Nanomaterials are materials with morphological properties smaller than 1 µm "Micrometer (unit of length)") in at least one dimension.[1] Despite the fact that there is no consensus on the minimum or maximum size of a nanomaterial, some authors restrict its size from 1 to 100 nm, a logical definition would place the nanoscale between the microscale (1 µm) and the atomic/molecular scale (around 0.2nm).
On 18 October 2011, the European Commission adopted the following definition of nanomaterial: "A natural, incidental or manufactured material containing particles, in an unagglomerated state or as an aggregate or as an agglomerate and for 50% or more of the particles in the numerical size distribution, one or more external dimensions is in the size range of 1 nm - 100 nm. In specific cases and where justified by concerns for the environment, health, safety or competitiveness, the threshold of 50% of the numerical size distribution may be replaced by a threshold between 1% and 50%".[2].
Fundamental concepts
A unique aspect of nanotechnology is the enormous surface-to-volume ratio present in many nanoscale materials that leads to the emergence of new quantum mechanical effects, for example, the "quantum size effect" in which the electronic properties of solids are altered with a large reduction in particle size. This effect is not important when going from macro to micro dimensions. However, it becomes dominant when the nanoscale is reached. Furthermore, several physical properties change when compared to macroscopic systems. The new properties of nanomaterials are the subject of nanomechanical research. Their catalytic activities reveal novel properties in the interaction with biomaterials.
Nanotechnology can be imagined as the extension of traditional disciplines towards the explicit consideration of the aforementioned properties. Furthermore, traditional disciplines can be reinterpreted as specific applications of nanotechnology. This dynamic reciprocity of ideas and concepts contributes to the modern understanding of the field. Broadly speaking, nanotechnology is the synthesis and application of ideas from science and engineering toward the understanding and production of novel materials and devices.
Materials reduced to the nanoscale can suddenly show very different properties than those exhibited on a macroscale, enabling unique applications. For example, opaque substances become transparent (copper); inert materials are transformed into catalysts (platinum); stable materials are transformed into fuels (aluminum); solids become liquids at room temperature (gold); insulators become conductors (silicone). Materials such as gold, which is chemically inert at normal scales, can serve as catalysts at nanoscales. Much of the fascination with nanotechnology comes from these peculiar quantum and surface phenomena that matter exhibits at the nanoscale.
Nanomaterials for air purification
Introduction
Nanomaterials are materials with morphological properties smaller than 1 µm "Micrometer (unit of length)") in at least one dimension.[1] Despite the fact that there is no consensus on the minimum or maximum size of a nanomaterial, some authors restrict its size from 1 to 100 nm, a logical definition would place the nanoscale between the microscale (1 µm) and the atomic/molecular scale (around 0.2nm).
On 18 October 2011, the European Commission adopted the following definition of nanomaterial: "A natural, incidental or manufactured material containing particles, in an unagglomerated state or as an aggregate or as an agglomerate and for 50% or more of the particles in the numerical size distribution, one or more external dimensions is in the size range of 1 nm - 100 nm. In specific cases and where justified by concerns for the environment, health, safety or competitiveness, the threshold of 50% of the numerical size distribution may be replaced by a threshold between 1% and 50%".[2].
Fundamental concepts
A unique aspect of nanotechnology is the enormous surface-to-volume ratio present in many nanoscale materials that leads to the emergence of new quantum mechanical effects, for example, the "quantum size effect" in which the electronic properties of solids are altered with a large reduction in particle size. This effect is not important when going from macro to micro dimensions. However, it becomes dominant when the nanoscale is reached. Furthermore, several physical properties change when compared to macroscopic systems. The new properties of nanomaterials are the subject of nanomechanical research. Their catalytic activities reveal novel properties in the interaction with biomaterials.
Nanotechnology can be imagined as the extension of traditional disciplines towards the explicit consideration of the aforementioned properties. Furthermore, traditional disciplines can be reinterpreted as specific applications of nanotechnology. This dynamic reciprocity of ideas and concepts contributes to the modern understanding of the field. Broadly speaking, nanotechnology is the synthesis and application of ideas from science and engineering toward the understanding and production of novel materials and devices.
Nanosized powder particles (also called nanoparticles) are potentially important in ceramics and powder metallurgy, achieving uniform nanoporosity and other similar applications. The strong tendency of small particles to form clumps is a serious technological problem that prevents such applications. However, some dispersants such as ammonia citrate (aqueous) and oleic alcohol") (non-aqueous) are promising additives for debinding.
Nanomaterials can be subdivided into nanoparticles, nanoshells and nanocomposites. The nanomaterials approach is a bottom-up approach to structural and functional effects so that building blocks of materials are designed and assembled in a controlled manner.
A recent Small Times report predicts strong growth in so-called nanomaterials. It discusses the different types that currently exist (such as nanoclays to reinforce plastics) or carbon nanotubes to add conductivity to various materials.
Many of these advances are being carried out by small and medium-sized North American companies in collaboration with leading companies.
There are three basic categories of nanomaterials from a commercial and development point of view: metal oxides, nanoclays and carbon nanotubes. Those that have advanced the most from a commercial point of view are metal oxide nanoparticles.
Sources
Engineering
Engineered nanomaterials have been deliberately designed and manufactured by humans to have certain properties.[3][4].
Legacy nanomaterials are those that were produced commercially before the development of nanotechnology as incremental advances over other colloidal or particulate materials,[5][6][7] such as carbon black and titanium dioxide nanoparticles").[8].
Incidental
Nanomaterials can be produced unintentionally as a byproduct of mechanical or industrial processes through combustion and vaporization. Sources of accidental nanoparticles include vehicle engine exhaust, foundry, welding fumes, combustion processes from solid fuel home heating, and cooking. For example, the class of nanomaterials called fullerenes are generated by burning gas, biomass "Biomass (energy)") and candles.[9] They can also be a byproduct of wear and corrosion products.[10] Incidental atmospheric nanoparticles are often called ultrafine particles, which are produced unintentionally during intentional operation, and could contribute to air pollution.[11][12].
Natural
Biological systems often present natural and functional nanomaterials. The structure of foraminifera (mainly limestone) and viruses (protein, capsid), the wax crystals that cover a lotus or nasturtium leaf, the silk of spiders and mites,[13] the blue tone of tarantulas,[14] the "spatulas" on the underside of the legs of geckos, some butterfly wing scales, natural colloids (milk, blood), horny materials (skin, claws, beaks, feathers, horns, hair), paper, cotton, mother-of-pearl, corals and even our own bone matrix are natural organic nanomaterials.
Natural inorganic nanomaterials are produced by growing crystals in the various chemical conditions of the Earth's crust. For example, clays exhibit complex nanostructures due to the anisotropy of their underlying crystalline structure, and volcanic activity can give rise to opals, which are an example of natural photonic crystals due to their nanoscale structure. Fires represent especially complex reactions and can produce pigments, cement, fumed silica"), etc.
Natural sources of nanoparticles are the combustion products of forest fires, volcanic ash, ocean splatter, and the radioactive decay of radon gas. Natural nanomaterials can also form through weathering processes of rocks containing metals or anions, as well as at sites of acid mine drainage.[15].
Guys
Contenido
Los nanoobjetos se suelen clasificar en función de cuántas de sus dimensiones entran en la nanoescala. Una nanopartícula se define como un nanoobjeto con las tres dimensiones externas en la nanoescala, cuyos ejes más largo y más corto no difieren significativamente.
Dimensiones.
La clasificación de los nanomateriales depende de cuántas de sus tres dimensiones espaciales se encuentran en la escala nanométrica [16].
Una nanofibra tiene dos dimensiones externas en la nanoescala, siendo los nanotubos nanofibras huecas y los nanorods nanofibras sólidas. Una nanoplaca/nanohoja tiene una dimensión externa en la nanoescala,[17] y si las dos dimensiones mayores son significativamente diferentes se denomina nanocinta. En el caso de las nanofibras y las nanoplacas, las otras dimensiones pueden estar o no en la nanoescala, pero deben ser significativamente mayores. En todos estos casos, se observa que una diferencia significativa suele ser al menos un factor de 3.[18].
Los materiales nanoestructurados suelen clasificarse según las fases de la materia "Fase (materia)") que contengan. Un nanocompuesto es un sólido que contiene al menos una región o conjunto de regiones física o químicamente distintas, con al menos una dimensión en la nanoescala. Una nanoespuma") tiene una matriz líquida o sólida, rellena de una fase gaseosa, donde una de las dos fases tiene dimensiones en la nanoescala. Un material nanoporoso") es un material sólido que contiene nanoporos, vacíos en forma de poros abiertos o cerrados de longitudes submicrónicas. Un material nanocristalino") tiene una fracción significativa de granos de cristal en la nanoescala.[19].
Nanoporous materials
The term nanoporous materials encompasses subsets of microporous and mesoporous materials. Microporous materials are porous materials with an average pore size less than 2 nm, while mesoporous materials are those with pore sizes in the region of 2-50 nm.[20] Microporous materials exhibit pore sizes with a length scale comparable to that of small molecules. For this reason, these materials can have valuable applications, such as separation membranes. Mesoporous materials are interesting for applications that require a high specific surface area, while allowing the penetration of molecules that may be too large to enter the pores of a microporous material. In some sources, nanoporous materials and nanofoam are sometimes considered nanostructures, but not nanomaterials, because only the voids, and not the materials themselves, are nanoscale.[21] Although the ISO definition only considers round nanoobjects as nanoparticles, other sources use the term nanoparticle for all shapes.[22]
Nanoparticles
Main article: Nanoparticles.
Nanoparticles have all three dimensions on the nanoscale. Nanoparticles can also be embedded in a solid to form a nanocomposite.[21].
Main article: Fullereno.
Fullerenes are a class of carbon allotropes that conceptually are sheets of graphene rolled into tubes or spheres. Among them are carbon nanotubes (or silicon nanotubes), interesting both for their mechanical resistance and for their electrical properties.[23].
The first fullerene molecule discovered and the namesake of the family, buckminsterfullerene (C), was prepared in 1985 by Richard Smalley, Robert Curl, James Heath, Sean O'Brien, and Harold Kroto at Rice University. The name was a tribute to Buckminster Fuller, whose geodesic domes it resembles. Since then, fullerenes have been discovered to be present in nature.[24] More recently, fullerenes have been detected in outer space.[25].
Over the past decade, the chemical and physical properties of fullerenes have been a hot topic in the field of research and development, and are likely to remain so for a long time. In April 2003, possible medicinal uses of fullerenes were being studied: binding specific antibiotics to the structure of resistant bacteria and even targeting certain types of cancer cells, such as melanoma cells. The October 2005 issue of Chemistry and Biology contains an article describing the use of fullerenes as light-activated antimicrobial agents. In the field of nanotechnology, heat resistance and superconductivity are some of the properties that spark intense research.
A common method of producing fullerenes is to send a large current between two nearby graphite electrodes in an inert atmosphere. The resulting carbon plasma arc "Plasma (state of matter)") between the electrodes cools to form a soot residue from which many fullerenes can be isolated.
Many calculations have been performed with ab-initio quantum methods applied to fullerenes. Using DFT and TDDFT methods, IR, Raman and UV spectra can be obtained. The results of these calculations can be compared with the experimental ones.
Inorganic nanomaterials (e.g., quantum dots, nanowires, and nanorods), due to their interesting optical and electrical properties, could be used in optoelectronics. Furthermore, the optical and electronic properties of nanomaterials, which depend on their size and shape, can be tuned using synthetic techniques. There are possibilities of using these materials in optoelectronic devices based on organic materials, such as organic solar cells, OLEDs, etc. The operating principles of these devices are governed by photoinduced processes such as electron transfer and energy transfer. The performance of the devices depends on the efficiency of the photoinduced process responsible for their operation. Therefore, it is necessary to better understand these photoinduced processes in organic/inorganic nanomaterial composite systems to be able to use them in optoelectronic devices.
One-dimensional nanostructures
The smallest possible crystalline threads, with a cross section as small as that of an atom, can be fabricated in cylindrical confinement.[30][31][32] Carbon nanotubes, a natural semi-dimensional nanostructure, can be used as a template for synthesis. Confinement provides mechanical stabilization and prevents linear atomic chains from disintegrating; Other 1D nanowire structures are predicted to be mechanically stable even when isolated from templates[33][34].
Two-dimensional nanostructures
2D materials are crystalline materials made up of a single two-dimensional layer of atoms. The most important representative, graphene, was discovered in 2004. Thin films with nanoscale thicknesses are considered nanostructures, but are sometimes not considered nanomaterials because they do not exist separate from the substrate.[21][35].
Bulk nanostructured materials
Some bulk materials contain nanoscale features, such as nanocomposites, nanocrystalline materials, nanostructured films, and nanotextured surfaces[21].
The box-shaped graphene (BSG) nanostructure is an example of a three-dimensional nanomaterial.[36] The BSG nanostructure has appeared after the mechanical cleavage of pyrolytic graphite"). This nanostructure is a multilayer system of parallel hollow nanochannels located along the surface and with a quadrangular cross section. The thickness of the channel walls is approximately equal to 1 nm. The typical width of the channel facets is about 25 nm.
Applications
Main article: Applications of nanotechnology.
Nanomaterials are used in a wide variety of manufacturing processes, products and healthcare, such as paints, filters, insulators and lubricant additives. In healthcare, nanozymes") are nanomaterials with characteristics similar to enzymes.[37] They are an emerging type of artificial enzymes, which have been used for broad applications in fields such as biosensing, bioimaging, tumor diagnosis[38] or antibiofouling, among others.
High-quality filters can be manufactured using nanostructures; These filters are capable of removing particles as small as a virus, as seen in a water filter created by Seldon Technologies. Recently, nanomaterial membrane bioreactors (NMs-MBR), the next generation of conventional MBRs, have been proposed for advanced wastewater treatment[39].
In the field of air purification, nanotechnology was used to combat the spread of MERS in hospitals in Saudi Arabia in 2012.[40] Nanomaterials are being used in modern, human-safe insulation technologies; in the past they were found in asbestos-based insulators.
As a lubricant additive, nanomaterials have the ability to reduce friction in moving parts. Worn and corroded parts can also be repaired with self-assembling anisotropic nanoparticles called TriboTEX.[40].
Nanomaterials have also been applied in various industries and consumer products. Mineral nanoparticles, such as titanium oxide "Titanium(IV) Oxide"), have been used to improve the UV protection of sunscreens. In the sports industry, lighter bats have been made with carbon nanotubes to improve their performance. Another application is in the military, where mobile pigment nanoparticles have been used to create more effective camouflage. Nanomaterials can also be used in three-way catalyst (TWC) applications. TWC converters have the advantage of controlling the emission of nitrogen oxides (NOx), precursors of acid rain and smog.[41] In the core-shell structure, nanomaterials form a shell as a support for the catalyst to protect noble metals, such as palladium and rhodium.[42] The main function is that the supports can be used to transport the active components of the catalysts, make them highly dispersed, reduce the use of noble metals, increase the activity of catalysts and improve mechanical resistance.
Synthesis
El objetivo de cualquier método de síntesis de nanomateriales es obtener un material que presente propiedades derivadas de su escala de longitud característica en el rango nanométrico (1 - 100 nm). Por consiguiente, el método sintético debe permitir controlar el tamaño en este intervalo para poder obtener una u otra propiedad. A menudo, los métodos se dividen en dos tipos principales, "ascendentes" y "descendentes".
Bottom-up methods
Bottom-up methods involve the assembly of atoms or molecules into nanostructured assemblies. In these methods, the raw material sources can be gases, liquids or solids. The latter require some type of disassembly before incorporation into a nanostructure. Bottom-up methods are usually divided into two categories: chaotic and controlled.
Chaotic processes involve raising constituent atoms or molecules to a chaotic state and then suddenly changing conditions so that that state becomes unstable. By intelligently manipulating any number of parameters, products are formed largely as a result of insurance kinetics. Collapse from the chaotic state can be difficult or impossible to control, so ensemble statistics typically govern the resulting size distribution and mean size. Consequently, the formation of nanoparticles is controlled by manipulating the final state of the products. Examples of chaotic processes are laser ablation,[43] wire explosion, arcing, flame pyrolysis, combustion[44] and precipitation synthesis techniques.
Controlled processes involve the controlled delivery of constituent atoms or molecules to the site or sites of nanoparticle formation, so that they can grow to a prescribed size in a controlled manner. Typically, the state of the constituent atoms or molecules is never far from that necessary for nanoparticle formation. Therefore, the formation of nanoparticles is controlled by controlling the state of the reactants. Examples of controlled processes are self-limiting growth solution, self-limiting chemical vapor deposition, patterned pulse femtosecond laser techniques, plant and microbial approaches[45], and molecular beam epitaxy.
Top-down methods
Top-down methods adopt some “force” (e.g., mechanical force, laser) to break bulk materials into nanoparticles. A very popular method of mechanically breaking down bulk materials into nanomaterials is “ball milling.” Additionally, nanoparticles can also be manufactured by laser ablation, which applies short pulse lasers (e.g., femtosecond laser) to ablate a target (solid).[43].
Characterization
Main articles: Nanometrology and Characterization of nanoparticles.
Novel effects in materials can occur when structures are formed with sizes comparable to any of many possible length scales, such as the Broglie wavelength of electrons or the optical wavelengths of high-energy photons. In these cases, quantum mechanical effects can dominate the properties of the materials. An example is quantum confinement"), in which the electronic properties of solids are altered with large reductions in particle size. The optical properties of nanoparticles, for example fluorescence, also become a function of the diameter of the particle. This effect does not come into play when going from macroscopic to micrometric dimensions, but is accentuated when the nanometer scale is reached.
In addition to optical and electronic properties, the novel mechanical properties of many nanomaterials are the subject of research in nanomechanics. of an increase in stability and an improvement in functionality.[46].
Finally, nanostructured materials with small particle sizes, such as zeolites and asbestos, are used as catalysts in a wide range of critical industrial chemical reactions. Further development of these catalysts can form the basis for more efficient and environmentally friendly chemical processes.
The first observations and measurements of the size of nanoparticles were made during the first decade of the century. Zsigmondy performed detailed studies of gold sols and other nanomaterials with sizes less than 10 nm. He published a book in 1914. He used an ultramicroscope that uses a dark field method to see particles with sizes much smaller than the wavelength of light.
There are traditional techniques developed over the century in interface and colloid science to characterize nanomaterials. These are widely used for first generation passive nanomaterials specified in the following section.
These methods include several different techniques to characterize the size distribution of particles.
There is also a group of traditional techniques to characterize the surface charge") or zeta potential of nanoparticles in solutions. This information is necessary for the correct stabilization of the system, preventing its aggregation or flocculation. These methods include microelectrophoresis"), electrophoretic light scattering") and electroacoustics. The latter, for example the colloid vibration current method"), is suitable for characterizing concentrated systems.
Mechanical properties
Ongoing research has shown that mechanical properties can vary significantly in nanomaterials compared to bulk material. Nanomaterials have substantial mechanical properties due to the volume, surface, and quantum effects of the nanoparticles. This is observed when nanoparticles are added to a common bulk material, the nanomaterial refines the grain and forms intergranular and intragranular structures that improve the grain boundaries and therefore the mechanical properties of the materials. Grain boundary refinement provides reinforcement by increasing the stress necessary to cause intergranular or transgranular fractures. A common example in which this can be observed is the addition of nano silica to cement, which improves tensile, compressive and flexural strength through the mechanisms just mentioned. Understanding these properties will improve the use of nanoparticles in novel applications in various fields such as surface engineering, tribology and nanofabrication.
Uniformity
The chemical processing and synthesis of high-performance technological components for the private, industrial and military sectors require the use of high-purity ceramics, polymers, glass-ceramics and composite materials. In condensed bodies formed from fine powders, the irregular sizes and shapes of nanoparticles in a typical powder often lead to non-uniform packing morphologies that give rise to packing density variations in the compact powder.
Uncontrolled agglomeration of powders due to attractive Van der Waals forces can also lead to microstructural inhomogeneities. The differential stresses that develop as a result of nonuniform drying shrinkage are directly related to the rate at which solvent can be removed and are therefore highly dependent on the porosity distribution. These stresses have been associated with a transition from plastic to brittle in consolidated bodies, and can lead to the propagation of cracks in the body.[48][49][50].
Furthermore, any fluctuations in packing density in the compact when preparing for the furnace are often amplified during the sintering process, leading to inhomogeneous densification. It has been shown that some pores and other structural defects associated with density variations play a detrimental role in the sintering process by growing and thus limiting the final densities. It has also been shown that differential stresses arising from inhomogeneous densification give rise to the propagation of internal cracks, thus becoming the defects that control strength.[51][52].
Therefore, it seems desirable to process a material in a way that is physically uniform in component distribution and porosity, rather than using particle size distributions that maximize raw density. Containment of a uniformly dispersed set of strongly interacting particles in suspension requires complete control of particle-particle interactions. Various dispersants, such as ammonium citrate (aqueous) and imidazoline or oleyl alcohol (non-aqueous), are promising solutions as potential additives to improve dispersion and deagglomeration. Monodisperse nanoparticles and colloids offer this potential.[53].
Monodisperse colloidal silica powders, for example, can be stabilized sufficiently to ensure a high degree of order in the colloidal crystal or in the polycrystalline colloidal solid resulting from aggregation. The degree of order appears to be limited by the time and space allowed for longer-range correlations to be established. Such defective polycrystalline colloidal structures appear to be the building blocks of submicron colloidal materials science and therefore Therefore, they provide the first step in developing a more rigorous understanding of the mechanisms involved in microstructural evolution in high-performance materials and components.[54][55].
Nanomaterials in articles, patents and products
Quantitative analysis of nanomaterials showed that nanoparticles, nanotubes, nanocrystalline materials, nanocomposites and graphene have been mentioned in 400,000, 181,000, 144,000, 140,000, and 119,000 ISI indexed articles, respectively, as of September 2018. Regarding patents, nanoparticles, Nanotubes, nanocomposites, graphene, and nanowires have played a role in 45,600, 32,100, 12,700, 12,500, and 11,800 patents, respectively. Monitoring of about 7,000 commercial nanoproducts available in global markets revealed that the properties of about 2,330 products have been facilitated or improved with the help of nanoparticles. Liposomes, nanofibers, nanocolloids and aerogels were also among the most common nanomaterials in consumer products.[56].
The European Union Nanomaterials Observatory (EUON) has developed a database (NanoData) that provides information on patents, products and research publications specific to nanomaterials.
Assessment Criteria
The manufactured synthetic nanomaterials must be considered under a rigorous evaluation to determine if they are suitable and thus ensure the safety of the new substances, mainly seeking to evaluate those that have commercial importance, for example: fullerenes, silver nanoparticles, iron nanoparticles, gold nanoparticles, nanoclays, aluminum oxide, zinc oxide, cerium oxide, silicon dioxide, titanium dioxide dendrimers, SWCNTs and MWCNTs. These assessment criteria are based on environmental safety and human health, they are mainly: [57].
[3] ↑ Portela, Carlos M.; Vidyasagar, A.; Krödel, Sebastian; Weissenbach, Tamara; Yee, Daryl W.; Greer, Julia R.; Kochmann, Dennis M. (2020). «Extreme mechanical resilience of self-assembled nanolabyrinthine materials». Proceedings of the National Academy of Sciences 117 (11): 5686-5693. Bibcode:2020PNAS..117.5686P. ISSN 0027-8424. PMC 7084143. PMID 32132212. doi:10.1073/pnas.1916817117.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pmc/articles/PMC7084143
[4] ↑ «Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes», U.S. National Institute for Occupational Safety and Health (en inglés estadounidense), November 2013: 1-3, 7, 9-10, 17-20, doi:10.26616/NIOSHPUB2014102, consultado el 5 de marzo de 2017 .: https://www.cdc.gov/niosh/docs/2014-102/default.html
[7] ↑ «Future challenges related to the safety of manufactured nanomaterials». Organisation for Economic Co-operation and Development. 4 de noviembre de 2016. p. 11. Consultado el 6 de septiembre de 2017. - [http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2016)58&doclanguage=en](http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2016)58&doclanguage=en)
[9] ↑ Barcelo, Damia; Farre, Marinella (2012). Analysis and Risk of Nanomaterials in Environmental and Food Samples. Oxford: Elsevier. p. 291. ISBN 9780444563286.
[10] ↑ Sahu, Saura; Casciano, Daniel (2009). Nanotoxicity: From in Vivo and in Vitro Models to Health Risks. Chichester, West Sussex: John Wiley & Sons. pp. 227. ISBN 9780470741375.: https://archive.org/details/nanotoxicityinvi0000unse
[16] ↑ Silva Yumi, J. E., & Medina S., C. A. (2024). Materiales y nanomateriales: Principios, aplicaciones y técnicas de caracterización. CIMOGSYS - ESPOCH. http://cimogsys.espoch.edu.ec/direccion-publicaciones/public/docs/books/2024-07-24-131511-Materiales%20y%20nanomateriales.pdf.
[17] ↑ Rawat, Pankaj Singh; Srivastava, R.C.; Dixit, Gagan; Asokan, K. (2020). «Structural, functional and magnetic ordering modifications in graphene oxide and graphite by 100 MeV gold ion irradiation». Vacuum 182: 109700. Bibcode:2020Vacuu.182j9700R. S2CID 225410221. doi:10.1016/j.vacuum.2020.109700.: http://adsabs.harvard.edu/abs/2020Vacuu.182j9700R
[19] ↑ «ISO/TS 80004-4:2011 - Nanotechnologies – Vocabulary – Part 4: Nanostructured materials». International Organization for Standardization. 2011. Consultado el 8 de enero de 2018.: https://www.iso.org/obp/ui/#iso:std:iso:ts:80004:-4:ed-1:v1:en
[20] ↑ Doustkhah E et al. (2021). «Bispropylurea bridged polysilsesquioxane: A microporous MOF-likematerial for molecular recognition». Chemosphere 276: 130181. Bibcode:2021Chmsp.276m0181D. PMID 33735650. S2CID 232304875. arXiv:2104.06715. doi:10.1016/j.chemosphere.2021.130181.: http://adsabs.harvard.edu/abs/2021Chmsp.276m0181D
[22] ↑ Klaessig, Fred; Marrapese, Martha; Abe, Shuji (2011). Nanotechnology Standards. Nanostructure Science and Technology (en inglés). Springer, New York, NY. pp. 21-52. ISBN 9781441978523. doi:10.1007/978-1-4419-7853-0_2.: https://dx.doi.org/10.1007%2F978-1-4419-7853-0_2
[26] ↑ Stephenson, C.; Hubler, A. (2015). «Stability and conductivity of self assembled wires in a transverse electric field». Sci. Rep. 5: 15044. Bibcode:2015NatSR...515044S. PMC 4604515. PMID 26463476. doi:10.1038/srep15044.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pmc/articles/PMC4604515
[27] ↑ Hubler, A.; Lyon, D. (2013). «Gap size dependence of the dielectric strength in nano vacuum gaps». IEEE Transactions on Dielectrics and Electrical Insulation 20 (4): 1467-1471. S2CID 709782. doi:10.1109/TDEI.2013.6571470.: https://api.semanticscholar.org/CorpusID:709782
[28] ↑ Valenti G, Rampazzo R, Bonacchi S, Petrizza L, Marcaccio M, Montalti M, Prodi L, Paolucci F (2016). «Variable Doping Induces Mechanism Swapping in Electrogenerated Chemiluminescence of Ru(bpy)32+ Core−Shell Silica Nanoparticles». J. Am. Chem. Soc. 138 (49): 15935-15942. PMID 27960352. doi:10.1021/jacs.6b08239. hdl:11585/583548.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/27960352
[29] ↑ Kerativitayanan, P; Carrow, JK; Gaharwar, AK (26 de mayo de 2015). «Nanomaterials for Engineering Stem Cell Responses». Advanced Healthcare Materials 4 (11): 1600-27. PMID 26010739. S2CID 21582516. doi:10.1002/adhm.201500272.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/26010739
[30] ↑ Suenaga R, Komsa H, Liu Z, Hirose-Takai K, Krasheninnikov A, Suenaga K (2014). «Atomic structure and dynamic behaviour of truly one-dimensional ionic chains inside carbon nanotubes». Nat. Mater. 13 (11): 1050-1054. Bibcode:2014NatMa..13.1050S. PMID 25218060. doi:10.1038/nmat4069.: http://adsabs.harvard.edu/abs/2014NatMa..13.1050S
[31] ↑ Medeiros PV, Marks S, Wynn JM, Vasylenko A, Ramasse QM, Quigley D, Sloan J, Morris AJ (2017). «Single-Atom Scale Structural Selectivity in Te Nanowires Encapsulated inside Ultranarrow, Single-Walled Carbon Nanotubes». ACS Nano 11 (6): 6178-6185. PMID 28467832. S2CID 30388342. arXiv:1701.04774. doi:10.1021/acsnano.7b02225.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/28467832
[32] ↑ Vasylenko A, Marks S, Wynn JM, Medeiros PV, Ramasse QM, Morris AJ, Sloan J, Quigley D (2018). «Electronic Structure Control of Sub-nanometer 1D SnTe via Nanostructuring within Single-Walled Carbon Nanotubes». ACS Nano 12 (6): 6023-6031. PMID 29782147. doi:10.1021/acsnano.8b02261.: http://eprints.whiterose.ac.uk/133545/1/acsnano.pdf
[33] ↑ Medeiros PV, Marks S, Wynn JM, Vasylenko A, Ramasse QM, Quigley D, Sloan J, Morris AJ (2017). «Single-Atom Scale Structural Selectivity in Te Nanowires Encapsulated inside Ultranarrow, Single-Walled Carbon Nanotubes». ACS Nano 11 (6): 6178-6185. PMID 28467832. S2CID 30388342. arXiv:1701.04774. doi:10.1021/acsnano.7b02225.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/28467832
[34] ↑ Vasylenko A, Marks S, Wynn JM, Medeiros PV, Ramasse QM, Morris AJ, Sloan J, Quigley D (2018). «Electronic Structure Control of Sub-nanometer 1D SnTe via Nanostructuring within Single-Walled Carbon Nanotubes». ACS Nano 12 (6): 6023-6031. PMID 29782147. doi:10.1021/acsnano.8b02261.: http://eprints.whiterose.ac.uk/133545/1/acsnano.pdf
[35] ↑ "Structural, functional and magnetic ordering modifications in graphene oxide and graphite by 100 MeV gold ion irradiation". Vacuum. 182: 109700. 2020-12-01. doi:10.1016/j.vacuum.2020.109700.
[36] ↑ Lapshin, Rostislav V. (January 2016). «STM observation of a box-shaped graphene nanostructure appeared after mechanical cleavage of pyrolytic graphite». Applied Surface Science 360: 451-460. Bibcode:2016ApSS..360..451L. S2CID 119369379. arXiv:1611.04379. doi:10.1016/j.apsusc.2015.09.222.: http://adsabs.harvard.edu/abs/2016ApSS..360..451L
[37] ↑ Wei, Hui; Wang, Erkang (21 de junio de 2013). «Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes». Chemical Society Reviews 42 (14): 6060-93. PMID 23740388. doi:10.1039/C3CS35486E.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/23740388
[38] ↑ Juzgado, A.; Solda, A.; Ostric, A.; Criado, A.; Valenti, G.; Rapino, S.; Conti, G.; Fracasso, G.; Paolucci, F.; Prato, M. (2017). «Highly sensitive electrochemiluminescence detection of a prostate cancer biomarker». J. Mater. Chem. B 5 (32): 6681-6687. PMID 32264431. doi:10.1039/c7tb01557g.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/32264431
[39] ↑ Pervez, Md Nahid; Balakrishnan, Malini; Hasan, Shadi Wajih; Choo, Kwang-Ho; Zhao, Yaping; Cai, Yingjie; Zarra, Tiziano; Belgiorno, Vincenzo et al. (5 de noviembre de 2020). «A critical review on nanomaterials membrane bioreactor (NMs-MBR) for wastewater treatment». NPJ Clean Water (en inglés) 3 (1): 1-21. ISSN 2059-7037. doi:10.1038/s41545-020-00090-2. Se sugiere usar |número-autores= (ayuda).: https://es.wikipedia.org//portal.issn.org/resource/issn/2059-7037
[40] ↑ a b Anis, Mohab; AlTaher, Ghada; Sarhan, Wesam; Elsemary, Mona (2017). Nanovate. Springer. p. 105. ISBN 9783319448619.
[41] ↑ Pham, Phuong; Minh, Thang; Nguyen, Tien; Van Driessche, Isabel (17 de noviembre de 2014). «Ceo2 Based Catalysts for the Treatment of Propylene in Motorcycle's Exhaust Gases». Materials 7 (11): 7379-7397. Bibcode:2014Mate....7.7379P. PMC 5512641. PMID 28788253. doi:10.3390/ma7117379.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pmc/articles/PMC5512641
[42] ↑ Kašpar, Jan; Fornasiero, Paolo; Hickey, Neal (January 2003). «Automotive catalytic converters: current status and some perspectives». Catalysis Today 77 (4): 419-449. doi:10.1016/S0920-5861(02)00384-X.: https://dx.doi.org/10.1016%2FS0920-5861%2802%2900384-X
[43] ↑ a b Wang, Shujun; Gao, Lihong (2019). «Laser-driven nanomaterials and laser-enabled nanofabrication for industrial applications». Industrial Applications of Nanomaterials. Elsevier. pp. 181-203. ISBN 978-0-12-815749-7. S2CID 202212003. doi:10.1016/B978-0-12-815749-7.00007-4.: https://api.semanticscholar.org/CorpusID:202212003
[44] ↑ Rawat, Pankaj Singh, R. C. Srivastava, Gagan Dixit, G. C. Joshi, and K. Asokan. "Facile synthesis and temperature dependent dielectric properties of MnFe2O4 nanoparticles." In AIP Conference Proceedings, vol. 2115, no. 1, p. 030104. AIP Publishing LLC, 2019.https://doi.org/10.1063/1.5112943.: https://doi.org/10.1063/1.5112943
[45] ↑ Alsaiari, Norah Salem; Alzahrani, Fatimah Mohammed; Amari, Abdelfattah; Osman, Haitham; Harharah, Hamed N.; Elboughdiri, Noureddine; Tahoon, Mohamed A. (January 2023). «Plant and Microbial Approaches as Green Methods for the Synthesis of Nanomaterials: Synthesis, Applications, and Future Perspectives». Molecules (en inglés) 28 (1): 463. ISSN 1420-3049. doi:10.3390/molecules28010463.: https://www.mdpi.com/1420-3049/28/1/463
[46] ↑ Ramsden, J.J. (2011) Nanotechnology: An Introduction, Elsevier, Amsterdam.
Materials reduced to the nanoscale can suddenly show very different properties than those exhibited on a macroscale, enabling unique applications. For example, opaque substances become transparent (copper); inert materials are transformed into catalysts (platinum); stable materials are transformed into fuels (aluminum); solids become liquids at room temperature (gold); insulators become conductors (silicone). Materials such as gold, which is chemically inert at normal scales, can serve as catalysts at nanoscales. Much of the fascination with nanotechnology comes from these peculiar quantum and surface phenomena that matter exhibits at the nanoscale.
Nanosized powder particles (also called nanoparticles) are potentially important in ceramics and powder metallurgy, achieving uniform nanoporosity and other similar applications. The strong tendency of small particles to form clumps is a serious technological problem that prevents such applications. However, some dispersants such as ammonia citrate (aqueous) and oleic alcohol") (non-aqueous) are promising additives for debinding.
Nanomaterials can be subdivided into nanoparticles, nanoshells and nanocomposites. The nanomaterials approach is a bottom-up approach to structural and functional effects so that building blocks of materials are designed and assembled in a controlled manner.
A recent Small Times report predicts strong growth in so-called nanomaterials. It discusses the different types that currently exist (such as nanoclays to reinforce plastics) or carbon nanotubes to add conductivity to various materials.
Many of these advances are being carried out by small and medium-sized North American companies in collaboration with leading companies.
There are three basic categories of nanomaterials from a commercial and development point of view: metal oxides, nanoclays and carbon nanotubes. Those that have advanced the most from a commercial point of view are metal oxide nanoparticles.
Sources
Engineering
Engineered nanomaterials have been deliberately designed and manufactured by humans to have certain properties.[3][4].
Legacy nanomaterials are those that were produced commercially before the development of nanotechnology as incremental advances over other colloidal or particulate materials,[5][6][7] such as carbon black and titanium dioxide nanoparticles").[8].
Incidental
Nanomaterials can be produced unintentionally as a byproduct of mechanical or industrial processes through combustion and vaporization. Sources of accidental nanoparticles include vehicle engine exhaust, foundry, welding fumes, combustion processes from solid fuel home heating, and cooking. For example, the class of nanomaterials called fullerenes are generated by burning gas, biomass "Biomass (energy)") and candles.[9] They can also be a byproduct of wear and corrosion products.[10] Incidental atmospheric nanoparticles are often called ultrafine particles, which are produced unintentionally during intentional operation, and could contribute to air pollution.[11][12].
Natural
Biological systems often present natural and functional nanomaterials. The structure of foraminifera (mainly limestone) and viruses (protein, capsid), the wax crystals that cover a lotus or nasturtium leaf, the silk of spiders and mites,[13] the blue tone of tarantulas,[14] the "spatulas" on the underside of the legs of geckos, some butterfly wing scales, natural colloids (milk, blood), horny materials (skin, claws, beaks, feathers, horns, hair), paper, cotton, mother-of-pearl, corals and even our own bone matrix are natural organic nanomaterials.
Natural inorganic nanomaterials are produced by growing crystals in the various chemical conditions of the Earth's crust. For example, clays exhibit complex nanostructures due to the anisotropy of their underlying crystalline structure, and volcanic activity can give rise to opals, which are an example of natural photonic crystals due to their nanoscale structure. Fires represent especially complex reactions and can produce pigments, cement, fumed silica"), etc.
Natural sources of nanoparticles are the combustion products of forest fires, volcanic ash, ocean splatter, and the radioactive decay of radon gas. Natural nanomaterials can also form through weathering processes of rocks containing metals or anions, as well as at sites of acid mine drainage.[15].
Guys
Contenido
Los nanoobjetos se suelen clasificar en función de cuántas de sus dimensiones entran en la nanoescala. Una nanopartícula se define como un nanoobjeto con las tres dimensiones externas en la nanoescala, cuyos ejes más largo y más corto no difieren significativamente.
Dimensiones.
La clasificación de los nanomateriales depende de cuántas de sus tres dimensiones espaciales se encuentran en la escala nanométrica [16].
Una nanofibra tiene dos dimensiones externas en la nanoescala, siendo los nanotubos nanofibras huecas y los nanorods nanofibras sólidas. Una nanoplaca/nanohoja tiene una dimensión externa en la nanoescala,[17] y si las dos dimensiones mayores son significativamente diferentes se denomina nanocinta. En el caso de las nanofibras y las nanoplacas, las otras dimensiones pueden estar o no en la nanoescala, pero deben ser significativamente mayores. En todos estos casos, se observa que una diferencia significativa suele ser al menos un factor de 3.[18].
Los materiales nanoestructurados suelen clasificarse según las fases de la materia "Fase (materia)") que contengan. Un nanocompuesto es un sólido que contiene al menos una región o conjunto de regiones física o químicamente distintas, con al menos una dimensión en la nanoescala. Una nanoespuma") tiene una matriz líquida o sólida, rellena de una fase gaseosa, donde una de las dos fases tiene dimensiones en la nanoescala. Un material nanoporoso") es un material sólido que contiene nanoporos, vacíos en forma de poros abiertos o cerrados de longitudes submicrónicas. Un material nanocristalino") tiene una fracción significativa de granos de cristal en la nanoescala.[19].
Nanoporous materials
The term nanoporous materials encompasses subsets of microporous and mesoporous materials. Microporous materials are porous materials with an average pore size less than 2 nm, while mesoporous materials are those with pore sizes in the region of 2-50 nm.[20] Microporous materials exhibit pore sizes with a length scale comparable to that of small molecules. For this reason, these materials can have valuable applications, such as separation membranes. Mesoporous materials are interesting for applications that require a high specific surface area, while allowing the penetration of molecules that may be too large to enter the pores of a microporous material. In some sources, nanoporous materials and nanofoam are sometimes considered nanostructures, but not nanomaterials, because only the voids, and not the materials themselves, are nanoscale.[21] Although the ISO definition only considers round nanoobjects as nanoparticles, other sources use the term nanoparticle for all shapes.[22]
Nanoparticles
Main article: Nanoparticles.
Nanoparticles have all three dimensions on the nanoscale. Nanoparticles can also be embedded in a solid to form a nanocomposite.[21].
Main article: Fullereno.
Fullerenes are a class of carbon allotropes that conceptually are sheets of graphene rolled into tubes or spheres. Among them are carbon nanotubes (or silicon nanotubes), interesting both for their mechanical resistance and for their electrical properties.[23].
The first fullerene molecule discovered and the namesake of the family, buckminsterfullerene (C), was prepared in 1985 by Richard Smalley, Robert Curl, James Heath, Sean O'Brien, and Harold Kroto at Rice University. The name was a tribute to Buckminster Fuller, whose geodesic domes it resembles. Since then, fullerenes have been discovered to be present in nature.[24] More recently, fullerenes have been detected in outer space.[25].
Over the past decade, the chemical and physical properties of fullerenes have been a hot topic in the field of research and development, and are likely to remain so for a long time. In April 2003, possible medicinal uses of fullerenes were being studied: binding specific antibiotics to the structure of resistant bacteria and even targeting certain types of cancer cells, such as melanoma cells. The October 2005 issue of Chemistry and Biology contains an article describing the use of fullerenes as light-activated antimicrobial agents. In the field of nanotechnology, heat resistance and superconductivity are some of the properties that spark intense research.
A common method of producing fullerenes is to send a large current between two nearby graphite electrodes in an inert atmosphere. The resulting carbon plasma arc "Plasma (state of matter)") between the electrodes cools to form a soot residue from which many fullerenes can be isolated.
Many calculations have been performed with ab-initio quantum methods applied to fullerenes. Using DFT and TDDFT methods, IR, Raman and UV spectra can be obtained. The results of these calculations can be compared with the experimental ones.
Inorganic nanomaterials (e.g., quantum dots, nanowires, and nanorods), due to their interesting optical and electrical properties, could be used in optoelectronics. Furthermore, the optical and electronic properties of nanomaterials, which depend on their size and shape, can be tuned using synthetic techniques. There are possibilities of using these materials in optoelectronic devices based on organic materials, such as organic solar cells, OLEDs, etc. The operating principles of these devices are governed by photoinduced processes such as electron transfer and energy transfer. The performance of the devices depends on the efficiency of the photoinduced process responsible for their operation. Therefore, it is necessary to better understand these photoinduced processes in organic/inorganic nanomaterial composite systems to be able to use them in optoelectronic devices.
One-dimensional nanostructures
The smallest possible crystalline threads, with a cross section as small as that of an atom, can be fabricated in cylindrical confinement.[30][31][32] Carbon nanotubes, a natural semi-dimensional nanostructure, can be used as a template for synthesis. Confinement provides mechanical stabilization and prevents linear atomic chains from disintegrating; Other 1D nanowire structures are predicted to be mechanically stable even when isolated from templates[33][34].
Two-dimensional nanostructures
2D materials are crystalline materials made up of a single two-dimensional layer of atoms. The most important representative, graphene, was discovered in 2004. Thin films with nanoscale thicknesses are considered nanostructures, but are sometimes not considered nanomaterials because they do not exist separate from the substrate.[21][35].
Bulk nanostructured materials
Some bulk materials contain nanoscale features, such as nanocomposites, nanocrystalline materials, nanostructured films, and nanotextured surfaces[21].
The box-shaped graphene (BSG) nanostructure is an example of a three-dimensional nanomaterial.[36] The BSG nanostructure has appeared after the mechanical cleavage of pyrolytic graphite"). This nanostructure is a multilayer system of parallel hollow nanochannels located along the surface and with a quadrangular cross section. The thickness of the channel walls is approximately equal to 1 nm. The typical width of the channel facets is about 25 nm.
Applications
Main article: Applications of nanotechnology.
Nanomaterials are used in a wide variety of manufacturing processes, products and healthcare, such as paints, filters, insulators and lubricant additives. In healthcare, nanozymes") are nanomaterials with characteristics similar to enzymes.[37] They are an emerging type of artificial enzymes, which have been used for broad applications in fields such as biosensing, bioimaging, tumor diagnosis[38] or antibiofouling, among others.
High-quality filters can be manufactured using nanostructures; These filters are capable of removing particles as small as a virus, as seen in a water filter created by Seldon Technologies. Recently, nanomaterial membrane bioreactors (NMs-MBR), the next generation of conventional MBRs, have been proposed for advanced wastewater treatment[39].
In the field of air purification, nanotechnology was used to combat the spread of MERS in hospitals in Saudi Arabia in 2012.[40] Nanomaterials are being used in modern, human-safe insulation technologies; in the past they were found in asbestos-based insulators.
As a lubricant additive, nanomaterials have the ability to reduce friction in moving parts. Worn and corroded parts can also be repaired with self-assembling anisotropic nanoparticles called TriboTEX.[40].
Nanomaterials have also been applied in various industries and consumer products. Mineral nanoparticles, such as titanium oxide "Titanium(IV) Oxide"), have been used to improve the UV protection of sunscreens. In the sports industry, lighter bats have been made with carbon nanotubes to improve their performance. Another application is in the military, where mobile pigment nanoparticles have been used to create more effective camouflage. Nanomaterials can also be used in three-way catalyst (TWC) applications. TWC converters have the advantage of controlling the emission of nitrogen oxides (NOx), precursors of acid rain and smog.[41] In the core-shell structure, nanomaterials form a shell as a support for the catalyst to protect noble metals, such as palladium and rhodium.[42] The main function is that the supports can be used to transport the active components of the catalysts, make them highly dispersed, reduce the use of noble metals, increase the activity of catalysts and improve mechanical resistance.
Synthesis
El objetivo de cualquier método de síntesis de nanomateriales es obtener un material que presente propiedades derivadas de su escala de longitud característica en el rango nanométrico (1 - 100 nm). Por consiguiente, el método sintético debe permitir controlar el tamaño en este intervalo para poder obtener una u otra propiedad. A menudo, los métodos se dividen en dos tipos principales, "ascendentes" y "descendentes".
Bottom-up methods
Bottom-up methods involve the assembly of atoms or molecules into nanostructured assemblies. In these methods, the raw material sources can be gases, liquids or solids. The latter require some type of disassembly before incorporation into a nanostructure. Bottom-up methods are usually divided into two categories: chaotic and controlled.
Chaotic processes involve raising constituent atoms or molecules to a chaotic state and then suddenly changing conditions so that that state becomes unstable. By intelligently manipulating any number of parameters, products are formed largely as a result of insurance kinetics. Collapse from the chaotic state can be difficult or impossible to control, so ensemble statistics typically govern the resulting size distribution and mean size. Consequently, the formation of nanoparticles is controlled by manipulating the final state of the products. Examples of chaotic processes are laser ablation,[43] wire explosion, arcing, flame pyrolysis, combustion[44] and precipitation synthesis techniques.
Controlled processes involve the controlled delivery of constituent atoms or molecules to the site or sites of nanoparticle formation, so that they can grow to a prescribed size in a controlled manner. Typically, the state of the constituent atoms or molecules is never far from that necessary for nanoparticle formation. Therefore, the formation of nanoparticles is controlled by controlling the state of the reactants. Examples of controlled processes are self-limiting growth solution, self-limiting chemical vapor deposition, patterned pulse femtosecond laser techniques, plant and microbial approaches[45], and molecular beam epitaxy.
Top-down methods
Top-down methods adopt some “force” (e.g., mechanical force, laser) to break bulk materials into nanoparticles. A very popular method of mechanically breaking down bulk materials into nanomaterials is “ball milling.” Additionally, nanoparticles can also be manufactured by laser ablation, which applies short pulse lasers (e.g., femtosecond laser) to ablate a target (solid).[43].
Characterization
Main articles: Nanometrology and Characterization of nanoparticles.
Novel effects in materials can occur when structures are formed with sizes comparable to any of many possible length scales, such as the Broglie wavelength of electrons or the optical wavelengths of high-energy photons. In these cases, quantum mechanical effects can dominate the properties of the materials. An example is quantum confinement"), in which the electronic properties of solids are altered with large reductions in particle size. The optical properties of nanoparticles, for example fluorescence, also become a function of the diameter of the particle. This effect does not come into play when going from macroscopic to micrometric dimensions, but is accentuated when the nanometer scale is reached.
In addition to optical and electronic properties, the novel mechanical properties of many nanomaterials are the subject of research in nanomechanics. of an increase in stability and an improvement in functionality.[46].
Finally, nanostructured materials with small particle sizes, such as zeolites and asbestos, are used as catalysts in a wide range of critical industrial chemical reactions. Further development of these catalysts can form the basis for more efficient and environmentally friendly chemical processes.
The first observations and measurements of the size of nanoparticles were made during the first decade of the century. Zsigmondy performed detailed studies of gold sols and other nanomaterials with sizes less than 10 nm. He published a book in 1914. He used an ultramicroscope that uses a dark field method to see particles with sizes much smaller than the wavelength of light.
There are traditional techniques developed over the century in interface and colloid science to characterize nanomaterials. These are widely used for first generation passive nanomaterials specified in the following section.
These methods include several different techniques to characterize the size distribution of particles.
There is also a group of traditional techniques to characterize the surface charge") or zeta potential of nanoparticles in solutions. This information is necessary for the correct stabilization of the system, preventing its aggregation or flocculation. These methods include microelectrophoresis"), electrophoretic light scattering") and electroacoustics. The latter, for example the colloid vibration current method"), is suitable for characterizing concentrated systems.
Mechanical properties
Ongoing research has shown that mechanical properties can vary significantly in nanomaterials compared to bulk material. Nanomaterials have substantial mechanical properties due to the volume, surface, and quantum effects of the nanoparticles. This is observed when nanoparticles are added to a common bulk material, the nanomaterial refines the grain and forms intergranular and intragranular structures that improve the grain boundaries and therefore the mechanical properties of the materials. Grain boundary refinement provides reinforcement by increasing the stress necessary to cause intergranular or transgranular fractures. A common example in which this can be observed is the addition of nano silica to cement, which improves tensile, compressive and flexural strength through the mechanisms just mentioned. Understanding these properties will improve the use of nanoparticles in novel applications in various fields such as surface engineering, tribology and nanofabrication.
Uniformity
The chemical processing and synthesis of high-performance technological components for the private, industrial and military sectors require the use of high-purity ceramics, polymers, glass-ceramics and composite materials. In condensed bodies formed from fine powders, the irregular sizes and shapes of nanoparticles in a typical powder often lead to non-uniform packing morphologies that give rise to packing density variations in the compact powder.
Uncontrolled agglomeration of powders due to attractive Van der Waals forces can also lead to microstructural inhomogeneities. The differential stresses that develop as a result of nonuniform drying shrinkage are directly related to the rate at which solvent can be removed and are therefore highly dependent on the porosity distribution. These stresses have been associated with a transition from plastic to brittle in consolidated bodies, and can lead to the propagation of cracks in the body.[48][49][50].
Furthermore, any fluctuations in packing density in the compact when preparing for the furnace are often amplified during the sintering process, leading to inhomogeneous densification. It has been shown that some pores and other structural defects associated with density variations play a detrimental role in the sintering process by growing and thus limiting the final densities. It has also been shown that differential stresses arising from inhomogeneous densification give rise to the propagation of internal cracks, thus becoming the defects that control strength.[51][52].
Therefore, it seems desirable to process a material in a way that is physically uniform in component distribution and porosity, rather than using particle size distributions that maximize raw density. Containment of a uniformly dispersed set of strongly interacting particles in suspension requires complete control of particle-particle interactions. Various dispersants, such as ammonium citrate (aqueous) and imidazoline or oleyl alcohol (non-aqueous), are promising solutions as potential additives to improve dispersion and deagglomeration. Monodisperse nanoparticles and colloids offer this potential.[53].
Monodisperse colloidal silica powders, for example, can be stabilized sufficiently to ensure a high degree of order in the colloidal crystal or in the polycrystalline colloidal solid resulting from aggregation. The degree of order appears to be limited by the time and space allowed for longer-range correlations to be established. Such defective polycrystalline colloidal structures appear to be the building blocks of submicron colloidal materials science and therefore Therefore, they provide the first step in developing a more rigorous understanding of the mechanisms involved in microstructural evolution in high-performance materials and components.[54][55].
Nanomaterials in articles, patents and products
Quantitative analysis of nanomaterials showed that nanoparticles, nanotubes, nanocrystalline materials, nanocomposites and graphene have been mentioned in 400,000, 181,000, 144,000, 140,000, and 119,000 ISI indexed articles, respectively, as of September 2018. Regarding patents, nanoparticles, Nanotubes, nanocomposites, graphene, and nanowires have played a role in 45,600, 32,100, 12,700, 12,500, and 11,800 patents, respectively. Monitoring of about 7,000 commercial nanoproducts available in global markets revealed that the properties of about 2,330 products have been facilitated or improved with the help of nanoparticles. Liposomes, nanofibers, nanocolloids and aerogels were also among the most common nanomaterials in consumer products.[56].
The European Union Nanomaterials Observatory (EUON) has developed a database (NanoData) that provides information on patents, products and research publications specific to nanomaterials.
Assessment Criteria
The manufactured synthetic nanomaterials must be considered under a rigorous evaluation to determine if they are suitable and thus ensure the safety of the new substances, mainly seeking to evaluate those that have commercial importance, for example: fullerenes, silver nanoparticles, iron nanoparticles, gold nanoparticles, nanoclays, aluminum oxide, zinc oxide, cerium oxide, silicon dioxide, titanium dioxide dendrimers, SWCNTs and MWCNTs. These assessment criteria are based on environmental safety and human health, they are mainly: [57].
[3] ↑ Portela, Carlos M.; Vidyasagar, A.; Krödel, Sebastian; Weissenbach, Tamara; Yee, Daryl W.; Greer, Julia R.; Kochmann, Dennis M. (2020). «Extreme mechanical resilience of self-assembled nanolabyrinthine materials». Proceedings of the National Academy of Sciences 117 (11): 5686-5693. Bibcode:2020PNAS..117.5686P. ISSN 0027-8424. PMC 7084143. PMID 32132212. doi:10.1073/pnas.1916817117.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pmc/articles/PMC7084143
[4] ↑ «Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes», U.S. National Institute for Occupational Safety and Health (en inglés estadounidense), November 2013: 1-3, 7, 9-10, 17-20, doi:10.26616/NIOSHPUB2014102, consultado el 5 de marzo de 2017 .: https://www.cdc.gov/niosh/docs/2014-102/default.html
[7] ↑ «Future challenges related to the safety of manufactured nanomaterials». Organisation for Economic Co-operation and Development. 4 de noviembre de 2016. p. 11. Consultado el 6 de septiembre de 2017. - [http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2016)58&doclanguage=en](http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2016)58&doclanguage=en)
[9] ↑ Barcelo, Damia; Farre, Marinella (2012). Analysis and Risk of Nanomaterials in Environmental and Food Samples. Oxford: Elsevier. p. 291. ISBN 9780444563286.
[10] ↑ Sahu, Saura; Casciano, Daniel (2009). Nanotoxicity: From in Vivo and in Vitro Models to Health Risks. Chichester, West Sussex: John Wiley & Sons. pp. 227. ISBN 9780470741375.: https://archive.org/details/nanotoxicityinvi0000unse
[16] ↑ Silva Yumi, J. E., & Medina S., C. A. (2024). Materiales y nanomateriales: Principios, aplicaciones y técnicas de caracterización. CIMOGSYS - ESPOCH. http://cimogsys.espoch.edu.ec/direccion-publicaciones/public/docs/books/2024-07-24-131511-Materiales%20y%20nanomateriales.pdf.
[17] ↑ Rawat, Pankaj Singh; Srivastava, R.C.; Dixit, Gagan; Asokan, K. (2020). «Structural, functional and magnetic ordering modifications in graphene oxide and graphite by 100 MeV gold ion irradiation». Vacuum 182: 109700. Bibcode:2020Vacuu.182j9700R. S2CID 225410221. doi:10.1016/j.vacuum.2020.109700.: http://adsabs.harvard.edu/abs/2020Vacuu.182j9700R
[19] ↑ «ISO/TS 80004-4:2011 - Nanotechnologies – Vocabulary – Part 4: Nanostructured materials». International Organization for Standardization. 2011. Consultado el 8 de enero de 2018.: https://www.iso.org/obp/ui/#iso:std:iso:ts:80004:-4:ed-1:v1:en
[20] ↑ Doustkhah E et al. (2021). «Bispropylurea bridged polysilsesquioxane: A microporous MOF-likematerial for molecular recognition». Chemosphere 276: 130181. Bibcode:2021Chmsp.276m0181D. PMID 33735650. S2CID 232304875. arXiv:2104.06715. doi:10.1016/j.chemosphere.2021.130181.: http://adsabs.harvard.edu/abs/2021Chmsp.276m0181D
[22] ↑ Klaessig, Fred; Marrapese, Martha; Abe, Shuji (2011). Nanotechnology Standards. Nanostructure Science and Technology (en inglés). Springer, New York, NY. pp. 21-52. ISBN 9781441978523. doi:10.1007/978-1-4419-7853-0_2.: https://dx.doi.org/10.1007%2F978-1-4419-7853-0_2
[26] ↑ Stephenson, C.; Hubler, A. (2015). «Stability and conductivity of self assembled wires in a transverse electric field». Sci. Rep. 5: 15044. Bibcode:2015NatSR...515044S. PMC 4604515. PMID 26463476. doi:10.1038/srep15044.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pmc/articles/PMC4604515
[27] ↑ Hubler, A.; Lyon, D. (2013). «Gap size dependence of the dielectric strength in nano vacuum gaps». IEEE Transactions on Dielectrics and Electrical Insulation 20 (4): 1467-1471. S2CID 709782. doi:10.1109/TDEI.2013.6571470.: https://api.semanticscholar.org/CorpusID:709782
[28] ↑ Valenti G, Rampazzo R, Bonacchi S, Petrizza L, Marcaccio M, Montalti M, Prodi L, Paolucci F (2016). «Variable Doping Induces Mechanism Swapping in Electrogenerated Chemiluminescence of Ru(bpy)32+ Core−Shell Silica Nanoparticles». J. Am. Chem. Soc. 138 (49): 15935-15942. PMID 27960352. doi:10.1021/jacs.6b08239. hdl:11585/583548.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/27960352
[29] ↑ Kerativitayanan, P; Carrow, JK; Gaharwar, AK (26 de mayo de 2015). «Nanomaterials for Engineering Stem Cell Responses». Advanced Healthcare Materials 4 (11): 1600-27. PMID 26010739. S2CID 21582516. doi:10.1002/adhm.201500272.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/26010739
[30] ↑ Suenaga R, Komsa H, Liu Z, Hirose-Takai K, Krasheninnikov A, Suenaga K (2014). «Atomic structure and dynamic behaviour of truly one-dimensional ionic chains inside carbon nanotubes». Nat. Mater. 13 (11): 1050-1054. Bibcode:2014NatMa..13.1050S. PMID 25218060. doi:10.1038/nmat4069.: http://adsabs.harvard.edu/abs/2014NatMa..13.1050S
[31] ↑ Medeiros PV, Marks S, Wynn JM, Vasylenko A, Ramasse QM, Quigley D, Sloan J, Morris AJ (2017). «Single-Atom Scale Structural Selectivity in Te Nanowires Encapsulated inside Ultranarrow, Single-Walled Carbon Nanotubes». ACS Nano 11 (6): 6178-6185. PMID 28467832. S2CID 30388342. arXiv:1701.04774. doi:10.1021/acsnano.7b02225.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/28467832
[32] ↑ Vasylenko A, Marks S, Wynn JM, Medeiros PV, Ramasse QM, Morris AJ, Sloan J, Quigley D (2018). «Electronic Structure Control of Sub-nanometer 1D SnTe via Nanostructuring within Single-Walled Carbon Nanotubes». ACS Nano 12 (6): 6023-6031. PMID 29782147. doi:10.1021/acsnano.8b02261.: http://eprints.whiterose.ac.uk/133545/1/acsnano.pdf
[33] ↑ Medeiros PV, Marks S, Wynn JM, Vasylenko A, Ramasse QM, Quigley D, Sloan J, Morris AJ (2017). «Single-Atom Scale Structural Selectivity in Te Nanowires Encapsulated inside Ultranarrow, Single-Walled Carbon Nanotubes». ACS Nano 11 (6): 6178-6185. PMID 28467832. S2CID 30388342. arXiv:1701.04774. doi:10.1021/acsnano.7b02225.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/28467832
[34] ↑ Vasylenko A, Marks S, Wynn JM, Medeiros PV, Ramasse QM, Morris AJ, Sloan J, Quigley D (2018). «Electronic Structure Control of Sub-nanometer 1D SnTe via Nanostructuring within Single-Walled Carbon Nanotubes». ACS Nano 12 (6): 6023-6031. PMID 29782147. doi:10.1021/acsnano.8b02261.: http://eprints.whiterose.ac.uk/133545/1/acsnano.pdf
[35] ↑ "Structural, functional and magnetic ordering modifications in graphene oxide and graphite by 100 MeV gold ion irradiation". Vacuum. 182: 109700. 2020-12-01. doi:10.1016/j.vacuum.2020.109700.
[36] ↑ Lapshin, Rostislav V. (January 2016). «STM observation of a box-shaped graphene nanostructure appeared after mechanical cleavage of pyrolytic graphite». Applied Surface Science 360: 451-460. Bibcode:2016ApSS..360..451L. S2CID 119369379. arXiv:1611.04379. doi:10.1016/j.apsusc.2015.09.222.: http://adsabs.harvard.edu/abs/2016ApSS..360..451L
[37] ↑ Wei, Hui; Wang, Erkang (21 de junio de 2013). «Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes». Chemical Society Reviews 42 (14): 6060-93. PMID 23740388. doi:10.1039/C3CS35486E.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/23740388
[38] ↑ Juzgado, A.; Solda, A.; Ostric, A.; Criado, A.; Valenti, G.; Rapino, S.; Conti, G.; Fracasso, G.; Paolucci, F.; Prato, M. (2017). «Highly sensitive electrochemiluminescence detection of a prostate cancer biomarker». J. Mater. Chem. B 5 (32): 6681-6687. PMID 32264431. doi:10.1039/c7tb01557g.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pubmed/32264431
[39] ↑ Pervez, Md Nahid; Balakrishnan, Malini; Hasan, Shadi Wajih; Choo, Kwang-Ho; Zhao, Yaping; Cai, Yingjie; Zarra, Tiziano; Belgiorno, Vincenzo et al. (5 de noviembre de 2020). «A critical review on nanomaterials membrane bioreactor (NMs-MBR) for wastewater treatment». NPJ Clean Water (en inglés) 3 (1): 1-21. ISSN 2059-7037. doi:10.1038/s41545-020-00090-2. Se sugiere usar |número-autores= (ayuda).: https://es.wikipedia.org//portal.issn.org/resource/issn/2059-7037
[40] ↑ a b Anis, Mohab; AlTaher, Ghada; Sarhan, Wesam; Elsemary, Mona (2017). Nanovate. Springer. p. 105. ISBN 9783319448619.
[41] ↑ Pham, Phuong; Minh, Thang; Nguyen, Tien; Van Driessche, Isabel (17 de noviembre de 2014). «Ceo2 Based Catalysts for the Treatment of Propylene in Motorcycle's Exhaust Gases». Materials 7 (11): 7379-7397. Bibcode:2014Mate....7.7379P. PMC 5512641. PMID 28788253. doi:10.3390/ma7117379.: https://es.wikipedia.org//www.ncbi.nlm.nih.gov/pmc/articles/PMC5512641
[42] ↑ Kašpar, Jan; Fornasiero, Paolo; Hickey, Neal (January 2003). «Automotive catalytic converters: current status and some perspectives». Catalysis Today 77 (4): 419-449. doi:10.1016/S0920-5861(02)00384-X.: https://dx.doi.org/10.1016%2FS0920-5861%2802%2900384-X
[43] ↑ a b Wang, Shujun; Gao, Lihong (2019). «Laser-driven nanomaterials and laser-enabled nanofabrication for industrial applications». Industrial Applications of Nanomaterials. Elsevier. pp. 181-203. ISBN 978-0-12-815749-7. S2CID 202212003. doi:10.1016/B978-0-12-815749-7.00007-4.: https://api.semanticscholar.org/CorpusID:202212003
[44] ↑ Rawat, Pankaj Singh, R. C. Srivastava, Gagan Dixit, G. C. Joshi, and K. Asokan. "Facile synthesis and temperature dependent dielectric properties of MnFe2O4 nanoparticles." In AIP Conference Proceedings, vol. 2115, no. 1, p. 030104. AIP Publishing LLC, 2019.https://doi.org/10.1063/1.5112943.: https://doi.org/10.1063/1.5112943
[45] ↑ Alsaiari, Norah Salem; Alzahrani, Fatimah Mohammed; Amari, Abdelfattah; Osman, Haitham; Harharah, Hamed N.; Elboughdiri, Noureddine; Tahoon, Mohamed A. (January 2023). «Plant and Microbial Approaches as Green Methods for the Synthesis of Nanomaterials: Synthesis, Applications, and Future Perspectives». Molecules (en inglés) 28 (1): 463. ISSN 1420-3049. doi:10.3390/molecules28010463.: https://www.mdpi.com/1420-3049/28/1/463
[46] ↑ Ramsden, J.J. (2011) Nanotechnology: An Introduction, Elsevier, Amsterdam.
Nanoparticles or nanocrystals of metals, semiconductors or oxides are of special interest due to their mechanical, electrical, magnetic, optical and chemical properties, among others.[26][27] Nanoparticles have been used as quantum dots and as chemical catalysts, such as catalysts based on nanomaterials. Recently, various nanoparticles are being investigated for biomedical applications such as tissue engineering, drug delivery or biosensors.[28][29].
Nanoparticles are of great scientific interest because they constitute a bridge between bulk materials and atomic or molecular structures. A bulk material should have constant physical properties regardless of its size, but at the nanometer scale this is usually not the case. Size-dependent properties such as quantum confinement) are observed in semiconductor particles, surface plasmonic resonance in some metallic particles, and superparamagnetism in magnetic materials.
Nanoparticles have a number of special properties in relation to the bulk material. For example, bending of bulk copper (wire, tape, etc.) occurs with the movement of copper atoms/clusters at a scale of approximately 50 nm. Copper nanoparticles smaller than 50 nm are considered superhard materials that do not have the same malleability and ductility as bulk copper. Changing properties is not always desirable. Ferroelectric materials smaller than 10 nm can change their polarization direction using thermal energy at room temperature, making them useless for memory storage. "Suspension (chemistry)") suspensions of nanoparticles are possible because the interaction of the particle surface with the solvent is strong enough to overcome density differences, which normally cause a material to sink or float in a liquid. Nanoparticles often have unexpected visual properties because they are small enough to confine their electrons and produce quantum effects. For example, gold nanoparticles appear dark red to black in solution.
The often very high surface-to-volume ratio of nanoparticles provides an enormous driving force for diffusion (Diffusion (physics)), especially at elevated temperatures. Sintering is possible at lower temperatures and for shorter periods than in the case of larger particles. In theory, this does not affect the density of the final product, although flow difficulties and the tendency of nanoparticles to agglomerate complicate matters. The surface effects of nanoparticles also reduce the incipient melting temperature.
Nanoparticles or nanocrystals of metals, semiconductors or oxides are of special interest due to their mechanical, electrical, magnetic, optical and chemical properties, among others.[26][27] Nanoparticles have been used as quantum dots and as chemical catalysts, such as catalysts based on nanomaterials. Recently, various nanoparticles are being investigated for biomedical applications such as tissue engineering, drug delivery or biosensors.[28][29].
Nanoparticles are of great scientific interest because they constitute a bridge between bulk materials and atomic or molecular structures. A bulk material should have constant physical properties regardless of its size, but at the nanometer scale this is usually not the case. Size-dependent properties such as quantum confinement) are observed in semiconductor particles, surface plasmonic resonance in some metallic particles, and superparamagnetism in magnetic materials.
Nanoparticles have a number of special properties in relation to the bulk material. For example, bending of bulk copper (wire, tape, etc.) occurs with the movement of copper atoms/clusters at a scale of approximately 50 nm. Copper nanoparticles smaller than 50 nm are considered superhard materials that do not have the same malleability and ductility as bulk copper. Changing properties is not always desirable. Ferroelectric materials smaller than 10 nm can change their polarization direction using thermal energy at room temperature, making them useless for memory storage. "Suspension (chemistry)") suspensions of nanoparticles are possible because the interaction of the particle surface with the solvent is strong enough to overcome density differences, which normally cause a material to sink or float in a liquid. Nanoparticles often have unexpected visual properties because they are small enough to confine their electrons and produce quantum effects. For example, gold nanoparticles appear dark red to black in solution.
The often very high surface-to-volume ratio of nanoparticles provides an enormous driving force for diffusion (Diffusion (physics)), especially at elevated temperatures. Sintering is possible at lower temperatures and for shorter periods than in the case of larger particles. In theory, this does not affect the density of the final product, although flow difficulties and the tendency of nanoparticles to agglomerate complicate matters. The surface effects of nanoparticles also reduce the incipient melting temperature.