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Search Results (6)

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Keywords = siloxane dendrimers

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13 pages, 1875 KiB  
Article
Approaches to the Functionalization of Organosilicon Dendrones Based on Limonene
by Aleksei I. Ryzhkov, Fedor V. Drozdov, Georgij V. Cherkaev and Aziz M. Muzafarov
Appl. Sci. 2023, 13(4), 2121; https://doi.org/10.3390/app13042121 - 7 Feb 2023
Cited by 2 | Viewed by 1970
Abstract
Previously, we reported the synthesis of carbosilane and carbosilane-siloxane dendrons of various generations based limonene, a natural terpene. Limonene that contains two double bonds, namely cyclohexene and isoprenyl ones, was shown to undergo regioselective hydrosilylation exclusively at its isoprenyl double bond. This finding [...] Read more.
Previously, we reported the synthesis of carbosilane and carbosilane-siloxane dendrons of various generations based limonene, a natural terpene. Limonene that contains two double bonds, namely cyclohexene and isoprenyl ones, was shown to undergo regioselective hydrosilylation exclusively at its isoprenyl double bond. This finding was used to prepare carbosilane dendrons (CDs) with a limonene moiety at the focal point. In this study, we present variants for the functionalization of the cyclohexene double bond by an epoxidation reaction in order to use the resulting dendrons for the preparation of various macromolecular objects, including Janus dendrimers (JDs), dendronized polymers, and macroinitiators. Moreover, it was shown that dendrons with peripheral azide functions could be obtained. These methods offer both the possibilities of the further growth of branches and the addition of polymers with a different nature by the azide–alkyne cycloaddition reaction. Full article
(This article belongs to the Special Issue Functional Polymers: Synthesis, Properties and Applications)
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12 pages, 1060 KiB  
Article
Synthesis of Carbosilane and Carbosilane-Siloxane Dendrons Based on Limonene
by Aleksei I. Ryzhkov, Fedor V. Drozdov, Georgij V. Cherkaev and Aziz M. Muzafarov
Polymers 2022, 14(16), 3279; https://doi.org/10.3390/polym14163279 - 12 Aug 2022
Cited by 7 | Viewed by 2192
Abstract
In this work, carbosilane dendrons of the first, second, and third generations were obtained on the basis of a natural terpenoid, limonene. Previously, we have shown the possibility of selective hydrosilylation and hydrothiolation of limonene. It is proved that during hydrosilylation, only the [...] Read more.
In this work, carbosilane dendrons of the first, second, and third generations were obtained on the basis of a natural terpenoid, limonene. Previously, we have shown the possibility of selective hydrosilylation and hydrothiolation of limonene. It is proved that during hydrosilylation, only the isoprenyl double bond reacts, while the cyclohexene double bond does not undergo into the hydrosilylation reaction. However, the cyclohexene double bond reacts by hydrothiolation. This selectivity makes it possible to use limonene as a dendron growth center, while maintaining a useful function—a double bond at the focal point. Thus, the sequence of hydrosilylation and Grignard reactions based on limonene formed carbosilane dendrons. After that, the end groups were blocked by heptamethyltrisiloxane or butyllithium. The obtained substances were characterized using NMR spectroscopy, elemental analysis and GPC. Thus, the proposed methodology for the synthesis of carbosilane dendrons based on the natural terpenoid limonene opens up wide possibilities for obtaining various macromolecules: dendrimers, Janus dendrimers, dendronized polymers, and macroinitiators. Full article
(This article belongs to the Section Polymer Applications)
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15 pages, 2908 KiB  
Article
Hybrid Polycarbosilane-Siloxane Dendrimers: Synthesis and Properties
by Sergey A. Milenin, Elizaveta V. Selezneva, Pavel A. Tikhonov, Viktor G. Vasil’ev, Alexander I. Buzin, Nikolay K. Balabaev, Andrey O. Kurbatov, Maxim V. Petoukhov, Eleonora V. Shtykova, Lev A. Feigin, Elena A. Tatarinova, Elena Yu. Kramarenko, Sergey N. Chvalun and Aziz M. Muzafarov
Polymers 2021, 13(4), 606; https://doi.org/10.3390/polym13040606 - 17 Feb 2021
Cited by 25 | Viewed by 5159
Abstract
A series of carbosilane dendrimers of the 4th, 6th, and 7th generations with a terminal trimethylsilylsiloxane layer was synthesized. Theoretical models of these dendrimers were developed, and equilibrium dendrimer conformations obtained via molecular dynamics simulations were in a good agreement with experimental small-angle [...] Read more.
A series of carbosilane dendrimers of the 4th, 6th, and 7th generations with a terminal trimethylsilylsiloxane layer was synthesized. Theoretical models of these dendrimers were developed, and equilibrium dendrimer conformations obtained via molecular dynamics simulations were in a good agreement with experimental small-angle X-ray scattering (SAXS) data demonstrating molecule monodispersity and an almost spherical shape. It was confirmed that the glass transition temperature is independent of the dendrimer generation, but is greatly affected by the chemical nature of the dendrimer terminal groups. A sharp increase in the zero-shear viscosity of dendrimer melts was found between the 5th and the 7th dendrimer generations, which was qualitatively identical to that previously reported for polycarbosilane dendrimers with butyl terminal groups. The viscoelastic properties of high-generation dendrimers seem to follow some general trends with an increase in the generation number, which are determined by the regular branching structure of dendrimers. Full article
(This article belongs to the Special Issue Organosilicon Polymers: From New Structures towards New Properties)
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18 pages, 2606 KiB  
Article
Adsorption of Silicon-Containing Dendrimers: Effects of Chemical Composition, Structure, and Generation Number
by Andrey O. Kurbatov, Nikolay K. Balabaev, Mikhail A. Mazo and Elena Yu. Kramarenko
Polymers 2021, 13(4), 552; https://doi.org/10.3390/polym13040552 - 13 Feb 2021
Cited by 7 | Viewed by 2272
Abstract
We studied the conformational behavior of silicon-containing dendrimers during their adsorption onto a flat impenetrable surface by molecular dynamics (MD) simulations. Four homologous series of dendrimers from the 4th up to the 7th generations were modeled, namely, two types of carbosilane dendrimers differing [...] Read more.
We studied the conformational behavior of silicon-containing dendrimers during their adsorption onto a flat impenetrable surface by molecular dynamics (MD) simulations. Four homologous series of dendrimers from the 4th up to the 7th generations were modeled, namely, two types of carbosilane dendrimers differing by the functionality of the core Si atom and two types of siloxane dendrimers with different lengths of the spacers. Comparative analysis of the fractions of adsorbed atoms belonging to various structural layers within dendrimers as well as density profiles allowed us to elucidate not only some general trends but also the effects determined by dendrimer specificity. In particular, it was found that in contrast to the carbosilane dendrimers interacting with the adsorbing surface mainly by their peripheral layers, the siloxane dendrimers with the longer –O–Si(CH3)2–O spacers expose atoms from their interior to the surface spreading out on it. These findings are important for the design of functional materials on the basis of silicon-containing dendrimers. Full article
(This article belongs to the Special Issue Organosilicon Polymers: From New Structures towards New Properties)
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19 pages, 9287 KiB  
Article
A Comparative Study of Intramolecular Mobility of Single Siloxane and Carbosilane Dendrimers via Molecular Dynamics Simulations
by Andrey O. Kurbatov, Nikolay K. Balabaev, Mikhail A. Mazo and Elena Yu. Kramarenko
Polymers 2018, 10(8), 838; https://doi.org/10.3390/polym10080838 - 30 Jul 2018
Cited by 13 | Viewed by 5040
Abstract
A comparative analysis of intramolecular dynamics of four types of isolated dendrimers from the fourth to the seventh generations belonging to the siloxane and carbosilane families, differing in spacer length, core functionality, and the type of chemical bonds, has been performed via atomic [...] Read more.
A comparative analysis of intramolecular dynamics of four types of isolated dendrimers from the fourth to the seventh generations belonging to the siloxane and carbosilane families, differing in spacer length, core functionality, and the type of chemical bonds, has been performed via atomic molecular dynamics simulations. The average radial and angular positions of all Si branching atoms of various topological layers within the dendrimer interior, as well as their variations, have been calculated, and the distributions of the relaxation times of their radial and angular motions have been found. It has been shown that the dendrons of all the dendrimers elongate from the center and decrease in a solid angle with an increasing generation number. The characteristic relaxation times of both angular and radial motions of Si atoms are of the order of a few nanoseconds, and they increase with an increasing generation number and decrease with temperature, with the angular relaxation times being larger than the radial ones. The relaxation times in the carbosilanes are larger than those in the siloxanes. The rotational angle dynamics of the carbosilane dendrimers show that the chain bending is mainly realized via trans-gauche transitions in the Si branching bonds. Full article
(This article belongs to the Special Issue Polymer Dynamics)
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12 pages, 247 KiB  
Review
Carbosilane and Carbosiloxane Dendrimers
by Chungkyun Kim and Jang Hwan Hong
Molecules 2009, 14(9), 3719-3730; https://doi.org/10.3390/molecules14093719 - 22 Sep 2009
Cited by 25 | Viewed by 12254
Abstract
This review focuses on novel carbosilane dendrimers containing branches with Si-C and Si-O-C bonds. Introduction of organic moieties into the dendrimers is performed by hydrosilation of carbon-carbon double/triple bonds. Versatile organic or organometallic moieties are introduced onto the peripheral regions of dendrimers by [...] Read more.
This review focuses on novel carbosilane dendrimers containing branches with Si-C and Si-O-C bonds. Introduction of organic moieties into the dendrimers is performed by hydrosilation of carbon-carbon double/triple bonds. Versatile organic or organometallic moieties are introduced onto the peripheral regions of dendrimers by coupling and complexation reactions, which clearly demonstrates their potential for variation. Full article
(This article belongs to the Special Issue Dendrimers - from Synthesis to Applications)
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