Activators of the anionic polymerization of cyclosiloxanes

Yuzhelevskii, Yu. A.; Kagan, Ye.G.; Fedoseyeva, N.N.

doi:10.1016/0032-3950(70)90326-6

Cited by 10 publications

(10 citation statements)

References 5 publications

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“…Thus, the intramolecular back‐biting and path b in the intermolecular redistribution reaction will be the main side reactions. Because of the weak donor character of THF and the inductive effects of fluorine atoms in the trifluoropropyl group,20–22 the rate of the anionic ROP of F 3 in THF was rapidly accelerated. Under the condition of low monomer concentrations, F 3 was rapidly consumed, but at the same time, the back‐biting reaction also happened.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of poly[styrene‐b‐methyl(3,3,3‐trifluoropropyl)siloxane] diblock copolymers via anionic polymerization

Zhan

Chen

et al. 2005

J. Polym. Sci. A Polym. Chem.

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A series of narrow molecular weight distribution (MWD) polystyrene‐b‐poly[methyl(3,3,3‐trifluoropropyl)siloxane] (PS‐b‐PMTFPS) diblock copolymers were synthesized by the sequential anionic polymerization of styrene and trans‐1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane in tetrahydrofuran (THF) with n‐butyllithium as the initiator. The diblock copolymers had narrow MWDs ranging from 1.06 to 1.20 and number‐average molecular weights ranging from 8.2 × 103 to 37.1 × 103. To investigate the properties of the copolymers, diblock copolymers with different weight fractions of poly[methyl(3,3,3‐trifluoropropyl)siloxane] (15.4–78.8 wt %) were prepared. The compositions of the diblock copolymers were calculated from the characteristic proton integrals of 1H NMR spectra. For the anionic ring‐opening polymerization (ROP) of 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane (F3) initiated by polystyryllithium, high monomer concentrations could give high polymer yields and good control of MWDs when THF was used as the polymerization solvent. It was speculated that good control of the block copolymerization under the condition of high monomer concentrations was due to the slowdown of the anionic ROP rate of F3 and the steric hindrance of the polystyrene precursors. There was enough time to terminate the ROP of F3 when the polymer yield was high, and good control of block copolymerization could be achieved thereafter. The thermal properties (differential scanning calorimetry and thermogravimetric analysis) were also investigated for the PS‐b‐PMTFPS diblock copolymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4431–4438, 2005

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Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of poly[styrene‐b‐methyl(3,3,3‐trifluoropropyl)siloxane] diblock copolymers via anionic polymerization

Zhan

Chen

et al. 2005

J. Polym. Sci. A Polym. Chem.

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“…As mentioned by Grubb et al [20], the anionic polymerization of cyclosiloxane is initiated by the free anions. Moreover, the stronger the solvation of the promoters to ion pairs of initiators is, the higher the initiators activity should be [11]. In the presence of EA, the more free ions were produced through the specific solvation of EA to the cations (Na + ) of initiators.…”

Section: Resultsmentioning

confidence: 99%

“…Owing to the introduction of fluorine into the side chain of polysiloxanes, poly[methyl(3,3,3‐trifluoropropyl)siloxane (PMTFPS) has a good solvent resistance besides the properties of polysiloxanes and is employed as release coatings [7], antifoams [8], surfactants, lubricants, gels, adhesives and sealants [9]. Despite its wide applications, only limited literatures [10–14] have been published on the preparation of PMTFPS with high molecular weights largely due to the unfavorable equilibrium between linear polymers and cyclic by‐products during the polymerization. As shown in Eq.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, ethyl acetate (EA) was employed as promoter in the anionic bulk polymerization of F 3 in view of its low boiling point (77.0°C). To investigate the promoting effect of EA, dimethyl sulfoxide (DMSO), a common promoter [10–13, 18], was also used as a control promoter. The reaction parameters were optimized to prepare PMTFPS with high molecular weight and yield in a short time.…”

Section: Introductionmentioning

confidence: 99%

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A novel approach for anionic bulk polymerization of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane

Gao

Jiang

Guan

et al. 2010

Polymer Engineering & Sci

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Present work gave a new method for preparing polymethyl(3,3,3‐trifluoropropyl)siloxane (PMTFPS) in the mixing chamber of a torque rheometer using sodium silanolate as initiator, and ethyl acetate (EA) and dimethyl sulfoxide (DMSO) as promoters. The promoting effect of EA in the anionic bulk polymerization of 1,3,5‐tris(trifluoropropylmethyl) cyclotrisiloxane (F3) was investigated in comparison with DMSO, a common promoter. Results showed that EA exhibited an effective promoting effect as DMSO did. When the polymerization was carried out for 4.0 min at 120°C in the presence of 0.30 mol L−1 EA, the maximum of number average molecular weight (Mn = 2.45 × 105 g mol−1) of PMTFPS was obtained with high yield (89.2 wt%). The back‐biting reactions during the polymerization were almost suppressed and less than 0.75 wt% cyclic by‐products were obtained by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) for EA promoter system. Investigations of differential scanning calorimetry and thermogravimetic analysis showed that PMTFPS could be used in a wide range of operational temperatures. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

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“…Moreover, the composition and sequences distribution of monomer units, namely, block, gradient, and random, significantly affect the performance of these copolymers . However, the comonomers exhibit unusually large reactivity difference toward polymerization; therefore, generation of these copolysiloxanes with well‐defined structures, especially for random sequence distribution, is extremely difficult to achieve …”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization, and properties of vinyl‐terminated copolysiloxanes containing trifluoropropyl and 4‐trifluoromethylphenyl groups

Fei

Gao

Han

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

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Novel fluorine containing siloxane monomer, namely, 4-trifluoromethylphenylmethyl cyclosiloxane (PF3) and mixed cyclosiloxane including both 4-trifluoromethylphenylmethyl siloxane (P) unit and trifluoropropyl siloxane (F) unit were successfully synthesized in this study. Furthermore, their series including vinyl-terminated copolymers with different compositions were synthesized. The microstructures of copolymers were investigated by 1 H NMR, 29 Si NMR, 19 F NMR, Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC). The results of characterizations confirmed that the copolymers exhibited random microstructure. Moreover, the analysis of the result of DSC also revealed that the copolymers had a low glass transition temperature. The thermogravimetric analysis indicated that poly(4-trifluoromethylphenylmethyl)siloxane (PPF3) exhibited higher thermal stability than conventional fluorosilicones rubber (FSR). The dynamic mechanical analysis showed that the damping factors of these copolymers were greater than 0.3 in a wide range of temperature. The mass swelling ratios were less than 5.5% when the samples were immersed in No. 3 jet fuel for a month.

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Activators of the anionic polymerization of cyclosiloxanes

Cited by 10 publications

References 5 publications

Synthesis and characterization of poly[styrene‐b‐methyl(3,3,3‐trifluoropropyl)siloxane] diblock copolymers via anionic polymerization

Synthesis and characterization of poly[styrene‐b‐methyl(3,3,3‐trifluoropropyl)siloxane] diblock copolymers via anionic polymerization

A novel approach for anionic bulk polymerization of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane

Synthesis, characterization, and properties of vinyl‐terminated copolysiloxanes containing trifluoropropyl and 4‐trifluoromethylphenyl groups

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