Chemistry Reference
In-Depth Information
5.14 Copolymerization of Cyclic Monomers
Many copolymers have been prepared from cyclic monomers. These can form through ring-opening
copolymerizations of monomers with similar functional groups as well as with different ones. Some
cyclic monomers can also copolymerize with some linear monomers. Only a few copolymers of
cyclic monomers, however, are currently used industrially.
The composition of the copolymers depends upon the reaction conditions, the counter ions, the
solvents, and the reaction temperatures. The initiator system can be very important when cyclic
monomers with different functional groups are copolymerized. Also, if different propagating centers
are involved in the propagation process, copolymerizations can be very difficult to achieve.
Prominent among copolymers of cyclic ethers are interpolymers of oxiranes with tetrahydrofuran.
Thus, ethylene oxide copolymerizes with tetrahydrofuran with the aid of boron trifluoride-ethylene
glycol catalytic system [
200
]. The resultant copolyether diol contains virtually no unsaturation.
Another example is a copolymer of allyl glycidyl ether with tetrahydrofuran formed with antimony
pentachloride catalyst [
201
]:
O
O
+
O
O
x
y
O
O
In addition to the above, liquid copolymers form from 1,3-dioxolane with ethylene oxide, when
boron trifluoride is used as the catalyst [
1
]. Also, a rubbery copolymer forms from tetrahydrofuran
and 3,3-diethoxycyclobutane with phosphorus pentafluoride catalyst [
202
]. A 3,3-bis(chloromethyl)
oxacyclobutane copolymerizes with tetrahydrofuran with boron fluoride or with ferric chloride
catalysis. The product is also a rubbery material [
1
].
Various copolymers were reported from trioxane with dioxolane or with glycidyl ethers [
2
,
3
]. For
instance, a copolymer of trioxane and dioxolane forms with SnCl
4
,BF
3,
or HClO
4
catalysts. The
products from each reaction differ in molecular weights and in molecular weight distributions.
Copolymerizations of trioxane with phenylglycidyl ether yield random copolymers [
203
].
Different lactones can be made to interpolymerize [
204
]. The same is true of different lactams
[
205
-
207
]. The products are copolyesters and copolyamides, respectively.
More interesting are copolymers from cyclic monomers of different chemical types. For
instance, cyclic phosphite will copolymerize with lactone at 150
C or above in the presence of
basic catalysts [
208
]:
O
O
P
O
O
O
O
O
+
n
O
P
O
Aziridine copolymerizes with succinimide to form a crystalline polyamide that melts at
300
C[
209
]:
