Solvent-free synthesis of reactive inorganic precursors for preparation of organic/inorganic hybrid materials

• Published in: Journal of sol-gel science and technology Vol. 59; no. 3; pp. 598 - 612
• Main Authors: Beneš, Hynek, Galy, Jocelyne, Gérard, Jean-François, Pleštil, Josef, Valette, Ludovic
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2011; Springer; Springer Nature B.V; Springer Verlag
• Subjects: Alkoxysilanes; Catalysis; Ceramics; Chemical Sciences; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Construction; Dynamic mechanical analysis; Exact sciences and technology; Formulations; General and physical chemistry; Glass; Inorganic Chemistry; Material chemistry; Materials Science; Mechanical analysis; Nanotechnology; Natural Materials; Networks; NMR; Nuclear magnetic resonance; Optical and Electronic Materials; Polymers; Precursors; Silicon dioxide; Small angle X ray scattering; Sol gel process; Sol-gel processes; Solvents; Tetraethoxysilane; Tetraethyl orthosilicate; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Hybrid; Alkoxysilane; Sol–gel; Epoxy; Nanomaterial; Silica; Binary compound; Amino group; Hybrid material; NMR spectrometry; Liquid phase; Small angle X ray scattering; Precursor; Particle; Sol―gel; Dynamics; Formulation; pH; Acid medium; Catalytic reaction; Acids; Solution structure; Sol gel process; Solvent free reaction; Preparation; Catalyst; Sol-gel
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-011-2534-4

Prehydrolyzed-condensed precursors containing amino or glycido groups were prepared via sol gel process using various alkoxysilanes in the bulk, without addition of solvent in any step of their preparation. The influence of the experimental set-up, the functionality and ratio of alkoxysilanes, and type of catalyst, on the structure buildup was studied. In the case of amino precursors, the sol–gel process was carried out at weak basic conditions while in the case of glycido precursors the sol–gel process was catalyzed by acid or neutral pH. The sol–gel process was monitored by 29 Si NMR in solution and the structure of the prehydrolysed-condensed precursors was characterized by small-angle X-Ray scattering. The systems with high content of tetraethoxysilane led to the fast gel formation. In weak acid medium tetraethoxysilane formed larger, more condensed species as well as small structures (based on Q 1 , Q 2 and Q 3 species) with silanol groups. Strong acidic conditions led to the fast formation of insoluble silica particles in liquid (sol) phase containing monomeric alkoxysilanes. The most suitable precursor formulations based on the alkoxysilanes with amino groups, as well as the most efficient set-up, were selected and used to prepare hybrid organic/inorganic networks based on an epoxy matrix. These networks were characterized using dynamic mechanical analysis.