Synthesis of oligomeric silsesquioxanes functionalized with (β-carboxyl)ester groups and their use as modifiers of epoxy networks
A silsesquioxane functionalized with (β-carboxyl)ester groups was synthesized by reacting a silsesquioxane functionalized with secondary hydroxyls with a stoichiometric amount of an acid anhydride. The reaction could be carried out to completion as shown by FTIR spectra and SEC chromatograms. The ca...
| Autores: | , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2007 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/75829 |
| Acceso en línea: | http://hdl.handle.net/11336/75829 |
| Access Level: | acceso abierto |
| Palabra clave: | Cooh-Functionalized Silsesquioxanes Epoxy Networks Epoxy-Acid Reaction Poly(Silsesquioxanes) Silsesquioxanes https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 https://purl.org/becyt/ford/2.5 https://purl.org/becyt/ford/2 |
| Sumario: | A silsesquioxane functionalized with (β-carboxyl)ester groups was synthesized by reacting a silsesquioxane functionalized with secondary hydroxyls with a stoichiometric amount of an acid anhydride. The reaction could be carried out to completion as shown by FTIR spectra and SEC chromatograms. The carboxyl-functionalized silsesquioxane was composed of polyhedra with 8-11 Si atoms, containing two (β-carboxyl)ester groups per organic branch (from 16 to 22 carboxyl groups per molecule). It was a stable glassy product at room temperature and could be dissolved in a variety of organic solvents. It was used as a modifier of epoxy networks based on diglycidylether of bisphenol A (DGEBA) cured with 4-(dimethylamino)pyridine (DMAP). A complete reaction of epoxy groups was observed in a higher temperature range than in the formulation devoid of the functionalized silsesquioxane. This was explained by the reversible complexation of the tertiary amine with (β-carboxyl)ester groups. The addition of the silsesquioxane produced a decrease in the crosslink density explained by the presence of transesterification and chain transfer reactions, and a maximum in the elastic modulus measured at room temperature, explained by a combination of variations of cohesive energy density and the magnitude of β-relaxations. © 2007 Elsevier Ltd. All rights reserved. |
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