Some features of the anionic copolymerization of 1,3,5-triphenyl-1,3,5-trimethylcylotrisiloxane and octamethylcyclotetrasiloxane in the presence of a crown ether

Terman, Lewis M.; Klapshina, Larisa G.; Kurskii, Yu. A.; Zislina, S.S.

doi:10.1016/0032-3950(87)90379-0

Cited by 7 publications

(2 citation statements)

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“…Polysiloxanes are well known mostly for their high thermal stability because of the strong strength of Si‐O bond (108 kcal mol −1 ) . In order to eliminate the influence of molecular weight, i.e.…”

Section: Resultsmentioning

confidence: 99%

Improved synthesis and properties of hydroxyl‐terminated liquid fluorosilicone

Zhang

et al. 2015

J of Applied Polymer Sci

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The synthesis of hydroxyl‐terminated poly(trifluoropropylmethyl)siloxane (PTFPMS‐OH) by anionic ring‐opening polymerization of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane (D3F) was studied in bulk using potassium hydroxide as an initiator in the presence of several reaction stabilizers. The promoting effect of the reaction stabilizers for the polymerization of D3F was investigated by GPC and NMR analyses. Results showed that the selected reaction stabilizers exhibited a significant promoting effect. This new process of polymerization produced well‐defined α,ω‐dihydroxylated polysiloxane in very high yields. The addition of reaction stabilizers could almost completely suppress back‐biting reactions during the polymerization. It was found that there lies an exponential decay relationship between the molecular weight of PTFPMS‐OH and amount of end‐capping agent. Thus, by adjusting the reaction conditions strictly, the molecular weight of the fluorosilicone could be controlled accurately, and meanwhile a broad “terminate window” could be implemented. Thermogravimetic (TG) analysis indicated that PTFPMS‐OH could be used in a wide range of operational temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43220.

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Section: Resultsmentioning

confidence: 99%

Improved synthesis and properties of hydroxyl‐terminated liquid fluorosilicone

Zhang

et al. 2015

J of Applied Polymer Sci

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“…Similar interactions of TiCl 4 with spirocyclic 6a may allow for the formation of unstable di- and trinuclear titanium species, which might be converted rapidly into 6a and 7a by ligand distribution reactions and further TiCl 4 insertions. The fact that both compounds 6a and 7a efficiently undergo ring-opening reaction into derivative 9 even at low temperatures clearly reflects the constraint nature of these six-membered ring complexes relative to larger ring compounds …”

Section: Resultsmentioning

confidence: 99%

Trisilane-1,3-diolato Complexes of Ti and Zr: Syntheses and X-ray Crystal Structures

et al. 2006

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The syntheses and structures of zirconium and titanium complexes containing the novel chelating trisilane-1,3-diolate ligand [Me2Si(R2SiO)2]2- (R = SiMe3) (5)-H2 are reported. The chloride complexes [Me2Si(R2SiO)2]TiCl2 (7a) and [Me2Si(R2SiO)2]ZrCl2 x 2 THF (7b) were prepared by the reaction of MCl4 (M = Ti, Zr) with [Me2Si(R2SiO)2]2Ti (6a) and [Me2Si(R2SiO)2]2Zr (6b), which are derived from the reaction of 5 with M(NEt2)4, respectively. In the presence of TiCl4, complexes 6a and 7a undergo a ring-opening reaction to produce the dinuclear complex [Me2Si(R2SiO)2][TiCl3]2 (9). [Me2Si(R2SiO)2]TiMe2 (10) and [Me2Si(R2SiO)2]TiBnz2 (11) were prepared in moderate yields from reactions of 7a with 2 equiv of MeMgBr and BnzMgCl, respectively. According to NMR spectroscopic investigations, the reaction of the dimethyltitanium complex 10 with B(C6F5)3 led to full exchange of both methyl groups by C6F5 groups under quantitative formation of [Me2Si(R2SiO)2]Ti(C6F5)2 (12) and a mixture of B(C6F5)(3-n)Me(n), where n = 1-3. The structure of 12 is further evidenced by the preparation of an identical sample from the reaction of 7a with 2 equiv of C6F5MgBr. Refluxing an ether solution of 12 surprisingly gave [Me2Si(R2SiO)2]2TiC6F5]2O (13) as a result of ether cleavage. The structures of the complexes 7a, 7b, 9, 10, and 13 were determined by X-ray crystallography, and structural discussion of the bond parameters will be given.

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