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Science and Technology of Nanomaterials: Introduction

Merin Sara Thomas1,2, Sabu Thomas2,3,4 and Laly A. Pothen2,5

1Mar Thoma College, Department of Chemistry, Kuttapuzha P.O., Tiruvalla, Kerala, 689103, India

2Mahatma Gandhi University, International and Interuniversity Centre for Nanoscience and Nanotechnology, Priyadarsini Hills P.O., Kottayam, Kerala, 686560, India

3Mahatma Gandhi University, School of Chemical Sciences, Priyadarsini Hills P.O., Kottayam, Kerala, 686560, India

4Mahatma Gandhi University, School of Energy Materials, Priyadarsini Hills P.O., Kottayam, Kerala, 686560, India

5CMS College Kottayam (Autonomous), Department of Chemistry, CMS College Road, Kottayam, Kerala, 686001, India

1.1 Introduction

The term nanotechnology refers to the organized study of materials having at least one dimension in the nanometer range (1-100?nm). Nanomaterials are characterized by their specific optical properties, magnetic properties, electrical properties, etc. These materials are widely used in biomedical, environmental, and electrical applications because of their unique properties. The properties of nanomaterials are, however, dependent on the length scales on the order of nanometers.

Opening up a new vista of study of nanoscience in the field of physics in the year 1959, Richard Feynman, a German scientist pointed out, "There is plenty of room at the bottom" [1]. Nanoscience discusses the management of nanomaterials, systems, and devices at atomic, molecular, and macromolecular levels, whereas, nanotechnology is the bunch of techniques involved in design, synthesis, characterization, and application of structures, materials, devices, and systems by manipulating shape and size at nanometer scale. Nanotechnology is the manufacturing of tools and nanodevices by controlling the matter at the atomic level.

Nanotechnology has a wide variety of applications in various fields, such as medicine, environmental remediation, and food science. Figure 1.1 depicts different applications of nanotechnology.

Figure 1.1 Applications of nanotechnology.

1.2 Classification of Nanomaterials

Nanomaterials are classified, based on their geometry, into zero-dimensional, one-dimensional, two-dimensional, and three-dimensional nanomaterials. Figure 1.2 represents the schematic sketch for each category.

1.3 Classes of Nanomaterials

Based on their origin, nanomaterials are mainly classified into organic nanoparticles (NPs), inorganic nanoparticles, and carbon-based nanoparticles.

Figure 1.2 Scheme of (a) zero-, (b) one-, (c) two-, and (d) three-dimensional nanostructured materials with different morphologies.

Source: Nikolova and Chavali [2]/MDPI/Licensed under CC 4.0.

Figure 1.3 Different types of organic nanoparticles.

Source: Gessner and Neundorf [3]/MDPI/Licensed under CC 4.0.

1.3.1 Organic Nanoparticles

Organic nanoparticles are solid particles derived from organic compounds. Dendrimers, ferritin, liposomes, and micelles come under this category (Figure 1.3). The biodegradability and nontoxicity of these materials are remarkable. Organic nanoparticles are mainly used in the biomedical field for drug delivery applications.

1.3.2 Inorganic Nanoparticles

Inorganic nanoparticles are mainly of two types - metal nanoparticles and metal oxide nanoparticles. Metal nanoparticles are synthesized from metals. They can be synthesized from almost all metals, such as aluminum (Al), cadmium (Cd), cobalt (Co), copper (Cu), gold (Au), iron (Fe), lead (Pb), silver (Ag), and zinc (Zn). These are characterized by their specific properties, such as high surface area-to-volume ratio, pore size, surface charge, and surface charge density.

The applicability of metal nanoparticles can be improved by the use of metal oxide nanoparticles. Table 1.1 gives a brief idea about applications of some metallic and metal oxide nanoparticles.

1.3.3 Carbon-Based Nanoparticles

If the complete skeleton of a nanoparticle is carbon, this class can be categorized into carbon-based nanoparticles. Fullerenes, graphene, carbon nanotubes (CNTs), carbon nanofibers, carbon black, etc., come under this category. Figure 1.4 represents the schematic diagram of different carbon-based nanoparticles, and Table 1.2 gives the applications of carbon-based nanoparticles.

1.4 Properties of Nanomaterials

1.4.1 Size and Surface Area

The interaction of nanomaterials mainly depends on their size and surface area. With decrease in size of nanomaterials, the surface area-to-volume ratio of nanomaterials increases and the reactivity of the surface becomes enhanced [60]. Each and every property of nanostructures depends on their size, shape, and surface area.

Table 1.1 Applications of some metallic and metal oxide nanoparticles.

Metals Application of metallic and metal oxide nanoparticles Titanium dioxide (Ti) Solar cells, food wraps, medicines, pharmaceuticals, lacquers, construction, medical devices, gas sensing, photocatalyst, agriculture, paint, food, cosmetic, sterilization, antibacterial coatings [4] Zinc and zinc oxide (Zn) Medical and healthcare goods, sunscreens, packaging, ultraviolet (UV)-protective materials, such as textiles [5, 6] Aluminum (Al) Automobile industry, aircraft, heat shielding coatings, military application, corrosion, fuel additive/propellant [7, 8] Gold (Au) Sensory probes, cellular imaging, electronic conductors, drug delivery, therapeutic agents, organic photovoltaics, catalysis, nanofibers, textiles [9] Iron (Fe) Magnetic imaging, environmental remediation, glass and ceramic industry, memory tape, resonance imaging, plastics, nanowires, coatings, textiles, alloy, and catalyst applications [10] Silica (Si) Drug and gene delivery, adsorbents, electronic, sensor, catalysis, remediation of the environmental pollutants, additive in rubber and plastic industry, filler, electric and thermal insulators [11, 12] Silver (Ag) Antimicrobial coatings, textiles, batteries, surgery, wound dressings, biomedical devices, photography, electrical devices, dental work, burns treatment [13] Copper (Cu) Biosensors and electrochemical sensors, plastic additives, such as antibiotic, antimicrobial, and antifungal agents, coatings, textiles, nanocomposite coating, catalyst, lubricants, inks, filler [14, 15] Cerium (Ce) Chemical mechanical polishing/planarization, computer chip, corrosion, solar cells, fuel oxidation catalysis, automotive exhaust treatment [16] Manganese and its oxides (Mn) Molecular meshing, solar cells, batteries, catalysts, optoelectronics, drug delivery ion-sieves, imaging agents, magnetic storage devices, water treatment and purification [17] Nickel (Ni) Fuel cells, membrane fuel cells, automotive catalytic converters, plastics, nanowires, nanofibers, textiles, coatings, conduction, magnetic properties, catalyst, batteries, printing inks [18]

Source: Attarilar et al. [19]/Frontiers Media/Licensed Under CC 4.0.

1.4.2 Mechanical Properties

Mechanical properties of different nanomaterials vary with respect to the nature of materials. Nanomaterials possess excellent mechanical properties due to the unique features of nanoparticles, such as volume, surface, and quantum effects. The addition of nanoparticles to other systems will improve the grain boundary and promote the mechanical properties of materials [61, 62]. Al Ghabban et al. [63] found that addition of 3?wt% nano-SiO2 to concrete can enhance its compressive strength, bending strength, and splitting tensile strength. Addition of up to 0.1?wt% of nanochitosan to electrospun poly lactic acid (PLA) fibers led to an increase in tensile strength of the PLA/chitosan nanoparticles (nCHS) nanocomposite membranes. Lower concentration of nCHS in the nanocomposite gave superior tensile strength compared to the neat PLA membrane [64]. The key factors that improved the mechanical properties of the composites with such a low concentration of the filler are uniform stress distribution, minimized formation of stress-concentration centers, increased interfacial area for stress transfer from the polymer matrix to the fillers, and the decreased fiber diameter [65]. However, at higher loading, above 0.1?wt% the tensile strength seemed to be lowered. This is because of the...