step growth polymerization 534/step growth... · oligomer, and polymer are of equal reactivity at...
TRANSCRIPT
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