Chemistry Reference
In-Depth Information
(a)
a
:
b
:
l = a
: 2 : 1
(b)
a
:
b
:
l
= 2 :
b
: 1
(d)
v
a
:
v
ab
:
v
b
= 1 : 0.5 :
v
b
(c)
a
:
b
:
l
= 2 : 2 :
l
(e)
v
a
:
v
ab
:
v
b
= 1 :
v
ab
: 0.2
Figure 2.23. The transition temperature against the molecular parameters: (a) rod's
length
a
; (b) spacer's length
b
; (c) persistence length of spacer
l
; (d) self coupling
constant of spacers
v
b
; (e) cross coupling constant
v
ab
. (From Wang & Warner, 1992a.)
The following conclusions can be obtained from these plots. The
transition temperature
T
c
increases significantly as
v
a
increases, and
increases at an intermediate speed with
v
ab
, but is weakly dependent on
v
b
.
T
c
increases as the length of the rods
a
and the persistence length
l
of
the worm spacers increase, while
T
c
decreases with increasing spacer length,
b
. The order of mesogenic units is generally greater than that of spacers.
