Oriented Thin Films of Insoluble Polythiophene Prepared by the Friction Transfer Technique.

A thin film of unsubstituted polythiophene (PT), an insoluble conjugated polymer, with molecular chains uniaxially oriented in plane was prepared by the friction transfer method. The structure of highly oriented thin films of PT was investigated using grazing-incidence X-ray diffraction (GIXD), ultraviolet-visible (UV-vis) spectroscopy, and infrared (IR) spectroscopy. The polarized UV-vis and IR spectra and GIXD measurements showed the PT molecular chains were well aligned in parallel to the friction direction. The GIXD studies clarified that the polymer backbones were aligned with very narrow distribution, such that the half-width was about 4 degrees. The degree of orientation of the PT friction-transferred film was higher compared with those of regioregular poly(3-alkylthiophene)s. Moreover, the GIXD results show a preferred orientation where the a-axis is perpendicular to the substrate plane.

X-ray diffraction and vibrational spectroscopic study of the influence of cis- and trans-unsaturation on the α-phase of triacylglycerols.

In order to clarify how cis- and trans-unsaturation of acyl chains influences the structure and properties of the metastable α-phase of triacylglycerols (TAGs), the conformation and packing of acyl chains and their temperature dependence were investigated by means of vibrational spectroscopy (IR and Raman) and powder X-ray diffractometry for typical saturated and cis- and trans-unsaturated TAGs, namely, tristearin, triolein, and trielaidin, which have clarified the following characteristics of each TAG. In the high-temperature range close to the melting point, the acyl chains form the hexagonal subcell for tristearin and trielaidin but they build the pseudohexagonal subcell for triolein. On the other hand, both cis- and trans-double bonds have a significant influence on the conformation of acyl chains. In triolein and trielaidin where the acyl chains are divided into two parts by a C═C bond, namely, the methyl-sided and the glycerol-sided chains, the glycerol-sided chain exhibits selective conformational disordering in the α-phase of these TAGs. The structural changes of acyl chains caused by cooling are also significantly affected by cis- and trans-unsaturation. For tristearin, the greater part of hydrocarbon segments change their packing from the hexagonal subcell to the pseudohexagonal subcell by cooling, while the greater part of hydrocarbon segments keep the hexagonal subcell structure and only the smaller part of them transform to the pseudohexagonal subcell for trielaidin. On the other hand, triolein does not exhibit any major changes with respect to subcell structure on cooling.

Incoherent quasielastic neutron scattering study on the polymorphism of tristearin: dynamical properties of hydrocarbon chains.

Dynamical properties of acyl chains in the three polymorphic phases alpha, beta', and beta of tristearin [C(3)H(5)(OCOC(17)H(35))3] have been studied by means of incoherent quasielastic neutron scattering (IQNS) using selectively deuterated samples. The mean square displacement of hydrogen atoms, , was estimated from the scattering vector Q dependence of the elastic scattering component under the harmonic approximation. It was shown that the temperature dependence of was significantly different between the three phases. There was no marked difference in between these phases up to 193 K, and the value increased linearly with temperature. Although the beta phase remained linear up to 293 K, the alpha and beta' phases started to show a nonlinear increase around 200 K, suggesting an anharmonic nature of molecular motions. The alpha phase exhibited the most conspicuous temperature dependence. These characteristics were ascribable to the difference in the lateral packing of acyl chains. Compared with the beta phase which has a tightly packed T// subcell, the beta' and alpha phases have looser O perpendicular and H subcells, respectively. The molecular motion in the alpha phase was analyzed using the model of uniaxial rotational diffusion in a onefold cosine potential. It has been clarified that the rotational fluctuation about the chain axis in the alpha phase is rather restricted compared with that in the rotator phase of n-alkanes.