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The self-diffusion coefficients (D) of long cyclic paraffin C24H48 with two transitions at 29 and 51 °C as observed in the DSC diagram are successfully measured within the temperature range from 30 to 70 °C by means of pulse field-gradient spin-echo 1H NMR method, in order to elucidate the diffusional behavior of the paraffin in the mesophase in the range of 29–51 °C and in the isotropic liquid phase above 51 °C. From the experimental results, it was found that the D value increased with increase in temperature and there is an abrupt turn in the temperature dependence for the mesophase and isotropic liquid phase in the diffusion process. [Copyright &y& Elsevier]

Solid-state high-resolution 13C NMR spectra of poly(l-aspartate) with mono-, di- and per-fluorinated benzyl side chains in the solid state were measured as a function of temperature, in order to elucidate structural behavior of the main chain by substituting hydrogen atoms in phenyl rings with fluorine atoms. From the experimental results, it was found that poly(l-aspartate)s with mono-fluorinated benzyl side chains take the αR-helix form and those with di- and per-fluorinated benzyl side chains take the ω-helix and β-sheet forms at room temperature, respectively. Further, structural behavior of the fluorinated poly(l-aspartate)s was elucidated by elevating the temperature. [Copyright &y& Elsevier]

Abstract: Pulse field-gradient spin-echo 1H NMR experiments on methane molecules charged into cylindrical channel cavities in the hexagonal columnar phase of oriented poly(p-biphenylene terephthalate) with long n-dodecyl side chains have been carried out in order to elucidate diffusion process of the methane molecules in the directions parallel and perpendicular to the cylindrical channel cavity axis. From these experimental results, it is found that methane molecules in the cylindrical channel cavities are not only diffusing in the direction parallel to the cylindrical channel cavity axis, but are diffusing through the wall of the cylindrical channel cavity. [Copyright &y& Elsevier]

13C CP/MAS NMR experiments on polypeptides, poly(β-benzyl l-aspartate) (PBLA), poly(γ-benzyl l-glutamate) (PBLG) and PBLA/PBLG blend have been carried out, in order to elucidate the conformational stability of the polypeptides in the solid state over a wide range of temperatures and its blending effect. The PBLA/PBLG blend with a mixture ratio of 1/1 is prepared by adding trifluoroacetic acid (TFA) solution to alkaline water (TFA-alkaline treatment). From these experimental results, it is found that the conformation of PBLA in the PBLA/PBLG blend sample is changed from left-handed helix (αL-helix and/or ωL-helix) form to the αR-helix form, and then the origin of the formation of the αR-helix form in PBLA comes from the existence of PBLG. Further, from the variable-temperature 13C CP/MAS NMR experiments results, it is shown that the conformational behavior of PBLA in the PBLA/PBLG blend is similar to that of the TFA-alkaline treated PBLA, and also the conformational behavior of PBLG in the PBLA/PBLG blend is similar to that of the TFA-alkaline treated PBLG. [Copyright &y& Elsevier]

Solid state 13C NMR experiments on poly(p-biphenylene terephthalate) with long n-dodecyl side chains have been carried out over a wide range of temperatures, in order to elucidate conformational and dynamical behavior of the polyester in the crystalline state and thermotropic liquid crystalline state. From these experimental results, it is found that at temperatures from room temperature to 80 °C the n-alkyl side chains take both of the immobile and the mobile regions, and at temperatures above 120 °C take only the mobile region. In the immobile region the n-alkyl side chains are in the all-trans zigzag conformation and in the mobile state are undergoing fast exchange between the trans and gauche conformations. On the other hand, the terephthalate moiety of the main chain undergoes rotational motion after the melt of n-alkyl side chains as the temperature is increased. [Copyright &y& Elsevier]