Poly(propylene carbonate): Insight into the Microstructure and Enantioselective Ring-Opening Mechanism

Handle URI:
http://hdl.handle.net/10754/599208
Title:
Poly(propylene carbonate): Insight into the Microstructure and Enantioselective Ring-Opening Mechanism
Authors:
Salmeia, Khalifah A.; Vagin, Sergei; Anderson, Carly E.; Rieger, Bernhard
Abstract:
Different poly(propylene carbonate) (PPC) microstructures have been synthesized from the alternating copolymerization of CO 2 with both racemic propylene oxide (PO) and various mixtures of PO enantiomers using chiral salen catalysts. The microstructures of the obtained copolymers as a function of polymerization time have been analyzed by a combination of chiral GC and high-resolution NMR spectroscopy. The 13C NMR spectra of selected poly(propylene carbonate) samples were recorded using a 900 MHz ( 1H) spectrometer, showing a previously unreported fine splitting of the carbonate resonances. This allowed a detailed assignment of signals for various copolymer microstructures taking into account the specifics in their stereo- and regioirregularities. For example, the enantioselectivity preference of the (R,R-salen)Co catalyst for (S)-PO at the beginning of the copolymerization leads predominantly to (S)-PO insertion, with any (R)-PO misinsertion being followed by incorporation of (S)-PO, so that the microstructure features isolated stereoerrors. K rel calculations for the copolymerization showed around 5-fold enantioselectivity for (S)-PO over (R)-PO at short reaction time. Analysis of the copolymer microstructures obtained under various reaction conditions appears to be an additional approach to differentiate the occurrence of bimetallic and bifunctional copolymerization mechanisms that are widely discussed in the literature. © 2012 American Chemical Society.
Citation:
Salmeia KA, Vagin S, Anderson CE, Rieger B (2012) Poly(propylene carbonate): Insight into the Microstructure and Enantioselective Ring-Opening Mechanism. Macromolecules 45: 8604–8613. Available: http://dx.doi.org/10.1021/ma301916r.
Publisher:
American Chemical Society (ACS)
Journal:
Macromolecules
KAUST Grant Number:
KSAC0069/UK-C0020
Issue Date:
13-Nov-2012
DOI:
10.1021/ma301916r
Type:
Article
ISSN:
0024-9297; 1520-5835
Sponsors:
This publication is based on work supported by Award KSAC0069/UK-C0020, made by the King Abdullah University of Science and Technology (KAUST).
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorSalmeia, Khalifah A.en
dc.contributor.authorVagin, Sergeien
dc.contributor.authorAnderson, Carly E.en
dc.contributor.authorRieger, Bernharden
dc.date.accessioned2016-02-25T13:54:56Zen
dc.date.available2016-02-25T13:54:56Zen
dc.date.issued2012-11-13en
dc.identifier.citationSalmeia KA, Vagin S, Anderson CE, Rieger B (2012) Poly(propylene carbonate): Insight into the Microstructure and Enantioselective Ring-Opening Mechanism. Macromolecules 45: 8604–8613. Available: http://dx.doi.org/10.1021/ma301916r.en
dc.identifier.issn0024-9297en
dc.identifier.issn1520-5835en
dc.identifier.doi10.1021/ma301916ren
dc.identifier.urihttp://hdl.handle.net/10754/599208en
dc.description.abstractDifferent poly(propylene carbonate) (PPC) microstructures have been synthesized from the alternating copolymerization of CO 2 with both racemic propylene oxide (PO) and various mixtures of PO enantiomers using chiral salen catalysts. The microstructures of the obtained copolymers as a function of polymerization time have been analyzed by a combination of chiral GC and high-resolution NMR spectroscopy. The 13C NMR spectra of selected poly(propylene carbonate) samples were recorded using a 900 MHz ( 1H) spectrometer, showing a previously unreported fine splitting of the carbonate resonances. This allowed a detailed assignment of signals for various copolymer microstructures taking into account the specifics in their stereo- and regioirregularities. For example, the enantioselectivity preference of the (R,R-salen)Co catalyst for (S)-PO at the beginning of the copolymerization leads predominantly to (S)-PO insertion, with any (R)-PO misinsertion being followed by incorporation of (S)-PO, so that the microstructure features isolated stereoerrors. K rel calculations for the copolymerization showed around 5-fold enantioselectivity for (S)-PO over (R)-PO at short reaction time. Analysis of the copolymer microstructures obtained under various reaction conditions appears to be an additional approach to differentiate the occurrence of bimetallic and bifunctional copolymerization mechanisms that are widely discussed in the literature. © 2012 American Chemical Society.en
dc.description.sponsorshipThis publication is based on work supported by Award KSAC0069/UK-C0020, made by the King Abdullah University of Science and Technology (KAUST).en
dc.publisherAmerican Chemical Society (ACS)en
dc.titlePoly(propylene carbonate): Insight into the Microstructure and Enantioselective Ring-Opening Mechanismen
dc.typeArticleen
dc.identifier.journalMacromoleculesen
dc.contributor.institutionTechnische Universitat Munchen, Munich, Germanyen
kaust.grant.numberKSAC0069/UK-C0020en
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