Characterization of n-butyl acrylate centered triads in poly(n-butyl acrylate-co-carbon monoxide-co-ethylene) by isotopic labeling and two dimensional NMR.
Poly(n-butylacrylate-co-carbon monoxide-co-ethylene) (polyEBC) samples prepared from 13C-labeled monomer, n-butyl acrylate, were characterized using two dimensional (2D) pulsed field gradient (PFG) 750 MHz NMR spectroscopy. To elucidate the complex structure of the terpolymer, 2D-1H/13C-heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) experiments were conducted by selectively exciting the enhanced resonances in the spectra of two polymer samples, one polymer resulting from synthesis with 1-13C-n-butylacrylate monomer and a second polymer obtained from a synthesis with 2-13C-n-butylacrylate monomer. High-resolution 2D-NMR combined with 13C-labeling of the polymer greatly simplifies the 2D-NMR spectra, selectively enhances the weak peaks from low occurrence B-centered triad structures, and aids in their resonance assignments. In all experiments, the sample temperature was 120 degrees C, to ensure a homogeneous solution and sufficient molecular mobility.


BACKGROUND
Supplementary material (1D 13C NMR spectra of the 13C-labeled and unlabeled polymers) is available in the online version of this article at http://dx.doi.org/100.1007/s00216-003-2402-3.
Monwar
Masud
M
Department of Chemistry, The University of Akron, Akron, OH 44325-3601, USA.
Oh
Sung Joon
SJ
Rinaldi
Peter L
PL
McCord
Elizabeth F
EF
Hutchinson
Robin A
RA
Buback
Michael M
MM
Latz
Henning
H
D000179:Acrylates / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry; D002248:Carbon Monoxide / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D007553:Isotope Labeling; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D015394:Molecular Structure; D011108:Polymers / Q000032:analysis* / Q000737:chemistry*
D000179:Acrylates; D002247:Carbon Isotopes; D005030:Ethylenes; D011108:Polymers; C032490:n-butyl acrylate; D002248:Carbon Monoxide; C036216:ethylene