Chemistry Reference
In-Depth Information
Very rapid proton exchanges follows. This results in equilibrium between the lactam and the
polymeric amide anions [
129
]:
O
O
O
O
C
C
N
N
C
HN
C
+
O
O
O
O
NH
N
C
C
C
N
C
+
The polymer amide anions can undergo acylation by acyllactam groups with accompanying ring
opening or with formation of lactam anions. In the first instance, it is an alternate path of propagation
with formation of imide groups:
O
O
O
O
O
C
C
N
N
C
N
C
+
C
N
C
O
O
O
C
N
N
C
+
C
O
O
O
O
O
C
N
N
C
+
C
C
N
+
N
H
H
O
O
O
C
C
N
+
N
+
H
N
C
N
H
O
C
O
O
O
H
NC
H
NC
C
N
+
N
O
C
The acylation reactions shown above are much faster than the initiation reactions [
129
,
131
]
As a result, there are induction periods in anionic polymerizations of lactams [
113
]. In addition,
steep increases in molecular weights take place at the beginning of the polymerizations. Bimolecu-
lar aminolyses may contribute to that, though their contributions to the total conversions are
negligible [
113
].
