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891.
应用测接触角并辅以XPS分析,研究了一种共聚物(MMA-Co-4Vp)在各种表面成型条件下及介质环境中的表面酸碱性变化,探索了其变化规律及导致变化的原因。 相似文献
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In order to investigate synthetic route of polyperfluorotriazine elastomer, 2-trifluoromethyl4,6-bis(4′-iodo-2′-oxahexafluorobutyl)-1,3,5-triazine (1), a novel triazine monomer, was synthesized from 5-iodo-3-oxa-octafluoropentanesulfonyl fluoride (2) in eight-steps. 2 was reduced by potassium sulfite to the sulfinate (3), which was treated with hydriodic acid to yield 5-iodo-3oxa-hexafluoropentanoic acid (4). Compound 4 was transformed to 5-iodo-3-oxa-hexafluoropentanenitrile (7) through the corresponding ester 5 and amide 6. The desired product 1 was prepared by acylation-cyclodehydration of the imidoylamidine 9, obtained by condensation of the nitrile 7 with the amidine 8.The various methods for the esterification of perfluorocarboxylic acid were studied and a possible mechanism for the transformation of perfluorosulfinate to the corresponding perfluorocarboxylic acid by hydriodic acid was proposed.Crude 1 contained compounds 6, 11, 13, as impurities which were removed by low temperature crystallization followed by filtration through a short alumina column. The monomer 1 was polymerized by UV-irradiation in the presence of Hg with or without solvent. Polyperfluorooxaalkyl triazine 17 thus obtained showed good thermal stability. In the main chain of the polymer there was no weak unit of the uncyclized ring. Polymer 17 had an average molecular weight of ca. 1.33—2.0×10~4 (D. P.=27—42) and the temperature of 10% weight loss in nitrogen was 340℃. 相似文献
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898.
The steric tacticity of polyphenylsilsesquioxanes (PPS) was studied by exeimer fluorescence spectroscopy. It was found that the fluorescence of PPS come mainly from its intramolecular excimers, The experimental results indicated that the steric-structure of PPS is most probably cisisotactic rather than the cis-syndiotactic as suggested in the literature. With the increase in defect content monomer fluorescence intensity increases because of the enhanced mobility of phenyl groups. Molecular weights and molecular weight distributions do not affect the fluorescence spectra of PPS. 相似文献
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