Polycarbonates:
Interfacial Polymerizations
Polymer Synthesis
CHEM 421
• Commercially Important
Brunelle, D. J. Am. Chem. Soc., 1990, pg. 2399.
Brunelle, D., Macromolecules, 1991, pg. 3035.
Step Growth Polymerization of
Poly(bisphenol A carbonate)
n
HO
OH
Polycarbonate
Oligomers
181-300 oC
+
+
LiOH
O
O C O
n
OH
(2n-1)
Polycarbonate Oligomers
O
O C O
O
O C O
OH
m
O
O C O
HO
OH
m
O
O C
O
O
O C O
m
Polymer Synthesis
CHEM 421
Traditional Routes
Interfacial
Route
Polymer Synthesis
CHEM 421
Advantages
•High Molecular Weight
•Excellent Optical Clarity

O-
O
Phase
+ Transfer + H2O
Catalyst
and color
Disadvantages
•Phosgene based
O
CH2Cl2
+
Cl
C
•Uses H2O and CH2Cl2
Cl
O
( O
C
O
)n
Melt Condensation
HO
OH
Advantages
•Solvent Free
•Potentially Phosgene Free
+
Disadvantages
O
O
C
O
•Colored Product
•Intermediate Molecular Weight
CO2 & Polymer Processing
Polymer Synthesis
CHEM 421
Swelling and Plasticization of a Polymer Melt
Impact:
Lower T
processing
Melt Phase Condensation
Polymerization
Polymer Synthesis
CHEM 421
• Viscosity () increases with conversion
• High  hinders mixing and removal of condensate,
causing slower reaction rates
• Addition of supercritical CO2 as a plasticizing agent
decreases , increasing mobility
• Supercritical CO2 extracts reaction byproducts, shifts
equilibrium, increases DP
CO2 + byproduct
outlet
CO2 inlet
Swollen polymer
melt
Swelling Measurements
0 psi
2000 psi
3000 psi
Polymer Synthesis
CHEM 421
4000 psi 5000 psi
• In a closed system, the polymer swelling
correlates to
CO2 mass uptake by the polymer
• Swelling measurements allow for the
determination of
the diffusion coefficient of CO2 in the polymer
Polymer Synthesis
CHEM 421
P
o
l
y
c
a
r
b
o
n
a
t
e
(
M
=
5
,
0
0
0
g
/
m
o
l
)
E
x
p
o
s
e
d
n
0
t
o
S
u
p
e
r
c
r
i
t
i
c
a
l
C
O
a
t
2
3
5
C
2
t-V 0)/V 0]x10%
6
0
5
0
4
0
3
0
PercntSweling[(V
2
0
1
0
0
0
1
0
0
0
2
0
0
0
3
0
0
0
P
r
e
s
s
u
r
e
(
p
s
i
)
4
0
0
0
5
0
0
0
Solvent-Induced (CO2)
Crystallization of Polycarbonate
Polymer Synthesis
CHEM 421
Polycarbonate
Pellets
Crystallized
with
Supercritical
CO2
Amorphous
Polycarbonate
Pellets
Solid State Polymerization
Polymer Synthesis
CHEM 421
Synthesize amorphous prepolymer
Crystallize the prepolymer with supercritical CO2 to
eliminate the need for organic solvents
Heat the semicrystalline prepolymer between Tg and Tm
Flow sweep fluid past the surface of the polymer
particle to remove condensation byproduct
Investigate the use of supercritical CO2 as a sweep fluid
Amorphous region
Crystalline region
Solid State Polymerization: SolventPolymer Synthesis
CHEM 421
Induced Crystallization
Solvent induced crystallization presents a unique opportunity to study solid
state polymerization
PET
PC
-Thermally crystallizes
crystallize
-Fixed level of crystallinity
-Uniform crystallinity
-Does not readily thermally
-Can control crystallinity
-Can control morphology
Solvent front
Mw(g/mol)
Mw versus Time as a Function of Temperature:
SSP of Polycarbonate Beads (3.6 mm)
with N2 as the Sweep Fluid
Polymer Synthesis
CHEM 421
Variable Temperature Profile:
Hours 0-2: 180 °C
Hours 4-6: 230 °C
Hours 2-4: 205 °C
Hours 6-12: 240 °C
2
5
0
0
0
2
0
0
0
0
V
a
r
i
a
b
l
e
T
e
m
p
e
r
a
t
u
r
e
,
I
n
i
t
i
a
l
l
y
5
,
0
0
0
g
/
m
o
l
1
5
0
0
0
V
a
r
i
a
b
l
e
T
e
m
p
e
r
a
t
u
r
e
:
I
n
i
t
i
a
l
l
y
2
,
5
0
0
g
/
m
o
l
1
8
0
C
1
0
0
0
0
1
6
0
C
5
0
0
0
0
0
2
4
6
8
1
0
1
2
T
i
m
e
(
H
o
u
r
s
)
Macromolecules, 1999, 32, 3167.
N2 flow rate 2 mL/min
Role of Phenol Diffusion
Polymer Synthesis
CHEM 421
Phenol must diffuse from the
particle to increase polymer
molecular weight.
core
intermediate
shell
Segment Radius
Core = 0.0 to 0.4 mm
Inter = 0.4 to 1.4 mm
Shell = 1.4 to 1.8 mm
The sample was separated into
three regions for analysis...
-molecular weight
-percent crystallinity
-melting point (Tm)
What is the role of….
-phenol diffusivity
-tortuosity
-end group mobility
MW as a Function of Diameter?
Polymer Synthesis
CHEM 421
M
v
e
r
s
u
s
T
i
m
e
a
s
a
F
u
n
c
t
i
o
n
o
f
R
a
d
i
a
l
P
o
s
i
t
i
o
n
w
[Condensate]
2
0
0
0
0
1
8
0
0
0
S
H
E
L
L
1
——
Xn2
1
6
0
0
0
1
4
0
0
0
Mw(g/mol)
1
2
0
0
0
I
N
T
E
R
1
0
0
0
0
8
0
0
0
C
O
R
E
6
0
0
0
4
0
0
0
2
0
0
0
0
0
2
4
6
8
1
0
1
2
T
i
m
e
(
H
o
u
r
s
)
C
O
R
E
0
.
0
t
o
0
.
4
m
m
I
N
T
E
R
0
.
4
t
o
1
.
4
m
m
S
H
E
L
L
1
.
4
t
o
1
.
8
m
m
T
=
1
8
0
C
1
T
=
2
0
5
C
2
T
=
2
3
0
C
3
T
=
2
4
0
C
4
Macromolecules, 2000, 33, 40.
PC Beads=3.6 mm
N2 Flow=2 mL/min
Mw versus Time for the SSP of PC Powder
(20 um) Using N2 as the Sweep Fluid
Polymer Synthesis
CHEM 421
40000
Variable
Temperature
M olecular W eight (M w )
35000
30000
o
T
=
1
8
0
C
f
o
r
2
h
o
u
r
s
1
o
25000
T
=
2
0
5
C
f
o
r
2
h
o
u
r
s
2
o
T
=
2
3
0
C
f
o
r
2
h
o
u
r
s
3
20000
o
T
=
2
4
0
C
f
o
r
1
8
h
o
u
r
s
4
15000
10000
180 ºC
5000
0
5
10
15
20
Time (hours)
N2 flow rate 2 mL/min
PDI versus Time for the SSP of PC Beads (d =3.6 mm) and
PC powder (20 um) at a variable temperature program
Polymer Synthesis
CHEM 421
Polydispersity Index (M w /M n)
2.6
PDI of Bead
2.4
o
T
=
1
8
0
C
f
o
r
2
h
o
u
r
s
1
2.2
o
T
=
2
0
5
C
f
o
r
2
h
o
u
r
s
2
o
T
=
2
3
0
C
f
o
r
2
h
o
u
r
s
3
o
T
=
2
4
0
C
f
o
r
1
8
h
o
u
r
s
4
2.0
1.8
PDI of Powder
0
5
10
15
20
25
Time (hours)
Significant molecular weight distribution broadening observed in larger polymer particles.
Copolymers in Step Growth
Polymerizations
Polymer Synthesis
CHEM 421