Chemistry Reference
In-Depth Information
Fig. 28 Formation of an
island of immiscibility in the
ternary system, caused by
favorable 1/P and 2/P
interactions [
27
]. For details,
see legend to Fig. 27
N
P
=
1000
0.00
1.00
0.25
0.75
0.50
0.50
0.75
0.25
1.00
0.00
0.00
0.25
0.50
0.75
1.00
N
1
=
1
N
2
=
1.3
combinatorial
PI* 12 w
Fig. 29 Phase diagram of the
CH/AC/PI* system at 25
C.
The polymer sample PI* (
M
n
5 kg/mol,
M
w
12 kg/mol)
consists of a mixture of
branched and linear chains.
Crossed circles
cloud points,
half closed circles
overall
composition of the
coexistence experiments,
open circles
compositions of
the polymer lean phases,
closed circles
compositions
of the polymer rich phases,
closed square
swelling point
of PI* in AC. The
composition area of possible
demixing is
hatched
[
71
]
0.00
1.00
0.25
0.75
0.50
0.50
0.75
0.25
1.00
0.00
0.00
0.25
0.50
0.75
1.00
AC
CH
W
AC
Complex Behavior
Phase diagrams for polymer solutions in mixed solvents can look much more
complicated than shown so far. Figure
29
gives an example observed in the course
of a study concerning differences in the thermodynamic behavior of branched as
compared with linear polymers [
71
].
The reason for uncommon phase diagram often lies in the polydispersity of the
polymer sample, which means that we are strictly speaking no longer dealing with
ternary but with multinary systems, for which the representation of phase diagrams
requires a projection into a plane. In the present case, the polydispersity is due to the
