Norbert Henzel

Analysis of β-CH2 signals in the 13C NMR spectra of the methyl methacrylate–ethyl acrylate copolymer as a tool for microstructure determination

The incremental method of the chemical shift calculation in the 13C NMR spectra of the methyl methacrylate–ethyl acrylate copolymer, PMMA/EA, has been applied to the β-CH2 carbons. A positive simulation of the DEPT sub-spectrum shows that it is possible to determine in this way the distribution of configurational-compositional tetrads providing a tool for microstructure analysis of acrylic copolymers.

Microstructure Study of Methyl Methacrylate/n-Butyl Acrylate Copolymer by 13C NMR Spectroscopy

Abstract Detailed analysis of carbonyl signal in the 100 MHz 13C NMR spectrum of methyl methacrylate/n-butyl acrylate copolymer samples, PMMA/nBA, of different compositions, prepared by free radical polymerization, provided information on distribution of configurational-compositional triads and pentads. Incremental calculation of chemical shifts of individual sequences permitted spectral simulation and verification of the signal attribution.

Computer aided analysis of carbon-13 nuclear magnetic resonance spectra of multicomponent mixtures. Part 2. Determination of the content of alkadienes in a light gasoline

A method for the computer aided analysis of 13C nuclear magnetic resonance spectra of multicomponent mixtures has been applied to determine the content of polymerizable compounds, especially alkadienes, in light gasolines derived from the steam cracking process of crude oil. The results obtained are in good agreement with those provided by gas chromatography–mass spectrometry.

Sequence Distribution of Poly(methyl acrylate) by Incremental Calculation

The carbonyl signal in the 100 MHz 13C NMR spectra of poly(methyl acrylate) (PMA) recorded in benzene-d6 exhibits configurational sensitivity up to pentads, and the signal of backbone β-CH2 carbons shows splitting up to configurational hexads with traces of octads. Assignment of the sequences to respective signals was confirmed by computer simulation of both carbonyl and methylene signals applying a method of incremental calculation of chemical shifts of individual sequences and second-order Markov statistics for sequence probabilities.

Incremental Calculation of Sequence Distribution of Poly(Butyl Acrylate)

Abstract The carbonyl signal in the 100 MHz 13C NMR spectra of both poly(n-butyl acrylate) and poly(t-butyl acrylate) exhibit configurational sensitivity up to pentads. Since the attribution of respective sequences cannot be performed in a straightforward manner, a method of incremental calculation of chemical shifts of individual sequences has been applied. The simulated spectrum for PnBA obtained in this way required only slight corrections to match the experimental carbonyl signal. This method can therefore be extended to determine the configurational sequences in acrylic copolymers containing n-butyl acrylate units.

Microstructure Analysis of Acrylate-Methacrylate Copolymers by 13C NMR Spectroscopy

Abstract The carbonyl signal in the 13C NMR spectra of copolymers of methyl methacrylate and several acrylates (methyl to butyl) has been investigated to obtain detailed information on distribution of sequences in the macromolecular chain up to configurational-compositional pentads. Complementary information on distribution of even sequences can be derived from the signal of β-CH2 carbons of the main chain. Incremental calculation of the chemical shifts of the individual sequences can be performed for both carbonyl and methylene signal and permit for spectral simulation and verification of the signal attribution to the respective sequences.

Microstructure Study of Poly(tert-butyl acrylate) by 13C NMR Spectroscopy

Abstract Two samples of poly(tert-butyl acrylate) (PtBA) of different tacticity, prepared by free radical and anionic polymerization, were investigated by 13C NMR spectroscopy. It was found that the carbonyl signal of the 100 MHz 13C NMR spectrum of PtBA was sensitive to configurational effects and provided sufficient resolution to perform detailed analysis of sequence distribution at the pentad level taking into account some heptads. The line attribution has been verified by positive simulation of the spectrum.

Microstructure of poly(methyl methacrylate-co-isopropyl acrylate) studied by 13C NMR

ABSTRACT The distribution of configurational–compositional sequences of poly(methyl methacrylate-co-isopropyl acrylate) (PMMA/iPrA) has been determined from the carbonyl and β-CH2 signals in the 100 MHz 13C NMR spectra of the copolymer. The carbonyl signal provided information on configurational–compositional sequences up to heptads, whereas β-CH2 signals offered complementary information on even sequences up to hexads. The assignment of the sequences to the respective signals was based on a comparison with the spectra of respective homopolymers, that is, PMMA and PiPrA followed by a computer simulation applying an incremental calculation of chemical shifts of the individual sequences.

Sequence distribution of PMMA/iBuA copolymer by incremental calculation of 13C NMR spectra

ABSTRACT An incremental method for characterizing triad and pentad distribution by 13C NMR spectroscopy was applied to the poly(methyl methacrylate-co-isobutyl acrylate) copolymer. Calculation of the intensity of individual lines was performed applying Bernoulli statistics, while the chemical shifts for each sequence were calculated by an incremental method. Based on these data, the carbonyl signal was simulated yielding good agreement at the triad and pentad level.

Computer aided analysis of 13C n.m.r. spectra of multicomponent mixtures: 4. Structural analysis of a heavy gasoline from liquefaction of Polish coal

It is shown that knowledge of individual compounds in a multicomponent mixture, acquired by computer aided analysis of 13C nuclear magnetic resonance (n.m.r.) spectra, can significantly increase structural analysis precision of synthetic gasoline, stemming from liquefaction of a Polish coal; especially, determination of the branching factor of the saturated fraction can be made, without previous Chromatographic separation.