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Polymer SynthesisCHEM 421
• Odian Book
Chapter 7
Polymer SynthesisCHEM 421
Ring-opening Polymerization (I)
Polymer SynthesisCHEM 421
Ring-opening Polymerization
• Anionic
• Cationic
• Ring Opening Metathesis Polymerization (ROMP)
Polymer SynthesisCHEM 421
Commercially Important ROP
H2C
O
CH2
O
CH2
O
CH2 O
n
O
H2C CH2
Tg Tm -82 181
cationic
cationicanionic
-41 66
cationic
PTMO-84 (57)
CH2 CH2 O
n
O
CH2 CH2 OCH2CH2
n
Polymer SynthesisCHEM 421
Commercially Important ROP
CH2
CH2
CO
H2C
H2C
H2C
O
CH2 CH2 C OCH2CH2 CH2
O
n
cationicanionic
Tg Tm
-60 67Poly(caprolactone)
cationicanionic Poly(caprolactam)
53 230
cationicanionic D4, D3, Di
-124 -50
CH2
CH2
CN
H2C
H2C
H2C
OH
CH2 CH2 N CCH2CH2 CH2
H
O n
O
Si
O Si
O
Si
OSi
Me
Me
Me
Me Me
Me
Me
Me Si O
Me
Me
n
Polymer SynthesisCHEM 421
X = ; ; ; ;
• Heteroatom provide site for coordination w/ appropriate anionic, cationic or coordinating initiator (kinetic accessibility)
Ring-opening Polymerization
S O O C
O
cyclic linear
kP
kdp
Keq= kP / kdp = 1 / [Monomer]e
G= - R T ln Keq= R T ln [M]e
H
N C
O
HC CH
CH2 Xi n* CH2
i
X
Polymer SynthesisCHEM 421
Ring Strain of Cycloalkanes
CYCLOALKANE (kcal/mole) (kJ/mole)
Cyclopropane 27.6 115Cyclobutane 26.4 110Cyclopentane 6.5 27Cyclohexane 0.0 0Cycloheptane 6.4 27Cyclooctane 10.0 42Cyclononane 12.9 54Cyclodecane 12.0 50Cyclopentadecane 1.5 6
Polymer SynthesisCHEM 421
Ring Strain
Ring Size 3,4
5,6,7
8
Polymer SynthesisCHEM 421
Free Energy G= H -TS
# atoms in Ring
H S G [M]eext. of pzn @
Equil
3,4
Polymer SynthesisCHEM 421
Ring Opening Pzn
Types of Ring Compound
Cycloalkenes
Cyclic Ethers
Caprolactam
Cyclic Siloxanes
Mx detected up to x =
14
9
5
400
Propagating Species
Metal Carbene
THF w/ CF3SO3H
Anionic
Anionic KOH
1) Series of Ring Sizes2) Concentration Distribution3) % Cyclics w/ decreasing [M]
Polymer SynthesisCHEM 421
Cyclic Ethers
O
O
O
O OO
tertrahydropyrandioxane
polymerization
unreactive
difficult(substituents usually will prevent it)
Polymer SynthesisCHEM 421
Cyclic Ethers
A MO
A CH2 CH2 O M
OBuLi
1) Ethylene Oxide
RO
(DMSO)
PEO
Living Polymerization
S
CH3
O
H3C
A = HO
R
Polymer SynthesisCHEM 421
Cyclic Ethers
O
CH3
O
CH3
H
2) Propylene Oxide
Monomer is usually a racemic mixture of enantiomers
O
H
CH3
Polymer SynthesisCHEM 421
Poly(propylene oxide)O
CH3
KOH
HO CH2 CH
CH3
O K
Initiation
Propagation
Terminationacidify
1o & 2o
Soft segments in polyurethane
Avg Mn limited to ~5,000 g/mol
Limited by CT to monomer
HO CH2 CH
CH3
O H
Polymer SynthesisCHEM 421
Chain Transfer to Monomer
CH2 CH
CH3
O Na O
H3C
CH2 CH
CH3
OHO
H2CNa
H2C CH CH2 O Na
200 oC Proton abstraction
fast
allylic structure
Allylic end group
f = 1
Leads to imperfect networkswith “dangling ends”
O
H2C CH CH2 O CH2 CH
CH3
O H
Polymer SynthesisCHEM 421
Functionality Control
CH2
CH
CH2
OH
OH
O
CH
CH3
CH2HO O H
CH2
CH
CH2
OH
OH
OH
Polyhydroxy compounds CTA
f = 3
(CTA)fAVG ~ 2.5 networks
CH2 CH
CH3
OCH
CH3
CH2HO O K
