Molecular dynamics of poly(l-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy

Nozirov, Farhod; Nazirov, Alovidin; Jurga, Stefan; Fu, Riqiang

doi:10.1016/j.ssnmr.2005.09.001

Cited by 11 publications

(7 citation statements)

References 41 publications

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“…Large-scale amplitude motion for the methyl groups in a-PLLA has been reported by Nozirov et al, who revealed C 3v dynamics of this residue in a broad range of temperatures. 36 Because of molecular dynamics of the methyl groups and the apparent influence of motion on the values of the chemical shift parameters in the next step of our project, these parameters have been neglected. In subsequent studies, we have focused our attention on the 13 C d ii values for CH and CQO residues.…”

Section: Resultsmentioning

confidence: 99%

NMR crystallography of α-poly(l-lactide)

Pawlak

Jaworska

Potrzebowski

2013

Phys. Chem. Chem. Phys.

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A complementary approach that combines NMR measurements, analysis of X-ray and neutron powder diffraction data and advanced quantum mechanical calculations was employed to study the α-polymorph of L-polylactide. Such a strategy, which is known as NMR crystallography, to the best of our knowledge, is used here for the first time for the fine refinement of the crystal structure of a synthetic polymer. The GIPAW method was used to compute the NMR shielding parameters for the different models, which included the α-PLLA structure obtained by 2-dimensional wide-angle X-ray diffraction (WAXD) at -150 °C (model M1) and at 25 °C (model M2), neutron diffraction (WAND) measurements (model M3) and the fully optimized geometry of the PLLA chains in the unit cell with defined size (model M4). The influence of changes in the chain conformation on the (13)C σ(ii) NMR shielding parameters is shown. The correlation between the σ(ii) and δ(ii) values for the M1-M4 models revealed that the M4 model provided the best fit. Moreover, a comparison of the experimental (13)C NMR spectra with the spectra calculated using the M1-M4 models strongly supports the data for the M4 model. The GIPAW method, via verification using NMR measurements, was shown to be capable of the fine refinement of the crystal structures of polymers when coarse X-ray diffraction data for powdered samples are available.

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Section: Resultsmentioning

confidence: 99%

NMR crystallography of α-poly(l-lactide)

Pawlak

Jaworska

Potrzebowski

2013

Phys. Chem. Chem. Phys.

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“…[21,22] If a molecular motion is really present for the tristearin in the α form, a minimum for the T 1 measurement should confirm this result because a break in the slope of the M 2 curve can be correlated with a minimum T 1 . These two parameters have already been used to determine the glass phase transition temperature, [19,30] to distinguish the mobility of specific sites [27,28,33] and to study the molecular motion of crystallized compounds. [21,22] No minimum was obtained for the β polymorphs, while a linear increase was observed for each TA in the temperature range studied.…”

Section: Discussionmentioning

confidence: 99%

Study of triacylglycerol polymorphs by nuclear magnetic resonance: effects of temperature and chain length on relaxation parameters

Adam-Berret¹,

Rondeau-Mouro²,

Riaublanc³

et al. 2008

Magnetic Reson in Chemistry

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It is very important to monitor the characteristics of triacylglycerol crystal network in fats, as these crystals have an impact on many food properties such as texture, sensory taste, and extended shelf life. Although time-domain NMR (TD-NMR) is now the reference technique to determine the solid fat index in food, the entire possibilities of this technique are not used. Some NMR studies have been performed to determine its power for the discrimination of polymorphism. In this study, extended investigations proved that TD-NMR could evaluate triacylglycerol (TA) polymorphism, independently from temperature and chain length. Study of the dipolar interactions through second moment M(2), which is characteristic of proton mobility in solid-state samples, provided a new understanding of the structural organization of crystal molecules. Proton spin-lattice relaxation, which has been proved to be a true probe of polymorphism, has provided information on crystal networks. Combination of the two techniques revealed two very interesting kinds of results, i.e. the presence of a minimum spin-lattice relaxation time T(1) for tristearin alpha, which is a characteristic of a dynamic molecular process, and differences in behavior between long and short chain lengths, both at a molecular and a crystal level.

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“…The solid‐state 1 H‐NMR spectra are broad especially owing to a strong direct dipolar interaction among protons and the broad‐line 1 H‐NMR spectra measured at the MAS frequency of about 2.5 kHz at room frequency for PLA show one unstructured broad line . Molecular motion in the studied material averages out anisotropic interactions and to some extent the dipolar interactions as well, which gives rise to a narrowing of the solid‐state NMR spectra …”

Section: Introductionmentioning

confidence: 95%

Morphology and molecular mobility of plasticized polylactic acid studied using solid‐state ¹³C‐ and ¹H‐NMR spectroscopy

Kovaľaková

Olčák

Hronský

et al. 2016

J of Applied Polymer Sci

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MAS 13 C-NMR measurements were used for the study of morphology and molecular mobility in amorphous quenched and triacetine-plasticized PLA samples and PLA samples which underwent cold crystallization during annealing at 80 and 100 8C. The single pulse MAS 13 C-NMR spectra indicate that plasticizer promotes cold crystallization which results in the decrease of the temperature of crystallization and formation of more perfect crystalline domains. The T 1 ( 13 C) spin-lattice relaxation times show that the presence of plasticizer molecules leads to an increase of local mobility in PLA chains but plasticized PLA after annealing at 100 8C shows more rigid structure. The series of broad line 1 H-NMR spectra performed at temperatures up to 100 8C provided information on the changes in relaxation processes and morphology of the studied samples. The interpretation of the results obtained using the techniques of NMR spectroscopy were supported by WAXD and DSC measurements.

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Molecular dynamics of poly(l-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy

Cited by 11 publications

References 41 publications

NMR crystallography of α-poly(l-lactide)

NMR crystallography of α-poly(l-lactide)

Study of triacylglycerol polymorphs by nuclear magnetic resonance: effects of temperature and chain length on relaxation parameters

Morphology and molecular mobility of plasticized polylactic acid studied using solid‐state ¹³C‐ and ¹H‐NMR spectroscopy

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Molecular dynamics of poly(l-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy

Cited by 11 publications

References 41 publications

NMR crystallography of α-poly(l-lactide)

NMR crystallography of α-poly(l-lactide)

Study of triacylglycerol polymorphs by nuclear magnetic resonance: effects of temperature and chain length on relaxation parameters

Morphology and molecular mobility of plasticized polylactic acid studied using solid‐state 13C‐ and 1H‐NMR spectroscopy

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Morphology and molecular mobility of plasticized polylactic acid studied using solid‐state ¹³C‐ and ¹H‐NMR spectroscopy