Microstructural analysis of methacrylonitrile-methyl methacrylate copolymers by carbon-13 NMR spectroscopy (original) (raw)
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Applied Chemical Engineering
The authors conducted free radical polymerization using an initiator to synthesize a copolymer of isobornyl methacrylate—Acrylonitrile (I/A). The reactivity ratios of I (r1) and A (r2) monomers were determined as r1 = 1.63 ± 0.14, r2 = 0.61 ± 0.06 for linear KT (Kelen–Tudos) method and r1 = 1.58, r2 = 0.60 for the EVM (Error-in-Variable Method). We interpreted 1H and 13C{1H} NMR spectra of the I/A copolymers using DEPT-135 and 2D HSQC spectra. The α-CH3 carbon in the I-unit was identified and confirmed using a 2D HSQC NMR spectrum, up to the level of triad of compositional and configurational sequences. The CH (C14) and β-CH2 carbon peaks were also identified up to the triad level and higher, respectively. A 2D TOCSY spectrum revealed geminal and vicinal interactions within various CH and β-CH2 protons. A 2D HMBC NMR spectrum provided a complete assignment of the coupling between nitrile, carbonyl, and quaternary carbons with CH3 and CH2 protons.
Acrylonitrile and glycidyl methacrylate copolymers: Nuclear magnetic resonance characterization
Macromolecules, 1998
Copolymers containing acrylonitrile (A) and glycidyl methacrylate (G) units of different compositions were synthesized by free radical solution polymerization. The reactivity ratios were estimated by Kelen Tudos and nonlinear error in variable methods. The triad sequence distributions in terms of A-and G-centered triads have been obtained from 13 C{ 1 H} NMR spectroscopy. The complete spectral assignments in terms of compositional and configurational sequences of the overlapping carbon and proton spectra of these copolymers were done with the help of distortionless enhancement by polarization transfer (DEPT), two-dimensional proton-detected heteronuclear correlation (inverse-HETCOR), and total correlated spectroscopy (TOCSY) experiments. The Monte Carlo simulation was used to study the effect of the fractional conversion on the triad fractions.
Polymer Journal, 2006
The acrylonitrile-butyl methacrylate (A/B) copolymers were synthesized by solution polymerization utilizing 2,2 0-azobisisobutyronitrile (AIBN) as free radical initiator. Reactivity ratios were assessed by Kelen-Tudos and non-linear error in variable method and were found to be r A ¼ 0:37 AE 0:03, r B ¼ 1:44 AE 0:16 (KT) and r A ¼ 0:36, r B ¼ 1:40 (RREVM) respectively which confirmed that butyl methacrylate monomer is more reactive than acrylonitirile towards propagating chain during radical polymerization. 2D HSQC spectroscopy in conjugation with TOCSY afforded explicit information about compositional and configurational sequences. Methine and-methylene regions revealed compositional sensitivity up to pentad and tetrad level respectively with meso and racemic configurations. TOCSY demonstrated the coupling between the methine protons of A centered triad and pentad units with-methylene protons of various tetrads. Heteronuclear multiple-bond correlation (HMBC) spectroscopy has been employed to study carbon (carbonyl/nitrile)-proton coupling. The carbonyl and nitrile carbons expressed compositional sensitivity up to the triad level.
European Polymer Journal, 2002
Glycidylmethacrylate/styrene copolymers of different compositions were prepared by free radical bulk polymerisation using benzoyl peroxide as an initiator. Copolymer composition was obtained from quantitative Carbon-13 NMR spectroscopy. Reactivity ratios for comonomers were calculated using the Kelen-Tudos (KT) and non-linear error in variable methods (EVM). The reactivity ratios obtained from KT and EVM are found to be r G-0 : 56 ±0.1, r S-0 : 44 ± 0 : 07 and r G-0 : 60, r S-0 : 48 respectively. The triad sequence distribution in terms of G and S centered triad were obtained from 13 Cf 1 Hg NMR spectroscopy. Complete spectral assignment of 13 C and 1 H-NMR spectra were done with the help of distortionless enhancement by polarization transfer and 2D 13 C-1 H heteronuclear single quantum coherence.
Structural investigations of the phenyl methacrylate and methyl methacrylate copolymer system
Materials Letters, 1994
The compositions of the copolymers of phenyl methacrylate and methyl methacrylate synthesized by free radical polymerization have been determined by nuclear magnetic resonance spectroscopy. X-ray diffraction analysis was employed for structural investigations. The results are discussed in terms of degree of amorphousness, interchain separation and mean crystallite size.
Characterisation of glycidylmethacrylate/methacrylonitrile copolymers by NMR spectroscopy
Journal of Molecular Structure, 2002
Glycidylmethacrylate/methacrylonitrile (G/M) copolymers of different compositions were prepared and a copolymer composition was obtained from quantitative 13 C NMR spectroscopy. Reactivity ratios for comonomers were calculated using the Kelen-Tudos (KT) and non linear error in variable (EVM) methods. The reactivity ratios obtained from KT and EVM are TQ = 1.14 ± 0.1, r M = 0.76 ± 0.06 and r G = 1.12, r M = 0.75, respectively. Complete spectral assignment of 13 C-and 'H-NMR spectra were done with the help of Distortionless Enhancement by Polarization Transfer (DEPT) and 2D "C-'H heteronuclear single quantum coherence (HSQC).
Journal of Applied Polymer Science, 1999
The acrylonitrile/methyl methacrylate copolymers of different monomer concentration were prepared by photo polymerization using uranyl ion as initiator. The carbon 13 and proton spectra of these copolymers are overlapping and complex. The complete spectral assignment of the 13 C-and 1 H-NMR spectra were done with the help of Distortionless Enhancement by Polarization Transfer (DEPT) and two dimensional 13 C-1 H Heteronuclear Single Quantum Correlation (HSQC) experiments. The methylene, methine and the methyl carbon resonances show both stereochemical (triad level) and compositional (dyad, triad, tetrad, pentad and hexad level) sensitivity. 2D Double Quantum Filtered Correlated Spectroscopy (DQFCOSY) experiment was used to ascertain the various geminal couplings between the methylene protons.
Polymer, 2002
Methyl methacrylate (MMA)±methyl acrylate (MA) copolymers, prepared in bulk at 50 8C using AIBN as initiator, were characterized by 150 MHz 13 C NMR spectroscopy, including use of the Distortionless Enhancement by Polarization Transfer (DEPT) experiment to obtain methylene and methine carbon resonances as subspectra. Dyad, triad, tetrad and partial pentad distributions were measured from the amethyl, methine and methylene carbon resonances. These were in good agreement with distributions calculated for the copolymers based on monomer feed compositions, conversions and reactivity ratios of 2.60 and 0.27 for methyl methacrylate and methyl acrylate, respectively.
Journal of Applied Polymer Science, 2004
itaconimide with methyl methacrylate was carried out by taking varying mole fractions (0.1 to 0.5) of N-aryl substituted itaconimide monomers in the initial feed using azobisisobutyronitrile as an initiator and tetrahydrofuran as the solvent. The copolymer composition was determined by 1 H-NMR spectroscopy using the ratio of proton resonance signal intensity attributed to -OCH 3 of MMA (␦ ϭ 3.5-3.8 ppm) and the aromatic protons The comonomer reactivity ratios were determined using Kelen-Tü dos and nonlinear error in variable methods. The reactivity ratios obtained by nonlinear error in variable methods were r 1 (PI) ϭ 1.26/r 2 (MMA) ϭ 0.35; r 1 (MI) ϭ 1.21/r 2 (MMA) ϭ 0.34; and r 1 (OI) ϭ 0.78/r 2 (MMA) ϭ 0.34. The carbonyl carbon signals of MMA (M) as well as N-aryl itaconimide (I) copolymers were used for the determination of the sequence distribution of M-and I-centered triads. The sequence distribution of M-and I-centered triads determined from 13 C{ 1 H}-NMR spectra of the copolymers are in good agreement with the triad concentrations calculated using the Alfrey-Mayo statistical model and Monte Carlo simulation method.