1.1

The World of Liquid Crystal

Department of Chemistry

Yonsei University

Moon-Gun Choi

1.2

Discovery of Liquid Crystals

The end of the 19th century

Austrian botanist Friedrich Reinitzer

to study the role of cholesterol in plants

1.3

Discovery of Liquid Crystals

Otto Lehmann, examined the cloudy ‘in-between phase’“mesophase”

1.4

Identifying a Liquid Crystal

Polarizing Optical Microscope

DSC(Differential Scanning Calorimeter)

0 50 100 150 200 250

1.5

Why Liquid Crystals Form?

Uneven distribution of electrons in the molecule

Intermolecular forces

Strong enough to cause the molecule line up in the

same overall direction but not strong enough to hold

them firmly in one place

(over a certain range of temperatures)

1.6

Why Liquid Crystals Form?

The Fourth State of Matter

1.7

Types of Liquid Crystals

1.8

Liquid Crystal Display Industry

1.9

The Chemistry of Liquid Crystals

Understand which factors of the molecular structure give

rise to LC behavior.

Tailor the molecules they made to give them the

properties required for useful applications.

Align parallel to an electric field

Liquid crystal phase over a large temperature range

High chemical stability

1.10

The Liquid Crystals that Revolutionized the Display Industry

1.11

The Polymer Dispersed Liquid Crystal(PDLC) Display(SMART WINDOW)

1.12

Discotic Liquid Crystal Materials and Molecular Wires

1.13

Types of Columnar LC Phases

1.14

Schematic Representation of Five Discotic Phases

1.15

Various phases of calamatics and discotics molecules

1.16

LC behavior depends

upon the concentration

in solution

Lyotropic Liquid Crystal

>

1.17

LC behavior depends upon the temperature

Thermotropic Liquid Crystal

1.18

Properties of Metallomesogen

Various 3-D Structure

Ferroelectric Property

NLO Property

Paramagnetic Property

by forming stable radical

1.19

Publications on Metallomesogen

1.20

Examples of Metallomesogen

1.21

Examples of Metallomesogen

COCl

COClH2n+1CnO

H2n+1CnO

H2n+1CnO

CO2 CO2 OH Fe+

NEt3CH2Cl2

4a~g(a:n=6, b:n=8, c:n=10, d:n=12, e:n=14, f:n=16, g:n=18)

OCnH2n+1

OCnH2n+1

OCnH2n+1H2n+1CnO

H2n+1CnO

H2n+1CnOO2CCO2

O2CCO2

Fe

O2C

CO2

Fe

Bicontinuous cubic (bcc)

Columnar Isotropic liquidCrystal

Temperature(o

C )

1.22

Applications of Liquid Crystals

1.23

Applications of LC Display Device

1.24

Ferroelectric, Antiferroelectric LC

Ferroelectric

permanent dipole moment in the

absence of an external electric

filed.

Ferroelectricity of smectic C*

switch very quickly (μs vs ms)

Antiferroelectric

tilt direction alternates between

layers

1.25

Liquid Crystal Polymers

1.26

Soaps and Detergents as an Example of LC

1.27

Liquid Crystals in Nature

1.28

Semi-flexible Main-Chain Polymer

1.29

Side-Group LC Polymers for Optical Memories

1.30

Liquid Crystals and Life

1.31

Liquid Crystals and Life