Cationic ring opening polymerization of octamethylcyclotetrasiloxane initiated by solid superacid

Xia, Yafeng; Cao, Du Xia; Sun, Yu; Li, Fengfu; Qi, Zhengjian

doi:10.1134/s1087659616030184

Cited by 4 publications

(3 citation statements)

References 21 publications

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“…Convenient method is acidolysis condensation, consisting in the opening of cyclosiloxane derivatives (usually D 3 or D 4 ) by acid. 26,27 In the early stages of conversion, there are formed oligomers which chain length corresponds to the one of the open cyclosiloxanes. Siloxane chains of such linear oligosiloxanes contain, respectively, a silanol (Si-OH) and a functionalized Si-A group.…”

Section: Fig 1 Synthesis Of Low Molecular Weight Pos By the Cationic Polymerization Methods With Ring Openingmentioning

confidence: 99%

Methods for the Preparation of Modified Polyorganosiloxanes (A Review)

Kostyukovich¹,

Valer’evich²,

Ivanov³

et al. 2018

Orient. J. Chem

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The review presents the main methods for the preparation of modified polyorganosiloxanes (POS) containing amino groups. Modified POS are the most important functional compounds for the synthesis of polyimide and polysiloxane copolymers used as a material for polymeric electrolytic membranes (PEM) of fuel cells (FC). The reactions of cationic and anionic polymerization, hydrosilylation, condensation of chlorosilanes are considered. The main advantages and disadvantages of these methods are discussed.

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Section: Fig 1 Synthesis Of Low Molecular Weight Pos By the Cationic Polymerization Methods With Ring Openingmentioning

confidence: 99%

Methods for the Preparation of Modified Polyorganosiloxanes (A Review)

Kostyukovich¹,

Valer’evich²,

Ivanov³

et al. 2018

Orient. J. Chem

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“…The first synthesis of polysiloxanes was carried out by Hyde and Wehrly using cationic ring-opening polymerization (CROP) of D 4 . To date, CROP has become one of the most important synthetic routes for polysiloxane production due to its tolerance to basic sensitive functionality, such as the Si–H group, as well as the ready availability of the cyclic monomers D 3 and D 4 . − CROP can be performed at appropriate rates even at room temperature, catalyzed by Lewis acids or proton acids such as trifluoroacetic acid (CF 3 CO 2 H), sulfuric acid (H 2 SO 4 ), and trifluoromethylsulfonic acid (CF 3 SO 3 H). − However, the use of soluble acidic catalysts in the reaction system has led to problems in product separation, wastewater treatment, and corrosion of the reactors. To address this issue, an environmentally friendly approach is to use solid catalysts such as cationic ion-exchange resins, which can be easily removed by filtration after the polymerization reaction …”

Section: Introductionmentioning

confidence: 99%

A Tandem Continuous Flow Process for the Synthesis of Functionalized PDMS

Wang,

2024

Ind. Eng. Chem. Res.

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The traditional industrial production of functionalized polydimethylsiloxane (PDMS) consists of a two-stage batch process, i.e., the ring-opening polymerization (ROP)/equilibrium of cyclic siloxane monomer followed by attaching functional groups to PDMS through hydrosilylation. In this study, we developed a continuous tandem flow process combining the two stages for the synthesis of functionalized PDMS using octamethylcyclotetrasiloxane (D 4 ) as the monomer. We investigated the kinetics of ROP/equilibrium reaction of D 4 using a flow tube reactor filled with the cationic resin catalyst Amberlyst 35. The reaction was found to be complete within a short residence time, 2−3 min, giving steady flow-out of the reaction mixture containing ca. 80% nonvolatile content for a period of up to 90 min. The catalyst was reusable for up to 80 times by rinsing with methyl isobutyl ketone (MIBK). The resulting PDMS-SiH, bearing two terminal -SiH groups, was used for subsequent hydrosilylation reaction with different vinyl compounds in the presence of the Speier catalyst. PDMSs possessing functionalities such as ethylene glycol (EG), epoxy (EPO), methacrylate (MA), and hydrocarbon chain were prepared through continuous tandem ROP/equilibrium and hydrosilylation reaction. These products exhibit excellent defoaming performance that is comparable with the commercial products from a batch process. The present study paves the way to a more efficient production of functionalized silicone oil through a flow reaction process.

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“…Polysiloxanes are a class of polymers with a backbone of alternating silicon and oxygen atoms with linear or branched structures. Due to their unique characteristics, such as low glass transition temperature at around −120 °C, high gas permeability, good oxidative and thermal properties, UV stability, high chain flexibility, and low surface energy, polydimethylsiloxanes (PDMS) offer critical solutions for specific needs [ 1 , 2 , 3 , 4 , 5 ]. Cyclosiloxanes, specifically octamethylcyclotetrasiloxane (D4) and hexamethylcyclotrisiloxane (D3), are the two most significant cyclic siloxane monomers for ionic ring-opening polymerization (ROP) to obtain polysiloxanes [ 6 , 7 , 8 , 9 , 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Photoinitiated Cationic Ring-Opening Polymerization of Octamethylcyclotetrasiloxane

2023

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Photochemical techniques have recently been revitalized as they can readily be adapted to different polymerization modes to yield a wide range of complex macromolecular structures. However, the implementation of the photoinduced cationic methods in the polymerization of cyclic siloxane monomers has scarcely been investigated. Octamethylcyclotetrasiloxane (D4) is an important monomer for the synthesis of polydimethylsiloxane (PDMS) and its copolymers. In this study, the cationic ring-opening polymerization (ROP) of D4, initiated by diphenyl iodonium hexafluorophosphate (DPI), has been studied. Both direct and indirect initiating systems acting at broad wavelength using benzophenone and pyrene were investigated. In both systems, photochemically generated protonic acids and silylium cations are responsible for the polymerization. The kinetics of the polymerization are followed by viscosimetry and GPC analyses. The reported approach may overcome the problems associated with conventional methods and therefore represents industrial importance for the fabrication of polysiloxanes.

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Cationic ring opening polymerization of octamethylcyclotetrasiloxane initiated by solid superacid

Cited by 4 publications

References 21 publications

Methods for the Preparation of Modified Polyorganosiloxanes (A Review)

Methods for the Preparation of Modified Polyorganosiloxanes (A Review)

A Tandem Continuous Flow Process for the Synthesis of Functionalized PDMS

Photoinitiated Cationic Ring-Opening Polymerization of Octamethylcyclotetrasiloxane

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