Transcript P020111127522715224692

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