded graphite differ significantly due to the material’s structural and elemental characteristics, which can be attributed to the intercalation method. This resulted in various degrees of exfoliation of the graphite and possible functionalisation of the graphene sheets within the structure. This affected the material's sorption capacity and its affinity for heavy metal sorption by incorporating selectivity towards the sorption of certain metals. It was found that sample EG3, which underwent a less harsh expansion, exhibited lower porosity than EG1, and thus, the sample absorbed less oil at 37.29 g/g compared to the more expanded samples EG1 and EG2 with 55.16 g/g and 48.82 g/g, respectively. However, it was able to entrap a wider variety of metal particles compared to EG1 and EG2, possibly due to its smaller cavities allowing for a capillary effect between the graphene sheets and greater Van der Waals forces. A second possibility is that ionic or coordination complexes could form with certain metals due to the possible functionalisation of the expanded graphite during the intercalation process. This would be in addition to coordination between the metals and expanded graphite carbon atoms. The findings suggest that there is evidence of functionalisation as determined by XRD and elemental analyses. However, further investigation is necessary to confirm this hypothesis. The findings in this work suggest that the first mechanism of sorption was more likely to be related to the degree of expansion of the expanded graphite. Various metals are present in used oil, and their removal can be challenging. Some metals in oil are not considered heavy since they have a relatively low density but can be associated with heavy metals in terms of toxicity.

Chemical Intercalation of Layered Materials: From Structure Tailoring to Applications.

The intercalation of layered materials offers a flexible approach for tailoring their structures and generating unexpected properties. This review provides perspectives on the chemical intercalation of layered materials, including graphite/graphene, transition metal dichalcogenides, MXenes, and some particular materials. The characteristics of the different intercalation methods and their chemical mechanisms are discussed. The influence of intercalation on the structural changes of the host materials and the structural change how to affect the intrinsic properties of the intercalation compounds are discussed. Furthermore, a perspective on the applications of intercalation compounds in fields such as energy conversion and storage, catalysis, smart devices, biomedical applications, and environmental remediation is provided. Finally, brief insights into the challenges and future opportunities for the chemical intercalation of layered materials are provided.

Robust shape memory chlorobutyl rubber/boron nitride polymer nanocomposites for oil-water separation application

BackgroundBoron nitride (h-BN), an excellent 2D material finds exceptional applications in various fields owing to its unique characteristics including excellent hydrophobicity. Incorporation of boron nitride in polymer matrices is a captivating strategy by the scientific community to tune the properties of polymer. Interestingly, the possibilities of incorporating h-BN in chlorobutyl rubber (CIIR) matrix has never been considered and tried till now. Moreover, the use of CIIR to create a clean environment and reduce water pollution is an unexplored area even though the CIIR rubber possess excellent barrier properties. MethodsIn this work, two techniques were used for the fabrication of BNNS/CIIR nanocomposite. We exfoliated h-BN via chemical exfoliation method and tried the reinforcement of CIIR with BNNS via solution intercalation method. Shape memory analysis was performed with the help of stearic acid and oil-water separation analysis was achieved through an easy experimental technique. Significant findingsEnhanced mechanical strength of 11.57 MPa, improved thermal degradation temperature and char yield, higher glass transition temperature of -45.98° were observed for BNNS/CIIR nanocomposite reinforced with higher BNNS loading owing to the uniform distribution and better intercalation of BNNS in CIIR. Excellent shape memory was exhibited by CIIR matrix when reinforced up to 5 g BNNS. In addition, the nanocomposites displayed excellent ability to perform oil-water separation with increase in BNNS loading owing to the good hydrophobic character of h-BN and inherent barrier properties of CIIR. Thus, the study proved successful towards the fabrication of advanced CIIR nanocomposites with excellent shape memory and oil water separation efficiency.

Hierarchical antibiotic delivery system based on calcium phosphate cement/montmorillonite-gentamicin sulfate with drug release pathways

Antibiotic-loaded calcium phosphate cement (CPC) has emerged as a promising biomaterial for drug delivery in orthopedics. However, there are problems such as the burst release of antibiotics, low cumulative release ratio, inappropriate release cycle, inferior mechanical strength, and poor anti-collapse properties. In this research, montmorillonite-gentamicin (MMT-GS) was fabricated by solution intercalation method and served as the drug release pathways in CPC to avoid burst release of GS, achieving promoted cumulative release ratios and a release cycle matched the time of inflammatory response. The results indicated that the highest cumulative release ratio and release concentration of GS in CPC/MMT-GS was 94.1 ± 2.8 % and 1183.05 μg/mL, and the release cycle was up to 504 h. In addition, the hierarchical GS delivery system was divided into three stages, and the kinetics followed the Korsmeyer-Peppas model, the zero-order model, and the diffusion-dissolution model, respectively. Meanwhile, the compressive strength of CPC/MMT-GS was up to 51.33 ± 3.62 MPa. Antibacterial results demonstrated that CPC/MMT-GS exhibited excellent in vitro long-lasting antibacterial properties to E. coli and S. aureus. Furthermore, CPC/MMT-GS promoted osteoblast proliferation and exhibited excellent in vivo histocompatibility. Therefore, CPC/MMT-GS has favorable application prospects in the treatment of bone defects with bacterial infections and inflammatory reactions.

New MoS2/Tegafur-Containing Pharmaceutical Formulations for Selective LED-Based Skin Cancer Photo-Chemotherapy.

Non-melanoma skin cancer (NMSC) is one of the most common types of cancer worldwide. Despite the low mortality rate, rising incidence and recurrence rates are a burden on healthcare systems. Standard treatments such as chemotherapy, radiotherapy, and surgery are either invasive or toxic to healthy tissues; therefore, new, alternative, selective treatments are needed. In this work, a combined photothermal and chemotherapeutic approach is proposed. MoS2 was used as photothermal agent. It was prepared by a liquid-phase exfoliation and intercalation method using polyvinylpyrrolidone (PVP), followed by recirculation through a custom-built high-power ultrasonication probe. After 6 h of ultrasonication treatment, the average particle size was 165 ± 170 nm. Near-infrared (NIR) irradiation assays (810 nm, 0.1 W/cm2, 30 min, 180 J/cm2) confirmed that MoS2 nanosheets can efficiently convert NIR light into heat and reach 52 °C. The therapeutic doses of MoS2 (125 µg/mL) and Tegafur (50 µg/mL) were optimized and both were simultaneously incorporated into a Carbopol hydrogel. The cells were brought into contact with the hydrogel and irradiated with a custom-built NIR LED system. In HFF-1 cells (normal human fibroblasts), the metabolic activity was 78% (above the 70% toxicity limit-ISO 10993-5:2009(E)), while in A-431 skin cancer cells, it was 28%. In addition, the MoS2 + Tegafur hydrogels led to a 1.9-fold decrease in A-431 cancer cell metabolic activity, 72 h after irradiation, in comparison to MoS2 hydrogels, indicating a combined effect of photothermal and chemotherapy.

Valence-Ordered Thin-Film Nickelate with Tri-component Nickel Coordination Prepared by Topochemical Reduction.

The metal-hydride-based "topochemical reduction" process has produced several thermodynamically unstable phases across various transition metal oxide series with unusual crystal structures and nontrivial ground states. Here, by such an oxygen (de-)intercalation method we synthesis a samarium nickelate with ordered nickel valences associated with tri-component coordination configurations. This structure, with a formula of Sm9Ni9O22 as revealed by four-dimensional scanning transmission electron microscopy (4D-STEM), emerges from the intricate planes of {303}pc ordered apical oxygen vacancies. X-ray spectroscopy measurements and ab initio calculations show the coexistence of square planar, pyramidal, and octahedral Ni sites with mono-, bi-, and tri-valences. It leads to an intense orbital polarization, charge-ordering, and a ground state with a strong electron localization marked by the disappearance of ligand-hole configuration at low temperature. This nickelate compound provides another example of previously inaccessible materials enabled by topotactic transformations and presents an interesting platform where mixed Ni valence can give rise to exotic phenomena.

Preparation of Polyethylene Clay Composites via Melt Intercalation Using Hydrophobic and Superhydrophobic Organoclays and Comparison of Their Textural, Mechanical and Thermal Properties.

Polymer clay nanocomposites, which can exhibit many superior properties compared to virgin polymers, have gained increasing interest and importance in recent years. This study aimed to prepare composites of two organoclays with unusual ratios and different degrees of lyophilicity with low-density polyethylene and compare their textural structures and thermal and mechanical properties with those of virgin polymer. For this purpose, firstly, organoclays, hydrophobic and superhydrophobic organoclays (OC and SOC), were prepared by solution intercalation method using cetyltrimethylammonium bromide with and without addition of a hydrocarbon substance. Then, using both organoclays, polyethylene organoclay composites were prepared and characterized using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Additionally, tensile and hardness tests were performed to determine the mechanical properties of the composites, and differential scanning calorimetry (DSC) thermograms were taken to examine their thermal behavior. XRD patterns and HRTEM images of hydrophobic and superhydrophobic organoclays and the composites show that the characteristic smectite peak of the clay shifts to the left and expands, that is, the interlayer space widens and, in the composites, it deforms immediately at low clay ratios. HRTEM images of the composites prepared especially with low clay ratios indicate that a heterogeneous dispersion of clay platelets occurs, indicating that nanocomposite formation has been achieved. On the contrary, in the composites prepared with high clay ratios, this dispersion behavior partially turns into aggregation. In the composites prepared using up to 20% by weight of superhydrophobic organoclay, extremely stable and continuous improvements in all mechanical properties were observed compared to those of the composites prepared using hydrophobic organoclay. This indicates that by using superhydrophobic organoclay, a ductile nanocomposite of polyethylene containing inorganic components in much higher than usual proportions can be prepared.

Effects of various types of organo-mica on the physical properties of polyimide nanocomposites

Poly(amic acid) (PAA) was synthesized using dianhydride 4,4’-oxydiphthalic anhydride and diamine 3,3'-dihydroxybenzidine, and polyimide (PI) hybrid films were synthesized by dispersing organo-mica in PAA through a solution intercalation method. Hexadimethrine-mica (HM-Mica), 1,2-dimethylhexadecylimidazolium-mica (MI-Mica), and didodecyldiphenylammonium-mica (DP-Mica), which were obtained via the organic modification of pristine mica, were used as the organo-micas for the PI hybrid films. The organo-mica content was varied from 0.5 to 3.0 wt% with respect to the PI matrix. The thermomechanical properties, morphology, and optical transparency of the resultant PI hybrid films were measured and compared. Dispersion of even small amounts of organo-mica effectively improved the physical properties of the PI hybrids, and maximum enhancements in physical properties were observed at a specific critical content. Electron microscopy of the hybrid films revealed that the organo-mica uniformly dispersed throughout the polymer matrix at the nanoscale level when added at low contents but aggregated in the matrix when added at levels above the critical content. Structural changes in the organo-mica closely influenced the changes in the physical properties of the hybrid films. All PI hybrid films with various organo-mica contents showed similar optical properties, but that prepared with MI-Mica demonstrated the best thermomechanical properties. All synthesized PI hybrid films were transparent regardless of the type and content of organo-mica used.

Li-ion intercalation-driven control of two-dimensional magnetism in van der Waals FePS3 bilayers.

Manipulating two-dimensional (2D) magnetism in layered van der Waals (vdW) materials like FePS3 (FPS), with its wide-ranging applications in flexible spintronic devices, poses a persistent challenge. Through first-principles calculations, we have achieved reversible ferrimagnetic (FiM, FePS3 bilayer) ↔ antiferromagnetic (AFM, 1Li-intercalated FePS3 bilayer) ↔ ferromagnetic (FM, 2Li-intercalated FePS3 bilayer) phase transitions by using a Li-ion intercalation method. Intercalated Li ions significantly enhance the Fe-3d and S-3p hybridization and reduce the Fe-Fe, Li-Fe, Li-S, and Li-P bond lengths. The manipulation of 2D magnetism in Li-intercalated FPS bilayers can be attributed to the charge transfer between two FPS monolayers mediated by Li ions. Moreover, this study offers insights into the underlying physical mechanisms that govern the variations of electronic structures, 2D magnetism, magnetic anisotropy energy, and exchange couplings. Our reversible Li-ion intercalation permits straightforward de-intercalation using a two-step route, thereby reinstating the initial magnetic order of the FPS bilayer. Our purpose-designed FPS bilayer with different Li concentrations and robust exchange coupling not only enriches the Li-intercalation physics in the FPS system but also offers a general pathway for manipulating 2D magnetism in Fe-based vdW trisulfides.

Effect of organoclay on the physical properties of colorless and transparent copoly(amide imide) nanocomposites.

Copoly(amic acid) was prepared using the diamine monomer N,N'-[2,2'-bis(trifluoromethyl)-4,4'-biphenylene]bis(4-aminobenzamide) (TFAB) and the anhydride monomers 4,4'-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA) and 4,4'-biphthalic anhydride (BPA). Thereafter, a colorless and transparent copoly(amide imide) (Co-CPAI) film was synthesized through various heat treatments. Co-CPAI hybrid films with a TFAB : 6FDA : BPA molar ratio of 1 : 0.5 : 0.5 were subsequently fabricated using organically modified hectorite (STN) with various contents ranging from 0 to 7 wt% via the solution intercalation method. Finally, the thermomechanical properties, clay dispersion, and optical transmittance of the hybrid films were investigated. The results of wide-angle X-ray diffractometry and transmission electron microscopy demonstrated good dispersion at low clay loadings; however, clay agglomeration was observed above a certain critical STN content. At the critical STN content of 3 wt%, the clay was evenly distributed in the matrix with a nanoscale thickness of approximately 10 nm. Hybrid films containing 3 wt% STN showed excellent thermomechanical properties. Beyond this critical clay content, the physical properties of the films decreased because of the agglomeration of excess clay. Regardless of the clay content, however, the optical properties of the hybrid films remained constant, and their yellow indices, which ranged from 2 to 4, indicated excellent colorless transparency.

Rheological, mechanical, and morphological behaviour of polypropylene composites reinforced with ultrafine kaolinite particles

To develop charge/matrix interactions and improve the rheological, mechanical, and morphological performances of the matrix polypropylene, PP/kaolinite composites were prepared using the melt intercalation method at 190 °C. The rheological and mechanical properties of polypropylene/kaolin composites have been evaluated at various concentrations of untreated and/or treated kaolin. It was shown that the melt flow index (MFI) varies visibly but slightly compared to that of the matrix with increasing kaolin content. Furthermore, when the kaolin loading is enhanced, the apparent shear viscosity (ηapp) of the composites increases compared to the matrix and decreases with the increase in the shear rate (γapp). Also, while the shear stress (τapp) is reduced, the flow curve shifts upwards with increasing the kaolin concentration. The systems obeyed the power-law model in shear stress-shear rate variations and were shear thinning as power-law index (n) values increased with kaolin content. Moreover, the mechanical properties of the obtained composites were significantly affected by the dispersion of the filler into the matrix and by the weak interactions at the interface PP/kaolinite. SEM micrographs show a poor dispersion of the nanoclay within the polypropylene matrix and the formation of agglomerates with different sizes.