Copolyamides and copolyesters containing the phenoxasilin ring

Copolyamides and copolyesters containing the phenoxasilin ring were prepared from 2,8-dichloroformyl-10,10-diphenylphenoxasilin, isophthaloyl chloride and m-phenylenediamine or bisphenol A by interfacial polycondensation in chloroform-aqueous alkali mixture. They were obtained in yields of 80% or above and at relatively high viscosities up to 1.30 dl/g. The copolymers with high phenoxasilin content were freely soluble in dimethylacetamide, dimethylformamide and N-methyl-2-pyrrolidone, but decreasing phenoxasilin content led to copolymers with slight solubilities in these solvents; the copolyesters also dissolved in chloroform, m-cresol and phenol-sym tetrachloroethane (60:40 in wt%). Flexible transparent films were obtained from chloroform solutions of the copolyesters, but the films cast from DMF solutions of the copolyamides became brittle as the phenoxasilin content decreased. The phenoxasilin-containing copolymers hardly degraded below 400° and had good thermal stability. Introduction of the phenoxasilin ring into the polymer backbones by copolycondensation did not reduce thermal stability.     

Absorption Spectra of Sodium Aluminate Solutions

The absorption spectra of sodium aluminate solutions have been examined at different concentrations. As a result, it was found that the characteristic absorption band due to aluminate ion shows a λ_max at 265–270 mm?.     

High-pressure synthesis of cyclic phenylacetylene oligomer

New conjugated oligomers were prepared by reacting phenylacetylene under high pressure of 0.11 to 0.92 GPa at 100–200°C for 0–5 h. The number-average molecular weight M?_n, the weight-average molecular weight M?_w, and the oligomer yield increased with pressure, tem-perature, and time. The average molecular weight of the oligomer showed the maximum value (M?_n: 830, M?_w: 2400) under 0.92 GPa, the maximum pressure, where phenylacetylene was oligomerized at a constant temperature. The structure of the oligomer was investigated from ESR, infrared, UV–VIS, field desorption mass (FDMS) spectra, and ¹³C NMR spec-trum. Analysis of the FDMS spectrum revealed that the molecular weight of the oligomer was multiple of the monomer. ¹³C NMR spectrum of the oligomer showed the absence of sp-carbon (? C?). We found that the oligomer had a cyclic structure. The cyclic oligomers of pentamer or more were new compounds. © 1995 John Wiley & Sons, Inc.     

Output and picosecond amplification characteristics of an efficient and high-power discharge excimer laser

Improvements in output pulse energy and efficiency of a conventional capacitor-transfer-type discharge excimer laser with automatic preionization have been achieved by extending the discharge volume and resulting moderate pumping of the active medium. The discharge laser produces a pulse energy of more than 1 J for XeCl, KrF, and ArF lasers in square beams of about 2×2 cm², and the maximum overall efficiency observed is 2.9% for XeCl, 3.2% for KrF and 1.8% for ArF. The laser device has been involved in a picosecond ( 32 ps) XeCl laser amplification system, and was operated as an amplifier at a repetitive frequency of 10 Hz. Saturation fluence for XeCl laser was measured to be 1.4 mJ/cm², and the picosecond pulse energy of 40 mJ was extracted from the amplifier.On leave from Ebara Corp., 6-6-7, Ginza, Chuo-ku, Tokyo 104, JapanOn leave from Mitsubishi Heavy Industries, LTD., 4-6-22, Kan-on shinmachi, Nishi-ku, Hiroshima 733, Japan