The transient absorption spectra (charge-resonance (CR) band) of polyfZV-vinylcarbazole) (PVCz) and the copolymers of -vinylcarbazole (VCz) with methyl methacrylate and vinyl acetate were measured by laser photolysis to investigate the charge delocalization in the polymers. For the copolymers in which the fraction of VCz (/vcz) is less than 0.4, the CR band appeared at ca. 1800 nm. In the case of /vcz > 0.5, the CR band was shifted to longer wavelengths with increasing /vcz and the copolymer with /vcz = 0.83 showed the same transient absorption spectrum as PVCz. By considering the sequential distribution of the copolymers, the charge formed in PVCz was found to be delocalized among more than two chromophores. For the copolymer (/vcz = 0.07) having no neighboring chromophore interaction, the radical-cation transfer to a series of amines was measured to investigate the free energy change (AG) dependence of an electron-transfer rate constant (k"). The result shows that there is a linear relationship between log ke and AG. By using this relationship, the stabilization energy of the carbazole radical cation in PVCz was estimated to be 0.5 ± 0.1 eV. This value is larger than that of the carbazole dimer radical cation, i.e., the stabilization by the charge delocalization among more than two chromophores is stronger than that of the dimer radical cation.

A comparative structural investigation of the characteristics of polymer liquid‐crystalline solutions including Kevlar® (PPD‐T)/sulfuric acid, poly(Cl‐p‐phenylene terephthalamide) (Cl‐PPD‐T)/sulfuric acid, poly(γ‐benzyl‐L‐glutamate) (PγBLG)/dioxane, and hydroxypropyl cellulose (HPC)/water was undertaken. Experimental procedures included polarized light microscopy, light scattering, absorption spectra, and x‐ray diffraction on solutions at various concentrations and temperatures. Both the two‐phase region at the onset of liquid‐crystal formation and the wholly anisotropic phase were investigated. Each solution exhibited distinctive characteristics. The PPD‐T and Cl‐PPD‐T solutions were nematic, and the PγBLG and HPC solutions were cholesteric. In the two‐phase region the PPD‐T, Cl‐PPD‐T, and PγBLG (but apparently not the HPC) exhibited negatively birefringent spherulites and aggregates of spherulites. The HPC solutions only exhibited spherulitic structures in the single‐phase anisotropic system. The structures and orientations in the anisotropic phase for the various polymer solutions is considered. The helicoidal structural characteristics of the PγBLG and HPC solutions are contrasted.

Molecular orientation of mono-and multilayered polyimide films has been studied by the fluorescence polarization method. The high sensitivity of the fluorescence method enabled us to measure the orientation of extremely thin films. A perylene pigment was synthesized as a fluorescence probe and was introduced into polyamic acid chains. Layered films of polyamic acid alkylamine salt were prepared by the Langmuir-Blodgett (LB) technique. Even after chemical conversion to polyimide, molecular axes of the polyimide chain retained a 2-dimensional distribution in the substrate plane. The perylene probes in the LB film showed fluorescence anisotropy, and their second moment of orientation, (cos2 w ) , was determined to be 0.54-0.58 by 2-dimensional analysis. The principal axis of the orientation was in agreement with the dipping direction. These measurements reveal the orientation of a "genuine surface" of molecular dimension. This LB polyimide surface aligns highly liquid-crystal molecules as a rubbed surface of polyimide film does. The ability of LB films to orient a liquid crystal correlated with the surface orientation measured by the fluorescence method.

A new method for measuring molecular orientation in polymer solids is developed involving the use of the polarization phenomena of fluorescence emitted from fluorescent groups dispersed in the media. This fluorescence method makes it possible to measure not only the extent of orientation but also the types of orientation. The theoretical background of this method is described and the theoretical patterns of the angular distribution of degree of polarization of fluorescence are given for several types of orientation, including random, perfect uniaxial, partial uniaxial, and perfect biaxial orientations. It is proved that this method is applicable to symmetrical biaxial orientations for which other optical methods fail to provide information. The procedure of this method is to measure the angular distribution of polarized components of fluorescence intensity emitted from the oriented samples. Examples are given for various orientations of poly(vinyl alcohol) films. The process of transformation in orientation pattern is observed in the course of biaxial stretching of the film. An apparatus for continuous measurements is described.