Abstract:
The polycondensation of [3-(methacryloxy)propyl]trimethoxysilane was performed in bulk, using 98 wt % formic acid (molar ratio HCOOH/Si = 3 or 6), at 50 or 70°C, for periods of time of up to 1 month. The resulting silsesquioxanes (SSOs) were characterized by 1H NMR, FTIR, SEC, UV-MALDI-TOF MS (linear, reflector, and post-source decay modes), and ESI-TOF MS. The residual concentrations of Si-OCH3 groups, and generated CH3OH and HCOOCH3, were quantitatively monitored by 1H NMR during the initial stage of the synthesis. After 2 days of reaction at 50°C, or about 6 h at 70°C, the resulting SSO mainly contained residual Si-OH groups with only traces of Si-OCH3 groups, as was also confirmed by FTIR and UV-MALDI-TOF MS in the reflector mode. After this time, the polycondensation continued slowly during storage at room temperature, basically through Si-OH + Si-OH reactions. The average fraction of intramolecular cycles increased continuously during the polycondensation. An average value, fav = 0.81, was found for species containing 6-24 Si atoms in a typical reaction product. This evidenced the presence of species with relatively closed structures. In MS/MS spectra, fragmentation of one or more ester groups attached to Si atoms was observed, following a McLafferty rearrangement. The addition of water to the initial formulation (about 3:1 H2O/Si molar ratio) led to a slower polycondensation rate and to a decrease of the average fraction of intramolecular cycles (formation of more open structures). Therefore, the use of 98 wt% formic acid was useful to synthesize SSOs containing a higher fraction of intramolecular cycles than those resulting from conventional formulations.
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Artículo
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Título: | Silsesquioxanes derived from the bulk polycondensation of [3-(methacryloxy)propyl]trimethoxysilane with concentrated formic acid: Evolution of molar mass distributions and fraction of intramolecular cycles |
Autor: | Eisenberg, P.; Erra-Balsells, R.; Ishikawa, Y.; Lucas, J.C.; Nonami, H.; Williams, R.J.J. |
Filiación: | Technological Research Center for the Plastics Industry (CITIP), National Institute of Industrial Technology (INTI), INDEMAT (University of San Martín), CC 157, 1650 San Martín, Argentina Department of Organic Chemistry, University of Buenos Aires, Pab.2, Ciudad Universitaria, 1428 Buenos Aires, Argentina Plant Biophysics/Biochemistry Research Laboratory, College of Agriculture, Ehime University, Matsuyama 790-8566, Japan Institute of Materials Science and Technology (INTEMA), University of Mar del Plata, CONICET, J. B. Justo 4302, 7600 Mar del Plata, Argentina
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Palabras clave: | Formic acid; Intramolecular cycles; Methacryloxypropyltrimethoxysilane; Molar mass distribution; Silsesquioxanes; Composition effects; Esters; Fourier transform infrared spectroscopy; Mass spectrometry; Molecular structure; Nuclear magnetic resonance spectroscopy; Polycondensation; Synthesis (chemical); Volume fraction; Organic acids |
Año: | 2002
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Volumen: | 35
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Número: | 4
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Página de inicio: | 1160
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Página de fin: | 1174
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DOI: |
http://dx.doi.org/10.1021/ma011305g |
Título revista: | Macromolecules
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Título revista abreviado: | Macromolecules
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ISSN: | 00249297
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CODEN: | MAMOB
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Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00249297_v35_n4_p1160_Eisenberg |
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Citas:
---------- APA ----------
Eisenberg, P., Erra-Balsells, R., Ishikawa, Y., Lucas, J.C., Nonami, H. & Williams, R.J.J.
(2002)
. Silsesquioxanes derived from the bulk polycondensation of [3-(methacryloxy)propyl]trimethoxysilane with concentrated formic acid: Evolution of molar mass distributions and fraction of intramolecular cycles. Macromolecules, 35(4), 1160-1174.
http://dx.doi.org/10.1021/ma011305g---------- CHICAGO ----------
Eisenberg, P., Erra-Balsells, R., Ishikawa, Y., Lucas, J.C., Nonami, H., Williams, R.J.J.
"Silsesquioxanes derived from the bulk polycondensation of [3-(methacryloxy)propyl]trimethoxysilane with concentrated formic acid: Evolution of molar mass distributions and fraction of intramolecular cycles"
. Macromolecules 35, no. 4
(2002) : 1160-1174.
http://dx.doi.org/10.1021/ma011305g---------- MLA ----------
Eisenberg, P., Erra-Balsells, R., Ishikawa, Y., Lucas, J.C., Nonami, H., Williams, R.J.J.
"Silsesquioxanes derived from the bulk polycondensation of [3-(methacryloxy)propyl]trimethoxysilane with concentrated formic acid: Evolution of molar mass distributions and fraction of intramolecular cycles"
. Macromolecules, vol. 35, no. 4, 2002, pp. 1160-1174.
http://dx.doi.org/10.1021/ma011305g---------- VANCOUVER ----------
Eisenberg, P., Erra-Balsells, R., Ishikawa, Y., Lucas, J.C., Nonami, H., Williams, R.J.J. Silsesquioxanes derived from the bulk polycondensation of [3-(methacryloxy)propyl]trimethoxysilane with concentrated formic acid: Evolution of molar mass distributions and fraction of intramolecular cycles. Macromolecules. 2002;35(4):1160-1174.
http://dx.doi.org/10.1021/ma011305g