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  1. 1. Inorganic and Organic synthesis of nanocomposites by self-assembly Aditya bhardwaj
  2. 2. NANOCOMPOSITES “ A Nanocomposite is a composite material, in which one of the components has at least one dimension that is around 10-9 m. or “ A Nanocomposite is a multiphase solid material where one of the phases has one, two or three dimensions of less than 100 nm, or structure having nano-scale repeat distance between the different phases that make up the material.
  3. 3. DIFFERENT TYPES OF NANOCOMPOSITES • Ceramic-matrix nanocomposites • Polymer-matrix nanocomposites • Polymer-silicate nanocomposites • Elastomeric nanocomposites • Bionanocomposites
  4. 4. CERAMIC-MATRIX NANOCOMPOSITES • In this group of composites, main part of volume is occupied by a ceramic i.e a compound of oxides, bromides,nitrides and silicides. • In most cases these encompass a metal as second component • Ideally both components, metallic one and ceramic one, are finely dispersed in each other in order to elicit particular nanoscopic properties • Nanocomposite from these combinations demonstrated in improving their optical, electrical and magnetic properties as well as tribiological, corrosion resistance and other protective properties
  5. 5. POLYMER-MATRIX NANOCOMPOSITES • An appropriately adding nanoparticulates to a polymer matrix can enhance its performance, often in very dramatic degree, by simply capitalizing on the nature and properties of the nanoscale filler. • These materials are better described by the term nanofilled polymer composites. • This strategy is particularly effective in yielding high performance composites, when good dispersion of the filler is achieved and the properties of the nanoscale filler are substantially different or better than those of the matrix, for example, reinforcing a polymer matrix by much stiffer nanoparticles of ceramics, clays, or carbon nanotubes.
  6. 6. POLYMER-SILICATE NANOCOMPOSITES • Polymer – silicate nanocomposites are hybrid organic inorganic materials, in which mixing of the filler phase is achieved at the nanometer level, so that at least one dimension of the filler phase is less than 100 nm. • The fillers generally used for such composites are layered aluminosilicates, and most commonly montmorillonites ( MMT s) from the family of aluminosilicates.
  7. 7. ELASTOMERIC NANOCOMPOSITES Elastomeric Nanocomposites are further divided into two types: • Clay-polymer (nano-)composites • Dendrimer Nanocomposites
  8. 8. CLAY-POLYMER(NANO-)COMPOSITES • The Clay minerals are aluminosilicates with a 2:1-layer structure i.e. a central alumina octahedral sheet is sandwiched between two silica tetrahedral sheets. • Examples are : muscovite, phlogopite, smectites. • The aluminosilicate layers are held together by cations (usually alkali or earth alkali metals) in the interlayer. • The thickness of one such layer is approximately 1 nm. • The surface cations as well as the interlayer cationsin smectites can be exchanged against organic cations(e.g. ammonium, phosphonium). • This offers the possibility to modify the silicate surfaces and hence tune the filler matrix interaction.
  9. 9. DENDRIMER NANOCOMPOSITES • Dendrimer composite nanoparticles are nanosized organic inorganic hybrid particles made from dendrimer templates that contain small clusters of inorganic nanomaterials of interest entrapped in the network of the macromolecular templates. • The method of reactive encapsulation involves preorganization of an appropriate reactant by the active interior sites of a dendrimer molecule, followed by immobilization of the product with respect to the host. • Combination of inorganic guests and dendritic building blocks into multiple structures such as chains, films and covalent clusters in solvents and solid matrices afford a wide repertoire of nanosized building blocks and architectures for more complex nanocomposite structures.
  10. 10. BIONANOCOMPOSITES • Bionanocomposites form a fascinating interdisciplinary area that brings together biology, materials science, and nanotechnology. • Bionanocomposites add a new dimension to enhance the properties in that they are biocompatible and/or biodegradable materials. • These nanocomposites are of immense interest to biomedical technologies such as tissue engineering, bone replacement/repair, dental applications, and controlled drug delivery.
  11. 11. PROPERTIES OF NANOCOMPOSITES Nanocomposites can dramatically improve properties like: • Mechanical properties including strength, modulus and dimensional stability • Electrical conductivity • Decreased gas, water and hydrocarbon permeability • Flame retardancy • Thermal stability • Chemical resistance • Surface appearance • Optical clarity
  12. 12. PROCESS OF SELF-ASSEMBLY • The process of self-assembly occurs by two mechanisms:- • First, the organic matrix serves as template on which to form a specific mineral. • Second, inorganic materials usually appear in cells at the protoplasmic surface boundary layer. Therefore, the arrangement of the biominerals is controlled by the surface tension between the cells, the vesicles, and the growing mineral
  13. 13. NANOCOMPOSITES BY SELF-ASSEMBLY • Self-assembling biomolecules act as the organic matrix templates to direct and facilitate the formation of different kinds of structured organic/inorganic composite materials. • The biomolecules are either natural or synthetic, including proteins, peptides, DNA, RNA, and polysaccharides.
  14. 14. ADVANTAGES OF BIOMOLECULES • Production of materials under mild reaction conditions(neutral pH, room temperature,etc). • Control over size, shape, chemistry and crystal structure of inorganic product. • Materials formed are highly specific and can perform multiple functions. • The use of these molecules are non toxic and hence are a green process and environmentally benign.
  15. 15. BIOMOLECULES USED FOR SYNTHESIS Different types of biomolecules used in bio-inspired synthesis can be broadly categorized into four categories: • Proteins • Peptides • Nucleic acids • Polysaccharides.
  16. 16. PROTEIN MEDIATED SYNTHESIS • Proteins provide functional building blocks for the development of multi-functional materials . The self- assembly property of proteins would allow controlled organization of the organic/inorganic interface based on molecular recognition, resulting in hierarchical organization with desirable properties at multiple length scales. • Proteins have superior specificity for target binding with complex molecular recognition mechanism . Through their unique and specific interactions with other macromolecules and inorganics, they process the ability to control structures and functions of biological hard and soft tissues in organisms
  17. 17. Protein mediated hydroxyapatite (HAp) formation • Collagen and some proteins are used in Hap formation. Collagen consists of bone which have 70% minerals (Ca,P) and 30% organics (glycoproteins,collagens). Calcium phosphates, notably HAp [Ca10(PO4)6(OH)2 ], are found in hierarchical structures of bones. Mineralized collagen fibrils are the basic building block for bone formation. • Collagens serve as extracellular matrix molecules for many other soft and hard tissues, such as cartilage, tendons, and ligaments.
  18. 18. HAp FORMATION CONTINUED.... • A nanocomposite of collagen and HAp was prepared in a continuous flow system, mimicking the situation in vivo, and resulted in a direct nucleation of HAp on the self-assembled collagen matrix. The biomineralization process of collagen and the self-organization mechanism were also analyzed. The inorganic crystals formed along the collagen fiber have similar a Ca-P ratio, crystalline degree, and carbonation extent to that observed in bone. When Osteonectin was added into the collagen solution, results indicated that spindle-like nano-HAp could be deposited on collagen I/osteonectin and pure osteonectin (control) groups, but not on collagen II/osteonectin . This helps in understanding the biomineralization process in nature.
  19. 19. HAp FORMATION CONTINUED.... • Collagen templated HAp nanocomposite showed equal or better biocompatibility than HAp ceramics, which was known to have excellent biocompatibility. HAp/collagen composite can be potentially used as an artificial bone material in medical and dental fields. • Proteins other than collagen are also used in bioinspired HAp synthesis. A novel human hair proteins and HAp composite was synthesized for using as a biomineral-scaffolding material. The human hair protein was soaked to a CaCl2 solution for fabrication into flat films. The flat films mainly consisted of α-keratin, which could bind 3 Ca2+ ions per 1 keratin molecule. The composite of the human hair protein and calcium phosphate was prepared via alternate soaking processes using CaCl2 and Na2 HPO4 solutions. The diameters of deposited calcium phosphate particles were about 2–4 μm. The human hair proteins were not soluble and degraded during the soaking processes. Synthetic proteins have also been developed as templates for bioinspired synthesis.
  20. 20. PROTEIN MEDIATED MAGNETIC MATERIALS FORMATION • Nano sized magnetic particles similar to those in magnetotactic bacteria were prepared in vitro by chemical synthesis of magnetite in the presence of the protein Mms6. • Recombinant Mms6 facilitated the formation of magnetite nanocrystals with uniform size (about 30 nm) in aqueous solution, which was verified by using TEM analysis and magnetization measurements. A polymeric gel was used to mimic the conditions at which magnetite nanocrystals were formed in magnetotactic bacteria and slow down the diffusion rates of the reagents. The nanocrystals formed in the presence of other proteins, did not exhibit the uniform sizes and shapes.
  21. 21. PROTEIN MEDIATED MAGNETIC MATERIALS FORMATION CONTD.... •Some inorganic magnetic materials which do not appear in living organisms, for example, cobalt ferrite (CoFe2O4) nanoparticles, were also synthesized in vitro by using Mms6 protein as a template. The recombinant full-length Mms6 protein or a synthetic C-terminal domain of Mms6 protein was covalently attached to self-assembling polymers (Pluronic F127) in order to template hierarchical growth of CoFe2O4 nanostructures, as shown in Fig.3. This new synthesis route enabled facile room- temperature shape-specific synthesis of complex magnetic crystalline nanomaterials with particle sizes of 40–100 nm, which were difficult to produce using conventional techniques
  22. 22. PROTEIN MEDIATED SILICA FORMATION • Silica proteins, were found to be enzymes (structural and catalytic proteins) that promote biosilica formation in nature . The silicateins exhibit catalytic activity at neutral pH and low temperature and are used as templates to direct the growth of silica particles along the axial protein filament. • Silicatein filaments also demonstrated the ability to form titanium dioxide, gallium oxohydroxide (GaOOH) and gamma- gallium oxide (gamma-Ga2O3) in vitro, which are three inorganic semiconductors that biological species have never naturally produced . An enzymatic biocatalyst from the marine sponge Tethya aurantia, was used to catalyze and template the hydrolysis and condensation of the molecular precursor BaTiF6 at low temperature to form nanocrystalline BaTiO4.
  23. 23. PROTEIN MEDIATED SILICA FORMATION Amorphous silica (or silica glass) is widely used in different applications, such as membranes, columns, heat-proof materials, optical communication fibers, and catalysts in organic synthesis . Silicatein from the freshwater sponge Cauxi catalyzed the polymerization of this type of silica in vitro. Briefly, the sponge shot the axial protein filament in the desired growth direction, and then silicatein polymerized a thin silica layer around the filament. However, this silica deposition inhibited the transport of the siliceous acid to the axial filament, and a new set of silicatein were shot onto the newly synthesized silica deposition. This shooting process continued until the final diameter of spicules was reached. The process is shown by Fig.5.
  24. 24. PEPTIDE MEDIATED BIOINSPIRED SYNTHESIS • Peptides consist of short amino acid sequences that have less intricate functionality than proteins. Although peptides may not perform highly specialized functions compared to proteins, they can be synthesized more easily with desired amino acid sequences by well established chemical and genetic engineering techniques. • Therefore, they are widely used in the applications ranging from controlled gene and drug release, nanofabrication, biomineralization, and membrane protein stabilization to three-dimensional (3D) cell culture and tissue engineering. Peptides are designed to be folded in desired conformations
  25. 25. PEPTIDE MEDIATED BIOINSPIRED SYNTHESIS • A 12-residue peptide (NPYHPTIPQSVH-GGGK-biotin: CLP12 peptide) has been identified for HAp biomineralization using phage display. The sequence responsible for the mineralizing activity resembled the tripeptide repeat (Gly- Pro-Hyp) of type I collagen. This peptide was capable of binding to single crystal HAp and templating the nucleation and growth of crystalline HAp mineral in a sequence- and composition-dependent manner. In another study, polylysine and polyleucine based block copolypeptides (K170L30) were found to form gels at very low concentrations in aqueous media. The block copolypeptides have been used as templates for forming self-assembled calcium phosphate nanocomposites. The synthesis method allowed for simultaneous formation of the selfassembled block copolypeptide gel and of the inorganic phase. The inorganic contents accounted for over 50 wt% in the nanocomposite, approaching the inorganic content in bone . Thermoreversibly gelling block copolymers (Pluronic F127) conjugated to hydroxyapatite- nucleating peptides (DSKSDSSKSESDSS) were used to template the growth of inorganic calcium phosphate in aqueous solutions. The inorganic phase in the organic/inorganic nanocomposite was confirmed to be HAp. This work offered a route for the development of novel, self-assembling, injectable nanocomposite biomaterials for potential orthopedic applications .
  26. 26. POLYSACCHARIDE-MEDIATED BIOINSPIRED SYNTHESIS • A slow but increasing interest has been developing to explore the role of polysaccharides in biomineralization, despite the fact that they have been prevalent since the early stages of evolution. Single types of polysaccharides are typically not associated with biominerals. Only hydroxylated, carboxylated, or sulfated polysaccharides, or those containing a mixture of these functional moieties, are found in biominerals . Chitin is the second most abundant natural polymer after cellulose on earth. It is a linear polysaccharide of β-(1-4)-2-acetamido-2- deoxy-d-glucose. The chemical structure of chitin is very similar to that of cellulose, with a hydroxyl group replaced by an acetamido group. Pure chitin with 100% acetylation does not exist in nature. Chitin tends to form a co-polymer with its N-deacetylated derivative, chitosan. Chitosan is a polymer of β-(1-4)-2-amino-2-deoxy-d-glucose.
  27. 27. POLYSACCHARIDE-MEDIATED BIOINSPIRED SYNTHESIS CNTD... • Chitosan composite materials have attracted much research interest in bone tissue engineering due to their minimal foreign body reactions, intrinsic antibacterial nature, biocompatibility, biodegradability, and ability to be molded into various geometries and forms. • Chitosan was also used as organic template to form HAp nanocrystals. Spindle shaped HAp with 30- 40 nm length and 7- 8 nm width was synthesized through the biomimetic method with chitosan as template. The spindle shaped nano HAp grew in a 0.5wt% chitosan solution for 7 days. The crystallinity of samples increased with the aging time. The HAp powders synthesized with chitosan as templates had good thermal stability up to 800 °C
  28. 28. APPLICATIONS • Electro catalyst in batteries for energy saving • Light weight materials for less fuel consumption. • In artificial joints, economically beneficial carbon nanotubes most widely speaking nanomaterial which can be made as nanocomposite fibers. • Abrasion and wear Applications • Marine Application
  29. 29. APPLICATIONS CONTINUED..... • Food packaging • Fuel tanks • Films • Environmental protection • Flame ability reaction • Erosion and corrosion Applications
  30. 30. CONCLUSION • Nanocomposites are upcoming materials which shows great changes in all the industrial fields and it is also going to be an economical barrier for developing countries as a tool of nanotechnology.
  31. 31. THANK YOU