Toshiaki Yatabe

Control of Wavelength Dispersion of Birefringence for Oriented Copolycarbonate Films Containing Positive and Negative Birefringent Units

The wavelength dispersion of birefringence for uniaxially oriented copolycarbonate films containing positive and negative birefringent units has been examined by polarization-modulated transmission spectro-ellipsometry, as a function of copolymerization ratio and stretching parameters. The copolymers were synthesized from 2,2-bis(4-hydroxyphenyl)propane (BPA), 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (BMPF) and phosgene by interfacial polycondensation. The films indicate reverse dispersion in the region of BMPF volume fraction from 0.65 to 0.80. The wavelength dispersion is controlled by the copolymerization ratio. The dispersion change of the 70 mol% BMPF copolycarbonate films as a function of stretching parameters is negligible. These behaviors are explained by the birefringence equation for a multicomponent system of the copolymer.

Optimization and Properties of Zn Doped Indium Oxide Films on Plastic Substrate

In this report, optimization of the Zn content in Zn doped indium oxide (IZO) films deposited on plastic substrates at low temperature (20°C) was investigated in relation to variation of the Zn content from 0 to 15.9 at%. In the series of IZO films, 12.2 at% Zn doped indium oxide films, (IZO(12.2)), showed the lowest resistivity (2.9×10-4 Ωcm). The resistivity of IZO(12.2) films deposited on 100-µm-thick polycarbonate foil was approximately one half of that of ITO films (6×10-4 Ωcm) deposited under comparable conditions. IZO(12.2) films exhibited the lowest resistivity, high transmittance of over 85%, a rapid etching rate and good alkaline durability. The reason for rapid etching rate originates from the amorphous structure of IZO films. The thermal property of IZO(12.2) evaluated by a differential scanning calorimeter (DSC) clarified that the phase transformation from amorphous to crystalline began at 350°C, which meant the structure of IZO(12.2) remained amorphous for a practical temperature of the plastic substrate. Optical gap and Hall measurements revealed that the carrier density was decreased after annealing, whereas, the mobility was increased in relation to a trade off with the carrier density.

Analysis of Extraordinary Birefringence Dispersion of Uniaxially Oriented Poly(2,6-dimethyl 1,4-phenylene oxide)/Atactic Polystyrene Blend Films

The birefringence dispersion of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide) (PPO)/atactic polystyrene blend films has been investigated by polarization-modulated transmission spectro-ellipsometry measurements. The films show reverse birefringence dispersion in the region of PPO volume fraction from 0.21 to 0.29, where the birefringence is negative and close to zero, indicating ordinary refractive index dispersion. The reverse birefringence dispersion can be explained by the birefringence equation of a multicomponent system based on the preconditions that the intrinsic birefringence of each component in the blend is not changed and the form birefringence is ignored. Furthermore, it has been found that the orientation functions change depending on the volume fractions by the new method for obtaining orientation functions from birefringence dispersion.

Control of Birefringence Dispersion of Uniaxially Oriented Poly(2,6-dimethyl 1,4-phenylene oxide)/Atactic Polystyrene Blend Films by Changing the Stretching Parameters

The birefringence dispersion of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide) (PPO)/atactic polystyrene (PS) blend films has been examined as a function of stretching temperature and draw ratio by polarization-modulated transmission spectro-ellipsometry. The normalized dispersion of Δn(450)/Δn(550) of the PPO/PS blends containing 25.6 wt% PPO decreases with increasing temperature between Tg and Tg+15°C at a draw ratio of 3, while it increases above Tg+15°C. The normalized birefringence dispersion as a function of draw ratio at Tg+15°C diverges at a draw ratio between 1.7 and 1.8. These phenomena can be explained by the change of the PS and PPO orientation functions in the birefringence equation of a multicomponent system on the assumptions that the intrinsic birefringence of PS and PPO is not changed by blending and the form birefringence is ignored.