Yukihiro Abe

Effects of hydrophilicity of rigid-rod polymers on the formation of poly-p-pyridylenebenzobisoxazole fibers

This study investigates the fiber structure of a newly developed poly-p-pyridylenebenzobisoxazole fiber. The molecular structure resembles that of poly-p-phenylenebenzobisoxazole fiber, which has a rigid-rod backbone structure with a thin-planar shape; thus, a similar preferential radial orientation of the molecular planes normal to the fiber axis is expected. We have focused on the change of fiber structures induced by copolymerizing hydrophilic groups in a rigid-rod backbone of PBO. The preferential orientation of the crystal planes in various positions of the fiber, the molecular orientation along the fiber axis and the crystal size were analyzed by micro-focus X-ray diffraction. The difference in molecular orientation and crystal size in the various positions was related to the formation of the crystal structure induced by radial preferential orientation of the (200) crystal plane sourced from the rigid-rod backbone structure with the thin-planar shape.

Spectroscopic studies of electron spin resonance and Raman scattering on novel hybrid poly-p-phenylenebenzobisoxazole (PBO) fibers with copper phthalocyanine

ABSTRACT As was shown in the previous study using X-ray analyses, poly-p-phenylene benzobisoxazole fibers can accommodate copper phthalocyanine molecules with a molecularly-dispersed state in the fiber structure. It is necessary for us to investigate the presence/absence of chemical interactions between the two molecules mentioned above for the purpose to make clear the mechanism why such characteristic structures with the well dispersion of copper phthalocyanine molecules in the hybrid fiber were realized. Spectroscopic analyses based on electron spin resonance and Raman scattering were adopted. Because the copper phthalocyanine molecule take a plane form having D4h symmetry in an ideal state, the spectra from the molecule would express the consequences based on its symmetry as the shape of the spectrum; the presence of characteristic bands in the spectra would be a proof of the existing state of copper phthalocyanine and poly-p-phenylene benzobisoxazole molecules in the hybrid fiber. It is found that both the spectroscopic methods suggested that there were no chemical bond observed between the two molecules of copper-phthalocyanine and poly-p-phenylene benzobisoxazole in the hybrid fiber.