<sup>13</sup>C NMR chemical shifts and crystal structures of saturated hydrocarbons

The molecular motion and structure in poly(y-methyl L-glutamate-co-y-stearyl L-glutamate)s with various molar compositions were investigated by means of spin-probe technique and 13 C CP/MAS NMR. By the latter, it was confirmed that a certain part of long alkyl chains forms paraffin-like crystallites as observed in homopolymer of stearyl L-glutamate, and other part exists as the amorphous phase below crystalline melt. An introduction of a small amount of stearyl group considerably raises the mobility of the spin-probe which is embedded in the side chain region surrounding the ix-helical main chain, and further increase of stearyl content does not remarkably alter mobility. It is suggested that spin-probes exist in the amorphous region composed of stearyl groups, and mainly reflect the motional state of this region. the difference of the mobility between methyl L-glutamate side chain and stearyl group are also investigated by the scalar decoupled 13 C NMR spectra in the solid state.KEY WORDS Molecular Motion / Poly(L-glutamate) / Long Alkyl Side Chain/ Spin-Probe Technique/ 13 C CP/MAS NMR /

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“…The line width of ESR spectra is expressed as follows. (1) where M is the projection quantumn number of 14 N spin. A, B, and C are given by…”

Section: Resultsmentioning

confidence: 99%

Investigation of Molecular Motion and Structures of Side Chains in Poly(γ-methyl L-glutamate-co-γ-stearyl L-glutamate) by Spin-Probe Technique and 13C Cross-Polarization Magic Angle Spinning Nuclear Magnetic Resonance

Yamaguchi

Tsutsumi

1990

Polym J

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“…Variable-temperature solid-state nuclear magnetic resonance (VT solid-state 13 C NMR) has been confirmed to be an effective and powerful way to study the structure and dynamics of materials in the solid state, especially for the n-alkanes with various crystallographic forms. 39,40 Therefore, in the present work VT solid-state 13 C NMR was chosen as an alternative tool to characterize the phase transitions in the crystallization process of microencapsulated n-docosane.…”

Section: Introductionmentioning

confidence: 99%

Phase change materials of n-alkane-containing microcapsules: observation of coexistence of ordered and rotator phases

Xie

et al. 2011

Phys. Chem. Chem. Phys.

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In the present investigation, the crystallization and phase transition behaviours of normal alkane (n-docosane) in microcapsules with a mean diameter of 3.6 μm were studied by the combination of differential scanning calorimetry (DSC), temperature-dependent X-ray diffraction (XRD) and variable-temperature solid-state nuclear magnetic resonance (VT solid-state (13)C NMR). The DSC and VT solid-state (13)C NMR results reveal that a surface freezing monolayer is formed prior to the bulk crystallization of the microencapsulated n-docosane. More interestingly, it is confirmed that after the bulk crystallization, the ordered triclinic phase coexists with the rotator phase I (RI) for the microencapsulated n-docosane. We argue that the reduction of the free energy difference between the two phases, resulting from the microencapsulation process, leads to the coexistence of the ordered triclinic and rotator phases of the normal alkanes.

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“…Recently, Watanabe et al 1 have reported that in a series of -helical poly(L-glutamates) with n-alkyl side chains of various lengths (n (number of carbon atoms in the alkyl group) = [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], n-alkyl side chains longer than = 10 form a crystalline phase composed of paraffin-like crystallites together with the -helical main chain packing into a characteristic layer structure. The polymers form thermotropic cholesteric liquid crystals by the melting of the side-chain crystallites.…”

Section: Introductionmentioning

confidence: 99%

Conformation and dynamic aspects of poly(.gamma.-n-octadecyl L-glutamate) in the solid state and liquid-crystalline state as studied by variable-temperature carbon-13 CP/MAS NMR spectroscopy

Yamanobe¹,

Tsukahara²,

Kōmoto³

et al. 1988

Macromolecules

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¹³C NMR chemical shifts and crystal structures of saturated hydrocarbons

Cited by 38 publications

References 8 publications

Investigation of Molecular Motion and Structures of Side Chains in Poly(γ-methyl L-glutamate-co-γ-stearyl L-glutamate) by Spin-Probe Technique and 13C Cross-Polarization Magic Angle Spinning Nuclear Magnetic Resonance

Investigation of Molecular Motion and Structures of Side Chains in Poly(γ-methyl L-glutamate-co-γ-stearyl L-glutamate) by Spin-Probe Technique and 13C Cross-Polarization Magic Angle Spinning Nuclear Magnetic Resonance

Phase change materials of n-alkane-containing microcapsules: observation of coexistence of ordered and rotator phases

Conformation and dynamic aspects of poly(.gamma.-n-octadecyl L-glutamate) in the solid state and liquid-crystalline state as studied by variable-temperature carbon-13 CP/MAS NMR spectroscopy

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13C NMR chemical shifts and crystal structures of saturated hydrocarbons

Cited by 38 publications

References 8 publications

Investigation of Molecular Motion and Structures of Side Chains in Poly(γ-methyl L-glutamate-co-γ-stearyl L-glutamate) by Spin-Probe Technique and 13C Cross-Polarization Magic Angle Spinning Nuclear Magnetic Resonance

Investigation of Molecular Motion and Structures of Side Chains in Poly(γ-methyl L-glutamate-co-γ-stearyl L-glutamate) by Spin-Probe Technique and 13C Cross-Polarization Magic Angle Spinning Nuclear Magnetic Resonance

Phase change materials of n-alkane-containing microcapsules: observation of coexistence of ordered and rotator phases

Conformation and dynamic aspects of poly(.gamma.-n-octadecyl L-glutamate) in the solid state and liquid-crystalline state as studied by variable-temperature carbon-13 CP/MAS NMR spectroscopy

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¹³C NMR chemical shifts and crystal structures of saturated hydrocarbons