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

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)(

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

37

36

35

34

Film

Thi

ckne

ss (

nm)

25020015010050

Temperature (o C)

P. F. Green et al, U Texas