1

Step Growth Polymerization Chain Polymerization

1. Proceed by stepwise intermolecular

mechanism, which is the same for all stages

and is usually equilibrium controlled.

1. Proceed by a kinetic chain reaction

mechanism, involving initiation, propagation,

and termination.

2. Monomers react with each other or any size

oligomer or polymer; no initiator necessary.

2. Reactions are initiated by an

external source (catalyst, energy, etc.).

3. Functional groups, belonging to monomer,

oligomer, and polymer are of equal reactivity

at low conversion.

3. Monomers react only with active

center (radical, ion) of growing chain, not

each other.

4. High % conversion is necessary to produce

high MW polymers.

4. Polymers attain high MW values at low %

conversion.

5. Polymerization rate decreases over time 5. Polymerization rate initially increases and

then remains constant

2

Mn

% Conversion

Mn

% Conversion

Very high purity monomers (>99.9%)

Difunctionality (f = 2.00)

Proper stoichiometry (e.g. 1/1)

Very high conversions (e.g., p > 0.99)(p = the fractional extent of reaction)

No side reactions

Accessibility of mutually reacting groups

For any polymer to exhibit properties desirable for commercial use, the molecular weight should be greater than 10,000 g/mol.

Reaction conditions that encourage high molecular weight formation include…

3

Polymer Typical Applications

Polyamides (Section 6.7) textile fibers, insulation and piping

Polycarbonates (Section 6.6) CDs, optical lenses

Polyesters (Section 6.6) textile fibers, plastics, coatings

Polyaryleneethers and polyethers

(Section 6.12)

precursors for polyurethanes,

lubricants, engineering plastics

Polyetherkteones (Section 6.14) insulation for wires and cables,

applications requiring resistance to

radiation

Polyimides (Section 6.8) applications requiring thermo-

oxidative and hydrolytic stability,

adhesives, composites

Polyphenylene sulfides (Section 6.11) electrical applications

Polysulfones (Section 6.13) fuel cells, electrical and medical

equipment

Polyureas (Section 6.10) automotive parts, drug

encapsulation

Polyurethanes (Section 6.10) foams, biomedical applications

Direct Reaction

Fischer Esterifcation: acid catalyzed Nu Acylsubstitution reaction between a carboxylic acid and an alcohol.

Fischer Esterifcation: acid catalyzed Nu Acylsubstitution reaction between a carboxylic acid and an alcohol.

Transesterification

Acid catalyzed Nu Acyl Substitution

reaction between an ester and an alcohol.

Acid catalyzed Nu Acyl Substitution

reaction between an ester and an alcohol.

Acid Chlorides

Nucleophilic AcylSubstitution reaction with diols. Due to the high reactivity of the

acid chloride no catalyst is necessary.

Nucleophilic AcylSubstitution reaction with diols. Due to the high reactivity of the

acid chloride no catalyst is necessary.

Acidolysis

Nucleophilic AcylSubstitution reaction between a carboxylic

acid and an acetic ester.

Nucleophilic AcylSubstitution reaction between a carboxylic

acid and an acetic ester.

4

C

O

OH + HO C

O

O + H2O

Catalyzed by acid protonation of carboxyl carbonyl group

C

O

OH + H+

k1

k2

C

OH

OH

+

e.g.

Remove H2O to shift equilibrium to right (e.g. toward higher MW)

Can follow reaction by titrating for unreacted -COOH

Rp = -d COOH

dte.g.

CC

O

OCH3

O

H3CO + HO R OH

(excess)

200°C 1 atm.

CC

O

O

O

O RRHO OH + 2 CH3OH

280°C vacuum

CC

O

O

O

O RRO OHH

n

+ HO R OH

5

� More Reactive than Carboxyl

� Use with Less Reactive “Glycols”(Bisphenols) or Aromatic Diamines

� Use in Solution or Interfacially

Cl C

O

R C

O

Cln

H2N NH2 n HO OH

(or bis-phenolate)

N H

N H

C

O

R C

O

O O C

O

R C

OAROMATIC POLYAMIDE

AROMATIC POLYESTER

n

n

COC

CH3

CH3

O C

O

H3C

O

CH3 + C C

O

HO

O

OH

>250°C vacuum

(or isomers)

(melt polymerization)

CO

CH3

CH3

O C

O

C

O

n

+ 2 CH3COOH

6

Nematic

Cholesteric

Smectic

Pictorial representation of the three classes of liquid crystals

Molecules have no positional order but tend to point in the same direction.

Molecules are arranged in a parallel and lateral order.

Molecules are arranged parallel to each other but the directions vary from one layer to the next.

G. W. Calundann & M. Jaffe in

“Proc. Robert A. Welch Conf. on Chem.

Res.,” XXVI, Houston, 1982, 247-291.

W. J. Jackson, Jr., Macromolecules, 16,

1927 (1983).

G. W. Calundann & M. Jaffe in

“Proc. Robert A. Welch Conf. on Chem.

Res.,” XXVI, Houston, 1982, 247-291.

W. J. Jackson, Jr., Macromolecules, 16,

1927 (1983).

200˚C, Inert Gas

CLEAR MELT

O.5 - 3 HOURS, 250 - 280˚C

Acetic Acid Collected

TURBID FLUID DISPERSION

10 Minutes - 1 Hour

280 - 340˚C, Vacuum

OPALESCENT POLYMER MELT

EXTRUDE

C

O C

O

O

n

O

m

COOH

O C

O

CH3

+

HOOC

O C

O

CH3

7

Tensile Strength, ksi 18.5 Izod Impact, notched, ftlb/in 3.9Tensile Modulus, ksi 1,200 Limiting Oxygen Index 43Flexural Modulus, ksi 19.7 Heat Deflection Temp., (˚C) 343Flexural Strength, ksi 1,900 Density, g/cc 1.38

Tensile Strength, ksi 18.5 Izod Impact, notched, ftlb/in 3.9Tensile Modulus, ksi 1,200 Limiting Oxygen Index 43Flexural Modulus, ksi 19.7 Heat Deflection Temp., (˚C) 343Flexural Strength, ksi 1,900 Density, g/cc 1.38

CO2H

O C

O

CH3

+

CO2H

CO2H

+

H3C C

O

O O C

O

CH3

Heat, Vacuum

O C

O

C

O

O C

O

O

n

TLC ~ 420ÞC + CH3COOH

Nylon 6,6Poly(hexamethylene Adipamide)

Nylon 6,6Poly(hexamethylene Adipamide)

H2N (CH2)6 NH2 + C (CH2)4 C

O

OH

O

HO

H3N (CH2)6 NH3

+ +C (CH2)4 C

O

O

O

O_ _

(1:1 "nylon salt")

200°C, then 280°C

N H

(CH2)6 N H

C

O

(CH2)4 C

O

n

+ 2 (n-1) H2O

8

Tough engineering thermoplastics

Polyesters of “carbonic” acid, amorphous, Tg=150˚C

Mostly based on “Bisphenol-A”(4,4’-isopropylidene diphenol)

D. Freitag, U. Grigo, P. R. Muller, W. Nouvertne, ”Polycarbonates”, Encyclopedia of Polymer Science & Engineering (J. Kroschwitz, Ed.) 2nd Ed., Vol. II, 648-718 (1988).

OH

2 + H3C C

O

CH3

HO C

CH3

CH3

OH

H+

Rapid Reaction

Occurs at Interface

Need two Immiscible Solvents

1 : 1 Stoichiometry ensured at Interface

Reference:

“Interfacial Synthesis,” Vol. I & II, F. Millich and C. E.Carraher, Jr., Ed., Marcel- Dekker (1977).

Reference:

“Interfacial Synthesis,” Vol. I & II, F. Millich and C. E.Carraher, Jr., Ed., Marcel- Dekker (1977).

9

R4N Cl is thought to facilitate the transferof phenate from the aqueous to organic layer where itreacts with COCl2

CHO

CH3

CH3

OH

CH2Cl2, H2O, NaOH

R3N or R4N Cl+ _ Cl C

O

Cl

CO

CH3

CH3

O C

O

O

x

+ NaCl

Usually endcapped with an alkyl phenol for molecular weight

control and to gain melt stability.

HO C

CH3

CH3

OH + C

O

OO

300°C, vacuum LiOH catalyst

n n

C

CH3

CH3

O C

O

O

n

+ 2n

OH

10

R. N. Johnson, A. G. Farnham, R. A. Clendinning, W. F. Hale, & C. L. Merriam, J. Polym. Sci., A-1, 5, 2375 (1967).

A. G. Farnham, L. M. Robeson, and J. E. McGrath, J. Appl. Polym. Sci., Symp. 26, 373 (1975).

R. N. Johnson and A. G. Farnham, U. S. Patent 4,175,175 (1979) to Union Carbide Corp.

T. E. Atwood, P. C. Dawson, J. L. Freeman, L. R. J. Hoy, J. B. Rose, & P. A. Staniland, Polymer, 22, 1096 (1981).

R. Viswanathan, B. C. Johnson, and J. E. McGrath, Polymer, 25, 1927 (1984).

P. E. Hergenrother, B. J. Jensen, and S. J. Havens, Polymer, 29, 357 (1988).

J.E. McGrath, H. Ghassemi, D. Riley,Y.N. Liu, I. Y. Wan, A. Bhatnagar, J. Geibel, and T. Kashiwagi, "The Synthesis and Characterization of New Thermoplastic Fire Resistant Materials," Polymer Engr. Sci., Vol. 42 (1997).

T.E. Long, J.E. McGrath and S. Richard Turner, Polymer, Synthesis from Encyclopedia of Physical Science and Technology, Third Edition, Volume 12, Academic Press (2002).

X Y X + HO Ar OH

Activated

Halide

Bisphenol

Polar aprotic solvent

NaOH, K2CO3, etc.

"DRY"

X = Cl, F, etc.

Y =

Aromatic

Nucleophilic

Substitution

Y O Ar O

n

+ MX

O

C ,

O

S

O, P

O

Cl S

O

O

Cl Cl S

O

O

Cl Cl S

O

O

Cl

Cl S

O

O

ClCl S

O

O

Cl

+

O C

CH3

CH3

O S

O

O

ClNa

O C

CH3

CH3

ONa

Cl

Na + Cl S

O

O

Cl

O C

CH3

CH3

O S

O

O

ClNa + NaCl

11

W. Hill Jr. and D. G. Brady in Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 18, 3rd Ed., John Wiley and Sons Inc., New York, 1982, p. 793.

J. Geibel, Comprehensive Polymer Science, Pergamon Press, New York, Vol. 5, 1989, p. 543.

D. R. Fahey and C. E. Ash, Macromolecules, 24, 4242 (1991).

Cl ClNa2S + Cl SNa2S + Cl

NMP

260ÞC, Pressure

S

n

+ 2 NaCl

RYTON

Linear PPS: T g = 85ÞC, Tm = 285ÞC, Mn = ~18000 g/mole

PPS300 - 370ÞC

Air

Crosslinked Polymer

Use Temperature > 232ÞC

T. E. Atwood, P. C. Dawson, J. L. Freeman, L. R. J. Roy, J. B. Roseand P. A. Staniland, Polym. Prepr. 20(1), 191 (1979); Polymer, 22, 1096 (1981).T. E. Atwood, P. C. Dawson, J. L. Freeman, L. R. J. Roy, J. B. Rose

and P. A. Staniland, Polym. Prepr. 20(1), 191 (1979); Polymer, 22, 1096 (1981).

HO OH + F C

O

F

Diphenylsulfone

K2CO3

300ÞC, 2-3 hours

O O C

O

n

PEEK

Tg = 144ÞC, Tm = 340ÞC Up to ~ 48% crystallinity

Available from Victrex, PLC

12

Excellent engineering polymers

Not processable unless carefully designed

Methods to improve processability and solubility:

Incorporate flexible bridging units

Incorporate monomers with bulky side groups

Incorporate monomers containing aromatic meta linkages

Dilute concentration of imide linkages (polyimide copolymers)

Control molecular weight and endcap with non-functional groups

solution Imidization

O S CO SO2 C(CF3)2 P

O

NH2 O NH2 O O

O

O

O

O

O NH NH

O

O

O

OHO OH

n

O N N

O

O

O

On

+ H2O

13

T. Takekoshi, Adv. Polym. Sci., 94, 1-25 (1990).

O

O

O

O C

CH3

CH3

OO

O

O

+

H2N NH2

o-Dichlorobenzene

O C

CH3

CH3

ON

O

O

N

O

O

n

180°C

In general, isocyanate groups can react with any group containing active hydrogens.

R N C O + R1 OH R N

H

C

O

O R1

R N C O + R2 NH2 R N

H

C

O

N R2

H

14

R N C O + H O

R N

H

C

O

OH

-CO2

H

R NH2 + R N C O

R N

H

C

O

N

H

R

25°C 80°CNH2

CH3 (CH2)3 OH

H2O

OH

NH C

O

NH

CH3 (CH2)2 COOH

10-20 --

2-4 30

0.4 6

0.01 --

-- 2

-- 2

R N C O + R3 COOH

R N

H

C

O

O C R3

O

-CO2

R N

H

C

O

R3

15

R N C O + R NH C

O

O R'heat

R N C

O

O R'

C O

NH

R

R N C O + R NH C

O

NH R'heat

R N C

O

NH

R'

C O

NH

R

CH3

NCO

NCO

2,4-

CH3

NCOOCN

2,6-

OCN CH2 NCO

OCN CH2 NCO OCN (CH2)6 NCO

H3C

H3C

H3C CH2NCO

NCO

•“Isophoronediisocyanate”

•3-isocyanate methyl-3,5,5-trimethyl

cyclohexylisocyanate

CH2

NCO NCO

CH2

n

NCO

16

HO R O C

O

(CH2)x C

O

O R OHn

HO CH2 CH2 CH2 CH2 O Hn

HO CH2 CH2 O Hn

HO CH CH2 O Hn

CH3

HO CH2 Si

CH3

CH3

O Si

CH3

CH3

CH2 OH

n

xx

(CH2)5

C

O

O

+

δ-

δ+

HO (CH2)4 OH

Sn(Octoate)2

O (CH2)4 O CC (CH2)5(CH2)5

O O

OO HHx x

To prepare difunctional oligomers,

use HO-(CH2)4-O- +M as an initiator.

“PCL”

O (CH2)4 O CC (CH2)5(CH2)5

O O

OO HHx

x

OCN CH2 NCO1.

2. HO (CH2)4 OH

PCL O C N H

O

MDIH N C

O

O (CH2)4 O C N H

O

MDI

17

HO CH2 OH4

HO CH2 OH6

CH2

CH

CH2

OH

OH

OH

H2N CH2CH2 NH2

H2N (CH2)6 NH2

CH3

NH2

CH2CH3

NH2

H3CH2C

18

HO OH

+

OCN R NCO

R' R'OCN NCO

+

OCN R NCO

+

HO R1 OH

19

CH2OCN NCO + HO (CH2)4 O Hx

Mn - 1000-2000 g/mole

60-80°C

O (CH2)4 O C

O

NHC

O

HNCH2 CH2OCN NCO CH2OCN NCO+x

25°CDMAc

H2N CH2CH2 NH2

(MDI)

MDI O (CH2)4 O C

O

NHC

O

HNx

MDI C

O

HN NH CH2CH2 NH C

O

NH

y z

Soft and hard segments are microphase separatedStrong hydrogen bonding in the urea phase can provide strong elastomers with low

moduli

20

IsocyanateTerminatedPrepolymer

+

CH3

NCO

NCO

CH

CH2 O

CH2

O

O

CH2

CH2

CH2

CH

CH

CH

O

O

O

CH3

CH3

CH3

H

H

H

x

x

x

excess

C

O

NH

NCO

CH3

CH

CH2 O

CH2

O

O

CH2

CH2

CH2

CH

CH

CH

O

O

O

CH3

CH3

CH3

x

x

x

C

O

NH

NCO

CH3

C

O

NH

NCO

CH3

H2O

O C

O

NH

NH

CH3 OC

O

NH

HN

H3C

C

O

R

H N C

O

OCH3O

HN C

O

OCH3O

HN C

O

OCH3O

+ H2N NH2

R

H N C

O

HN C

O

HN C

O

R

H N

NH

NHC

O

C

O

C

O

N H

N H

N H

N H

+ OCH3HO

Component 1

Component 2

“Blocking” the isocyanate with a phenol provides “working time.”

21

HN C

O

Oalkyl alkyl

HN C

O

Oaryl alkyl

HN C

O

Oalkyl aryl

HN C

O

Oaryl aryl

250°C

200°C

180°C

120°C

NH C

O

ORheat

R N C O +

OH

C NOH + R-NCO

R'2NH-70°C-80-1100 min.

C N O C

O

NH R R'2N C

O

NH R

NH C

O

ORheat

R N C O +

OH

NH

CO

+ RNCO N

CO

C NH

O

R-70°C

-160°C

22

Component 1 Wt. %

Blocked Prepolymer 33%

(≈6,000 g/mol Mn polypropylene oxide triol reacted with

a diisocyanate blocked with nonylphenol)

Oils and Plasticizers 11%

CaCO3 20%

Pigments, UV stabilizer, mineral spirits 4%

Component 2

Plasticizers 19%

Diamine Crosslinking Agents 11%

SiO2 2%

CH3-Si-(OCH3)3, Urethane Catalyst, pigments 4%

100%

HO OH + HOH2C C

CH3

CH2OH

COOH

+ OCN R NCOexcess

OH2C C

CH3

CH2O

COOH

C CHN

O O

NH RRHN NHC C

O

O

O

OO OC C

O

HN

O

NHR ROCN NCO

triethylamine

OH2C C

CH3

CH2O

C

C CHN

O O

NH RRHN NHC C

O

O

O

OO OC C

O

HN

O

NHR ROCN NCO

O

O _

N Et

Et

EtH

+

waterH2N R' NH2

OH2C C

CH3

CH2O

C

C CHN

O O

NH RRHN NHC C

O

O

O

OO OC C

O

HN

O

NHR RHN NH

O

O _

N Et

Et

EtH

+

H2N CH2CH2 NH

(CH2)

SO3Na2-3

HO CH2CH2 CH CH2OH

SO3Na

HOH2C C

CH3

CH2OH

COOH

H2N CH2CH2 NH

(CH2)

COOH2-3

H2N (CH2)4 CH NH2

COOH

N

CH3

CH2CH2OHHOH2CH2C

HOH2C N CH2OH

CH2CH3

CH2

N

H3C CH3

B. K. Kim, “Aqueous polyurethane dispersions,” Colloid Polym. Sci.,

274:599-611 (1996).

23

original # of molecules [M o]XN = =

# of molecules at time t [M ]

Define “p” as the fraction of molecules whichhave reacted at time “t.”

[M ] = [M o] - p[M o] = [M o](1 - p)

1XN =

(1 - p)

% Conversion XN

50 2

75 4

90 10

95 20

98 50

99 100

99.9 1,000

99.99 10,000

XN: average number of structural units per polymer chain

DPN: average number of repeating units per polymer chain

XN is not necessarily equal to DPN.

Example using two different polyesters…

Polyester A

• Synthesized via ring opening

polymerization

• Originated from ONE difunctional cyclic

monomer

•Only has one structural unit.

∴DPN = 100, XN = 100

Polyester B

• Synthesized via step growth

polymerization

• Originated from TWO difunctional

monomers

•Has two structural units.

∴DPN = 100, XN = 200

24

Stoichiometric imbalance: One of the monomers is present in slight excess.

Addition of mono-functional monomer

A-A + B-B POLYMER(bifunctional monomers)

Let the number of “A” functional groups = NA

Let the number of “B” functional groups = NB

NA and NB equal twice the number of A-A and B-Bmolecules and the total # of molecules is (NA + NB)/2

Then stoichiometric imbalance is: (NB is larger by convention)r =NA

NB

Fraction of unreacted A groups:

Fraction of unreacted B groups:

Number of unreacted A groups:

Number of unreacted B groups:

1 - p

1 - rp

NAo(1 – p)

NBo(1 – rp)

25

Total number of polymer chain ends:

Total number of polymer molecules:

Total number of polymer molecules initially:

Since,

XN =

When the polymerization is 100% complete, XN =

NAo(1 – p) + NBo(1 – rp)

( )

2r

1 + 1 N =

2

N + N AoBoAo

( ) ( )

2

rp - 1N + p - 1NBoAo

( )( ) ( )[ ] 2rp -r 1

r 1

2 rp - 1N p - 1N

2r

1 1N

BoAo

Ao

+

+=

+

+

r - 1

r 1 +

When the monomers are in stoichiometric amounts, XN = p - 1

1

o

nN

M

M DP ≈

Polyester A Polyester B

where Mo is the molecular weight of the repeat unit in the Polyester A or the mean molecular weight of monomers in Polyester B and Meg is the moelcular weight of the endgroups.

Since the molecular weight of the endgroups are small relative to the polymer backbone, a best approximation of the molecular weight is…

Rearranging to solve for XN

ego

egon n M p) - (1

M M MX M +=+•=

p) - (1

M MX M o

on n ≈≈ •

o

nN

M

M X ≈ DPN also equals the same

thing but remember that the

Mo is MW of the repeat unit.

MW of repeat unit in

Polyester A

Mean MW of monomers in

Polyester B

26

Calculate the feed ratio of hexamethylene diamine and adipic acid that should be employed to obtain a polyamide of approximately 10 K molecular weight at 99% conversion. What is the identity of the endgroups of this product?

Repeating unit:

Formula weight of repeat unit = 226 g/mol

Mo = 0.5 226 g/mol = 113 g/mol

XN = 10,000 g /mol 113 g/mol = 88.5

740.99 r

88.5 2r(0.99) -r 1

r 1 XN

=

=+

+=

r =NA

NB + 2NB'

The previous equation for XN still applies!

p2r-r 1

r 1 Xn

+

+=

27

A heat resistant aromatic polyamide of MN = 24,100 yielded the following composition on hydrolysis: 39.3 by weight m-aminoaniline, 59.8% terephthalic acid, and 0.9% benzoic acid. (a) Write the formula for this polymer. (b) Calculate the degree of polymerization and extent of reaction in polymerization. (c) Calculate the effect on the degree of polymerization if the polymerization had been carried out with twice the amount of benzoic acid.

m-aniline

FW = 108 g/mol

terephthalic acid

FW = 166 g/mol

benzoic acid

FW = 122 g/mol

39.3 g 108 g/mol = 0.3639 mol

59.8 g 166 g/mol = 0.3602 mol

0.9 g 122 g/mol = 0.0074 mol

m-aniline

FW = 108 g/mol

terephthalic acid

FW = 166 g/mol

benzoic acid

FW = 122 g/mol

39.3 g 108 g/mol = 0.3639 mol

2 amino groups 0.3639 mol = 0.7278 mol

59.8 g 166 g/mol = 0.3602 mol

2 COOH groups × 0.3639 mol = 0.7204 mol

0.9 g 122 g/mol = 0.0074 mol

1 COOH group × 0.0074 mol = 0.0074 mol

However, these moles are in terms of reactants and we are interested in moles of functional groups!

NA = 0.7278 mol amino groups in m-aniline

NB = 0.7204 mol COOH groups in terephthalic acid

NB’= 0.0074 mol COOH groups in benzoic acid