Rapid and high-concentration exfoliation of montmorillonite into high-quality and mono-layered nanosheets

Silicon-containing nanomedicine and biomaterials: materials chemistry, multi-dimensional design, and biomedical application

The invention of silica-based bioactive glass in the late 1960s has sparked significant interest in exploring a wide range of silicon-containing biomaterials from the macroscale to the nanoscale. Over the past few decades, these biomaterials have been extensively explored for their potential in diverse biomedical applications, considering their remarkable bioactivity, excellent biocompatibility, facile surface functionalization, controllable synthesis, etc. However, to expedite the clinical translation and the unexpected utilization of silicon-composed nanomedicine and biomaterials, it is highly desirable to achieve a thorough comprehension of their characteristics and biological effects from an overall perspective. In this review, we provide a comprehensive discussion on the state-of-the-art progress of silicon-composed biomaterials, including their classification, characteristics, fabrication methods, and versatile biomedical applications. Additionally, we highlight the multi-dimensional design of both pure and hybrid silicon-composed nanomedicine and biomaterials and their intrinsic biological effects and interactions with biological systems. Their extensive biomedical applications span from drug delivery and bioimaging to therapeutic interventions and regenerative medicine, showcasing the significance of their rational design and fabrication to meet specific requirements and optimize their theranostic performance. Additionally, we offer insights into the future prospects and potential challenges regarding silicon-composed nanomedicine and biomaterials. By shedding light on these exciting research advances, we aspire to foster further progress in the biomedical field and drive the development of innovative silicon-composed nanomedicine and biomaterials with transformative applications in biomedicine.

Controllable synthesis of layered double hydroxide nanosheets to build organic inhibitor-loaded nanocontainers for enhanced corrosion protection of carbon steel

The development of layered double hydroxide (LDH) nanosheets as nanocontainers has been intensively studied in recent years. Despite their potential for application on a large scale, their synthesis in an aqueous medium is rarely reported. Herein, we report a straightforward approach for the controllable synthesis of uniform MgAl-LDH nanosheets by an aqueous nucleation process followed by a hydrothermal treatment. The key to this method relies on the well-dispersed LDH nuclei that are produced by high-speed homogenization. Following the nucleation step, the coalescence of the aggregate hydroxide layers is diminished by hydraulic shear forces, leading to the disaggregation and even distribution of LDH nuclei. As a result, the oriented growth of individual crystals along the horizontal plane becomes predominant, leading to a high surface charge density of the hydroxide sheets and preventing their stacking. The electron microscope virtual proofs showed that the particles had a well-defined circular shape with a thickness of about 2-3 nm. Afterward, for the first time, LDH nanosheets were used to prepare LDH nanocontainers loaded with 2-benzothiazolythio-succinic acid (BTSA) by anion exchange. The incorporation of BTSA into the interlayer region and the emission behavior of the inhibitor were investigated. These results indicate that the prepared nanosheets can be utilized as effective nanocontainers for organic inhibitor loading and anti-corrosion application.

Layered Clay Minerals in Cancer Therapy: Recent Progress and Prospects

Cancer is one of the deadliest diseases, and current treatment regimens suffer from limited efficacy, nonspecific toxicity, and chemoresistance. With the advantages of good biocompatibility, large specific surface area, excellent cation exchange capacity, and easy availability, clay minerals have been receiving ever-increasing interests in cancer treatment. They can act as carriers to reduce the toxic side effects of chemotherapeutic drugs, and some of their own properties can kill cancer cells, etc. Compared with other morphologies clays, layered clay minerals (LCM) have attracted more and more attention due to adjustable interlayer spacing, easier ion exchange, and stronger adsorption capacity. In this review, the structure, classification, physicochemical properties, and functionalization methods of LCM are summarized. The state-of-the-art progress of LCM in antitumor therapy is systematically described, with emphasis on the application of montmorillonite, kaolinite, and vermiculite. Furthermore, the property-function relationships of LCM are comprehensively illustrated to reveal the design principles of clay-based antitumor systems. Finally, foreseeable challenges and outlook in this field are discussed.

Preparation of Montmorillonite Nanosheets with a High Aspect Ratio through Heating/Rehydrating and Gas-Pushing Exfoliation

Montmorillonite (MMT) is an abundant silicate mineral with ultrahigh stability. The exfoliation of stacked MMT into high-aspect-ratio nanosheets is of crucial importance for various applications such as toxic gas suppression, barrier property enhancement, flame retardancy, and ion conduction. In this work, we develop a new heating/rehydrating and gas-pushing method that can successfully exfoliate MMT into nanosheets with aspect ratios (600-5000) far higher than the currently reported values (1-120). The MMT first goes through a "starvation pretreatment" under different heating temperatures to improve its hydrophilicity and is then rehydrated in a hydrogen peroxide solution. The hydrogen peroxide in the MMT interlayer space can decompose into water and oxygen bubbles, thus finally leading to the exfoliation via gas-pushing while preserving the large lateral size (mainly in the range of 1-6 μm) of the nanosheets. By changing the pretreatment temperature and pH value of the hydrogen peroxide solution, the exfoliation performance can be tuned. This simple and low-cost exfoliation method is promising to achieve the mass production of MMT nanosheets with a high aspect ratio and may promote its application in various fields such as energy conversion, drug delivery, and photocatalysis.

Kelly A, Bai S. Using Asphalt as an Additive for Waste Cross-Linked Polyethylene Recycled Materials to Improve Thermoplastic Processing

With good insulation, cross-linked polyethylene (XLPE) cables are widely used as an important basic material for power transportation. Due to being insoluble and infused, the cross-linked network structure caused a challenge in the recycling of waste XLPE, which is usually treated by incineration and landfilling. In this research, XLPE was part-de-cross-linked via solid-state shear milling (S³M) technology, but the resulting powder was difficult to process. In order to improve the re-processability of XLPE, asphalt with a similar structure was added during the thermoplastic processing. To deeply understand the influence of asphalt on the matrix, the compatibility, dispersion, and rheological properties of the composites were characterized. Due to the good compatibility between de-cross-linked XLPE and asphalt, the viscosity of the composites decreased significantly. Some sea-island structures also formed in composites, which increased the toughness of the composites, so the elongation at break reached as high as 322%. The use of asphalt to achieve the processing performance of part-de-cross-linked XLPE powder was highly effective. Furthermore, the prepared composites showed potential application in the field of waterproofing, which could recycle waste XLPE cables on a large scale.

Halogen-free instinct flame-retardant waterborne polyurethanes: composition, performance, and application

Ideal halogen-free instinct flame-retardant waterborne polyurethanes have high flame-retardant efficiency, environmental friendliness, fine compatibility, and good thermostability. Phosphorus flame-retardants are currently widely used in halogen-free instinct flame-retardant waterborne polyurethanes (HIFWPU), especially those with phosphorous-nitrogen co-structures. Phosphorous-nitrogen HIFWPU have become a hotspot because their co-structures provide higher flame-retardance as compared to waterborne polyurethanes. This review introduces three main types of HIFWPU based on composition, performance and application. HIFWPU not only have improved flame-retardance but also satisfy the various requirements for functionality. HIFWPU have been widely developed in textile, furniture, automobile, and aerospace applications.

Inclusion of organic species in exfoliated montmorillonite nanolayers towards hierarchical functional inorganic-organic nanostructures

Montmorillonite (Mt) can readily undergo spontaneous delamination or exfoliation into nanolayers by various physical and chemical processes, which allow various strategies to engineer hierarchical functional inorganic-organic nanostructures. This review aims to discuss the recent progress in the liquid-phase exfoliation of Mt into individual nanolayers and the inclusion chemistry of functional organic species, ions, or molecules into the exfoliated Mt nanolayers to produce hierarchical functional inorganic-organic nanostructures. The exfoliation methods include mechanical force, ultrasonication, and intercalation-assisted exfoliation. Techniques for quickly assessing the quality of the exfoliated Mt nanolayers are still needed. Layer-by-layer (LbL) deposition, template, and evaporation-induced inclusions are examined to fabricate hierarchical Mt-organic species nanocomposites with unique functionalities and properties. The nanocomposites can be produced as multilayered porous films, brick-and-mortar coatings, hydrogels with a house-of-cards structure, core-shell materials, and hollow and mesoporous spherical nanocomposites, which exhibit significant potential for adsorption, catalysis, targeted delivery and controlled drug release, highly sensitive sensors, flame retardant coatings, and thermal energy storage and release (i.e. phase change materials). Finally, the challenges and prospects for the future development of hierarchical nanocomposites of exfoliated Mt nanolayers and organic species, particularly in hierarchical supramolecular nanostructured composites, are highlighted.