Transcript Birds do it, Bees do it, Can Liquid Crystals / Polymers do it?

Birds do it, Bees do it,
Can Liquid Crystals /
Polymers
do it?
Liquid Crystals
Thermotropic
High Molar Mass
Materials
Main-chain Polymers Side-chain
Polymers
Lyotropic
Low Molar Mass
Materials
Calamitic
Discotic
SOLID
MESOPHASE
3D
1 or 2D
POSITION
ORIENTATION
ORIENTATION
POSITION
ISOTROPIC
LIQUID
ZERO
order
NONE
NEMATIC LIQUID CRYSTAL
Long Range Orientational Order
No Positional Order
SMECTIC C LIQUID CRYSTAL
q
Molecules Tilted in Diffuse Layers
No Long Range Positional Order
Long Range Tilt Order
SMECTIC A LIQUID CRYSTAL
Molecules Orthogonal to the Diffuse
Layers
No Long Range Positional Order
Effect of structure on thermal properties
C5H11
CN
Cr 31.0 N 55.0 Iso
F
CN
C5H11
C5H11
Cr < 20 Iso
Cr 62.0 N 85.0 Iso
R'
SmA / SmC / N
F
F
F
R
CN
R
R'
N
Effect of structure on physical properties
Viscosity
Dielectric Properties

R
R
R
CN
CO2
CO2
CN
OR
R
+ 16
CN
24
R
CO2
CN
50
R
CO2
OR
65
+ 13
- 1.5
Liquid Crystals
Lyotropic
Thermotropic
High Molar Mass
Main-chain
Polymers
Side-chain
Polymers
Low Molar Mass
Materials
Calamitic
Discotic
A
A
MG
B
MG
A
MG
B
B
Main Chain Liquid Crystalline Polymers
MG
B
Side Chain Liquid Crystalline Polymers
Polymer
Backbone
Spacer
Group
Mesogenic
Side-chain
The Principle
Polarisation holography ensures almost 100% diffraction efficiency and is based on the light-induced change in a material's
refractive index. It requires a photoanisotropic material.
CN
N
N
OR
Trans-isomer
CN
RO
N
N
N
N
OR
Cis-isomer
PS Ramanujam and Hvilsted, Monatschefte fur chemie, 2001, 132, 43.
Trans-isomer
CN
The Idea
HO2C
HO
CO2H
OH
+
Essentially amorphous azobenzene polyesters
give films of very high optical quality
(transparent and non-scattering) but
unfortunately, only short-term retention of
information.
Liquid crystalline
azo-chromophoric
diacid
Liquid crystalline diol
Whereas liquid crystalline azobenzene
polyesters give long-term storage
(more than 9 years), due to the formation
of liquid crystalline domains, the films
have poor optical quality (scattering).
Therefore, the ideal scenario appears to
be a 'half-way house' situation comprising
the best properties of both essentially
amorphous and liquid crystalline polyesters.
O
O
O
C
C
O
Liquid crystalline polyester
CHEMISTRY
LIQUID
CRYSTAL
DEVICES
PHYSICS
ENGINEERING