skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

This content will become publicly available on October 14, 2020

Title: Investigating the Microstructure of Poly(cyclosilane) by 29Si Solid-State NMR Spectroscopy and DFT Calculations

Abstract

Using high-resolution magic-angle spinning (MAS) solid-state NMR spectroscopy and density-functional theory (DFT) calculations, we determine the microstructure of the silicon-based functional polymer poly( 1,4Si6) arising from the dehydrocoupling polymerization of cyclosilane 1,4Si6. 1H- 29Si refocused-INEPT experiments allow the unambiguous determination of the number of attached protons to a silicon atom for each 29Si signal in 1,4Si6 and poly( 1,4Si6). One-dimensional 1H→ 29Si cross-polarization MAS (CPMAS) spectra of poly( 1,4Si6) show the development of SiH resonances upon polymerization and peak integration indicates an average degree of polymerization of 20. The 1H→ 29Si CPMAS spectrum of poly( 1,4Si6) also shows two sets of isotropic signals, suggesting the presence of at least two distinct species. Two-dimensional 29Si dipolar double-quantum-single-quantum and single-quantum-single-quantum homonuclear correlation spectra reveal similar connectivity in the two species, pointing to stereochemical and/or conformational heterogeneity. DFT calculations on trimer models predict that chair or twist-boat conformations and with cis or trans diastereomers are all energetic minima. 29Si chemical shift calculations of the lowest energy structures show that conformers and stereoisomers are expected to give rise to distinct 29Si NMR peaks and likely explain the appearance of multiple sets of 29Si NMR signals. Finally, the strategy outlined in this article is expectedmore » to be widely useful for the microstructural elucidation of silicon-based functional polymers.« less

Authors:
 [1];  [2];  [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Ames Lab., and Iowa State Univ., Ames, IA (United States)
  2. Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemistry
Publication Date:
Research Org.:
Johns Hopkins Univ., Baltimore, MD (United States); Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1570241
Alternate Identifier(s):
OSTI ID: 1574816
Report Number(s):
IS-J-10085
Journal ID: ISSN 0897-4756
Grant/Contract Number:  
SC0013906; AC02-08CH11358; AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 31; Journal Issue: 21; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Dorn, Rick W., Marro, Eric A., Hanrahan, Michael P., Klausen, Rebekka S., and Rossini, Aaron J. Investigating the Microstructure of Poly(cyclosilane) by 29Si Solid-State NMR Spectroscopy and DFT Calculations. United States: N. p., 2019. Web. doi:10.1021/acs.chemmater.9b03606.
Dorn, Rick W., Marro, Eric A., Hanrahan, Michael P., Klausen, Rebekka S., & Rossini, Aaron J. Investigating the Microstructure of Poly(cyclosilane) by 29Si Solid-State NMR Spectroscopy and DFT Calculations. United States. doi:10.1021/acs.chemmater.9b03606.
Dorn, Rick W., Marro, Eric A., Hanrahan, Michael P., Klausen, Rebekka S., and Rossini, Aaron J. Mon . "Investigating the Microstructure of Poly(cyclosilane) by 29Si Solid-State NMR Spectroscopy and DFT Calculations". United States. doi:10.1021/acs.chemmater.9b03606.
@article{osti_1570241,
title = {Investigating the Microstructure of Poly(cyclosilane) by 29Si Solid-State NMR Spectroscopy and DFT Calculations},
author = {Dorn, Rick W. and Marro, Eric A. and Hanrahan, Michael P. and Klausen, Rebekka S. and Rossini, Aaron J.},
abstractNote = {Using high-resolution magic-angle spinning (MAS) solid-state NMR spectroscopy and density-functional theory (DFT) calculations, we determine the microstructure of the silicon-based functional polymer poly(1,4Si6) arising from the dehydrocoupling polymerization of cyclosilane 1,4Si6. 1H-29Si refocused-INEPT experiments allow the unambiguous determination of the number of attached protons to a silicon atom for each 29Si signal in 1,4Si6 and poly(1,4Si6). One-dimensional 1H→29Si cross-polarization MAS (CPMAS) spectra of poly(1,4Si6) show the development of SiH resonances upon polymerization and peak integration indicates an average degree of polymerization of 20. The 1H→29Si CPMAS spectrum of poly(1,4Si6) also shows two sets of isotropic signals, suggesting the presence of at least two distinct species. Two-dimensional 29Si dipolar double-quantum-single-quantum and single-quantum-single-quantum homonuclear correlation spectra reveal similar connectivity in the two species, pointing to stereochemical and/or conformational heterogeneity. DFT calculations on trimer models predict that chair or twist-boat conformations and with cis or trans diastereomers are all energetic minima. 29Si chemical shift calculations of the lowest energy structures show that conformers and stereoisomers are expected to give rise to distinct 29Si NMR peaks and likely explain the appearance of multiple sets of 29Si NMR signals. Finally, the strategy outlined in this article is expected to be widely useful for the microstructural elucidation of silicon-based functional polymers.},
doi = {10.1021/acs.chemmater.9b03606},
journal = {Chemistry of Materials},
number = 21,
volume = 31,
place = {United States},
year = {2019},
month = {10}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on October 14, 2020
Publisher's Version of Record

Save / Share: