Chemistry Reference
In-Depth Information
7.4 Aromatic Polyamide-Imides and Aromatic Polyester-Imides
The aromatic polyamide-imides are related to the aromatic polyamides described in the previous
section. Aliphatic materials of this type were reported originally in 1947. They were formed by
reacting tricarboxylic acids with diamines [
83
]:
O
OH
O
O
+
R
n
H
2
N
NH
2
n
HO
OH
O
OH
O
O
O
O
R
R
Δ
R
H
2
N
N
N
NH
2
n
H
2
N
N
N
NH
2
R
n
H
H
H
O
The aliphatic polyamide-imides prepared to date don't have desirable properties. When aromatic
diacids are employed, however, the products exhibit good heat stability and toughness. This led to a
development of a number of useful materials.
Three general methods are employed to form aromatic polyamide-imides [
88
]. The first one
consists of an initial reaction of a mole of a diacid chloride with two moles of a diamine. The product
is then reacted with a dianhydride and after that condensed to an imide:
O
NH
2
H
H
Cl
H
2
N
N
N
NH
2
+
interfacial
polycondensation
2
O
O
Cl
NH
2
O
HOOC
COOH
O
O
H
H
H
H
O
O
N
N
N
N
O
O
n
O
O
O
O
O
O
H
H
H
N
N
N
O
O
+
H
2
O
n
O
O
O
O
In the second method, a dianhydride is prereacted with an excess of a diamine. The product is then
reacted with a diacid chloride by interfacial polymerization technique.
