Chemistry Reference
In-Depth Information
O
Si
O
O
PdCl
2
Br
2
P
3
2
O
O
O
K
2
CO
3
O
O
Si
O
2
2
The synthesis is completed by condensation with a tetramine:
O
O
H
2
N
H
2
N
NH
2
NH
2
+
O
2
N
N
O
n
N
N
T
g
values. The materials, however, exhibited
lowered thermo oxidative stability. The same was found to be true when the ethynyl moieties were
replaced by phenylethynyl groups [
219
].
Other functional groups that were investigated [
229
] are phenylethynyl, phenylbutadiynyl,
phenylbutenyl, biphenylene,
Above shown reactions yield polymers with high
styryl, maleimide, nadimide
(5-norbornene-2,3-dicarboximide),
cyanate, and
-cyanourea [
230
]. The advantage of terminally capped prepolymers is that they melt
at lower temperatures and can be dissolved in different solvent. Heating of these materials converts
them to thermally stable polymeric networks.
A recent paper reports preparation of quinoline oligomers that were end-capped with 4-
acetylbenzocyclobutene, 6-acetyl-8-phenyl-1,2-dihydro-[3, 4]cyclobuta-[1,2-
N
b
]quinone (CBQ), and
8-acetyl-6
b
,10
b
-dihydrobenzo-[
j
]cyclobuta-[1,2-
a
]-acenaphthalene(BCBAN) [
230
]. The structures
of the two cross-linking groups are:
O
Ph
O
N
CBQ
BCBAN
It was reported [
230
] that the oligomer capped with BCBAN yields a cured film that exhibits good
flexural moduli and superior heat stability in air at 400
C.
