Chemistry Reference
In-Depth Information
Table 6.12. The phase transitions of small molecular mass
liquid crystals: L1, L2 and L3.
Sample
K
S
1
S
C
∗
S
A
Ch
I
L1
*
52
*
105
*
130
*
L2
*
42
*
100
*
130
*
132
*
L3
* 0* 6* 1* 8
*
∗
S
1
is an unknown smectic phase.
and chiral monomers in a liquid crystalline copolymer, as side groups, are
alternatively attached to the backbone, the liquid crystalline polymer may
exhibit the cholesteric phase. Such a polymer may show a ferroelectric
phase S
C
∗
.
Shibaev
et al.
(1984) first synthesized a ferroelectric side chain polymeric
liquid crystal. In the following years a lot of liquid crystalline polymers of
such kind were synthesized. In early research studies techniques used to
understand polymers and whether they showed the liquid crystal phase
were limited so that the conclusion was ambiguous. It was only in 1988
when Uchida
et al.
(1988) measured the spontaneous polarization and
the tilt angle that people became convinced that this side chain poly-
mer in the literature (Shibaev
et al.
, 1984) is indeed a ferroelectric liquid
crystal.
The following three molecules show the ferroelectric liquid crystal phase
S
C
∗
(Sekiya
et al
., 1993). Their phase transitions are listed in Table 6.12.
*
L
1
:
C
10
H
21
O
COO
COOCH(CH
3
)C
3
H
7
*
COOCH(CH
3
)COOC
2
H
5
L
2
:
C
10
H
21
O
COO
*
COOCH(CH
3
)C
6
H
13
C
10
H
21
O
COO
L
3
:
The side chain polysiloxane liquid crystalline polymers P1, P2 and P3
composed of the above three ferroelectric liquid crystals as the side groups
exhibit the ferroelectric liquid crystal phase, their chemical formulae being
respectively.
