Mica Nanosheets Research Articles

+Improving the corrosion protection properties of epoxy resin coating by using HKUST-1-BTA@e-Mica two-dimensional nanocomposites

In order to enhance the performance of epoxy coatings to cope with more severe working environments, we develop a convenient energy-saving and fast method to develop an eco-friendly pH-responsive smart coating with long-term corrosion protection. In this paper, HKUST-1 crystals were rapidly synthesised on mica nanosheets (e-Mica) using hydroxyl complex salt (HDS) as an intermediate at room temperature and loaded with the corrosion inhibitor BTA to obtain the composite material HBeM. The use of e-Mica in coatings offers numerous benefits, including extended resistance to corrosive media and the ability to adjust mechanical properties. It is important to note, however, that e-Mica is less compatible with epoxy resin. HKUST-1 can not only be used as a pH-responsive nanocontainer to load a large amount of corrosion inhibitor, but also to regulate the compatibility between mica nanosheets and epoxy resin with a large number of functional groups on HKUST-1. The results of electrochemical impedance spectroscopy showed that HKUST-1-BTA@e-Mica (HBeM) composite enables the coating to provide long-term corrosion protection. The low frequency impedance of the HBeM/EP composite coating, |Z|f=0.01 Hz, was improved by almost three orders of magnitude and remained higher than that of the pure epoxy coating after 30 days of immersion, and the addition of fillers enhances the mechanical properties of the coating. In conclusion, this paper provides a simple, energy-efficient and rapid method for the preparation of smart corrosion-resistant coatings, which has great potential for industrial use.

Large-Size ultrathin mica nanosheets: Reinforcements of biobased PEF polyester

Due to the superior physical properties and high-level alignment of the nanoscale building blocks, assembly of high-quality two-dimensional (2D) nanosheets into macroscopic engineering structure materials can achieve many unexpected performance. Natural mica nanosheets (MNSs) are abundant and with superlative properties, showing huge prospect for engineering structural materials. However, the difficulty of the mass production with large size and high aspect ratio are the current factors that limit this. Inspired by the well-known scotch-tape exfoliation, herein we develop a gummy-tape exfoliation (GTE) method by using liquid oligomers as mediums in ball-milling process to massively produce large-size and ultrathin MNSs. As a confirmation, the obtained MNSs show a record high aspect ratio of ≈1320 and a large actual yield of ∼ 80 %. A transparent biobased aromatic polyester nanocomposite film made of such MNSs and polyethylene furandicarboxylate (PEF) matrix possesses remarkably improved mechanical, barrier properties, and UV-shielding performances at an extremely low filler loading (≤0.5 vol%), making it a novel potential engineering material for packing fields in foods, drugs, and electronic products, etc.

Intelligent double-layer films based on gellan gum/mica nanosheets/anthocyanin/konjac glucomannan/carrageenan for food real-time freshness monitoring

In this work, double-layer intelligent films were designed and synthesized based on Broussonetia papyrifera fruit anthocyanin (BPFA), mica nanosheets (MN), konjac glucomannan (KG), carrageenan (CA) and gellan gum (GG) using layer-by-layer casting strategy for real-time and in situ food freshness monitoring. The KG/CA/BPFA layer served as the indicator layer, while the GG/MN layer acted as the protective outer layer. It was observed that the water vapor permeability value of the GG-MN/KG-CA-BPFA double-layer film was reduced by 4.7 times, and the tensile strength was increased by 4.1 times compared with the GG film, which could be related to the reinforcing effect and proper barrier property of MN. Notably, the double-layer film blocked most of UV-light and oxygen, and its water contact angle reached 102.4° ± 1.18°. In particular, the films showed favorable visually detectable colorimetric responses to different pH buffer solutions and volatile ammonia. More importantly, visual assessment using shrimps as test specimens demonstrated distinct color alteration from red to blue-grey on spoilage. The color change of the film was also highly correlated with TVB-N (R2 = 0.964) and pH (R2 = 0.999). In conclusion, the newly designed double-layer film exhibited excellent performance, which guides an innovative approach for advanced food-packing material development.

Mica nanosheets synthesized via liquid Ga embrittlement: demonstrating enhanced CO2 capture

We introduce a pioneering approach to synthesize 2D mica nanosheets by leveraging the liquid gallium embrittlement mechanism, effectively addressing the challenges involved in exfoliating mica due to its strong non-van-der-Waals bonds.

Significantly Enhanced the Energy Density of Dielectric Composites by Sandwich Structure with Highly Insulating Mica Nanosheets.

Dielectric polymer composites exhibit great application prospects in advanced pulse power systems and electric systems. However, the decline of breakdown strength by loading of single high dielectric constant nanofiller hinders the sustained increase in energy density of the composites. Here, a sandwich-structured nanocomposite prepared with mica nanosheets as the second filler exhibits decoupled modulation of dielectric constant and breakdown strength. The traditional layered clay mineral mica is exfoliated into nanosheets and filled into polyvinylidene difluoride (PVDF), which shows a special depolarization effect in the polymer matrix. In Kelvin probe microscopy characterization and thermally stimulated depolarization current indicates that the mica nanosheets provided space charge traps for the polymer matrix and effectively suppressed the carrier motion. A sandwich structure composite material with mica nanosheets as the central layer has achieved a high energy density of 11.48 Jcm-3, 2.4 times higher than the pure PVDF film. This is due to the fact that randomly oriented distribution of nanosheets in a polymer matrix provide better current blocking. This work provides an effective method to improve the energy density of dielectric polymer composites by synergistically introducing insulating nanosheets and high dielectric constant nanofillers.

Bio-inspired seaweed-based nanocomposite materials with excellent degradability and multifunctional barrier properties for green packaging

The widespread use of petroleum-based plastics brings potential hazards to the ecological environment. In order to solve this issue, the development of biodegradable materials with both high mechanical, barrier performances and food safety is imminent. In this work, a natural nacre-inspired seaweed-based nanocomposite material with the structure of “brick and mortar” is synthesized by rational assembling mica nanosheets in a mixture of glycerol and sodium alginate. The resultant SA/nano-mica film (1 wt% of phlogopite powder) shows high thermal stability (>180 °C) and exhibits great tensile strength of ∼ 16 MPa at ambient condition, surpassing some other reported nanocomposite materials (1.9–14.74 MPa). Meanwhile, the composite can be easily processed into different shapes for packaging applications, which could long-term preserve the freshness of foods owing to their strong ultraviolet (UV) shielding and gas barrier properties (UV transmittance of ∼ 4 % and oxygen transmission rates (100 µm) of ∼ 18.52 cc m−2 day−1 bar−1). Importantly, the material could completely degrade in soil within 15 days. These results indicate the great application prospect of seaweed-based nanocomposite materials in food packaging.

Facile preparation of hydroxyl−functionalized mica nanosheets assisted by plasma treatment

The efficient exfoliation of mica, a naturally layered material, into two-dimensional (2D) nanosheets has received much attention due to its low price, good chemical stability, and better shielding function against UV light. However, fast and simple exfoliation of mica in a large-scale face a great challenge. In this work, we developed a simple and effective method for obtaining OH−functionalized mica nanosheets (MNs). The process involved calcination, plasma treatment, and ultrasonic exfoliation, resulting in a yield of 7.535%. Furthermore, the effects of sonication time, solvent type and particle sizes of mica were investigated. The conditions for the preparation of MNs were determined: mica calcination, plasma treatment, and sonication in ethanol for 5 h. XPS and FT−IR demonstrated that more hydroxyl groups were introduced to mica after the plasma treatment, which facilitated the exfoliation of mica.

Breaking new ground in mica exfoliation: Harnessing biaxial straining principles through H2 and N2 intercalation for enhanced layer separation

This study introduces a novel method for mica exfoliation using biaxial straining principles through H2 and N2 intercalation. Our two-stage approach combines microwave irradiation with biaxial straining triggered by H2 and N2. Our first principles simulations showed that N2 leads to a larger drop in bulk modulus per tensile strain than H2, resulting in decreased mica strain entropy (or less disordering) and ineffective exfoliation due to the resulting positive (H2) and negative (N2) Poisson ratio. Therefore, we applied H2 and performed SEM, FT-IR, and XRD analyses. The results indicate that our pre-treatment methods did not alter the mica's crystalline structure, and our two-step treatment method increased the interlayer distances of bulk mica particles. TEM analysis revealed the presence of mica nanosheets in single layers. This study represents a significant breakthrough in 2D exfoliation research not only for mica but also for non-van der Waals bonded crystals. By utilizing innovative biaxial straining principles through H2 and N2 interclation, our approach offers a promising avenue for achieving enhanced layer separation in layered materials.

Injectable Hydrogels Including Magnetic Nanosheets for Multidisciplinary Treatment of Hepatocellular Carcinoma via Magnetic Hyperthermia.

Relapse and unresectability have become the main obstacle for further improving hepatocellular carcinoma (HCC) treatment effect. Currently, single therapy for HCC in clinical practice is limited by postoperative recurrence, intraoperative blood loss and poor patient outcomes. Multidisciplinary therapy has been recognized as the key to improving the long-term survival rate for HCC. However, the clinical application of HCC synthetic therapy is restricted by single functional biomaterials. In this study, a magnetic nanocomposite hydrogel (CG-IM) with iron oxide nanoparticle-loaded mica nanosheets (Iron oxide nanoparticles@Mica, IM) is reported. This biocompatible magnetic hydrogel integrated high injectability, magnetocaloric property, mechanical robustness, wet adhesion, and hemostasis, leading to efficient HCC multidisciplinary therapies including postoperative tumor margin treatment and percutaneous locoregional ablation. After minimally invasive hepatectomy of HCC, the CG-IM hydrogel can facilely seal the bleeding hepatic margin, followed by magnetic hyperthermia ablation to effectively prevent recurrence. In addition, CG-IM hydrogel can inhibit unresectable HCC by magnetic hyperthermia through the percutaneous intervention under ultrasound guidance.

High-performance triboelectric nanogenerators based on TPU/mica nanofiber with enhanced tribo-positivity

As a promising energy harvesting technology, triboelectric nanogenerator (TENG) has brought a leap forward to the development of self-powered systems. Many materials, especially inorganic non-metallic materials, proved to possess excellent triboelectric property, have rarely been practically used due to their fragility and rigidity. Here, fragile and rigid mica with strong triboelectric positivity is exfoliated into 2D nanosheets and electrospun into flexible and stretchable thermoplastic polyurethane (TPU) nanofibers for high-performance TENGs. Paired with polyvinylidene fluoride/MXene (PVDF/MXene) nanofibers, the transferred charge of the TENG with TPU/mica nanofibers significantly enhanced to 82.4 nC from 38.6 nC due to the enhanced tribo-positivity. Kelvin probe force microscopy (KPFM) measurements of single pure TPU and TPU/mica nanofibers showed mica apparently enhanced the positive electrostatic surface potential (ESP) of TPU. The mean peak ESP of pure TPU nanofiber was about 194 mV, while it was increased to 218 mV on the regions of TPU/mica nanofiber without mica nanosheets aggregation and 305 mV on the regions where mica nanosheets aggregated. The power density of the TENG with TPU/mica nanofiber reached 1458 mW/m2, exhibiting a 16-fold enhancement compared with the one based on pure TPU nanofiber. A thin and flexible TENG was fabricated and conformally worn on a wrist and palm for body motion monition and object gripping sorting. This work proposed high-performance triboelectric nanogenerators based on TPU/mica nanofibers and a general approach to effectively utilize rigid and fragile materials with excellent triboelectric property for making triboelectric layers.

A green approach to mica nanosheet production: Liquid-phase exfoliation in natural seawater

The development of environmentally friendly and sustainable methods for the exfoliation of nanosheets is of paramount importance in the field of nanotechnology. In this study, high-quality mica nanosheets (MNs) were prepared through a seawater-based liquid-phase exfoliation process that utilized ions intercalation for the first time. The morphological characteristics of the MNs were extensively characterized using various analytical techniques, such as field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Further analysis using X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy confirmed the structural integrity and stability of the obtained MNs. Additionally, this work investigated the impact of reaction time, temperature, cycle number, and initial concentration on the production rate of MNs. Overall, this study highlights the potential of natural seawater as an effective solvent for the efficient exfoliation of high-quality MNs.

Layer-dependent stability of 2D mica nanosheets

We report on the layer-dependent stability of muscovite-type two-dimensional (2D) mica nanosheets (KAl3Si3O10(OH)2). First-principles calculations on mica nanosheets with different layer thicknesses (n = 1, 2, and 3) reveal their layer-dependent stability; odd-numbered 2D mica nanosheets are more stable than even-numbered ones, and the preferable stability of odd-numbered layers originates from electronic effects. A core-shielding model is proposed with a reasonable assumption, successfully proving the instability of the even-numbered mica nanosheets. Raman imaging supports that the population of odd-numbered mica nanosheets is predominant in exfoliated mica products. The alternating charge states with odd/even layers were evidenced by Kelvin probe force microscopy. We also demonstrate a unique photocatalytic degradation, opening new doors for environmental applications of mica nanosheets.

Efficient Synthesis of 2D Mica Nanosheets by Solvothermal and Microwave-Assisted Techniques for CO2 Capture Applications

Mica, a commonly occurring mineral, has significant potential for various applications due to its unique structure and properties. However, due to its non-Van Der Waals bonded structure, it is difficult to exfoliate mica into ultrathin nanosheets. In this work, we report a rapid solvothermal microwave synthesis of 2D mica with short reaction time and energy conservation. The resulting exfoliated 2D mica nanosheets (eMica nanosheets) were characterized by various techniques, and their ability to capture CO2 was tested by thermogravimetric analysis (TGA). Our results showed an 87% increase in CO2 adsorption capacity with eMica nanosheets compared to conventional mica. Further characterization by Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), as well as first-principles calculations, showed that the high specific surface area and deposited K2CO3 layer contribute to the increased CO2 adsorption on the mica nanosheets. These results speak to the potential of high-quality eMica nanosheets and efficient synthesis processes to open new avenues for new physical properties of 2D materials and the development of CO2 capture technologies.

Energetic and configurational mechanisms to facilitate mica nanosheets synthesis by organo-ammonium cation intercalation

It is currently challenging to synthesis large, high-quality mica nanosheets to exploit nanoelectronics based on 2D mica. We carried out a first-principles investigation of the crystal and electronic structure as well as the interlayer interaction of mica intercalated with various organo-ammonium cations. The long-chain organo-ammonium cation intercalation expands interlayer spacing more efficiently, while the branched organo-ammonium cation intercalation is more effective in reducing exfoliation energy to facilitate exfoliation. Two exfoliation mechanisms are proposed as M1 (by increasing configurational entropy to destabilize interlayer structure, e.g., the interlayer spacing rises from 3.31 Å to 6.27 Å) and M2 (by increasing enthalpy to destroy interlayer structure, e.g., the exfoliation energy reduces from 2.51 eV to 1.13 eV). In addition, the intercalated mica shows remarkably narrowed bandgap attributed to ionic H-O bonds between mica tetrahedral sheets and organo-ammonium cations, which are dependent on the cation's degree of branching. Applying the energetic and structural analysis of organo-ammonium cation intercalated mica, our research furthers the understanding of cation intercalation and exfoliation of layer structured materials, opening the way for the effective massive production of nanosheets.

Mussel-inspired preparation of superhydrophobic mica nanosheets for long-term anticorrosion and self-healing performance of epoxy coatings

Research and development of coatings with long-term corrosion resistance and self-healing capabilities remains an important and pressing topic in the field of metal corrosion protection. Adding functional fillers with superhydrophobicity and excellent polymer compatibility to the organic coating is an effective way to address this issue. In this work, inspired by mussels, functional mica nanosheets (MNs) were successfully prepared by interacting catechol groups of natural urushiol (Ur) with the surface of MNs, as validated by XRD, UV–vis, FTIR, XPS, and TGA. The synthesized MNs@Ur exhibited superhydrophobic properties (150° ± 1°) and great dispersion in solvents and epoxy resin, making them ideal nanofillers for enhancing the anticorrosive performance of epoxy (EP) coatings. The electrochemical impedance spectroscopy (EIS) results revealed that the obtained MNs@Ur/EP coatings had outstanding long-term corrosion resistance (>129 d). The impedance at low frequency (|Z|f=0.01 Hz) of the 0.5 wt% MNs@Ur/EP coating was maintained at >1010 Ω·cm2 after 52 d of immersion, which was approximately four orders of magnitude greater than that of the pure EP coating. More importantly, the scratch test demonstrated the self-healing ability of the MNs@Ur/EP coating.

Anticorrosion Coating with Heterogeneous Assembly of Nanofillers Modulated by a Magnetic Field.

An anticorrosive coating with randomly distributed passive barriers and regionally enriched active corrosion inhibitors is developed by integrating mica nanosheets (MNSs) and magnetic-responsive core-shell mesoporous nanoparticles with 2-mercaptobenzothiazole (Fe3O4@mSiO2/MBT) under magnetic field incubation. The bottom enriched Fe3O4@mSiO2/MBT rapidly releases the MBT to form a passivation layer on corrosion sites, enhancing the corrosion inhibition efficiency by 30.36% compared with the control (NP0.7EP-R). The impedance modulus |Z|0.01Hz of the sample (NP0.7/MNS0.5/EP) increases by five orders of magnitude compared with that of its control (NP0.7/MNS0EP) after 30 days of corrosion immersion. NP0.7/MNS0.5/EP exhibited the lowest corrosion rate (3.984 × 10-5 mm/year) as compared to the other samples. Notably, the coating in a fractured state still maintains superior corrosion inhibition even after 40 day salt spray testing. The differentiated distribution of nanofillers was well confirmed by optical microscopy and SEM-EDS, and the synergistic effect of the active/passive integrated anticorrosive coating with merits of both comprehensive protection and fast responsiveness was systematically explored.

A new multifunctional energy harvester based on mica nanosheet-dispersed PVDF nanofabrics featuring piezo-capacitive, piezoelectric and triboelectric effects

Mica nanosheets and electrospinning synergistically improved the electroactive β-phase content and dielectric properties of PVDF. Consequently, the piezoelectric and triboelectric performance of mica-dispersed electrospun PVDF was enhanced.

Mussel-inspired preparation of dispersible mica nanosheets for waterborne epoxy coatings with reinforced anticorrosive performance

Mica is a low-cost, naturally layered material with superior insulation, high-temperature resistance, acid and alkali resistance, but the preparation of its nanosheets on a large scale and their compatibility with resin are still to be solved. In this work, hydroxyl-functionalized mica nanosheets (MNs) were prepared by the introduction of plasma treatment with a yield of 6.695 %. Inspired by mussels, natural tannic acid (TA) was chosen to modify MNs via the interaction of catechol groups with OH to prepare functionalized MNs (MNs@TA). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) proved the successful preparation of TA-modified MNs. The obtained MNs@TA exhibited good dispersion in solvent and waterborne epoxy (WEP) coating, enhancing the compatibility with WEP resin. In addition, the MNs@TA/WEP composite coatings were used on Q235 carbon steel, and their corrosion protection performance and mechanism were investigated by electrochemical impedance spectroscopy (EIS), ultra-depth three-dimensional microscope, and energy dispersive spectrometer (EDS). The results illustrated that the incorporation of 0.5 wt% MNs@TA significantly improved the anticorrosive performance of the WEP coating via enhanced barrier properties.

Recyclable Nacre‐Like Aramid‐Mica Nanopapers with Enhanced Mechanical and Electrical Insulating Properties

AbstractThe emerging aramid‐mica nanopapers, composed of aramid nanofibers (ANFs) and mica nanosheets (Mica), exhibit superiority in the field of electrical insulation compared with commercial aramid‐mica micropapers. Unfortunately, their mechanical and electrical insulating properties are still less than ideal due to insufficient control of their microstructures. Herein, it is presented that by integrating ANFs and Mica into nacre‐like aramid‐mica nanopapers with improved structural orderliness, densification, and interlayer interaction, simultaneously improved mechanical and electrical insulating properties are achieved. Their maximum tensile strength and breakdown strength reach ≈292 MPa and ≈176 kV mm−1, respectively, which are superior to those of the state‐of‐the‐art ANFs‐based nanopapers. Particularly, the aramid‐mica nanopapers show high resistance to high‐temperature (250–300 °C) and oil‐bath (100 °C) environments commonly involved in practical applications, and can be recycled many times, demonstrating their great potential as high‐performance sustainable electrical insulating papers to be applied in advanced electrical equipment.

Nacre‐Inspired Nanocomposite Films with Enhanced Mechanical and Barrier Properties by Self‐Assembly of Poly(Lactic Acid) Coated Mica Nanosheets

AbstractDeveloping biodegradable materials such as poly(lactic acid) (PLA) is a promising strategy to reduce the reliance on non‐degradable plastics and the accumulation of those wastes. However, the fabrication of high‐performance biodegradable films which integrate excellent mechanical and barrier properties remains a major challenge. To address this problem, the “brick and mortar” structure, one of the most effective biomimetic models, is introduced to improve the comprehensive properties of materials. Here, a PLA‐assisted exfoliation and dispersion method to prepare the PLA coated mica nanosheets (Nano‐mica/PLA) from a natural mineral phlogopite is presented. By introducing the sheer force assembly, a kind of nacre‐inspired nanocomposite film with the “brick and mortar” structure can be fabricated. Such a nacre‐inspired nanocomposite film shows excellent mechanical properties, UV‐shielding, and gas barrier properties. The overall performance of the nacre‐inspired nanocomposite film is superior to commercial plastic films, which will allow it possible to break a path for practical applications of PLA in the field of packaging.