Engineered Nanomaterials (Topic 3: Part II) PDF

ENGINEERED NANOMATERIALS Topic 3: Part II Polymers HISTORCIAL BACKGROUND The word “nanothecnology” was first used by Norio Taniguchi in 1974 to refer tor precise and accurate tolerance required for machining and finishing of materials. The term nano derives from...

ENGINEERED NANOMATERIALS Topic 3: Part II Polymers HISTORCIAL BACKGROUND The word “nanothecnology” was first used by Norio Taniguchi in 1974 to refer tor precise and accurate tolerance required for machining and finishing of materials. The term nano derives from the Greek work for dwarf (nm) billionth of meter 10^-9meters Introduction What are nanomaterials? The materials having at least one dimension in nanometric scale are called nanomaterials. Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers. Nanomaterials Particles having sizes in the range of 1 to 100 nm are termed as nanoparticles and the application of nanosized particles is what we called “nanotechnology”.  Special in Nanomaterials At the nanoscale, physical, chemical, and biological properties of materials differ in fundamental and valuable ways from the properties of individual atoms and molecules or bulk matter. Nanoparticles color absorptions Color dependence of Au NPs on size and shape. Nanoparticles Structures (a) The surface layer, which may be functionalized with a variety of small molecules, metal ions, surfactants and polymers. (b) The shell layer, which is chemically different material from the core in all aspects, and (c) The core, which is essentially the central portion of the NP and usually refers the NP itself FE-SEM micrographs of (a) nonporous MA-SiO2 NPs, (b) mesoporous MA-SiO2 NPs. TEM images of, (c) nonporous MA-SiO2 NPs and, (d) mesoporous MA-SiO2 NPs  Quantum sizes in Nanostructures Zero-dimensional objects: Usual names are nanoparticles, clusters, colloids, nanocrystals, and fullerenes. They are composed of several tens to a few thousand atoms. Electrons are confined in all three directions.  Quantum sizes in Nanostructures One-dimensional objects: Cylinder-like objects like wires and tubes with diameters on the nanoscale and lengths typically in the micometer range. Confinement effects for electrons may appear in the transverse direction while electrons are free to move in one dimension (along the structure).  Quantum sizes in Nanostructures Two-dimensional objects: Thin films with thickness of the order of a few nanometers are usually deposited on a bulk material. In the two dimensions parallel to the film the electrons behave like in a bulk material.  Quantum sizes in Nanostructures Three-dimensional objects: 3D nanomaterials have structures containing interconnected macro/mesopores that prevent aggregation and restacking. This provides the highest accessible surface area among nanomaterials. Quantum sizes in Nanostructures CLASSIFIATION OF NANOPARTICPLES C 60 C70 Carbon-based NanoParticles: Fullerenes and carbon nanotubes (CNTs) represent two major classes of carbon-based NPs. Fullerenes contain nanomaterial that are made of globular hollow cage such as allotropic forms of carbon. These materials possess arranged pentagonal and hexagonal carbon units, while each carbon is sp2 hybridized.. CLASSIFIATION OF NANOPARTICPLES Metal NPs: Metal NPs are purely made of the metals precursors. Due to well-known localized surface plasmon resonance (LSPR) characteristics, these NPs possess unique optoelectrical properties. NPs of the alkali and noble metals i.e. Cu, Ag and Au have a broad absorption band in the visible zone of the electromagnetic solar spectrum. The facet, size and shape controlled synthesis of metal NPs is important in present day cutting-edge materials CLASSIFIATION OF NANOPARTICPLES Ceramics Nps: Ceramics NPs are inorganic nonmetallic solids, synthesized via heat and successive cooling. They can be found in amorphous, polycrystalline, dense, porous or hollow forms. Therefore, these NPs are getting great attention of researchers due to their use in applications such as catalysis, photocatalysis, photodegradation of dyes, and imaging applications. CLASSIFIATION OF NANOPARTICPLES Semiconductor NPs: Semiconductor NPs possess wide bandgaps and therefore showed significant alteration in their properties with bandgap tuning. Therefore, they are very important materials in photocatalysis, photo optics and electronic devices. CLASSIFIATION OF NANOPARTICPLES Polymeric NPs: These are normally organic based NPs and in the literature a special term polymer nanoparticle (PNP) collective used for it. They are mostly nanospheres or nanocapsular shaped. The former are matrix particles whose overall mass is generally solid and the other molecules are adsorbed at the outer boundary of the spherical surface. In the latter case the solid mass is encapsulated within the particle completely. CLASSIFIATION OF NANOPARTICPLES Lipid-Based NPs: Like polymeric NPs, lipid NPs possess a solid core made of lipid and a matrix contains soluble lipophilic molecules. Surfactants or emulsifiers stabilized the external core of these NPs. Lipid nanotechnology is a special field, which focus the designing and synthesis of lipid NPs for various applications such as drug carriers and delivery and RNA release in cancer therapy. Types of Nanostructures Approaches to Nanomaterials Synthesis 1. Top down approach 2. Bottom up approach  Approaches to Nanomaterials Synthesis 1. Top down approach A bulk materials is taken and machinized and modify to obtain required size and shape. Example: Production of integrated circuits by etching or lithography. Approaches to Nanomaterials Synthesis 1. Top down approach For nanomaterials systhesis, ball milling is used Microcrystalline structures are broken down to nanocrystalline structures  Approaches to Nanomaterials Synthesis 1. Bottom up approach Used to build from basic materials e.g. assembling materials from atom/molrecules Characterization of Nanomaterials 1. Morphological Characterizations There are different characterization techniques for morphological studies, but microscopic techniques such as polarized optical microscopy (POM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) are the most important of these.  Characterization of Nanomaterials SEM technique is based on electron scanning principle, and it provides all available information about the NPs at nanoscale level. SEM images of ZnO modified MOFs at different temperatures  Characterization of Nanomaterials TEM is based on electron transmittance principle, so it can provide information of the bulk material from TEM images of different form of gold NPs, very low to higher synthesized by different techniques magnification. Characterization of Nanomaterials 2. Structural Characterizations The structural characteristics are of the primary importance to study the composition and nature of bonding materials. It provides diverse information about the bulk properties of the subject material. XRD, energy dispersive X-ray (EDX), XPS, IR, Raman, BET, and Zieta size analyzer are the common techniques used to study structural properties of NPs. Characterization of Nanomaterials 3. Particle size an d surface area Characterizations Different techniques can be used to estimate the size of the NPs. These include SEM, TEM, XRD, AFM, and dynamic light scattering (DLS). SEM, TEM, XRD and AFM can give better idea about the particle size, but the zeta potential size analyzer/DLS can be used to find the NPs size at extremely low level. Characterization of Nanomaterials 4. Optical Characterizations These techniques give information about the absorption, reflectance, luminescence and phosphorescence properties of NPs. It is widely known that NPs especially metallic and semiconductor NPs possess different colors and therefore, best harmonized for photo-related applications. Physicochemical Properties of NPs 1. Electronic and Optical Properties The optical and electronic properties of NPs are inter-dependent to greater extent. For instance, noble metals NPs have size dependent optical properties and exhibit a strong UV–visible extinction band that is not present in the spectrum of the bulk metal. Physicochemical Properties of NPs Graphical illustration exemplifying the localized surface plasmon (LSPR) on nanoparticle outer surface Physicochemical Properties of NPs 2. Magnetic Properties Great curiosity for investigators from an eclectic range of disciplines, which include heterogenous and homogenous catalysis, biomedicine, magnetic fluids, data storage magnetic resonance imaging (MRI), and environmental remediation such as water decontamination. The literature revealed that NPs perform best when the size is