17.2 Nanostructured polymers and nanocomposites

Nanostructured polymers and nanocomposites are revolutionizing materials science. These tiny wonders, with features between 1-100 nanometers, pack a punch in strength, stability, and conductivity. They're changing the game in everything from electronics to aerospace.

Creating these materials involves clever techniques like in-situ polymerization and template synthesis. The result? Materials with supercharged mechanical, thermal, and electrical properties. From tougher airplane parts to better batteries, nanostructured polymers are shaping our future.

Nanostructured Polymers and Nanocomposites

Nanostructured polymers and nanocomposites

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  Functional conductive nanomaterials via polymerisation in nano-channels: PEDOT in a MOF ... View original

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  Enhanced Thermal Conductivity and Dielectric Properties of Iron Oxide/Polyethylene ... View original

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  Facile preparation of polyimide/graphene nanocomposites via an in situ polymerization approach ... View original

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Top images from around the web for Nanostructured polymers and nanocomposites

• 

  Facile preparation of polyimide/graphene nanocomposites via an in situ polymerization approach ... View original

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• 

  Functional conductive nanomaterials via polymerisation in nano-channels: PEDOT in a MOF ... View original

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• 

  Enhanced Thermal Conductivity and Dielectric Properties of Iron Oxide/Polyethylene ... View original

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• 

  Facile preparation of polyimide/graphene nanocomposites via an in situ polymerization approach ... View original

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• 

  Functional conductive nanomaterials via polymerisation in nano-channels: PEDOT in a MOF ... View original

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• Nanostructured polymers possess structural features on the nanoscale range (1-100 nm) exhibit unique properties compared to bulk polymers such as enhanced mechanical strength (tensile strength, modulus), improved thermal stability (higher melting and glass transition temperatures), and increased electrical conductivity (for conductive nanofillers like carbon nanotubes or graphene)
• Nanocomposites consist of composite materials with at least one component having nanoscale dimensions comprising a matrix (continuous phase) and reinforcement (dispersed phase) that together yield synergistic properties derived from the interaction between matrix and reinforcement including improved stiffness and strength (due to load transfer from matrix to reinforcement), enhanced barrier properties (reduced permeability to gases and liquids), and increased flame retardancy (through formation of char layer or release of flame retardant agents)

Synthesis methods for nanostructures

• In-situ polymerization involves monomer polymerization in the presence of nanoscale reinforcements ensuring good dispersion and strong interfacial interactions between the polymer matrix and nanofillers
• Solution blending mixes the polymer and nanoscale reinforcements in a common solvent followed by solvent removal (evaporation, precipitation) to obtain the nanocomposite
• Melt blending directly mixes the polymer melt and nanoscale reinforcements using high shear forces (extrusion, injection molding) providing an economical and scalable method for nanocomposite production
• Template synthesis uses nanoporous templates (anodic aluminum oxide, block copolymers) to guide the formation of nanostructured polymers allowing precise control over the size and shape of the resulting nanostructures (nanorods, nanotubes, nanopores)

Effects of nanoscale reinforcements

• Mechanical properties:
  1. Increased modulus and strength due to efficient load transfer from the polymer matrix to the high-stiffness nanoscale reinforcements
  2. Improved toughness and impact resistance resulting from energy dissipation mechanisms (crack deflection, plastic deformation) at the matrix-reinforcement interface
  3. Enhanced fatigue resistance and creep resistance attributed to restricted polymer chain mobility in the presence of nanoscale reinforcements
• Thermal properties see increases in glass transition temperature ($T_g$) and melting temperature ($T_m$) due to restricted polymer chain mobility, improved thermal stability and reduced thermal expansion from the high thermal stability of nanoscale reinforcements (ceramic nanoparticles, carbon nanotubes), and enhanced thermal conductivity for better heat dissipation especially with high-aspect-ratio nanofillers (carbon nanotubes, graphene)
• Electrical properties exhibit increased electrical conductivity with conductive nanoscale reinforcements (carbon nanotubes, graphene, metal nanoparticles) at low percolation thresholds, improved dielectric properties for energy storage applications (high-permittivity ceramic nanoparticles), and enhanced electromagnetic interference (EMI) shielding effectiveness with conductive nanofillers forming a percolating network

Applications of nanostructured materials

• Electronics utilize conductive nanocomposites for printed electronics (flexible circuits, RFID tags) and sensors (strain gauges, chemical sensors), dielectric nanocomposites for high-performance capacitors (embedded capacitors, energy storage), and nanostructured polymers for organic solar cells (bulk heterojunction morphology) and light-emitting diodes (LEDs) (quantum dot-polymer nanocomposites)
• Aerospace applications leverage lightweight and high-strength nanocomposites for aircraft components (fuselage, wings), nanostructured polymers for anti-icing and self-cleaning coatings (superhydrophobic surfaces), and nanocomposites for improved flame retardancy and fire resistance (carbon nanotube-polymer nanocomposites)
• Energy storage employs nanocomposites for high-capacity lithium-ion battery electrodes (silicon nanoparticle anodes, lithium iron phosphate cathodes), nanostructured polymer electrolytes for solid-state batteries (block copolymer electrolytes), and nanocomposites for supercapacitors (carbon nanotube-conducting polymer nanocomposites) and fuel cells (nanostructured proton exchange membranes)