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141.
There has been a great demand in the field of kitchen appliances to develop transparent water repellent films which have high heat-resistance around 300°C. However, those films have not been obtained by conventional sol–gel methods. In this paper, we propose a new method for fabricating transparent water repellent films with high heat-resistance using the sol–gel method, in which silicon or germanium substrates were coated with a solution including tetraethoxysilane (Si(OC2H5)4) and (2-perfluorooctyl)ethyltrimethoxysilane (CF3(CF2)7C2H4Si(OCH3)3), followed by ‘ammonia-treatment' and annealed at 300°C. The contact angles of water on the ammonia-treated film maintained its initial value, 110° after the heat treatment at 300°C for 250 h while those on the untreated film decreased to 70°, indicating that the ammonia-treatment improves heat-resistance on the film. The mechanism of ammonia-treatment was inferred from FT-IR results; the ammonia-treatment should accelerate hydrolysis and polymerization of FAS and TEOS molecules, resulting in high density of siloxane bonds between FAS and silica glass. These bonds suppress the evaporation of FAS molecules from the film during the heat treatment at 300°C, thus the film has high heat-resistance. 相似文献
142.
To clarify the kinetics and mechanisms of o/w microemulsion polymerization, the o/w microemulsion polymerizations of styrene were carried out with different kinds and types of initiators and surfactants. The number of polymer particles and the molecular weight of polymer formed were not affected by the kinds and types of initiators and surfactants. The rate of polymerization with different kinds of azo-type oil-soluble initiators with widely different water-solubility was almost the same, but was much lower than that with KPS. A kinetic model proposed by us could mostly explain the kinetic behavior except for the difference in the polymerization rate with KPS and that with oil-soluble initiators. 相似文献
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144.
Fumiko Kimura Tsunehisa Kimura Akira Sugisaki Mamoru Komatsu Hiroaki Sata Eiko Ito 《Journal of Polymer Science.Polymer Physics》1997,35(16):2741-2747
In situ Fourier transform infrared (FTIR) measurements were carried out to elucidate conformation changes occurring during the isothermal melt crystallization of poly(ethylene-2,6-naphthalate) (PEN). Based on the band assignments for the components of the amorphous, α-crystal form, and β-crystal form of PEN in film samples, the in situ data was analyzed in terms of the amorphous- and crystal-trans conformations. It was observed at a higher isothermal crystallization temperature that the formation of amorphous-trans conformations precedes the growth of crystals. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2741–2747, 1997 相似文献
145.
Yu Chen Zu-En Huang Rui-Fang Cai Bo-Cheng Yu Osamu Ito Jun Zhang Wei-Wen Ma Chao-Fan Zhong Li Zhao Yu-Fen Li Lei Zhu Mamoru Fujitsuka Akira Watanabe 《Journal of Polymer Science.Polymer Physics》1997,35(8):1185-1190
The phenomena of aggregation and coalescence of fullerenes in the UV-laser ablation time-of-flight mass spectrometric investigation of C60-modified poly(N-vinylcarbazole) both in the positive and in the negative ion channels have been observed. The results indicate that in C60 chemically modified PVK (C60–PVK) copolymer the nascent fullerene fragments ruptured from main chain can easily coalesce into large fullerenes through collisions, whereas in the C60-doped PVK the aggregation and coalescence of C60 were relative weak due to nonbounding action and incomplete charge transfer behavior between C60 and PVK. Furthermore, the photoinduced electron transfer behavior between C60 and carbazole units in the C60 chemically modified poly(N-vinylcarbazole) in benzonitrile by laser flash photolysis at 355 nm has also been investigated. Efficiency of the anion radical of C60 in copolymer at 1080 nm is higher than that of the C60-doped poly(N-vinylcarbazole) polymers. The formation of a C60 radical anion may be ascribed to photoinduced electron transfer between C60 pendanted on the main chain backbone and the inter-, and intrachain carbazole units in the copolymer. © 1997 John Wiley & Sons, Inc. 35 : 1185–1190, 1997 相似文献
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147.
The photopatternability of various silyl hydride containing organosilicone resins containing the photobase generators N‐methylnifedipine or O‐(2‐nitrobenzyl)‐N‐octyl carbamate have been examined, with the goal of identifying potential photopatternable compositions with high thermal stability after cure. Two different categories of silicone resins have been prepared from combinations of diphenylsiloxane and methyl and hydrogen silsesquioxane units and a combination of phenyl and hydrogen silsesquioxane monomer units. The photobase generators were incorporated into these resins at concentrations up to 10 weight percent. UV‐irradiation of micrometer thick silicone resin‐photobase films through a photomask, under an air atmosphere, yielded micrometer scale features after development. Photopatternable compositions have been identified with photosensitivities of less than 50 mJ/cm2. The photopatterning process is believed to proceed by base‐catalyzed reaction of resin‐based silanol groups with neighboring silyl hydride groups to yield thermally stable siloxane crosslinks. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
148.
149.
提出了一种结构模型来分析由工艺引起的波导侧壁起伏对于聚合物波导光学梳状滤波器的滤波特性的影响。含氟聚酰亚胺高分子聚合物制备多级马赫一曾德尔串联型光学梳状滤波器件的工作参量为中心波长1550nm,波长间隔为0.8nm,40通道的波长交错分离。模拟计算:表明,对由高分子聚合物材料制备的多级马赫-曾德尔串联型光学梳状滤波器件,其主要影响是增大了信道之间的串扰,中心波长1550nm处的信道串扰由理想情况下的-40dB降为-12dB,极大地影响了器件的性能。在此基础上,提出一种改善光学梳状滤波器串扰性能的新结构,该结构由多级马赫-曾德尔耦合器和微环共振滤波器串接构成,40个通道的串扰改善为-0dB以下。 相似文献
150.
Tachikawa T Chung HR Masuhara A Kasai H Oikawa H Nakanishi H Fujitsuka M Majima T 《Journal of the American Chemical Society》2006,128(50):15944-15945
The growth dynamics of fluorescent perylene nanocrystals, which are fabricated by the reprecipitation method, was investigated using in situ and ex situ single-particle fluorescence measurements. A red shift in the emission maxima as the aging time increased was observed by single-particle fluorescence spectral measurements. The number and size of the nanocrystals increased with the increasing aging time in water. It was concluded that the metastable intermediates, such as clusters and initial nanoparticles, are relevant for the early stages of nucleation and growth of the perylene nanocrystals. 相似文献