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Keywords = polyphenylsilsesquioxane

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13 pages, 2607 KB  
Article
Ladder Polyphenylsilsesquioxanes and Their Niobium–Siloxane Composite as Coating Materials: Spectroscopy and Atomic Oxygen Resistance Study
by Ulyana S. Andropova, Rinat R. Aysin, Olga A. Serenko, Tatyana O. Ershova, Anton A. Anisimov and Vladimir N. Chernik
Polymers 2023, 15(15), 3299; https://doi.org/10.3390/polym15153299 - 4 Aug 2023
Cited by 4 | Viewed by 2190
Abstract
In order to expand the range of materials that can be used in outer space and in development of small spacecraft, ladder polyphenylsilsesquioxanes with different molar weights and the Nb-siloxane composites based on them were studied. The properties of the polymer films were [...] Read more.
In order to expand the range of materials that can be used in outer space and in development of small spacecraft, ladder polyphenylsilsesquioxanes with different molar weights and the Nb-siloxane composites based on them were studied. The properties of the polymer films were studied, including tests in an oxygen plasma flow. Both initial and filled ladder polymers feature extremely low erosion coefficients in the region of 10–26 cm3/atom O at a high fluence of atomic oxygen of 1.0 × 1021 atom O/cm2. Ladder polyphenylsilsesquioxane films irradiated with atomic oxygen (AO) retain their integrity, do not crack, and exhibit good optical properties, in particular, a high transmittance. The latter slightly decreases during AO exposure. The Nb-siloxane filling retains the AO resistance and slight decrease in optical transmission due to diffuse scattering on the formed Nb-[(SiO)x] nanoparticles. Ladder polyphenylsilsesquioxanes demonstrate their suitability for creating protective, optically transparent coatings for small spacecraft that are resistant to the erosive effects of incoming oxygen plasma. Full article
(This article belongs to the Special Issue Polymer-Containing Nanomaterials: Synthesis, Properties, Applications)
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13 pages, 2141 KB  
Article
Pervaporation and Gas Separation Properties of High-Molecular Ladder-like Polyphenylsilsesquioxanes
by Tatiana S. Anokhina, Tatyana O. Ershova, Anton A. Anisimov, Maxim N. Temnikov, Evgenia A. Grushevenko, Ilya L. Borisov, Alexey V. Volkov and Aziz M. Muzafarov
Polymers 2023, 15(15), 3277; https://doi.org/10.3390/polym15153277 - 2 Aug 2023
Cited by 8 | Viewed by 2485
Abstract
This paper presents the results of studies on the pervaporation properties (for benzene/hexane mixtures) and gas permeability (for He, H2, N2, O2, CO2, CH4, C2H6, and C4H [...] Read more.
This paper presents the results of studies on the pervaporation properties (for benzene/hexane mixtures) and gas permeability (for He, H2, N2, O2, CO2, CH4, C2H6, and C4H10) of ladder-like polyphenylsesquioxanes (L-PPSQ) with improved physical and chemical properties. These polymers were obtained by condensation of cis-tetraphenylcyclotetrasiloxanetetraol in ammonia medium. The structure of L-PPSQ was fully confirmed by a combination of physicochemical analysis methods: 1H, 29Si NMR, IR spectroscopy, HPLC, powder XRD, and viscometry in solution. For the first time, a high molecular weight of the polymer (Mn = 238 kDa, Mw = 540 kDa) was achieved, which determines its improved mechanical properties and high potential for use in membrane separation. Using TGA and mechanical analysis methods, it was found that this polymer has high thermal (Td5% = 537 °C) and thermal-oxidative stability (Td5% = 587 °C) and good mechanical properties (Young’s module (E) = 1700 MPa, ultimate tensile stress (σ) = 44 MPa, elongation at break (ε) = 6%), which is important for making membranes workable under various conditions. The polymer showed a high separation factor for a mixture of 10% wt. benzene in n-hexane (126) at a benzene flow of 33 g/(m2h). Full article
(This article belongs to the Section Polymer Chemistry)
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19 pages, 4472 KB  
Article
Interaction of Polyphenylsilsesquioxane with Various β-Diketonate Complexes of Titanium by Mechanochemical Activation
by Vitalii Libanov, Alevtina Kapustina, Nikolay Shapkin, Anna Tarabanova and Anna Rumina
Powders 2023, 2(2), 445-463; https://doi.org/10.3390/powders2020027 - 8 Jun 2023
Viewed by 1890
Abstract
In the present work, we studied the interaction of polyphenylsilsesquioxane with various β-diketonate complexes of titanium by mechanochemical activation. Polyphenylsilsesquioxane, bis-(2,4-pentanedionate) titanium dichloride, bis-(1-phenyl-1,3-butanedionate) titanium dichloride, and bis-(1,3-diphenyl-1,3-propanedionate) titanium dichloride were used as starting reagents. Various chemical and physicochemical methods of analysis were [...] Read more.
In the present work, we studied the interaction of polyphenylsilsesquioxane with various β-diketonate complexes of titanium by mechanochemical activation. Polyphenylsilsesquioxane, bis-(2,4-pentanedionate) titanium dichloride, bis-(1-phenyl-1,3-butanedionate) titanium dichloride, and bis-(1,3-diphenyl-1,3-propanedionate) titanium dichloride were used as starting reagents. Various chemical and physicochemical methods of analysis were used to study the synthesis products. The composition of the obtained compounds has been determined. It is shown that under conditions of mechanochemical activation, high-molecular-weight products with a Si/Ti ratio different from the specified ones are formed. In addition, under the action of mechanical stresses, the initial titanium complexes (except for acetylacetonate complex) polymerize with the formation of coordination of high-molecular-weight compounds, which are destroyed by the addition of ethyl alcohol. It has been established that with an increase in the volume of the organic ligand, titanium atoms enter the polymer siloxane chain to a lesser extent. This work is aimed at finding efficient and environmentally friendly methods for the synthesis and modification of organometallic macromolecular compounds. Full article
(This article belongs to the Special Issue Particle Technologies)
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14 pages, 14510 KB  
Article
Nano-Modified Meta-Aramid Insulation Paper with Advanced Thermal, Mechanical, and Electrical Properties
by Xiying Qian, Long Yue, Keruo Jiang, Hongxue Wang, Jingyin Lai, Hailiang Xia and Chao Tang
Processes 2022, 10(1), 78; https://doi.org/10.3390/pr10010078 - 30 Dec 2021
Cited by 10 | Viewed by 4014
Abstract
Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid [...] Read more.
Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarization, and a reduction in defects at the interface. Full article
(This article belongs to the Special Issue Thermodynamics: Modeling and Simulation)
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16 pages, 5166 KB  
Article
A Versatile Equilibrium Method for the Synthesis of High-Strength, Ladder-like Polyphenylsilsesquioxanes with Finely Tunable Molecular Parameters
by Tatyana O. Ershova, Anton A. Anisimov, Maxim N. Temnikov, Maxim A. Novikov, Mikhail I. Buzin, Galina G. Nikiforova, Yulia S. Dyuzhikova, Ivan E. Ushakov, Olga I. Shchegolikhina and Aziz M. Muzafarov
Polymers 2021, 13(24), 4452; https://doi.org/10.3390/polym13244452 - 18 Dec 2021
Cited by 19 | Viewed by 3977
Abstract
A versatile equilibrium method for synthesizing ladder-like polyphenylsilsesquioxanes (L-PPSQs) with various molecular weights (from 4 to 500 kDa) in liquid ammonia was developed. The effect of diverse parameters, such as temperature, monomer concentration, reaction time, addition or removal of water from the reaction [...] Read more.
A versatile equilibrium method for synthesizing ladder-like polyphenylsilsesquioxanes (L-PPSQs) with various molecular weights (from 4 to 500 kDa) in liquid ammonia was developed. The effect of diverse parameters, such as temperature, monomer concentration, reaction time, addition or removal of water from the reaction medium, on the polycondensation process was determined. The molecular weight characteristics and structure of the L-PPSQ elements obtained were determined by GPC, 1H, 29Si NMR, IR spectroscopy, viscometry, and PXRD methods. The physicochemical properties of L-PPSQs were determined by TGA and mechanical analyses. Full article
(This article belongs to the Special Issue Organosilicon Polymers: From New Structures towards New Properties)
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12 pages, 4437 KB  
Article
Void Formation/Elimination and Viscoelastic Response of Polyphenylsilsesquioxane Monolith
by Yusuke Daiko, Yuki Oda, Sawao Honda and Yuji Iwamoto
Materials 2018, 11(5), 846; https://doi.org/10.3390/ma11050846 - 19 May 2018
Viewed by 3635
Abstract
Polyphenylsilsesquioxane (PhSiO3/2) particles as an organic-inorganic hybrid were prepared using sol-gel method, and monolithic samples were obtained via a warm-pressing. The reaction mechanism of particles’ polymerization and transformation to the monolith under the warm-press were investigated using solid state 29Si [...] Read more.
Polyphenylsilsesquioxane (PhSiO3/2) particles as an organic-inorganic hybrid were prepared using sol-gel method, and monolithic samples were obtained via a warm-pressing. The reaction mechanism of particles’ polymerization and transformation to the monolith under the warm-press were investigated using solid state 29Si nuclear magnetic resonance (NMR) spectrometer, thermal gravimetric-differential thermal analyzer (TG-DTA), mass spectrometer (MS) and scanning electron microscope (SEM). Transparent and void-free monoliths are successfully obtained by warm-pressing above 180 °C. Both the terminal –OH groups on particles’ surface and warm-pressing are necessary for preparation of void-free PhSiO3/2 monolith. From the load-displacement measurement at various temperatures, a viscoelastic deformation is seen for PhSiO3/2 monolith with voids. On the other hand, an elastic deformation is seen for void-free PhSiO3/2 monolith, and the void-free monolith shows much higher breakdown voltage. Full article
(This article belongs to the Section Advanced Materials Characterization)
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