Chemistry Reference
In-Depth Information
Cl
OCH
2
CF
3
N
P
N
P
n
n
Cl
Cl
OCH
2
CF
3
N
P
n
O
Br
OCH
2
CF
3
OCH
2
CF
3
N
P
N
P
n
n
O
OH
O
O
O
10.5.2 Polymers with Functional Chalcone Groups
Pendant chalcone groups on polymers behave similarly to pendant cinnamate groups. Thus,
photocross-linkable polymer can be formed, for instance, from poly(vinyl alcohol) by a reaction
with 4
0
-substituted-4-caboxychalcone in homogeneous dimethyl formamide solution, using 2,4,6-
trinitrochlorobenzene as the condensing agent [
155
].
n
O
R
O
O
The photosensitivity of this polymer is in the range of 1-5 mJ/cm
2
, according to Watanabe et al.
[
155
]. When the R group shown above is
-NO
2
, or (CH
3
)
2
N, the cross-linking is via formation
of biradicals derived from the double bonds of the cinnamoyl groups and an abstraction of protons
from the neighboring methyne or methylene groups. This reaction of dimerization can be illustrated
as follows [
156
]:
p
-Br,
m
