Nanocomposite is a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nanometers (nm) or structures having nano-scale repeat distances between the different phases that make up the material.[1][2]
The idea behind Nanocomposites is to use building blocks with dimensions in nanometre range to design and create new materials with unprecedented flexibility and improvement in their physical properties.
In the broadest sense this definition can include porous media, colloids, gels and copolymers, but is more usually taken to mean the solid combination of a bulk matrix and nano-dimensional phase(s) differing in properties due to dissimilarities in structure and chemistry. The mechanical, electrical, thermal, optical, electrochemical, catalytic properties of the nanocomposite will differ markedly from that of the component materials. Size limits for these effects have been proposed:[3]
Nanocomposites are found in nature, for example in the structure of the abalone shell and bone. The use of nanoparticle-rich materials long predates the understanding of the physical and chemical nature of these materials. Jose-Yacaman et al.[4] investigated the origin of the depth of colour and the resistance to acids and bio-corrosion of Maya blue paint, attributing it to a nanoparticle mechanism. From the mid-1950s nanoscale organo-clays have been used to control flow of polymer solutions (e.g. as paint viscosifiers) or the constitution of gels (e.g. as a thickening substance in cosmetics, keeping the preparations in homogeneous form). By the 1970s polymer/clay composites were the topic of textbooks,[5][6] although the term "nanocomposites" was not in common use.
In mechanical terms, nanocomposites differ from conventional composite materials due to the exceptionally high surface to volume ratio of the reinforcing phase and/or its exceptionally high aspect ratio. The reinforcing material can be made up of particles (e.g. minerals), sheets (e.g. exfoliated clay stacks) or fibres (e.g. carbon nanotubes or electrospun fibres).[7] The area of the interface between the matrix and reinforcement phase(s) is typically an order of magnitude greater than for conventional composite materials. The matrix material properties are significantly affected in the vicinity of the reinforcement. Ajayan et al.[8] note that with polymer nanocomposites, properties related to local chemistry, degree of thermoset cure, polymer chain mobility, polymer chain conformation, degree of polymer chain ordering or crystallinity can all vary significantly and continuously from the interface with the reinforcement into the bulk of the matrix.
This large amount of reinforcement surface area means that a relatively small amount of nanoscale reinforcement can have an observable effect on the macroscale properties of the composite. For example, adding carbon nanotubes improves the electrical and thermal conductivity. Other kinds of nanoparticulates may result in enhanced optical properties, dielectric properties, heat resistance or mechanical properties such as stiffness, strength and resistance to wear and damage. In general, the nano reinforcement is dispersed into the matrix during processing. The percentage by weight (called mass fraction) of the nanoparticulates introduced can remain very low (on the order of 0.5% to 5%) due to the low filler percolation threshold, especially for the most commonly used non-spherical, high aspect ratio fillers (e.g. nanometer-thin platelets, such as clays, or nanometer-diameter cylinders, such as carbon nanotubes). The orientation and arrangement of asymmetric nanoparticles, thermal property mismatch at the interface, interface density per unit volume of nanocomposite, and polydispersity of nanoparticles significantly affect the effective thermal conductivity of nanocomposites.[9]
Ceramic-matrix nanocomposites
Ceramic matrix composites (CMCs) consist of ceramic fibers embedded in a ceramic matrix. The matrix and fibers can consist of any ceramic material, including carbon and carbon fibers. The ceramic occupying most of the volume is often from the group of oxides, such as nitrides, borides, silicides, whereas the second component is often a metal. Ideally both components are finely dispersed in each other in order to elicit particular optical, electrical and magnetic properties[10] as well as tribological, corrosion-resistance and other protective properties.[11]
The binary phase diagram of the mixture should be considered in designing ceramic-metal nanocomposites and measures have to be taken to avoid a chemical reaction between both components. The last point mainly is of importance for the metallic component that may easily react with the ceramic and thereby lose its metallic character. This is not an easily obeyed constraint because the preparation of the ceramic component generally requires high process temperatures. The safest measure thus is to carefully choose immiscible metal and ceramic phases. A good example of such a combination is represented by the ceramic-metal composite of TiO2 and Cu, the mixtures of which were found immiscible over large areas in the Gibbs’ triangle of ' Cu-O-Ti.[12]
The concept of ceramic-matrix nanocomposites was also applied to thin films that are solid layers of a few nm to some tens of µm thickness deposited upon an underlying substrate and that play an important role in the functionalization of technical surfaces. Gas flow sputtering by the hollow cathode technique turned out as a rather effective technique for the preparation of nanocomposite layers. The process operates as a vacuum-based deposition technique and is associated with high deposition rates up to some µm/s and the growth of nanoparticles in the gas phase. Nanocomposite layers in the ceramics range of composition were prepared from TiO2 and Cu by the hollow cathode technique[13] that showed a high mechanical hardness, small coefficients of friction and a high resistance to corrosion.
Metal-matrix nanocomposites
This section needs expansion. You can help by adding to it. (November 2008)
Metal matrix nanocomposites can also be defined as reinforced metal matrix composites. This type of composites can be classified as continuous and non-continuous reinforced materials. One of the more important nanocomposites is Carbon nanotube metal matrix composites, which is an emerging new material that is being developed to take advantage of the high tensile strength and electrical conductivity of carbon nanotube materials.[14] Critical to the realization of CNT-MMC possessing optimal properties in these areas are the development of synthetic techniques that are (a) economically producible, (b) provide for a homogeneous dispersion of nanotubes in the metallic matrix, and (c) lead to strong interfacial adhesion between the metallic matrix and the carbon nanotubes. In addition to carbon nanotube metal matrix composites, boron nitride reinforced metal matrix composites and carbon nitride metal matrix composites are the new research areas on metal matrix nanocomposites.[15]
A recent study, comparing the mechanical properties (Young's modulus, compressive yield strength, flexural modulus and flexural yield strength) of single- and multi-walled reinforced polymeric (polypropylene fumarate—PPF) nanocomposites to tungsten disulfide nanotubes reinforced PPF nanocomposites suggest that tungsten disulfide nanotubes reinforced PPF nanocomposites possess significantly higher mechanical properties and tungsten disulfide nanotubes are better reinforcing agents than carbon nanotubes.[16] Increases in the mechanical properties can be attributed to a uniform dispersion of inorganic nanotubes in the polymer matrix (compared to carbon nanotubes that exist as micron sized aggregates) and increased crosslinking density of the polymer in the presence of tungsten disulfide nanotubes (increase in crosslinking density leads to an increase in the mechanical properties). These results suggest that inorganic nanomaterials, in general, may be better reinforcing agents compared to carbon nanotubes.
Another kind of nanocomposite is the energetic nanocomposite, generally as a hybrid sol–gel with a silica base, which, when combined with metal oxides and nano-scale aluminum powder, can form superthermite materials.[17][18][19][20]
In the simplest case, appropriately adding nanoparticulates to a polymer matrix can enhance its performance, often dramatically, by simply capitalizing on the nature and properties of the nanoscale filler[21] (these materials are better described by the term nanofilled polymer composites[21]). This strategy is particularly effective in yielding high performance composites, when uniform dispersion of the filler is achieved and the properties of the nanoscale filler are substantially different or better than those of the matrix. The uniformity of the dispersion is in all nanocomposites is counteracted by thermodynamically driven phase separation. Clustering of nanoscale fillers produces aggregates that serve as structural defects and result in failure. Layer-by-layer (LbL) assembly when nanometer scale layers of nanoparticulates and a polymers are added one by one. LbL composites display performance parameters 10-1000 times better that the traditional nanocomposites made by extrusion or batch-mixing.
Nanoparticles such as graphene,[22] carbon nanotubes,[23] molybdenum disulfide and tungsten disulfide are being used as reinforcing agents to fabricate mechanically strong biodegradable polymeric nanocomposites for bone tissue engineering applications. The addition of these nanoparticles in the polymer matrix at low concentrations (~0.2 weight%) cause significant improvements in the compressive and flexural mechanical properties of polymeric nanocomposites.[24][25][26] Potentially, these nanocomposites may be used as a novel, mechanically strong, light weight composite as bone implants. The results suggest that mechanical reinforcement is dependent on the nanostructure morphology, defects, dispersion of nanomaterials in the polymer matrix, and the cross-linking density of the polymer. In general, two-dimensional nanostructures can reinforce the polymer better than one-dimensional nanostructures, and inorganic nanomaterials are better reinforcing agents than carbon based nanomaterials. In addition to mechanical properties, polymer nanocomposites based on carbon nanotubes or graphene have been used to enhance a wide range of properties, giving rise to functional materials for a wide range of high added value applications in fields such as energy conversion and storage, sensing and biomedical tissue engineering.[27] For example, multi-walled carbon nanotubes based polymer nanocomposites have been used for the enhancement of the electrical conductivity.[28]
An alternative route to synthesis of nanocomposites is sequential infiltration synthesis, in which inorganic nanomaterials are grown within polymeric substrates using vapor-phase precursors that diffuse into the matrix.
Nanoscale dispersion of filler or controlled nanostructures in the composite can introduce new physical properties and novel behaviors that are absent in the unfilled matrices. This effectively changes the nature of the original matrix[21] (such composite materials can be better described by the term genuine nanocomposites or hybrids[21]). Some examples of such new properties are fire resistance or flame retardancy,[29] and accelerated biodegradability.
A range of polymeric nanocomposites are used for biomedical applications such as tissue engineering, drug delivery, cellular therapies.[30][31] Due to unique interactions between polymer and nanoparticles, a range of property combinations can be engineered to mimic native tissue structure and properties. A range of natural and synthetic polymers are used to design polymeric nanocomposites for biomedical applications including starch, cellulose, alginate, chitosan, collagen, gelatin, and fibrin, poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG), poly(caprolactone) (PCL), poly(lactic-co-glycolic acid) (PLGA), and poly(glycerol sebacate) (PGS). A range of nanoparticles including ceramic, polymeric, metal oxide and carbon-based nanomaterials are incorporated within polymeric network to obtain desired property combinations.[32]
Magnetic nanocomposites
Nanocomposites that can respond to an external stimulus are of increased interest due to the fact that, because of the large amount of interaction between the phase interfaces, the stimulus response can have a larger effect on the composite as a whole. The external stimulus can take many forms, such as a magnetic, electrical, or mechanical field. Specifically, magnetic nanocomposites are useful for use in these applications due to the nature of magnetic material's ability to respond both to electrical and magnetic stimuli. The penetration depth of a magnetic field is also high, leading to an increased area that the nanocomposite is affected by and therefore an increased response. In order to respond to a magnetic field, a matrix can be easily loaded with nanoparticles or nanorods The different morphologies for magnetic nanocomposite materials are vast, including matrix dispersed nanoparticles, core-shell nanoparticles, colloidal crystals, macroscale spheres, or Janus-type nanostructures.[33][34]
Magnetic nanocomposites can be utilized in a vast number of applications, including catalytic, medical, and technical. For example, palladium is a common transition metal used in catalysis reactions. Magnetic nanoparticle-supported palladium complexes can be used in catalysis to increase the efficiency of the palladium in the reaction.[35]
Magnetic nanocomposites can also be utilized in the medical field, with magnetic nanorods embedded in a polymer matrix can aid in more precise drug delivery and release. Finally, magnetic nanocomposites can be used in high frequency/high-temperature applications. For example, multi-layer structures can be fabricated for use in electronic applications. An electrodeposited Fe/Fe oxide multi-layered sample can be an example of this application of magnetic nanocomposites.[36]
In applications such as power micro-inductors where high magnetic permeability is desired at high operating frequencies.[37] The traditional micro-fabricated magnetic core materials see both decrease in permeability and high losses at high operating frequency.[38] In this case, magnetic nano composites have great potential for improving the efficiency of power electronic devices by providing relatively high permeability and low losses. For example, As Iron oxide nano particles embedded in Ni matrix enables us to mitigate those losses at high frequency.[39] The high resistive iron oxide nanoparticles helps to reduce the eddy current losses where as the Ni metal helps in attaining high permeability. DC magnetic properties such as Saturation magnetization lies between each of its constituent parts indicating that the physical properties of the materials can be altered by creating these nanocomposites.
Heat resistant nanocomposites
In the recent years nanocomposites have been designed to withstand high temperatures by the addition of Carbon Dots (CDs) in the polymer matrix. Such nanocomposites can be utilized in environments wherein high temperature resistance is a prime criterion. [40]
Nanomaterials describe, in principle, materials of which a single unit is sized between 1 and 100 nm.
A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead.
A non-carbon nanotube is a cylindrical molecule often composed of metal oxides, or group III-Nitrides and morphologically similar to a carbon nanotube. Non-carbon nanotubes have been observed to occur naturally in some mineral deposits.
Hybrid solar cells combine advantages of both organic and inorganic semiconductors. Hybrid photovoltaics have organic materials that consist of conjugated polymers that absorb light as the donor and transport holes. Inorganic materials in hybrid cells are used as the acceptor and electron transporter in the structure. The hybrid photovoltaic devices have a potential for not only low-cost by roll-to-roll processing but also for scalable solar power conversion.
Nanochemistry is an emerging sub-discipline of the chemical and material sciences that deals with the development of new methods for creating nanoscale materials. The term "nanochemistry" was first used by Ozin in 1992 as 'the uses of chemical synthesis to reproducibly afford nanomaterials from the atom "up", contrary to the nanoengineering and nanophysics approach that operates from the bulk "down"'. Nanochemistry focuses on solid-state chemistry that emphasizes synthesis of building blocks that are dependent on size, surface, shape, and defect properties, rather than the actual production of matter. Atomic and molecular properties mainly deal with the degrees of freedom of atoms in the periodic table. However, nanochemistry introduced other degrees of freedom that controls material's behaviors by transformation into solutions. Nanoscale objects exhibit novel material properties, largely as a consequence of their finite small size. Several chemical modifications on nanometer-scaled structures approve size dependent effects.
Tungsten disulfide is an inorganic chemical compound composed of tungsten and sulfur with the chemical formula WS2. This compound is part of the group of materials called the transition metal dichalcogenides. It occurs naturally as the rare mineral tungstenite. This material is a component of certain catalysts used for hydrodesulfurization and hydrodenitrification.
Carbon nanotubes (CNTs) are cylinders of one or more layers of graphene (lattice). Diameters of single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) are typically 0.8 to 2 nm and 5 to 20 nm, respectively, although MWNT diameters can exceed 100 nm. CNT lengths range from less than 100 nm to 0.5 m.
As the world's energy demand continues to grow, the development of more efficient and sustainable technologies for generating and storing energy is becoming increasingly important. According to Dr. Wade Adams from Rice University, energy will be the most pressing problem facing humanity in the next 50 years and nanotechnology has potential to solve this issue. Nanotechnology, a relatively new field of science and engineering, has shown promise to have a significant impact on the energy industry. Nanotechnology is defined as any technology that contains particles with one dimension under 100 nanometers in length. For scale, a single virus particle is about 100 nanometers wide.
The following outline is provided as an overview of and topical guide to nanotechnology:
Polymer nanocomposites (PNC) consist of a polymer or copolymer having nanoparticles or nanofillers dispersed in the polymer matrix. These may be of different shape, but at least one dimension must be in the range of 1–50 nm. These PNC's belong to the category of multi-phase systems that consume nearly 95% of plastics production. These systems require controlled mixing/compounding, stabilization of the achieved dispersion, orientation of the dispersed phase, and the compounding strategies for all MPS, including PNC, are similar. Alternatively, polymer can be infiltrated into 1D, 2D, 3D preform creating high content polymer nanocomposites.
David Carroll is a U.S. physicist, materials scientist and nanotechnologist, Fellow of the American Physical Society, and director of the Center for Nanotechnology and Molecular Materials at Wake Forest University. He has contributed to the field of nanoscience and nanotechnology through his work in nanoengineered cancer therapeutics, nanocomposite-based display and lighting technologies, high efficiency nanocomposite photovoltaics and thermo/piezo-electric generators.
Exfoliated graphite nano-platelets (xGnP) are new types of nanoparticles made from graphite. These nanoparticles consist of small stacks of graphene that are 1 to 15 nanometers thick, with diameters ranging from sub-micrometre to 100 micrometres. The X-ray diffractogram of this material would resemble that of graphite, in that the 002 peak would still appear at ~26o 2 theta. However, the peak would appear considerably smaller and broader. These features indicate that the interplanar distance in exfoliated graphite is similar to that of the parent graphite, but the stack size is small. Since xGnP is composed of the same material as carbon nanotubes, it shares many of the electrochemical characteristics, although not the tensile strength. The platelet shape, however, offers xGnP edges that are easier to modify chemically for enhanced dispersion in polymers.
In polymer chemistry, in situ polymerization is a preparation method that occurs "in the polymerization mixture" and is used to develop polymer nanocomposites from nanoparticles. There are numerous unstable oligomers (molecules) which must be synthesized in situ for use in various processes. The in situ polymerization process consists of an initiation step followed by a series of polymerization steps, which results in the formation of a hybrid between polymer molecules and nanoparticles. Nanoparticles are initially spread out in a liquid monomer or a precursor of relatively low molecular weight. Upon the formation of a homogeneous mixture, initiation of the polymerization reaction is carried out by addition of an adequate initiator, which is exposed to a source of heat, radiation, etc. After the polymerization mechanism is completed, a nanocomposite is produced, which consists of polymer molecules bound to nanoparticles.
Single-walled carbon nanohorn is the name given by Sumio Iijima and colleagues in 1999 to horn-shaped sheath aggregate of graphene sheets. Very similar structures had been observed in 1994 by Peter J.F. Harris, Edman Tsang, John Claridge and Malcolm Green. Ever since the discovery of the fullerene, the family of carbon nanostructures has been steadily expanded. Included in this family are single-walled and multi-walled carbon nanotubes, carbon onions and cones and, most recently, SWNHs. These SWNHs with about 40–50 nm in tubule length and about 2–3 nm in diameter are derived from SWNTs and ended by a five-pentagon conical cap with a cone opening angle of ~20o. Moreover, thousands of SWNHs associate with each other to form the ‘dahlia-like' and ‘bud-like’ structured aggregates which have an average diameter of about 80–100 nm. The former consists of tubules and graphene sheets protruding from its surface like petals of a dahlia, while the latter is composed of tubules developing inside the particle itself. Their unique structures with high surface area and microporosity make SWNHs become a promising material for gas adsorption, biosensing, drug delivery, gas storage and catalyst support for fuel cell. Single-walled carbon nanohorns are an example of the family of carbon nanocones.
A chemiresistor is a material that changes its electrical resistance in response to changes in the nearby chemical environment. Chemiresistors are a class of chemical sensors that rely on the direct chemical interaction between the sensing material and the analyte. The sensing material and the analyte can interact by covalent bonding, hydrogen bonding, or molecular recognition. Several different materials have chemiresistor properties: metal-oxide semiconductors, some conductive polymers, and nanomaterials like graphene, carbon nanotubes and nanoparticles. Typically these materials are used as partially selective sensors in devices like electronic tongues or electronic noses.
Niveen M. Khashab is a Lebanese chemist and an associate Professor of chemical Sciences and engineering at King Abdullah University of Science and Technology in Saudi Arabia since 2009. She is a laureate of the 2017 L'Oréal-UNESCO Awards for Women in Science "for her contributions to innovative smart hybrid materials aimed at drug delivery and for developing new techniques to monitor intracellular antioxidant activity." She is also a fellow of the Royal Chemical Society, and a member of the American Chemical Society.
In materials science, a polymer matrix composite (PMC) is a composite material composed of a variety of short or continuous fibers bound together by a matrix of organic polymers. PMCs are designed to transfer loads between fibers of a matrix. Some of the advantages with PMCs include their light weight, high resistance to abrasion and corrosion, and high stiffness and strength along the direction of their reinforcements.
Oxycarbide glass, also referred to as silicon oxycarbide, is a type of glass that contains oxygen and carbon in addition to silicon dioxide. It is created by substituting some oxygen atoms with carbon atoms. This glass may contain particles of amorphous carbon, and silicon carbide. SiOC materials of varying stoichiometery are attractive owing to their generally high density, hardness and high service temperatures. Through diverse forming techniques high performance parts in complex shapes can be achieved. Unlike pure SiC, the versatile stoichiometry of SiOC offers further avenues to tune physical properties through appropriate selection of processing parameters.
Gurpreet Singh is a professor of Mechanical and Nuclear Engineering at [Kansas State University]. He is endowed by the Harold O. and Jane C. Massey Neff Professorship in Mechanical Engineering. Singh was born in Ludhiana, India; he currently resides in the United States.
Nanotech metallurgy is an emerging interdisciplinary domain of materials science and engineering, manufacturing, and nanoscience and engineering to study how nanophases can be applied to significantly improve the processing/manufacturing, micro/nano-structures, and physical/chemical/mechanical behaviors of metals and alloys. This definition was first proposed by Xiaochun Li at the University of California, Los Angeles in 2018.
↑ F. E. Kruis, H. Fissan and A. Peled (1998). "Synthesis of nanoparticles in the gas phase for electronic, optical and magnetic applications – a review". J. Aerosol Sci. 29 (5–6): 511–535. doi:10.1016/S0021-8502(97)10032-5.
↑ S. Zhang; D. Sun; Y. Fu; H. Du (2003). "Recent advances of superhard nanocomposite coatings: a review". Surf. Coat. Technol. 167 (2–3): 113–119. doi:10.1016/S0257-8972(02)00903-9.
↑ G. Effenberg, F. Aldinger & P. Rogl (2001). Ternary Alloys. A Comprehensive Compendium of Evaluated Constitutional Data and Phase Diagrams. Materials Science-International Services.
↑ S. R. Bakshi, D. Lahiri, and A. Argawal, Carbon nanotube reinforced metal matrix composites - A Review, International Materials Reviews, vol. 55, (2010), http://web.eng.fiu.edu/agarwala/PDF/2010/12.pdf
↑ Zeidi, Mahdi; Kim, Chun IL; Park, Chul B. (2021). "The role of interface on the toughening and failure mechanisms of thermoplastic nanocomposites reinforced with nanofibrillated rubbers". Nanoscale. 13 (47): 20248–20280. doi:10.1039/D1NR07363J. ISSN2040-3372. PMID34851346. S2CID244288401.
↑ Gatti, Teresa; Vicentini, Nicola; Mba, Miriam; Menna, Enzo (2016-02-01). "Organic Functionalized Carbon Nanostructures for Functional Polymer-Based Nanocomposites". European Journal of Organic Chemistry. 2016 (6): 1071–1090. doi:10.1002/ejoc.201501411. ISSN1099-0690.
↑ Varga, L.K. (2007). "Soft magnetic nanocomposites for high-frequency and high-temperature applications". Journal of Magnetism and Magnetic Materials. 316 (2): 442–447. Bibcode:2007JMMM..316..442V. doi:10.1016/j.jmmm.2007.03.180.
↑ Markondeya Raj, P.; Sharma, Himani; Sitaraman, Srikrishna; Mishra, Dibyajat; Tummala, Rao (December 2017). "System Scaling With Nanostructured Power and RF Components". Proceedings of the IEEE. 105 (12): 2330 - 2346. doi:10.1109/JPROC.2017.2748520. S2CID6587533.
↑ Han, Kyu; Swaminathan, Madhavan; Pulugurtha, Raj; Sharma, Himani; Tummala, Rao; Yang, Songnan; Nair, Vijay (2016). "Magneto-Dielectric Nanocomposite for Antenna Miniaturization and SAR Reduction". IEEE Antennas and Wireless Propagation Letters. 15: 72–75. Bibcode:2016IAWPL..15...72H. doi:10.1109/LAWP.2015.2430284. S2CID1335792.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
