APS Dallas
Transcript of APS Dallas
Supramolecular Arrest and Activation
for the Network formation of Acid
Catalyzed Epoxy Polymerization
Matthew J. Spencer, James V. Crivello, Chang Y. RyuDepartment of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute
Motivation
• Epoxy network formation triggered by
– Hardening Agent
– Acid generation with UV
• Develop a one component system that cures
quickly at low temperatures yet has RT stability
– Supramolecular chemistry
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
System
• Super Acid Generation by Onium Salts
– Photo-initiation
– Redox-initiation
• Polymerizations monitored by
– Optical Pyrometry
– Rheology
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
Ar2I+ MtXn-
hAr2I+ MtXn
-* ArI+ MtXn
- + Ar
Ar+ MtXn- + ArI
. .HMtXn
k1
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0 20 40 60 80 100 120 140 160
Tem
pera
ture
(oC
)
Irradiation Time (s)
O
O
OO
1M%
O
O
O
O
O O
O
O
O
O
O
O
OO
O
2620 mJ/cm2
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
3,4-epoxycyclohexylmethyl 3’,4’-epoxycyclohexane carboxylate
Ring Opening Polymerizations
• Highly exothermic due to ring strain
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
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0 20 40 60 80 100
Time (s)
Tem
per
atu
re (
oC
)
OO
O
OO
2700 mJ/cm2
I+ O n-C11H23
SbF6-
Supramolecular Arrest though Monomer Design
• Alkyl glycidal ethers have long induction periods
• Increasing coordination by the monomer
O
O
+
O
O
O
O
H
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
Neopentlyglycoldiclycidyl ether Trimethylolpropane
triglycidyl ether
Methyl glycidylether
Dynamic Shear Rheology
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
G* = G’ + iG’’
δ = atan(G’’/G’)
Dynamic and Steady Shear Experiments
Dynamic
Steady
Model CompoundDipropylene Glycol Dyglicidal Ether
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
Modifying Reaction Kinetics with Crown Ethers
18-crown-6
1050 mJ/cm2
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
10
30
50
70
90
110
130
150
170
190
0 20 40 60 80 100 120 140 160
Tem
pera
ture
(oC
)
Irradiation Time (s)
O
O
OO
1M%
O
O
O
O
O O
O
O
O
O
O
O
OO
O
2620 mJ/cm2
Modifying Reaction Kinetics with Crown Ethers
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
Dynamic Shear Experiments with 15-Crown-5 at 40C
Moles IOC-11 / moles Monomer ~ 0.002
The Supramolecular Complex
• 2,6-di-t-butylpyridine is a ‘proton trap’, but will not neutralize larger
species like an tertiary oxonium ion
• Crown ethers serve as a
‘molecular ruler’ for acid species
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu
Polyether ring Pore Size (A)
12-crown-4 1.2-1.5
15-crown-5 1.7-2.2
18-crown-6 2.6-3.2
Summary & Future Work
• Development of one component epoxy system
– Long working life and low temperature cure
• Control of cationic ring opening polymerizations
– Monomer Design
– Modifying reaction kinetics with crown ethers
– Crown ether size effect is observed
• Epoxy Blends
• NMR Complex Determination
Matthew J. Spencer, James V. Crivello, Chang Y. Ryu