Embed Size (px)
Citation preview
O
OO
O
OO
O
OO1
2
O
OO3
4
O[Sc]
O [Sc]
O
[Sc]
δ+O
[Sc]
O
OOδ+
b
a ΔG‡1 = 29.7 kcal mol–1
ΔG‡2 = 27.5 kcal mol–1
b
a
ΔG‡3 = 24.2 kcal mol–1
ΔG‡4 = 23.0 kcal mol–1
Architectural control of isosorbide-based polyethers via ring-opening polymerizationDerek J. Saxon, Mohammadreza Nasiri, Mukunda Mandal, Saurabh Maduskar, Paul J. Dauenhauer, Christopher J. Cramer, Anne M. LaPointe, and Theresa M. Reineke
We thank the NSF Center for Sustainable Polymers (CHE-1413862) for financial support.
References: (1) Saxon, D. J.; Nasiri, M.; Mandal, M.; Maduskar, S.; Dauenhauer, P. J.; Cramer, C.J.; LaPointe, A. M.; Reineke, T. M. J. Am. Chem. Soc. 2019, 141, 5107. (2) Fenouillot, F.;Rousseau, A.; Colomines, G.; Saint-Loup, R.; Pascault, J.-P. Prog. Polym. Sci. 2010, 35, 578. (3)Cope, A. C.; Shen, T. Y. J. Am. Chem. Soc. 1956, 78, 5912. (4) You, L.; Hogen-Esch, T. E.; Zhu, Y.;Ling, J.; Shen, Z. Polymer 2012, 53, 4112.
Monomer Synthesis + Initial Screening
Conclusions + Future Directions
Ring-Opening Polymerization + Architectural Control
Note: SGP = step-growth polymerization; RP = radical polymerization; ROP = ring-opening polymerization
Motivation + Goals
Computational Selectivity of Bridgehead vs Terminal Ether
Acknowledgements
ROP
O
OO
O
OO
H
H
O = bridgehead; O = terminal
5
• mild, catalytic conditions » architectual control
This work
O
OHO
OH
H
H
RP
SGP
O
OO
O
H
HR
OO
O
OR
O
H
H
ROP
• energy intensive• limited control
• oligomers only (DP ~ 5)• undesirable crosslinking
• non-degradable backbone
Previous work
OO O
O O
O
OHO
OHO
OAcO
OH
H
H
P. fluorescens
acetonert, 24 h
H
H
OAcK2CO3
MeOHrt, 10 min
O
OAcO
OTsTsCl, py
rt, 24 h
H
H
99% 70%
High-throughput screening• ~ 250 polymerizations• Identified cationic ROP • Mn up to 10 kg mol–1
O
OOR1
H
H
O
OO OR2
O
OO
Me
O
OO
Me
O
OO1
2
O
OO3
4
TfOMeOTf
ΔG‡1 = 30.4 kcal mol–1
ΔG‡2 = 32.1 kcal mol–1
O
OO MeOTf
ΔG‡3 = 29.1 kcal mol–1
ΔG‡4 = 28.7 kcal mol–1
TfO
We aim to exploit the structureand functionality of isosorbide toemploy controlled polymerizationunder mild conditions to designrenewable materials.Project Goals:
1. Prepare annulated derivative2. Exploit computation + high-
throughput screening3. Control polymer architecture
ü Renewable / non-toxicü Versatile functionalityü High Tg polymers with
good optical clarity
O
OO
OH
H
Classical initiatorLewis acid + epoxide
Theory: M06-2X/6-311+G(d,p)//M06-L/6-31+G(d,p) at 298.15 K
Quasi-zwitterionic control (MeOTf + PO):
Developed a platform for tailored polymer architectures from isosorbide via ring-opening polymerizationü High-yielding monomer synthesis requiring minimal purificationü High-throughput screening + computation informed follow-up workü Control over macromolecular architectureü Recycle unreacted monomer via sublimationOngoing and future work: (i) target high Mn polymers, (ii) access statistical/block copolymers, and (iii) study thermal + mechanical properties
70% cyclicpolymers 100% linear
polymers
85% linearpolymers!
Ring-opening selectivity (1H NMR):
isosorbide
PO-initiated polyether
–15.2 kcal mol–1 –9.1 kcal mol–1∆H =
bridgeheadfavored
O
OHO
OTs
H
H O
OOKOtBu
THFrt, 3 h
KOH
300 ºC
97% 89% (KOtBu)≥95% selectivity (KOH)
ROP
