Chemistry Reference
In-Depth Information
Such prepolymers are
. Following is an example of one such material,
an oligomer, polyquinoxaline terminated by acetylene groups:
terminated by functional groups
N
N
N
N
N
O
N
N
N
N
O
N
No volatiles can be detected by mass spectrometry [
215
,
216
] or by thermo gravimetric analyses
during the cross-linking reaction. The thermo oxidative stability of the resultant polymers is at least
equivalent to polyphenylquioxalines not terminated by acetylene. The cross-linking reaction was
shown on a model compound to be an intramolecular cyclization [
215
-
217
]:
It is not necessary for the acetylenic groups to be on the terminal ends of the prepolymers. They
can also be located as pendant structures [
216
].
Aromatic polyamides with terminal acetylenic groups [
218
] were formed from 2,2
0
-
diiododiphenyl-4,4
0
-dicarbonyl chloride reacted with aromatic diamines. The phenylethynyl groups
were introduced by reacting the iodine moieties with copper phenyl acetylide. Thermal treatment
converted the prepolymers to 9-phenyl dibenzanthracene-based rigid-rod polymers that fail to melt
below 500
C.
High molecular weight polyquinoxaline polymers were prepared from 3,3
0
,4,4
0
-tetraamino-
biphenyl that was reacted with aromatic bis(
a
-diketones) and/or ethynyl-substituted aromatic bis
(
-diketones) [
219
]. The polymers contain 0, 5, 10, 30, and 100% pendant groups. Also, ethynyl-
substituted diketones were synthesized by the following procedure:
a
O
O
1. AlCl
3
2. hydrolysis
+
2
Br
Cl
O
O
Br
2
SO
2
