Narrow Results

Etching dynamics of urethane–urea copolymer film was investigated by utilizing nanosecond time-resolved interferometry and tuning excitation wavelength. From the behavior of fringe pattern deformation at the irradiated areas, it is considered that irradiated polymer film was decomposed more effectively with decrease in excitation wavelength. Excitation wavelength dependence of etching dynamics of urethane–urea copolymer film was not well interpreted in terms of total energy density which was stored within the polymer film due to laser irradiation, while photochemical and photothermal processes can explain mostly the results of shorter wavelength (≤ 475 nm) and longer wavelength (≥ 530 nm) excitations, respectively.

In this paper, a polyurethane (PU) was prepared from polyether polyols, isophorone diisocyanate and 2-[4-(N,N-hydroxyethyl)-aminophenyl-azo]-6-nitrobenzothiazole. The T_g and T_d (5% mass loss) are 112°C and 273°C, respectively. The refractive index, transmission loss and Sellmyer coefficients of PU were investigated. Polymeric 1 × 2 digital optical switch (DOS) and 2 × 2 Mach–Zehnder interferometer (MZI) thermo-optic switches based on PU as waveguide at the infrared communication wavelength 1.55 μm were designed and simulated. Simulation results showed that the power consumption of 1 × 2 DOS is only 0.60 mW; and the response times of 1 × 2 and MZI switches are 9 ms and 2.5 ms, respectively.

A surfactant-assisted method for preparing colloidal spheres with narrow size distribution from a polydispersed azo polymer has been developed in this work. The colloidal spheres were formed through gradual hydrophobic aggregation of the polymeric chains in THF-H₂O dispersion media, which was induced by a steady increase in the water content. Results showed that the addition of a small amount of surfactant (SDBS) could significantly narrow the size distribution of the colloidal spheres. The size distribution of the colloidal spheres was determined by the concentrations of azo polymer and the amount of surfactant in the systems. When the concentrations of polymer and surfactant amount were in a proper range, colloidal spheres with narrow size distribution could be obtained. The colloidal spheres formed by this method could be elongated along the polarization direction of the laser beams upon Ar⁺ laser irradiation. The colloidal spheres are considered to be a new type of the colloid-based functional materials.