Chemistry Reference
In-Depth Information
NLO active groups can be tailored and controlled. Moreover, the orienta-
tion of NLO active groups in the copolymer form are better than in the
guest-host mode. The NLO coe
cient
d
33
of a side chain polymeric liquid
crystal is plotted as a function of restore time in Figure 6.33 (Singer
et al.,
1988).
d
33
(6
3) is another expression of the second NLO coecient
χ
(2)
ijk
.
The side chain polymeric liquid crystal is PMMA. DCV is the NLO active
unit either as the side groups in copolymer DCM-PMMA or as the guest
in the guest-host system DCV/PMMA. The chemical formula of DCV is
shown in Figure 6.33. It is demonstrated that
d
33
of the copolymer is almost
unchanged after one month's restore time while
d
33
in guest-host mixture
is reduced by 70%.
χ
(2)
of copolymers increases as the concentration of NLO active side
groups increases, see Figure 6.34.
×
(a)
(b)
Figure 6.33. The NLO coe
cient
d
33
of a side chain liquid crystalline polymer PMMA
as a function of restore time. (Modified from Singer
et al.
, 1988.)
