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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 Nanocomposite as a Multiscale SystemMultiscale System
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
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0 50 100 150 200 250
h (nm)
PS
PS+1wt% layered silicate clay
PS+5 wt% layered silicate clay
3/1
1)(
h
aThT gg
PS: =9Nanocomposite: =4
Decrease in 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
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Film
Thi
ckne
ss (
nm)
25020015010050
Temperature (o C)
P. F. Green et al, U Texas
