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Sartaz Khan

Nanocomposites have increased surface area due to nanoparticles, which are much smaller than microparticles. This small size leads to a high surface-to-volume ratio and small distances between fillers, resulting in bulk interfacial material. Nanocomposites demonstrate improved mechanical and optical properties compared to macroscale composites. They are also multiscale systems as nanoparticles can cluster at the micron scale while polymer chains are immobilized at the nanoscale particle surface. Research also shows that adding nanoparticles like carbon nanotubes and clay to polymer thin films increases the effective fraction of slowly relaxing domains, raising the glass transition temperature over films without nanoparticles.

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Why Nanocomposites?Why Nanocomposites? Increased surface area on nanoparticles NanoparticlesNanoparticlesMicroparticlesMicroparticles Size does matter
? Small filler size: – High surface to volume ratio ? Small distance between fillers → bulk interfacial material – Mechanical Properties ? Increased ductility with no decrease of strength, ? Scratching resistance – Optical properties ? Light transmission characteristics particle size dependent Why Nanocomposites?Why Nanocomposites? ?? Multi-Multi- functionalityfunctionality
– Macroscale composite structures – Clustering of nanoparticles - micron scale – Interface - affected zones - several to tens of nanometers - gradient of properties – Polymer chain immobilization at particle surface is controlled by electronic and atomic level structure Nanocomposite as a MultiscaleNanocomposite as a Multiscale SystemSystem 10 -12 s 10 -9 - 1 s 1 s - 1h
The Glass transition temperature of nanocomposite thin films - Background: The glass transition temperature of polymer thin films Influence of - i) single walled carbon nanotubes, - (ii) C60 fullerenes (“buckyballs”) and - (iii) mica-type layered silicate inorganic clays on the Tg of thin polymer films in the nanometer thickness range 20-50 nm Polymer coil Rg~2-20 nm from mmptdpublic.jsc.nasa.gov/jscnano/ P. F. Green et al, U Texas
The Glass transition of Polymer thin film nanocomposites ? C60, and carbon nanotubes have a similar effect 85 90 95 100 105 110 115 120 125 0 50 100 150 200 250 h (nm) PS PS+1wt% layered silicate clay PS+5 wt% layered silicate clay ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?≈ 3/1 1)( ν β h a ThT gg PS: β=9 Nanocomposite: β=4 Decrease in β reflects the increase in fraction of the slowly relaxing domains The effect of nanoparticles is to increase the effective fraction of slowly relaxing domains in the sample 37 36 35 34 FilmThickness(nm) 25020015010050 Temperature ( o C) P. F. Green et al, U Texas
The Glass transition of Polymer thin film nanocomposites ? C60, and carbon nanotubes have a similar effect 85 90 95 100 105 110 115 120 125 0 50 100 150 200 250 h (nm) PS PS+1wt% layered silicate clay PS+5 wt% layered silicate clay ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?≈ 3/1 1)( ν β h a ThT gg PS: β=9 Nanocomposite: β=4 Decrease in β reflects the increase in fraction of the slowly relaxing domains The effect of nanoparticles is to increase the effective fraction of slowly relaxing domains in the sample 37 36 35 34 FilmThickness(nm) 25020015010050 Temperature ( o C) P. F. Green et al, U Texas

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  • 1. Why Nanocomposites?Why Nanocomposites? Increased surface area on nanoparticles NanoparticlesNanoparticlesMicroparticlesMicroparticles Size does matter
  • 2. ? Small filler size: – High surface to volume ratio ? Small distance between fillers → bulk interfacial material – Mechanical Properties ? Increased ductility with no decrease of strength, ? Scratching resistance – Optical properties ? Light transmission characteristics particle size dependent Why Nanocomposites?Why Nanocomposites? ?? Multi-Multi- functionalityfunctionality
  • 3. – Macroscale composite structures – Clustering of nanoparticles - micron scale – Interface - affected zones - several to tens of nanometers - gradient of properties – Polymer chain immobilization at particle surface is controlled by electronic and atomic level structure Nanocomposite as a MultiscaleNanocomposite as a Multiscale SystemSystem 10 -12 s 10 -9 - 1 s 1 s - 1h
  • 4. The Glass transition temperature of nanocomposite thin films - Background: The glass transition temperature of polymer thin films Influence of - i) single walled carbon nanotubes, - (ii) C60 fullerenes (“buckyballs”) and - (iii) mica-type layered silicate inorganic clays on the Tg of thin polymer films in the nanometer thickness range 20-50 nm Polymer coil Rg~2-20 nm from mmptdpublic.jsc.nasa.gov/jscnano/ P. F. Green et al, U Texas
  • 5. The Glass transition of Polymer thin film nanocomposites ? C60, and carbon nanotubes have a similar effect 85 90 95 100 105 110 115 120 125 0 50 100 150 200 250 h (nm) PS PS+1wt% layered silicate clay PS+5 wt% layered silicate clay ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?≈ 3/1 1)( ν β h a ThT gg PS: β=9 Nanocomposite: β=4 Decrease in β reflects the increase in fraction of the slowly relaxing domains The effect of nanoparticles is to increase the effective fraction of slowly relaxing domains in the sample 37 36 35 34 FilmThickness(nm) 25020015010050 Temperature ( o C) P. F. Green et al, U Texas
  • 6. The Glass transition of Polymer thin film nanocomposites ? C60, and carbon nanotubes have a similar effect 85 90 95 100 105 110 115 120 125 0 50 100 150 200 250 h (nm) PS PS+1wt% layered silicate clay PS+5 wt% layered silicate clay ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?≈ 3/1 1)( ν β h a ThT gg PS: β=9 Nanocomposite: β=4 Decrease in β reflects the increase in fraction of the slowly relaxing domains The effect of nanoparticles is to increase the effective fraction of slowly relaxing domains in the sample 37 36 35 34 FilmThickness(nm) 25020015010050 Temperature ( o C) P. F. Green et al, U Texas