Nanoparticles Of Synthetic Clay Research Articles

Temperature Responsive Composite Gel-Polymer Electrolytes for Lithium-Sulfur Batteries

Due to its high theoretical capacity of 1672 mAh g-1 and high energy density of 2600 Wh kg-1 sulfur is an attractive candidate as a cathode material for rechargeable lithium battery [1-2]. However, both LIBs and Li/S batteries rely on conventional liquid organic carbonate based electrolytes, which intrinsically has several critical drawbacks including volatility, flammability and potential leakage, which are triggering the safety issues [3]. Therefore, investigation for safer and more reliable electrolytes is urged, and polymer electrolytes are promising candidate in this regard. Poly(ethylene oxide)-based solid polymer electrolytes are common examples of a safe electrolyte. However, since they are limited by low ion conductivity at ambient temperature, the development of novel gel electrolytes, which entraps large amount of liquid electrolyte batteries attracts big interest. One of the major problems of sulfur cathode comes from solubility and shuttling phenomenon of the long chain lithium polysulfides in a conventional organic solvent based electrolyte, which causes a rapid irreversible loss of sulfur of the cathode over repeated cycles, and deposition of products of their transformation on the anode, leading to both electrodes degradation. In this work, we develop novel composite gel polymer electrolytes (GPEs) with high conductivity, high organic solvent uptake and high mechanical and thermal stability, which advantageously use the complementary properties of temperature-responsive polymer and ceramic filler. The composite GPEs are fabricated allowing for facile transport of Li+ ions but preventing leakage of electrolyte solution contained within the polymer membrane structure. Such GPEs have three unique features: electrolyte solution immobilization during battery cycling with rapid lithium ion transport, blocking of polysulfides shuttling phenomenon and battery shut down function in case of temperature increase. Furthermore, addition of functionalized natural and synthetic clay nanoparticles as ceramic filler allows overcoming the main problem of GPE – the loss of their mechanical strength when they are plasticized. We have combined polymers and temperature responsive polymers with Li-ion containing salt solutions. Among the inorganic layered hosts, montmorillonite and halloysite offer high aspect ratio, high cation exchange capacity, large specific surface area, appropriate interlayer charge. Undesired diffusion of polysulfide through electrolyte in Li/S batteries might be hindered in case of using composite GPE. A Li/S polymer cell containing a composite GPE has exhibited a good cycling performance with improved coulombic efficiency. The systems are under investigation with evaluation of polymer matrices and their ratio in the composite electrolyte.

Are There Generalizable Trends in the Release of Airborne Synthetic Clay Nanoparticles from a Jet Milling Process?

Despite recent efforts to assess the release of nanoparticles to the workplace during different nanotechnology activities, the existence of a generalizable trend in the particle release has yet to be identified. This study aimed to characterize the release of synthetic clay nanoparticles from a laboratory-based jet milling process by quantifying the variations arising from primary particle size and surface treatment of the material used, as well as the feed rate of the machine. A broad range of materials were used in this study, and the emitted particles mass (PM2.5) and number concentrations (PNC) were measured at the release source. Analysis of variance, followed by linear mixed-effects modeling, was applied to quantify the variations in PM2.5 and PNC of the released particles caused by the abovementioned factors. The results confirmed that using materials of different primary size and surface treatment affects the release of the particles from the same process by causing statistically-significant variations in PM2.5 and PNC. The interaction of these two factors should also be taken into account as it resulted in variations in the measured particles release properties. Furthermore, the feed rate of the milling machine was confirmed to be another influencing parameter. Although this research does not identify a specific pattern in the release of synthetic clay nanoparticles from the jet milling process generalizable to other similar settings, it emphasizes that each tested case should be handled individually in terms of exposure considerations.

Can clay nanoparticles accelerate environmental biodegradation of polyolefins?

Synthetic polyolefins have been used in an enormous array of applications in the modern society, due to a combination of reliable raw materials, low cost processing, tailorable mechanical properties, low density and inertness or stability towards environmental factors. In the last two decades, with the concern of sustainable development, these polyolefins have necessitated further research into: i) finding alternative or renewable raw materials resources, ii) developing polymeric materials from renewable feedstocks that are capable of giving rise to comparable performance to the petrochemical based polymer counterparts and iii) triggering the biological degradation of polyolefins. In order to overcome the issues associated with waste accumulation and disposal, the biological recycling or degradation in the landfill or soil burial, composting and sewage have all been considered as less energy consuming, less toxic and environmentally friendly ways of sustainably managing the life cycle of high volume commodity polymers. It has also been well accepted that an abiotic oxidation (photo-, thermo-oxidation) is a prerequisite for enhancing the biodegradability or biological accessibility of polyolefins. For this purpose, several pro-oxidant approaches have been reported. The present paper reviews how the natural or synthetic clay nanoparticles, which are potential nanoscale fillers recently used for reinforcing polymers, can affect or enhance the biodegradability of polyolefins. They have also been discussed from the perspective of nanocomposite materials with controlled degradability and their associated applications.

Interaction of Human Arylamine N-Acetyltransferase 1 with Different Nanomaterials

Humans are exposed to nanoparticles in the environment as well as those in nanomaterials developed for biomedical applications. However, the safety and biologic effects of many nanoparticles remain to be elucidated. Over the past decade, our understanding of the interaction of proteins with various nanomaterials has grown. The protein corona can determine not only how nanoparticles interact with cells but also their biologic effects and toxicity. In this study, we describe the effects that several different classes of nanoparticles exert on the enzymatic activity of the cytosolic protein human arylamine N-acetyltransferase 1 (NAT1), a drug-metabolizing enzyme widely distributed in the body that is also responsible for the activation and detoxification of known carcinogens. We investigated three metal oxides (zinc oxide, titanium dioxide, and silicon dioxide), two synthetic clay nanoparticles (layered double hydroxide and layered silicate nanoparticles), and a self-assembling thermo-responsive polymeric nanoparticle that differ in size and surface characteristics. We found that the different nanoparticles induced very different responses, ranging from inhibition to marked enhancement of enzyme activity. The layered silicates did not directly inactivate NAT1, but was found to enhance substrate-dependent inhibition. These differing effects demonstrate the multiplicity of nanoparticle-protein interactions and suggest that enzyme activity may be compromised in organs exposed to nanoparticles, such as the lungs or reticulo-endothelial system.