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Keywords = cyclosiloxane

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29 pages, 9234 KiB  
Article
Dual-Functional Organosilicon Additives Containing Methacrylate and Trimethoxysilyl Groups Enhancing Impact Toughness of Polylactide (PLA): Structure–Property Relationship
by Julia Głowacka, Miłosz Frydrych, Eliza Romańczuk-Ruszuk, Yi Gao, Hui Zhou, Robert E. Przekop and Bogna Sztorch
Materials 2025, 18(12), 2903; https://doi.org/10.3390/ma18122903 - 19 Jun 2025
Viewed by 968
Abstract
The demands of the green economy necessitate modern polymer materials that are not only environmentally friendly but also durable and capable of long service life. Bio-based polylactide (PLA) polyesters have gained significant traction in various industrial markets; however, their application in specialized sectors [...] Read more.
The demands of the green economy necessitate modern polymer materials that are not only environmentally friendly but also durable and capable of long service life. Bio-based polylactide (PLA) polyesters have gained significant traction in various industrial markets; however, their application in specialized sectors is hindered by high brittleness. This study extensively examines the effects of 1–5% of synthetically obtained tetracyclosiloxane (CS) and octaspherosilicate (OSS) derivatives with methacrylate (MA) and trimethoxysilyl (TMOS) groups as functional modifiers for PLA. The research provides a detailed characterization of PLA/CS and PLA/OSS materials, including a comparative analysis of mechanical properties such as tensile, flexural, and dynamic resistance. Notably, incorporating 5% CS-2MA-2TMOS into PLA resulted in a remarkable 104% increase in impact resistance. The study further evaluates the influence of these modifications on thermal properties (DSC, TGA), heat deflection temperature (HDT), and surface character (WCA). The miscibility between the organosilicon additives and PLA was assessed using oscillatory rheometry and SEM-EDS analysis. The melt-rheology analysis explained the mechanisms behind the interaction between the CS and OSS additives with the PLA matrix, highlighting their lubricating effects on the melt flow behavior. The study was complemented by XRD structural analysis and verification of the structure of PLA-based materials by optical microscopy and SEM analysis, demonstrating a plasticizing effect and uniform distribution of the modifiers. The findings strongly suggest that, even at low concentrations, organosilicon additives serve as effective impact modifiers for PLA. Full article
(This article belongs to the Special Issue Sustainable Materials: Preparation, Characterization and Applications)
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17 pages, 1934 KiB  
Article
Evaluation of Litchi Honey Quality in Southern China
by Cuiping Zhang, Shujing Zhou, Chenxinzi Wu, Xinjian Xu and Xiangjie Zhu
Foods 2025, 14(3), 510; https://doi.org/10.3390/foods14030510 - 5 Feb 2025
Viewed by 954
Abstract
Honey is a sweet substance laboriously collected and crafted from nectar by bees, and since ancient times, it has been deeply cherished by humans for its unique flavor and nutritional value. Litchi honey stands out among various types of honey with its unique [...] Read more.
Honey is a sweet substance laboriously collected and crafted from nectar by bees, and since ancient times, it has been deeply cherished by humans for its unique flavor and nutritional value. Litchi honey stands out among various types of honey with its unique flavor and sweet taste, and it is particularly favored by consumers. In accordance with the testing methodologies specified in relevant Chinese national standards, we conducted an exhaustive analysis of the physicochemical properties of six litchi honey samples in Southern China. The results showed that the moisture content fell within a range of 17.18% to 22.7%, while the electrical conductivity remained below 0.28 mS/cm, and amylase activity surpassed 7.7 mL/(g·h). The fructose content varied from 36.5% to 39.6%, with glucose content ranging between 30.57% and 37.63%. The combined total of these two monosaccharides was found to be within the spectrum of 69.63% to 77.23%, and sucrose content was recorded between 0.59% and 1.15%. The F/G was between 1.05 and 1.28, the proportion of fructose in reducing sugars ranged from 51.28% to 56.22%, and the maltose content was between 1.09% and 1.51%. The HMF content was measured between 1.04 and 3.49 mg/kg. Moreover, the presence of C-4 plant sugars was absent in all tested honey samples. These results definitively demonstrate that the physicochemical attributes of all litchi honey samples align with the standards set forth by Chinese national regulations and international authorities such as CODEX. During our in-depth examination of volatile constituents, we identified 26 common compounds, with trans-linalool oxide, linalool, lilac aldehyde B, lilac aldehyde D, α-terpineol, and cedrol emerging as pivotal in crafting the unique flavor and aroma profile of litchi honey. Additionally, the detection of methyl cyclosiloxane in litchi honey has garnered our attention, necessitating a comprehensive investigation into the honey production process. In conclusion, this study not only establishes a robust scientific basis for the quality assurance and product development of litchi honey but also provides valuable reference information for consumers in their selection of honey products. Full article
(This article belongs to the Special Issue Bee Products Consumption and Human Health)
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13 pages, 9667 KiB  
Article
Molecular Aggregation Strategy for Pore Generation in SiOC Ceramics Induced by the Conjugation Force of Phenyl
by Gang Yi and Yuxi Yu
Polymers 2023, 15(12), 2676; https://doi.org/10.3390/polym15122676 - 14 Jun 2023
Cited by 2 | Viewed by 1713
Abstract
Porous silicon oxycarbide (SiOC) ceramics with tailorable microstructure and porosity were fabricated using phenyl-substituted cyclosiloxane (C-Ph) as a molecular-scale porogen are analyzed in this study. A gelated precursor was synthesized via the hydrosilylation of hydrogenated and vinyl-functionalized cyclosiloxanes (CSOs), followed by pyrolysis at [...] Read more.
Porous silicon oxycarbide (SiOC) ceramics with tailorable microstructure and porosity were fabricated using phenyl-substituted cyclosiloxane (C-Ph) as a molecular-scale porogen are analyzed in this study. A gelated precursor was synthesized via the hydrosilylation of hydrogenated and vinyl-functionalized cyclosiloxanes (CSOs), followed by pyrolysis at 800–1400 °C in flowing N2 gas. Tailored morphologies, such as closed-pore and particle-packing structures, with porosities in the range 20.2–68.2% were achieved by utilizing the high boiling point of C-Ph and the molecular aggregation in the precursor gel induced by the conjugation force of phenyl. Moreover, some of the C-Ph participated in pyrolysis as a carbon source, which was confirmed by the carbon content and thermogravimetric analysis (TGA) data. This was further confirmed by the presence of graphite crystals derived from C-Ph, as determined by high-resolution transmission electron microscopy (HRTEM). In addition, the proportion of C-Ph involved in the ceramic process and its mechanism were investigated. The molecular aggregation strategy for phase separation was demonstrated to be facile and efficient, which may promote further research on porous materials. Moreover, the obtained low thermal conductivity of 27.4 mW m−1 K−1 may contribute to the development of thermal insulation materials. Full article
(This article belongs to the Special Issue Novel Synthetic Methodologies for Organosilicon Materials)
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11 pages, 1988 KiB  
Article
Adsorption Characteristics of Dodecamethylcyclohexasiloxane and Dodecamethylpentasiloxane from Landfill Leachate by Municipal Solid Waste under the Landfill Circumstance
by Qingna Kong, Peili Zhang, Hao Wang, Xing Lin, Jiadong Xu, Ben Zhang, Zhicheng Zhang, Hui Chen and Jun Yao
Water 2023, 15(1), 102; https://doi.org/10.3390/w15010102 - 28 Dec 2022
Cited by 2 | Viewed by 2197
Abstract
The release of siloxane from landfill leachate has attracted wide attention. In this study, dodecamethylcyclohexasiloxane (D6) and dodecamethylpentasiloxane (L5) were chosen as the target pollutants to investigate the adsorption characteristics of cyclosiloxane and linear siloxane on municipal solid waste (MSW) under the landfill [...] Read more.
The release of siloxane from landfill leachate has attracted wide attention. In this study, dodecamethylcyclohexasiloxane (D6) and dodecamethylpentasiloxane (L5) were chosen as the target pollutants to investigate the adsorption characteristics of cyclosiloxane and linear siloxane on municipal solid waste (MSW) under the landfill circumstance. The adsorption behavior could be well described by the Langmuir–Freundlich model, with a maximum adsorption capacity of 0.677 μg g−1 and 15.864 μg g−1 for L5 and D6, respectively. It seems that D6 has a stronger affinity to MSW compared with L5. The maximum adsorption was observed when the pH was 5.0 and 5.5 for D6 and L5. The optical temperature was 30 °C. The organic acid and inorganic ions in the leachate could restrict the adsorption to a low level. The results suggested that the adsorption of siloxane on MSW could be limited at the methanogenic and mature stages, which may promote the distribution of siloxane in the leachate. The results could help to understand the release behavior of siloxane from landfill leachate during the running of a landfill. Full article
(This article belongs to the Special Issue Landfill Leachate Pollution Control)
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14 pages, 4572 KiB  
Article
Various Approaches to Studying the Phase Transition in an Octamethylcyclotetrasiloxane Crystal: From X-ray Structural Analysis to Metadynamics
by Alexander D. Volodin, Alexander F. Smol’yakov and Alexander A. Korlyukov
Int. J. Mol. Sci. 2022, 23(16), 9073; https://doi.org/10.3390/ijms23169073 - 13 Aug 2022
Cited by 1 | Viewed by 2482
Abstract
The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown [...] Read more.
The structure, thermodynamic parameters, and the character of thermal motion in octamethylcyclotetrasiloxane (D4) were investigated using the combination of experimental (single-crystal X-ray diffraction, thermochemistry) and theoretical (density functional theory calculations, ab initio molecular dynamics and metadynamics) methods. Single crystals of D4 were grown in a glass capillary in situ and the structures of high- (238–270 K) and low-temperature (100–230 K) phases were studied in detail. In the temperature interval 230–238 K, a phase transition with rather low enthalpy (−1.04(7) kcal/mol) was detected. It was found that phase transition is accompanied by change of conformation of cyclosiloxane moiety from boat-saddle (cradle) to chair. According to PBE0/6-311G(d,p) calculation of isolated D4, such conformation changes are characterized by a low barrier (0.07 kcal/mol). The character of molecular thermal motion and the path of phase transition were established with combination of periodic DFT calculations, including molecular dynamics and metadynamics. The effect of crystal field led to an increase in the calculated phase transition barrier (4.27 kcal/mol from low- to high-temperature phase and 3.20 kcal/mol in opposite direction). Full article
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10 pages, 1985 KiB  
Article
Unexpected Formation of a Silicon-Centered Spirocyclic Oligosiloxane Bearing Eight Pendant Ferrocene Units
by Sonia Bruña, Isabel Cuadrado and Josefina Perles
Crystals 2022, 12(8), 1122; https://doi.org/10.3390/cryst12081122 - 11 Aug 2022
Cited by 1 | Viewed by 2107
Abstract
An intriguing but rare silicon-centered spirocyclic compound, spiro[5.5]octaferrocenylpentasiloxane (4) featuring silicon fused six-membered ferrocenyl-functionalized siloxane rings, has been obtained during the thermally induced transformation of triferrocenylsilane Fc3Si–H (1) into triferrocenylsilanol Fc3Si–OH (2), when [...] Read more.
An intriguing but rare silicon-centered spirocyclic compound, spiro[5.5]octaferrocenylpentasiloxane (4) featuring silicon fused six-membered ferrocenyl-functionalized siloxane rings, has been obtained during the thermally induced transformation of triferrocenylsilane Fc3Si–H (1) into triferrocenylsilanol Fc3Si–OH (2), when N,N-dimethylformamide (DMF) was used as a solvent in the presence of the metal carbonyl Mo(CO)6. The unexpected formation of the maximally ferrocenyl substituted silicon centered spirocyclic 4 involves the obtention, and subsequent condensation, of different ferrocenylsilanol intermediates. Spirocyclic silicate 4 has been characterized using a combination of MALDI-TOF mass spectrometry, elemental analysis, and single crystal X-ray diffraction analysis. Full article
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13 pages, 22831 KiB  
Article
Synthesis of 1,1,3,3,5,5-Hexamethyl-7,7-diorganocyclotetrasiloxanes and Its Copolymers
by Evgeniya V. Talalaeva, Aleksandra A. Kalinina, Evgeniy V. Chernov, Alina G. Khmelnitskaia, Marina A. Obrezkova, Georgii V. Cherkaev and Aziz M. Muzafarov
Polymers 2022, 14(1), 28; https://doi.org/10.3390/polym14010028 - 22 Dec 2021
Cited by 2 | Viewed by 3366
Abstract
This paper reports a method for the synthesis of 1,1,3,3,5,5-hexamethyl-7,7-diorganocyclotetrasiloxanes by the interaction of 1,5-disodiumoxyhexamethylsiloxane with dichlorodiorganosilanes such as methyl-, methylvinyl-, methylphenyl-, diphenyl- and diethyl dichlorosilanes. Depending on the reaction conditions, the preparative yield of the target cyclotetrasiloxanes is 55–75%. Along with mixed [...] Read more.
This paper reports a method for the synthesis of 1,1,3,3,5,5-hexamethyl-7,7-diorganocyclotetrasiloxanes by the interaction of 1,5-disodiumoxyhexamethylsiloxane with dichlorodiorganosilanes such as methyl-, methylvinyl-, methylphenyl-, diphenyl- and diethyl dichlorosilanes. Depending on the reaction conditions, the preparative yield of the target cyclotetrasiloxanes is 55–75%. Along with mixed cyclotetrasiloxanes, the proposed method leads to the formation of polymers with regular alternation of diorganosylil and dimethylsylil units. For example, in the case of dichlorodiethylsilane, 70% content of linear poly(diethyl)dimethylsiloxanes with regular alternation of units can be achieved in the reaction product. Using 7,7-diethyl-1,1,3,3,5,5-hexamethylcyclotetrasiloxane as an example, the prospects of the mixed cycle in copolymer preparation in comparison with the copolymerization of octamethyl- and octaethylcyclotetrasiloxanes are shown. Full article
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9 pages, 1534 KiB  
Communication
Cationic Polymerization of Hexamethylcyclotrisiloxane in Excess Water
by Quentin Barnes, Claire Longuet and François Ganachaud
Molecules 2021, 26(15), 4402; https://doi.org/10.3390/molecules26154402 - 21 Jul 2021
Cited by 4 | Viewed by 3191
Abstract
Ring-opening ionic polymerization of cyclosiloxanes in dispersed media has long been discovered, and is nowadays both fundamentally studied and practically used. In this short communication, we show some preliminary results on the cationic ring-opening polymerization of hexamethylcyclotrisiloxane (D3), a crystalline strained [...] Read more.
Ring-opening ionic polymerization of cyclosiloxanes in dispersed media has long been discovered, and is nowadays both fundamentally studied and practically used. In this short communication, we show some preliminary results on the cationic ring-opening polymerization of hexamethylcyclotrisiloxane (D3), a crystalline strained cycle, in water. Depending on the catalyst or/and surfactants used, polymers of various molar masses are prepared in a straightforward way. Emphasis is given here on experiments conducted with tris(pentafluorophenyl)borane (BCF), where high-molar polymers were generated at room temperature. In surfactant-free conditions, µm-sized droplets are stabilized by silanol end-groups of thus generated amphiphilic polymers, the latter of which precipitate in the course of reaction through chain extension. Introducing various surfactants in the recipe allows generating smaller emulsions in size with close polymerization ability, but better final colloidal stability, at the expense of low small cycles’ content. A tentative mechanism is finally proposed. Full article
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19 pages, 4294 KiB  
Article
Creation of a PDMS Polymer Brush on SiO2-Based Nanoparticles by Surface-Initiated Ring-Opening Polymerization
by Karin Koch, Sven Geller, Kubilay Acar, Patricia Bach, Ekaterina Tsarenko and Annette Schmidt
Polymers 2020, 12(4), 787; https://doi.org/10.3390/polym12040787 - 2 Apr 2020
Cited by 3 | Viewed by 4509
Abstract
The incorporation of nanoparticles into soft matrices opens a broad spectrum of novel property combinations. However, one of the major challenges for these systems remains the compatibilization of particles with the surrounding matrix by proper surface functionalization. For silicon-based systems or liquid crystalline [...] Read more.
The incorporation of nanoparticles into soft matrices opens a broad spectrum of novel property combinations. However, one of the major challenges for these systems remains the compatibilization of particles with the surrounding matrix by proper surface functionalization. For silicon-based systems or liquid crystalline phases, polydimethylsiloxane (PDMS) brushes at the surface of particles increase the stability against particle agglomeration in such systems. Here, we report a novel approach for the functionalization of particles with a polysiloxane brush by surface-initiated ring-opening polymerization of a cyclosiloxane. For this purpose, surface hydroxy groups of silica and silica-coated hematite particles are used as initiators in combination with phosphazene bases as catalysts. The ring–chain equilibrium of a model-based solution polymerization is investigated in detail to find the appropriate reaction parameters. The corresponding molar masses are determined and compared by 1H-NMR and SEC measurements to confirm the underlying mechanism. In the resulting hybrid nanostructures, a covalently bound PDMS fraction is achieved up to 47 mass %. Full article
(This article belongs to the Special Issue Nanoparticle Functionalization by Polymers: Methods and Applications)
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