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Syntheses and Characterization of Polymetallosiloxanes from Silicic Acid and Metal Chlorides (1997)

Gunji, Takahiro ; Toyota, Kouichi ; Arai, Kayo ; [et al.]

Springer

Journal of sol gel science and technology 10 (1997), S. 139-152

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ISSN: 1573-4846

Keywords: precursor method ; polytitanosiloxane ; polyzirconosiloxane ; esterification ; non-hydrolysis process

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Syntheses and characterization of polymetallosiloxanes by the non-hydrolysis sol-gel process using no metal alkoxides were investigated. The reaction of silicic acid (SA) with MCl4 (M = Ti, Zr) in the molar ratios SA/MCl4 = 0.5–3.0 using a tetrahydrofuran-methanol solvent formed polymetallosiloxane (PMS), which was insoluble in organic solvents regardless of the molar ratio. The PMS was isolated as esterified polymetallosiloxane by esterification with isopropyl alcohol for various periods, which were soluble in methanol, acetone, and tetrahydrofuran. The number average molecular weight was 1000–3200 for esterified polytitanosiloxane and 3400–11000 for esterified polyzirconosiloxane. Esterified polymetallosiloxanes had no melting point but decomposition point. The results of analytical data indicated that esterified polymetallosiloxane and/or polymetallosiloxane consisted of the main chain of Si–O–Si and Si–O–M linkage with the pendants of alkoxy, silanol, and chloro group.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018395428835

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2

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Hydrolytic polycondensation of vinyltrimethoxysilane and formation of vinylpolysiloxane films (1994)

Abe, Yoshimoto ; Taguchi, Kinya ; Hatano, Hideaki ; [et al.]

Springer

Journal of sol gel science and technology 2 (1994), S. 131-134

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ISSN: 1573-4846

Keywords: polycondensation ; vinyltrimethoxysilane ; polysiloxanes ; film ; tensile strength

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Hydrolytic polycondensation of vinyltrimethoxysilane (VTM) was investigated in detail to prepare vinylpolysiloxanes (VPS) having spinnability and tough gel films. VTM was hydrolyzed in various molar ratios r1 (H2O/VTM) = 0.5–1.6 (HCl/VTM = 0.105, EtOH/VTM = 1.44) at 70°C under a N2 stream with stirring at 150 rpm to give vinylpolysiloxanes with $$\overline {{\text{Mn}}} $$ =510–2100 ( $$\overline {{\text{Mw}}} /\overline {{\text{Mn}}} $$ =1.1–10.4). The controlled hydrolysis in r1 = 1.40–1.64 formed VPSs having the various degrees of spinnability at N2 flow rates of 100–500 ml/min. Transparent films of thickness 0.1–0.05 mm and tensile strength 5–16 MPa were prepared when a 20 wt% acetonemethanol (1:1, V/V) solution of VPS (r1=1.64) was cast at 80°C for several ten days. The reaction was followed by 29Si-NMR spectroscopy to investigate the distribution of unit structures T1, T2 and T3 in VPS depending on r1.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00486226

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Preparation of continuous zirconia fibres from polyzirconoxane synthesized by the facile one-pot reaction (1998)

Abe, Yoshimoto ; Kudo, Takahiro ; Tomioka, Hiroshi ; [et al.]

Springer

Journal of materials science 33 (1998), S. 1863-1870

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ISSN: 1573-4803

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract A one-pot reaction of zirconium oxychloride octahydrate (ZOC) with ethyl acetoacetate (Hetac) in the presence of triethylamine was investigated. The reaction was carried out in molar ratios of Hetac/ZOC=1.0, 1.5, 2.0 to give highly viscous solutions with good spinnability and stability to self-condensation. Polyzirconoxanes (PZOs) were isolated as white powders by reprecipitation of the solutions with tetrahydrofuron (THF)-hexane that were soluble in acetone, methanol and THF. The molecular weight of PZO was Mn=1000–2000, and was dependent on the molar ratio and the reaction time. Dry spinning of the solution (Hetac/ZOC=1.5) containing 3mol% tris(acetylacetonato)yttrium [Y(acac)3] gave continuous precursor fibres (3.0Y–PZO). Yttria stabilized zirconia fibres of 12–18 μm diameter with a tensile strength of 1.4GPa were obtained by heat treatment of the 3.0Y–PZO at 1100 or 1200 °C. The fibre consisted of submicrometre-sized particles of tetragonal crystallites. © 1998 Chapman & Hall

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004357405815

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4

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Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. IV. Properties of SiO2-TiO2 oxide fibers from polytitanosiloxane (1992)

Gunji, Takahiro ; Nagao, Yukinori ; Misono, Takahisa ; [et al.]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 371-377

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ISSN: 0887-624X

Keywords: inorganic polymer ; silicic acid ; polytitanosiloxane ; SiO2-TiO2 ; oxide fibers ; tensile strength ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: From polytitanosiloxanes (PTS), SiO2-TiO2 oxide fibers with fairly good tensile strength were prepared, and their mechanical and thermal properties were investigated. The precursor fibers PTS-0.5 and PTS-1.0 were obtained by dry spinning of a highly viscous PTS solution which were formed as the reaction mixture of silicic acid (SA) with bis(2,4-pentanedionato)titanium diisopropoxide (PTP) in the molar ratios (SA/PTP) of 0.5 and 1.0. The precursor fibers PTS-0.5 were too brittle to measure their tensile strength, whereas PTS-1.0 and the heat-treated fibers were found to have tensile strength of 130 (precursor), 540 (500°C), and 450 (900°C) MPa, respectively. Heat-treatment of the fibers PTS-1.0 at above 1000°C forms anatase and rutile of titanium dioxide. The crystallization is resulted from the unreacted PTP which is not incorporated into the polymer network.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1992.080300304

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Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. V. Preparation and properties of polytitanosiloxanes from silicic acid and bis(2,4-pentanedionato)titanium diisopropoxide (1991)

Gunji, Takahiro ; Nagao, Yukinori ; Misono, Takahisa ; [et al.]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 941-947

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ISSN: 0887-624X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Preparation and properties of polytitanosiloxanes (PTS) as a preceramic polymer for SiO2-TiO2 fibers were investigated. The PTS was prepared by the reaction of bis(2,4-pentanedionato) titanium diisopropoxide (PTP) with silicic acid (SA), extracted with tetrahydrofuran from an aqueous solution, in methanol. They were soluble in methanol, ethanol, and THF. The molecular weight (Mn) was 1500-4200 depending on the reaction molar ratio (SA/PTP). A Concentrated methanol solution of PTS showed an appreciable stability to self-condensation and good spinnability. Dry spinning of the solution provided golden yellow precursor fibers which can be subjected to thermal-treatment to give ceramic fibers. The PTS is considered to be a copolymer formed by the condensation of oligomeric silicic acid with PTP consisting of Si—O—Ti and Si—O—Si linkages in the molecular main chain with the ligand and hydroxy groups as pendants.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1991.080290701

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6

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Synthesis of polytitanosiloxanes and their transformation to SiO2-TiO2 ceramic fibers (1994)

Gunji, Takahiro ; Sopyan, Iis ; Abe, Yoshimoto

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 3133-3139

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ISSN: 0887-624X

Keywords: polytitanosiloxane ; tetraethoxysilane ; titanium chelate ; dry-spinning ; SiO2-TiO2 fibers ; tensile strength ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: A one-pot synthesis of polytitanosiloxanes (PTS) and its transformation to SiO2-TiO2 ceramic fibers were investigated. PTS was prepared by the hydrolysis of tetraethoxysilane followed by the reaction with bis(2,4-pentanedionato)titanium diisopropoxide in methanol in 33-95 SiO2 mol %. PTS was considered to be a ladder- or sheet-type polymer consisting of Si—O—Si and Si—O—Ti linkages as a main chain with pendant hydroxyl and 2,4-pentanedionato groups. SiO-TiO ceramic fibers were prepared by the pyrolysis of SiO2-TiO2 precursor fibers, which were prepared by the dry spinning of PTS followed by steam treatment. The tensile strength was 610 MPa for the SiO2-TiO2 fibers (SiO2/TiO2 = 20) after the pyrolysis at 7000C. © 1994 John Wiley & Sons, Inc.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1994.080321613

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7

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Condensation and structure of silicic acid in tetrahydrofuran (1992)

Gunji, Takahiro ; Nagao, Yukinori ; Misono, Takahisa ; [et al.]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1779-1787

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ISSN: 0887-624X

Keywords: silicic acid ; tetrahydrofuran ; silylation ; ladder structure ; GC-mass analysis ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Silicic acid (SA) was extracted with THF from aqueous sodium metasilicate (SMS) solutions neutralized with hydrochloric acid, followed by silylation to give silylated SA from which the condensation and structure of SA in tetrahydrofuran (THF) were investigated. The degree of extraction markedly depends on SA and HCl concentrations. The condensation of 0.86 and 3.5 mol/L SA-THF solutions was followed by measuring the viscosity of the solutions at 0 and 20°C. The silylated SA was isolated as a distillate (LS) and a residue (HS) with low and high M̄ns (ca. 1300 and 3800) by vacuum distillation. The ratio of LS against HS decreased as a SA concentration in THF increased. In an aqueous solution, SA exists as lower molecular weight SAs compared with those in THF. SAs such as monomer, dimer, cyclic tri- and tetramer were the main components in a 0.1 mol/L aqueous solution. On the extraction with THF from an aqueous solution, SA was found to undergo condensations to form more polymerized SAs. From the THF solutions of SA concentration above 0.5 mol/L, the HS was obtained as a main component (73%) which was expected to have ladder-like structures. © 1992 John Wiley & Sons, Inc.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1992.080300901

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8

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Studies on the syntheses of polymetalloxanes and their properties as a precursor for amorphous oxide. VII. Preparation and properties of polyzirconoxanes as a precursor for zirconia fibers by the hydrolysis of bis (ethyl acetoacetato) zirconium dialkoxide (1992)

Gunji, Takahiro ; Goto, Hitoshi ; Kimata, Yoshinori ; [et al.]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2295-2301

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ISSN: 0887-624X

Keywords: zirconium chelate ; polyzirconoxane ; structure ; precursor ; zirconia ; fiber ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Acid-catalyzed hydolysis of bis(ethyl acetoacetato) zirconium dialkoxide in methanol or THF was investigated. The hydrolysis of the chelates in the molar ratios of H2O/ chelate = 1.0-2.0 and HCl/chelate = 0.1-0.2 provided concentrated solutions (ca. 83 wt %) of polyzirconoxanes (PZO) which showed excellent spinnability and stability to self-condensation. Continuous gel fibers were prepared by dry spinning the solutions. Polyzirconoxanes were isolated as powders when the concentrated solution was precipitated with hexane. Silylation allowed the investigation of the structure of PZO. It was confirmed to be the polymers of a low degree of polymerization with the ligand and hydroxy group as pendants. © 1992 John Wiley & Sons, Inc.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1992.080301102

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9

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Preparation and properties of silicon-containing polymer hybrids from 3-methacryloxypropyltrimethoxysilane (1998)

Abe, Yoshimoto ; Honda, Yuki ; Gunji, Takahiro

New York, NY [u.a.] : Wiley-Blackwell

Applied Organometallic Chemistry 12 (1998), S. 749-753

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ISSN: 0268-2605

Keywords: polymer ; silicon ; gel ; films ; Chemistry ; Industrial Chemistry and Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The preparation of organic-inorganic polymer hybrids consisting of carbon-carbon and siloxane chains was investigated by radical polymerization of 3-methacryloxypropyltrimethoxysilane (MAS) followed by acid-catalyzed hydrolytic polycondensation. The condensation of poly(3-methacryloxypropyltrimethoxysilane) (S-PMA) of various molecular weights Mn =830-12000 prepared by polyaddition provided transparent and flexible free-standing hybrid gel films. The mechanical properties of these films were highly dependent on the carbon-carbon chain length: with an increase in the carbon-carbon chain length, the elasticity of gel films increased, while the tensile strength and Young's modulus decreased. Hydrolyzability of S-PMA decreased with an increase in the carbon-carbon chain length, resulting in the formation of rubber-like films with flexibility. © 1998 John Wiley & Sons, Ltd.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

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