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Luminescent stilbenoid chromophores with diethoxysilane end groups are prepared via Heck reactions. Diethoxysilane-substituted styrenes are used as vinylic components, thus allowing the combined connection of the chromophore to the silane moiety with an extension of the π-system. Monodisperse oligo(phenylenevinylene)s of different conjugation lengths and bromine or iodine as reactive sites are used as coupling partners. Electrical and optical properties are tuned via the length of the conjugated system, electron withdrawing cyanide and electron donating alkoxy side chains, the latter guarantee high solubility of the final compounds.Dedicated to Prof. Dr. H. Ringsdorf on the occasion of his 75th birthday 相似文献
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Takuya Ogawa Jun Watanabe Yoshito Oshima 《Journal of polymer science. Part A, Polymer chemistry》2009,47(10):2656-2663
A catalyst‐free polysiloxane synthetic process that uses high temperature and pressure water for the hydrolysis and subsequent polycondensation of phenyltrimethoxysilane was studied in detail to gain insights into the reaction mechanism. It was suggested that this process is essentially composed of two stages: (1) oligomerization of phenyltrimethoxysilane yielding low‐molecular weight species with high contents of silanol and methoxy groups and (2) polycondensation of the oligomers yielding high‐molecular weight species. The use of a preformed oligosiloxane as a starting material was informative to understand the polycondensation stage. A modified synthetic process in which a stop valve was introduced to control the internal pressure was developed based on the understanding of the present process. This modified process enabled a two‐stage reaction resulting in a discernible increase of the molecular weight of polysiloxane. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2656–2663, 2009 相似文献
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A palladium NNC‐pincer complex at a 5 mol ppm loading efficiently catalyzed the Hiyama coupling reaction of aryl bromides with aryl(trialkoxy)silanes in propylene glycol to give the corresponding biaryls in excellent yields. This method was applied to the syntheses of adapalene and a biaryl‐type liquid‐crystalline compound, as well as to the derivatization of dextromethorphan and norfloxacin. ESI‐MS and NMR analyses of the reaction mixture suggested the formation of pentacoordinate spirosilicate intermediates in situ. Preliminary theoretical studies revealed that the glycol‐derived silicate intermediates formed in situ are quite reactive silicon reagents in the transmetalation step. 相似文献
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Filip Ciesielczyk Karolina Szwarc‐Rzepka Teofil Jesionowski 《Surface and interface analysis : SIA》2013,45(6):998-1007
Preparation of a new group of hybrid fillers, of SiO2/silane/oligomeric silsesquioxane type, characterised by specific desirable physicochemical properties, was studied. Synthetic SiO2 was precipitated by the emulsion method. At first, as a result of improved adhesion between SiO2 and selected POSS compound, SiO2 surface was functionalised with alkoxysilanes containing characteristics functional groups. Functionalised SiO2 was used in the process of hybrid filler preparation according to hydrolytic condensation using methacryl POSS® mixture. To evaluate potential application of such fillers, SiO2 systems, bifunctionalised using innovative method, were thoroughly characterised to determine their physicochemical properties as well as the effectiveness of functionalisation with silanes and POSS compound. Proposed method of SiO2 surface modification using selected alkoxysilanes and oligosilsesquioxanes is innovative and gives very promising results. Bifunctionalisation of inorganic fillers with those compounds will substantially extended the range of their applications and probably will lead to improvement of mechanical properties of final polymer composites and reduction in the cost of their production which is the main feature of this research. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Dennis Meier Volker Huch Guido Kickelbick 《Journal of polymer science. Part A, Polymer chemistry》2021,59(20):2265-2283
Polysiloxanes are an important class of polymers for optoelectronic applications. Novel polysiloxanes with high-refractive index (RI) based on phenanthrenyl-substituted monomers are prepared by a polycondensation reaction starting from various substituted dialkoxysilanes as monomers. The substitution patterns on the Si atom are systematically changed to vary the properties of the linear polymers as well as the final cured material. The two monomers with polycyclic aromatic side groups 9-phenanthrenylmethyldimethoxysilane and 9-phenanthrenylphenyldimethoxysilane are synthesized and fully characterized, including their single crystal X-ray structures. Linear polysiloxanes with variations in hydride, methyl, vinyl, phenyl, and phenanthrenyl side group content are prepared by acid- and base-catalyzed polycondensation reactions. Both Si H and Si vinyl substituted polymers with molecular weights up to 30 kDa and adjustable RI's from 1.52 to 1.63 are obtained and the thermally cured by Pt-catalyzed hydrosilylation reactions. Polysiloxane resins are obtained with high-RI's, optical transmittance above 95% and thermal stabilities up to 420°C. Long-term thermal stability tests show transmittance values above 85% even after 60 days of thermal treatment at 180°C. 相似文献
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Cationic Emulsion Polymerization of Octamethylcyclotetrasiloxane (D4) in Mixtures with Alkoxysilanes
Janusz Kozakiewicz Joanna Trzaskowska Micha Kdzierski Joanna Sotysiak Elbieta U. Stolarczyk Izabela Ofat-Kawalec Jarosaw Przybylski 《Molecules (Basel, Switzerland)》2022,27(3)
The cationic emulsion polymerization of octamethylcyclotetrasiloxane (D4) in mixtures with methyltriethoxysilane (MTES) and vinyltriethoxysilane (VTES) was studied by FTIR ATR, GC, the development of a toluene insoluble fraction of the polymer and a gravimetric analysis. The polymerization of D4 alone was also conducted for comparison and, additionally, the development of molecular weight of polydimethylsiloxane (PDMS) obtained in that process was studied by GPC. Dodecylbenzenesulphonic acid (DBSA) was used as a surfactant and catalyst. The process was carried out in a “starved feed” mode by adding dropwise the monomer mixture to the aqueous solution of DBSA. FTIR ATR spectra were recorded by the sensor placed in the probe tip of a ReactIR 15TM apparatus. It was found that the silicone polymer formation proceeded faster when D4 was polymerized in the mixture with alkoxysilanes, especially in the beginning of the process, and that already at the beginning of the process, the partly crosslinked polymer was formed. The induction period of ca. 30 min was observed and the concentration of cyclic siloxanes (D4 and decamethylcyclopentasiloxane—D5) remained at a very low level in the course of the reaction and only traces were detected in the final product. The particle size development in the course of the reaction was also studied and it was found that the particle size distribution was bimodal and was broadening as the reaction proceeded, though this phenomenon was less distinct when D4 was polymerized in the mixtures with alkoxysilanes. The structure of the reaction product was confirmed by 29Si NMR. 相似文献
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