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FUNCTIONAL MATERIALS - Coggle Diagram

- - - - Gold, Silver, Iron etc.
    - - Cadmium Sulfide, Cadmium Selenide etc.
      - quantum dots (QDs) are semiconductor particles of few nanometers (<10 nm) in size, having optical and electronic properties that differ from larger particles.
        
        band gap decreases as QDs size increases.
        
        emission wavelength becomes red shifted with increase in size of QDs.
      - synthesis methods of quantum dots:
        
        high temperature synthesis
        
        hydrothermal synthesis
        
        microwave synthesis
        
        ultrasonication synthesis
    - - Zinc Oxide, Iron Oxide, Cerium Oxide etc.
  - - - High-energy Ball Milling / Machining
        
        Chemical Oxidation Process (CNTs to QDs)
        
        Electrochemical Oxidation Process (Graphite rods to QDs)
        
        Lithography (photo- and electro-chemical)
        
        Etching / Cutting
        
        Coating
        
        Atomization
        
        Mechanical Milling
        
        particle size reduction, solid-state alloying, mixing or blending, and particle shape changes.
        
        restricted to relatively hard, brittle materials which fracture and/or deform and cold weld during the milling operation.
        
        to produce non-equilibrium structures including nanocrystalline, amorphous and quasicrystalline materials.
        
        users are tumbler mills, attrition mills, shaker mills, vibratory mills, planetary mills etc.
        
        powders diameter of about 50µm with a number of hardened steel or tungsten carbide (WC) coated balls in a sealed container which is shaken or violently agitated. the most effective ratio for the ball to powder mass is 5:10.
        
        shaker mills (eg. SPEX model 8000) use small batches of powder (approximately 10cm^3 is sufficient).
        
        ADVANTAGE - high production rates
        
        LIMITATIONS -
        
        severe plastic deformation associated with mechanical attrition due to generation of high temp. in the interphase, 100 to 200 degree celsius.
        
        difficulty in braking down to the required particle size.
        
        contamination by the milling tools (Fe) and atmosphere (trace elements of O2, N2 in rare gases) can be a problem (inert condition necessary like G love Box) (Fe < 1-2% and Trace elements < 300ppm).
        
        protective coating to reduce milling tools contamination (MTC) increases cost of the process.
        
        working duration (>30h) increases MTC (>10%)
    - - Gas Condensation Processing (GCP) / Aerosol Based Processes
        
        Chemical Vapour Condensation (CVC)
        
        Atomic or Molecular Condensation
        
        Laser Ablation
        
        Supercritical Fluid Synthesis
        
        Wet Chemical Synthesis of Nanomaterials (Sol-gel Process)
        
        Precipitation Method
        
        Spinning
        
        Self-Assembly
        
        DNA Origami
        
        Wet Chemical Synthesis of Nanomaterials (Sol - gel Process)
        
        SOL - nanoparticle dispersion
        GEL - crosslinked network
        
        Step 1: formation of different stable solutions of the alkoxide (the sol).
        Step 2: gelationresulting from the formation of an oxide- or alcohol-bridged network (the gel) by a polycondensation or polyesterification reaction.
        Step 3: aging of the gel, during which the polycondensation reactions continue until the gel transforms into a solid mass, accompanied by contraction of the gel network and expulsion of solvent from gel pores.
        Step 4: drying of the gel, when water and the other volatile liquids are removed from the gel network.
        
        if isolated by thermal evaporation, the resulting monolith is termed xerogel.
        
        if the solvent (such as water) is extracted under supercritical or near supercritical conditions, the product is an aerogel.
        Step 5: dehydration, during which surface-bound M-OH groups are removed, thereby stabilizing the gel against rehydration. this is normally achieved by calcining the monolith at temperatures up to 800 degrees celsius.
        Step 6: densification and decomposition of the gels at high temperatures (T > 800 degrees celsius). the pores of the gel network are collapsed, and remaining organic species are volatilized.
        
        sol/gel transition controls the particle size and shape.
        
        calcination of the gel produces the product (eg. Oxide).
        
        sol-gel processing > hydrolysis and condensation of alkoxide-based precursors such as Si(OEt(4 (tetraethyl orthosilicate, or TEOS).
        
        reactions:
        MOR + H2O → MOH + ROH (hydrolysis)
        MOH + ROM → M-O-M + ROH (condensation)
        
        if the aging process of the gel exceeds 7 days it is critical to prevent the cracks in gels that have been cast.
        
        steps are:
        Sol → Gel → Ageing → Drying → Dehydration → Densification & Decomposition → Product
        
        ADVANTAGES:
        
        synthesizing non-metallic inorganic materials like glasses, glass ceramics or ceramic materials at a very low temperatures compared to melting glass or firing ceramics.
        
        monosized nanoparticles possible by this bottom-up approach.
        
        DISADVANTAGES:
        
        controlling the growth of the particles and then stopping the newly formed particles from agglomerating.
        
        difficult to ensure complete reaction so that no unwanted reactant is left on the product.
        
        complete removal of any growth aids.
        
        production rates of nanopowders are very slow by this process.
- - - - doping
        
        p-doping (achieved by oxidation)
        
        oxidative doping.
        
        involves treatment of polyacteylene with a Lewis acid or iodine which leads to oxidation process and positive charges on the polymer backbone are created.
        
        oxidation (removal of one electron) > formation of delocalized radical ion > polaron.
        
        second oxidation > radical recombination > generates two mobile positive charge carriers > soliton > responsible for conduction.
        
        p-dopants: I2, Br2, AsF5, FeCl3, HClO4, PF5 etc.
        
        n-doping (achieved by reduction)
        
        reductive doping.
        
        involves treatment of polyacetylene with a Lewis base which leads to reduction process and negative charges on the polymer backbone are created.
        
        reduction (donation of one electron) > formation of delocalized radical anion > anionic polaron.
        
        second reduction > radical recombination > generates two mobile negative charge carriers > soliton > responsible for conduction.
        
        n-dopants: Li, Na, Ca, sodium naphthalide etc.
        
        mechanism followed by polyacetylene for the transfer of charge from one chain to another - intersoliton hopping
    - - soliton - the soliton is a charged or a neutral defect in the polyacetylene chain that propagates down the chain, thereby reducing the barrier for interconversion.
  - - - filled with carbon black, metallic fibres, metal oxides etc.
        
        polymer acts as a binder to those elements.
        
        have good bulk conductivity.
        
        low in cost.
        
        light weight.
        
        strong.
        
        durable.
        
        can be in different shapes and sizes.
    - - product obtained by blending a conventional polymer with a conducting polymer either by physical or chemical change.
        
        can be processed and possess better physical, chemical and mechanical strength.
- - - - TEFLON or FLOUN
      - ABS (Acrylonitrile butadiene styrene)
        
        properties
        
        opaque thermoplastic.
        
        amorphous polymer.
        
        can be easily recycled.
        
        relatively non-toxic.
        
        has a strong resistance to corrosive chemicals and/or physical impacts.
        
        very easy to mold; low melting temperature making it particularly simple to use in injection molding manufacturing processes or 3-D printing on an FDM machine.
        
        relatively inexpensive.
        
        applications
        
        most widely identifiable: keys on a computer keyboard, power-tool housing, the plastic face-guard on wall sockets (often a PC/ABS blend), and LEGO toys.
        
        3-D printing and prototype development.
        
        camera housings, protective housings and packaging.
      - PVC
  - - - Novolac
      - Bakelite
        
        properties
        
        resistant to acids, salts and most organic solvents, but is attacked by alkalis because of the presence of -OH groups.
        
        possesses excellent electrical insulating property.
        
        difficult to recycle.
        
        applications
        
        adhesive in plywood laminations and grinding wheels.
        
        widely used in paints and varnishes.
        
        used for making electrical insulator parts like plugs, switches, heater handles, paper laminated products, thermally insulation foams etc.
      - (condensation polymerisation products of phenol derivative and aldehydes)