10.1 introduction chapter 10. step-reaction and ring-opening polymerization 10.2 step-reaction...
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10.1 Introduction
Chapter 10. Step-Reaction and Ring-Opening Polymerization
10.2 Step-reaction polymerization---Kinetics
10. 3 Stoichiometric Imbalance.
10. 4 Molecular weight Distribution
10. 5 Network Step Polymerization
10. 6 Step-Reaction Copolymerization.
10. 7 Step polymerization Techniques.
10. 8 Dendritic Polymers.
10. 9 Ring-opening polymerization. POLYMER CHEMISTRY
10.1 Introduction
A. Characteristics of step-reaction polymers. a. Polymers containing functional group in backbones b. Synthesizing dendritic polymers
B. Examples of commercialized step-reaction polymers. Note) Table 10.1
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10.2 Step-reaction polymerization---Kinetics
A. Types of monomer
a. AB type
HO COOH
b. AA and BB type
HOOC COOH HOCH2CH2OH
c. Three functional group for crosslinked polymers
HOCH2CHCH2OH
OH POLYMER CHEMISTRY
B. Condensation of difunctional monomers. a.
b.
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10.2 Step-reaction polymerization---Kinetics
C. Kinetics of step-polymerization. a. Assumption : Independence on chain length. b. Rate equation and
A + B Polymerscondensation
]][[][
BAkdt
Ad ][][ BA
ktAA o
][
1
][1
1][ ktADP o
Integration
Combining Carothers equation.
][][
Akdt
Ad 2
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c. Polyesterification : self-acid catalyzed reaction.
Integration
Combining Carothers equation.
ktAA o
2][
1
][
122
3][][
Addt
Ad
1][2 22 oAktDP
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C. Kinetics of step-polymerization.
10. 3 Stoichiometric Imbalance.
A. Chain length control. a. High molecular weight. b. Oligomers for free polymer. 1) Epoxy oligomer. 2) Unsaturated polyester. 3) Polyamide
B. Preparing methods for oligomers.
a. Quenching : unsaturated polyester.
b. Stoichiometric imbalance : epoxy resin.
c. Addition of monofunctional reactant. POLYMER CHEMISTRY
C. Modification of Carothers equation.
a. parameter r : stoichiometric imbalance.
: initial unreacted groups.
: unreacted group.
: Carothers equation.
r
rDP
1
11p
pDP
1
11rrpr
rDP
11
1
BNAN
r
NprNpN
oAo
BB )1()1(
oAA NpN )1(
oB
oA
N
Nr
if , then
if , then
,
oBN
oAN ,
10. 3 Stoichiometric Imbalance.
10. 4 Molecular weight Distribution
A. Conversion and Nx
)1(1 pNpN xx
o
o
N
NNp
B. Conversion and Wx
C. Polydispersity index
o
x
oo
oxx N
xN
MN
MxNW 12)1( x
x ppxW
p
MM o
n
1 p
pMM o
w
1
)1(
pM
MPI
n
w 1
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10. 4 Molecular weight Distribution
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A. Greater than two functionality polymers. a. Alkyd-type polyester :
b. Phenol-formaldehyde resin :
c. Melamine-formaldehyde resin :
HOCH2CHCH2OH
OH
OH
N
N
N
NH2
H2N NH2
10. 5 Network Step Polymerization
B. Gelatin : High conversion of greater than two functionality.
a. Gel point : onset of gelatin.
sudden increase in viscosity.
change from liquid to gel.
bubbles no longer rising.
impossible stirring.
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10. 5 Network Step Polymerization
C. Gel point conversion.
: critical reaction conversion. : average functionality.
rrpc
[
1
avf
cp
avc fp
2
o
o
N
NNp
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10. 5 Network Step Polymerization
4.25
)32()23(
avf
D. Examples of gel point conversion.
O
O
O
HOCH2CHCH2OH
OH
3mol of 1 2mol of 4
Gel point conversion : 77% (Experiment) 83% (Calculate)
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10. 5 Network Step Polymerization
10. 6 Step-Reaction Copolymerization.
A. Random copolymers.
1:1:2 mixture of terephthalic acid, isophtahlic acid, ethylene glycol.
B. Alternating copolymers. a.
b. Randomization : Trans-esterification. POLYMER CHEMISTRY
C. Block copolymer. Telechelic polymers. a.
b.
c.
10. 6 Step-Reaction Copolymerization.
10. 7 Step polymerization Techniques.
A. Significant difference between vinyl and nonvinyl polymerization. a. Vinyl polymerization : Large enthalpy factor. Exotherm reaction.
b. Nonvinyl polymerization : High activation energy. Low exotherm.
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2) Disadvantage : Solvent removing process.
B. Step polymerization techniques. a. Bulk polymerization. 1) Advantage : Free of contaminants. 2) Disadvantage : High viscosity. b. Solvent polymerization. 1) Advantage : Lower viscosity. Removing by products by azeotropic distillation.
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10. 7 Step polymerization Techniques.
c. Interfacial polymerization. Polymerization at the interface between immiscible two solvents. Water : Diamine. Organic solvent : Diacid chloride. 1) Low temperature polymerization. 2) Rapid polymerization. 3) Higher molecular weight. 4) Not necessary stoichiometric balance. ․Schotten-Baumann reaction.
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10. 7 Step polymerization Techniques.
d. Phase-transfer catalysis polymerization(PTC). 1) Phase-transfer catalyst : Benzyltriethylammonium chloride. C6H5CH2N+(C2H5)3Cl- 2) Mechanism : Dissolve in water and make ion pair. Move to organic layer.
10. 7 Step polymerization Techniques.
10. 8 Dendritic Polymers.
A. Terminology (Since 1980s) Dendrimer : Dendron = like tree. Starburst polymer.
B. Commercial application.
a. Drug delivery system : Controlled release of agricultural chemicals b. Molecular sensors. c. Rheology modifiers.
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C. Characteristics feature.
a. Structure : Three component parts.
1) Core. 2) Interior dendritic structure. 3) Exterior surface. b. Easy control macromolecular dimension by a repetitive sequence of step. c. More soluble than linear polymer : high surface functionality. d. Low viscosity : No entanglement. e. Supramolecular assembly : Guest molecules among the interior branches
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10. 8 Dendritic Polymers.
D. Synthsis of dendrimer.
a. Divergent : 1) Polyamidamine (PAMAM).
10. 8 Dendritic Polymers.
2)
b. Convergent.
10. 8 Dendritic Polymers.
E. Hyperbranched polymer. a. Types of monomer : AxB ( x > 1).
F. Nanostructure of dendrimer. a. Molecules dimension : 1-100nm. b. Molecules devices : Mimicking nanoscopic biomolecules.
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10. 8 Dendritic Polymers.
10. 9 Ring-opening polymerization.
A. Commercially important ring-opening polymers. Ring-opening polymers : Condensation polymers. Not polycondensation reaction. No byproduct.
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B. Mechanism of ring-opening polymerization. a. Initiator : Ionic or coordination species (X*). 1)
2)
b. Initiator : XY. 1)
C. Ring strain : Possibility of ring-opening polymerization. 3 > 4 > 8 > 7 > 5 > 6
D. Ring-opening block copolymerization. AB, [AB] , ABA Block copolymer.
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10. 9 Ring-opening polymerization.