Poly(propylene carbonate): Insight into the Microstructure and Enantioselective Ring-Opening Mechanism
Type
ArticleKAUST Grant Number
KSAC0069/UK-C0020Date
2012-10-31Online Publication Date
2012-10-31Print Publication Date
2012-11-13Permanent link to this record
http://hdl.handle.net/10754/599208
Metadata
Show full item recordAbstract
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.Sponsors
This publication is based on work supported by Award KSAC0069/UK-C0020, made by the King Abdullah University of Science and Technology (KAUST).Publisher
American Chemical Society (ACS)Journal
Macromoleculesae974a485f413a2113503eed53cd6c53
10.1021/ma301916r