This document summarizes different polymerization techniques: 1. Bulk, solution, suspension, emulsion, and interfacial polymerization techniques are described. Bulk polymerization uses liquid monomer while others use solvent/water. 2. Solution polymerization uses an inert solvent to help control heat transfer. Suspension polymerization forms polymer beads in water stabilized by suspending agents. Emulsion polymerization forms very small polymer particles in water using an emulsifier. 3. Interfacial polymerization produces polymer at the interface of two immiscible liquids such as water and a nonpolar solvent, allowing reaction at room temperature without high pressures.

1. 1
Chapter 5:Polymerization Techniques
1. Bulk polymerization
2. Solution polymerization
3. Suspension polymerization
4. Emulsion polymerization
5. Interfacial condensation polymerization
6. Etc.

2. 2
1. Bulk Polymerization :
- Liquid monomer
- Initiator
- Inhibitors
- Chain transfer agents
Homogeneous : polymer remains dissolved in monomers.
Ex. PMMA
Heterogeneous : aka. Precipitation polymerization
polymer is insoluble in its monomers.
Ex. Polyacrylonitrile, PVC
Problem : heat transfer not good
Make objects with a desirable shape by polymerization in a mold.
In the reactor:-

3. 3
I
I
I
I
Initiator
I
I
I
I
Initiator
Monomer
Model of Batch Polymerization

4. 4
Pros & Cons of Bulk Polymerization
Advantage Disadvantage
- Obtain purest possible polymer
- Conveniently cast to shape
- Obtain highest polymer yield per
reactor volume
- Difficult to control
- Reaction has to be run slowly
- Cannot get high rate and high
MW at the same time
- Difficult to remove last traces
of unreacted monomer

5. 5

6. 6
Ex. 1 The maximum possible temperature
rise in a polymerizing batch may be
calculated by assuming that no heat is
transferred from the system. Estimate the
adiabatic temperature rise for the bulk
polymerization of styrene, ∆Hp = -16.4
kcal/mol, molecular weight = 104
• Solution ∆Hp for polymerization of
styrene = 16,400 cal/mol (assuming
complete conversion)  meaning that
polymerization of 1 mol styrene release
heat in the amount of 16,400 calories.
•In the absense of heat transfer, all this
energy heats up the reaction mass.
• To a reasonable approximation, the heat
max
1
16,400 315 (!)
104 0.5
o
ocal mol g C
T x x C
mol g cal
∆ = ≈
(Note that- Boiling point of styrene = 146 o
C)

7. 7
Solution Polymerization : Monomer dissolved into inert-
solvent / inhibitor
- Monomer
- Initiator
- CTA
- Inert solvent
Use for :
Solvent helps controlling heat transfer from reaction.
- Thermosetting condensation polymer (stop before gel
- Ionic polymerization
- Ziegler-Natta solution process
2. Solution Polymerization

8. 8
Model of Solution Polymerization
I
I
I
I
I
Monomer
Solvent
Initiator

9. 9
The effect of solvent solubility on
the molecular weight of
polyurethane produced by solution
method
Solvent Viscosity of
polymer
solution
Precipitation of
polymer out of
the solution
Xylene
Chlorobenz
ene
Nitrobenze
ne
Dimethyl
sulfoxide
0.06
0.17
0.36
0.69
Precipitate immediately
Precipitate immediately
Precipitate within 0.5 hr.
Polymer remain dissolved in
solution
Viscosity of polymer ∝ MWpolymer
∴ High viscosity = high molecular weight !

10. 10
- Rate ∝[M] → reduce rate,
chain length xn
- Solvent waste
- Need solvent separation &
recovery
- Have traces of solvent, monomer
- Lower yield
-Solvent may not be really inert
(May interfere w/ rxn.-act as CTA)
Advantage Disadvantage
solvent
- Reduces the tendency toward
autoacceleration
- Increases heat capacity/heat-
transfer
- Reduces viscosity
- Minimize runaway reaction
Pros & Cons of Solution Polymerization

11. 11
Ref: S.L. Rosen, John Wiley & Sons 1993

12. 12
Ex. 2 Estimate the adiabatic temperature rise for the
polymerization of a 20% (by weight) solution of styrene
in an inert organic solvent
Solution In 100 g of the reaction mass, there are 20 g of styrene,
so the energy liberated on its complete conversion to polymer is
• Temperature rise is calculated from Q =
mc ∆T
Therefore, the adiabatic temperature rise is then
max
( ) 1
(3150 ) 63
(0.5 ) (100 )
o
og C
T cal C
cal g
∆ = ≈
(1 ) (16400 )
(20 ) 3150
(104 ) ( )
mol cal
g cal
g mol
=

13. 13
Ref: S.L. Rosen, John Wiley & Sons 1993

14. 14
Ref: S.L. Rosen, John Wiley & Sons 1993

15. 15
3. Suspension Polymerization :
Monomer into water,
suspending agents (Ex.Ionic detergent, barium sulfate)
- Ex. Polyvinyl alcohol
- Beads of polymer ( 10-1000 µm)
Water
monomer
Water
(Hydrophilic)
Initiator
+
(Hydrophobic)
Suspending agent
Model of suspension polymerization

16. 16
Typical Composition:
Monomer (hydrophobic)
Initiator (dissolved in monomer)
Monomer phase
Chain-transfer agent (dissolved in monomer)
Water – suspending medium
Protective Colloid
Suspending agent
Insoluble inorganic salt

17. 17
Pros & Cons of Suspension Polymerization
Advantage
1. Easy heat removal
and control
2. Obtain polymer in a
directly useful from
Disadvantage
1. Low yield / reactor volume
2. Traces of suspending agent
on particle surfaces
3. Cannot run continuously
4. Cannot be used for
-condensation polymers
-ionic or Ziegler-Natta
polymerization

18. 18
Ref: S.L. Rosen, John Wiley & Sons 1993

19. 19
Emulsion Polymerization : Use emulsifier / soap
monomer
Water
Soap
Initiator
(Hydrophilic)
-Reaction occurs in water phase until polymer gets very
hydrophobic and then dissolve back in the monomer reg
Ex. Latex - very very small particle stable in solution
- particle size << 1 µm
- can generate very high MW. polymer
4. Emulsion Polymerization

20. 20
Emulsion Polymerization (cont.):
Typical ingredient
100 part (by wt.) monomer (water insoluble)
180 part water
2-5 parts acid soap
0.1-0.5 part water-soluble initiator
0-1 part CTA (monomer soluble)

21. 21
-growing polymer particle
-Monomers inside the micelle decrease
Unreacted monomers in other
micelles and in droplets diffuse
through water to the growing particles
Reaction terminates when 2nd
radical gets in
reaction starts again for the 2nd
chain when 3rd
particle gets in.
Steps in Emulsion Polymeriztion
Water-soluble initiator
Polymer born in water
Monomer swollen micelle
Polymer moves to micelle

22. 22Ref: S.L. Rosen, John Wiley & Sons 1993

23. 23
Ref: S.L. Rosen, John Wiley & Sons 1993

24. 24
Interfacial Polycondensation of Nylon 6/11
water
CCl4
Advantage :
( ) 2622 NHCHNH
( ) ClCCHCCl −− 82
o
=
o
=
Monomer1 : Hexamethlyene diamine
Monomer2 : Sebacoyl chloride
( ) ( ) ( ) ( )[ ] HClCCHCNCHNClCCHCClNHCHNH +−→−−+ 8262822622
o
=
o
=
o
=
o
=
H
=
H
=
Polymer formed at interface
( ) 2622 NHCHNH
( ) ClCCHCCl −− 82
o
=
o
=
Commercial scale → easier to stir the phases together
- Reaction → rapid at room temperature
(no need for high T., vacuum P.)
5. Interfacial Polycondensation

25. 25
การดึงเส้นใยไนลอนจากผิวสัมผัสของ
สารละลาย
Experiment on
Interfacial Polycondensation of Nylon 6/11

26. 26
Pros Cons
Bulk - easy
- No contamination
- Difficult to control temp. and heat transfer
- High viscosity
Solution -good heat transfer
-easy to control reaction temp.
-low viscosity
-polymer produced may be used directly
in the solution form
- Need to use solvent –adding cost
-Difficult to eliminate solvent entirely
-Solvents sometimes act as chain transfer agent 
leading to lower MW polymer
Suspension - Good heat transfer
- easy to control reaction temp.
- low viscosity
- polymer produced may be used directly
as polymeric suspension
-Need extra process in washing out suspending
agent/contaminants and drying the polymer beads
-Polymer beads may stick together and maybe
contaminated with suspending agent
-Good only for addition polymerization using
hydrophobic free radical initiator.
Emulsion -- Good heat transfer
- easy to control reaction temp.
- low viscosity
- polymer produced may be used directly
as polymer latex
-Need extra process in washing out emulsifier/
contaminants and drying
-Good only for addition polymerization using
hydrophilic initiator.
Interfacial -Reaction is fast at room temp. and
pressure.  No need for high temp. like
in normal polycondensation.
-Can produce polymer in fiber form
- Good heat transfer
- low viscosity
-Limited to polycondensation where the two reactants
are insoluble in each other ex. Acid chloride (quite
expensive)
- Need extra process in recovering solvent and excess
reactants
Pros & Cons of some polymerization techniques

27. 27
conditions บัลค์
(bulk)
สารละลาย
(solution)
ระหว่างผิว
(interfacial)
Temp สูง จำากัดอยู่ที่จุดหลอมเหลวและ
จุดเดือดของตัวทำาละลายโดย
ทั่วไปทำาที่อุณหภูมิห้อง
Heat stabilization จำาเป็น ไม่จำาเป็น ไม่จำาเป็น
Kinetic of
Reaction
สมดุล เป็นขั้น สมดุล เป็นขั้น บ่อยครั้งไม่
สมดุล คล้าย
ปฏิกิริยาลูกโซ๋
Reaction
time
1 ชั่วโมงถึง
หลายวัน
หลายนาทีถึง
1ชั่วโมง
หลายนาทีถึง
1ชั่วโมง
Productivit
y
สูง ตำ่าถึงสูง ตำ่าถึงสูง
Equality of
reactants
จำาเป็น ไม่ค่อยจำาเป็น ไม่จำาเป็น
Purity of
reactants
จำาเป็น ไม่จำาเป็น ไม่จำาเป็น
Equipment พิเศษ ระบบปิด ง่ายๆ ระบบ ง่ายๆ ระบบ
Comparing different techniques for Polycondensation

28. 28
6. Gas-Phase Olefin Polymerization :
- Use Zieler-Natta catalyst
- Moderate P (7-20 atm)
- Low temperature ( < 100 o
C)
- Use fluidized bed reactor
Good Point :
- No solvent
- Monomer separation is easy
- Low capital + operating cost

29. 29
Ref: S.L. Rosen, John Wiley & Sons 1993

30. 30Ref: S.L. Rosen, John Wiley & Sons 1993