Phase structure and the orientational order of water in the lyotropic mesophase of the hexadecyltriethylammonium bromide-water-pentanol system by deuterium and oxygen-17 nuclear magnetic resonance

The use of 2H nuclear magnetic resonance for the characterization of the polymorphic behavior of lipids is illustrated. Different lipid phase preferences may be expected to influence the orientational order and its variation along the acyl chains. Several results are presented to support that view. An increase of motional freedom and a redistribution of the order along the acyl chains are observed during the lamellar-to-hexagonal phase transition, showing that the order profile is sensitive to the lipid phase symmetry. In addition, if the preferences for nonlamellar phases are not expressed explicitly, the presence of "nonbilayer" lipids constrained in bilayer environment induces increased hydrocarbon order. This suggests that order parameters of the acyl chains and lipid polymorphic tendencies are intimately related.Key words: lipid, polymorphism, 2H nuclear magnetic resonance, hydrocarbon order.

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Analysis of molecular orientational order in solid samples by nuclear magnetic resonance: application to lignin and cellulose in wood

Analytical Chemistry ◽

10.1021/ac00140a017 ◽

1987 ◽

Vol 59 (13) ◽

pp. 1659-1664 ◽

Cited By ~ 14

Author(s):

Galen R. Hatfield ◽

Maziar. Sardashti ◽

Gary E. Maciel

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Orientational Order ◽

Solid Samples ◽

Nuclear Magnetic

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13C/7Li Solid-State Nuclear Magnetic Resonance Study on Poly(Ethylene Glycol)-Poly(Propylene Glycol)-Poly(Ethylene Glycol)/LiCF3SO3 Copolymer Electrolytes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.982.26 ◽

2020 ◽

Vol 982 ◽

pp. 26-33

Author(s):

Ling Wei ◽

Da Wei Li

Keyword(s):

Nuclear Magnetic Resonance ◽

Solid State ◽

Magnetic Resonance ◽

High Resolution ◽

Ethylene Glycol ◽

Phase Structure ◽

Poly Ethylene Glycol ◽

Chain Dynamics ◽

Poly Ethylene ◽

Nuclear Magnetic

Solid-state high-resolution 13C/7Li nuclear magnetic resonance (NMR) study was performed on the phase structure and chain dynamics of PEG-PPG-PEGn/LiCF3SO3 (n=3, 6, 12) copolymer electrolytes. PEG repeating units and Li+ form PEG3:LiCF3SO3 crystalline complex and PE3/Li+ amorphous complex in all the samples. PPG repeating units and Li+ form different complexes with respect to O:Li+ feed ratio (denoted as PP/Li+-3/6/12). The 13C chemical shifts and half widths of the signals from PP/Li+-3/6/12 remain unchanged, which implies the structures of PP/Li+-3/6/12 are similar at least in a very short range. The half width of the 7Li signals from PP/Li+-3/6/12 becomes narrower and narrower as the Li+ concentration decreases. This indicates the chain mobility of the amorphous phase increases with the decrease of ionic concentration. Moreover, neat crystalline PEG, neat amorphous PEG and neat amorphous PPG start to appear when O:Li+ is greater than 3:1 and their contents increase with the increase of O:Li+. Overall, solid-state high-resolution NMR is a powerful and unique method for understanding the phase structure and chain dynamics of solid polymer electrolytes (SPEs), more applications of this technique to studies on SPEs is expecting.

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