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991.
Mitsuru Ueda Hideaki Toyoda Tomonari Nakayama Tomomi Abe 《Journal of polymer science. Part A, Polymer chemistry》1996,34(1):109-115
Poly(ether ether ketone)s containing alkyl groups were prepared by nucleophilic substitution reaction of alkyl-substituted difluoro diaryl ethers with hydroquinone or by electrophilic substitution reaction of alkyl-substituted diaryl ether with 4,4′-oxydibenzoic acid in PPMA. Polycondensations proceeded smoothly and produced polymers having inherent viscosities up to 0.5-–1.6 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, and chloroform at room temperature. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight loses of the polymers were observed in the range above 450°C in nitrogen atmosphere. The glass transition temperatures of the polymers ranged from 128 to 146°C. Furthermore, Polymer 3b functioned as a photosensitive resist of negative type for UV radiation. The resist had a sensitivity of 42 mJ/cm2 and a contrast of 2.5, when it was postbaked at 100°C for 10 min, followed by development with THF/acetone at room temperature. © 1996 John Wiley & Sons, Inc. 相似文献
992.
993.
Takashi Inoue Hisashi Sugiyama Kazuo Nate Akiko Mizushima 《Macromolecular Symposia》1989,24(1):189-199
Two new families of photosensitive organo-silicon polymers are described. One is based on the Si-Si σ-bond photochemistry and another is based on the combinations of new alkaline-soluble organosilicon polymers with diazoquinone photosensitizers. Both of these photoactive materials not only give positive photoresist formulations but can act as oxygen reactive ion etch masks in the double-layer resist scheme to finally offer steep submicrometer organic patterns with high aspect ratio. 相似文献
994.
995.
996.
Polymerization of 1,3-butadiene with the CoBr2(PPh3)2/MgCl2/SiPh2(OCH3)2-Al(CH3)3 catalyst system was conducted in the presence of ethylene. It was found that addition of ethylene causes a marked decrease in the molecular weight of polybutadiene although ethylene is not incorporated at the chain-end. The structure of chain-ends was analyzed using very low molecular-weight polybutadiene produced in the presence of ethylene, which led to the conclusion that 1,2 and 2,1 insertion reactions predominate at the initiation and propagation steps, respectively. 相似文献
997.
998.
999.
Simultaneous double-color high-power continuous wave (CW) Raman fiber laser at 1239 nm and 1484 nm is demonstrated which uses CW 8.4 W Yb-doped double-clad fiber laser at 1064 nm as a pump, 1 km phosphosilicate fiber, and cascaded cavities consisting of two pairs of fiber Bragg grating (FBG) mirrors. Maximum output powers are 0.65 W at 1239 nm and 0.97 W at 1484 nm with a 50%/50% output mirror reflectivity pair, and 0.37 W at 1239 nm and 1.06 W at 1484 nm with a 75.5%/50% pair. The output characteristics of this laser for different FBG mirror reflectivities are reported. 相似文献
1000.
Kazumasa Ueda Toyonari Sugimoto Toshiji Tada Kei‐ichiro Nishimura Tomoyuki Mochida 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):400-402
In the tetramethylarsonium salt of 2,5‐dichloro‐7,7,8,8‐tetracyanoquinodimethanide [systematic name: tetramethylarsonium 2,2′‐(2,5‐dichlorocyclohexa‐2,5‐diene‐1,4‐diylidene)bis(propanedinitrile)], C4H12As+·C12H2Cl2N4? or [As(CH3)4](C12H2Cl2N4), the cation lies disordered about a twofold axis and the radical ion lies about an inversion center forming a uniform [interplanar distance 3.35 (2) Å] and one‐dimensional stacking without any slip. The electrical conductivity of the single crystal at room temperature was less than 10?9 S cm?1, and the temperature dependence of paramagnetic susceptibility obeyed a one‐dimensional antiferromagnetic Heisenberg model with a spin‐exchange integral of 83 K in the temperature range 1.8–320.0 K. 相似文献