Synthesis of Layered Inorganic−Organic Nanocomposite Films from Mono-, Di-, and Trimethoxy(alkyl)silane−Tetramethoxysilane Systems

Abstract

Transparent thin films of layered inorganic−organic nanocomposites were prepared by the sol−gel reactions of alkyldimethylmethoxysilane, alkylmethyldimethoxysilane, and alkyltrimethoxysilane in the presence of tetramethoxysilane followed by spin-coating. The macroscopic homogeneity and the nanostructural ordering of the films were strongly affected by the degree of polycondensation in the precursor solutions. The formation of siloxane networks containing organosiloxane units was confirmed by 29Si MAS NMR, suggesting that the structure of the inorganic−organic interface can be designed at a molecular level by the functionalities in the alkylmethoxysilanes used. On the other hand, the 29Si NMR spectra of the precursor solutions showed that the monomeric species almost disappeared and that co-condensed oligomers were formed at the initial stages of the reactions. In the cases of mono- and dimethoxysilanes, the ability to form ordered structures depends largely on the co-condensation with tetramethoxysilane in the precursor solutions.

Designed synthesis of nanostructured siloxane–organic hybrids from amphiphilic silicon-based precursors

“…Alkylmethyldimethoxysilane (3) and alkyldimethylmethoxysilane (4) can be used to prepare layered hybrid films by co-hydrolysis and polycondensation with tetramethoxysilane (TMOS) (Scheme 2). 33 The d spacing of the hybrid films increased as the number of methoxy groups decreased, which is possibly due to the structural difference at the inorganic-organic interface.…”

Design of nanohybrid and nanoporous materials through self-assembly of organosilane molecules

“…25) The precursor solution at the early stage of the reaction gave less-ordered films with phase-separated morphologies. The liquid-state 29 Si NMR analysis of the precursor solution that formed highly ordered films confirmed that hydrolyzed monomers had been almost completely condensed to form oligomeric species.…”

“…21) By taking advantage of this principle, we were successful in synthesizing similar lamellar hybrid films from alkylmethyldimethoxysilane (2) and alkyldimethylmethoxysilane (3) by co-hydrolysis and polycondensation with tetramethoxysilane (TMOS). 25) Note that 2 and 3 never produce lamellar hybrids; they form dimer and linear (or cyclic) siloxanes, respectively, because of their poor cross-linking abilities. Even in the presence of TMOS, the precursor solutions immediately after hydrolysis produced disordered films, which strongly suggests that the co-condensation of 2 (or 3) and TMOS is essential for self-assembly (see Fig.…”

Formation of Ordered Silica–Organic Hybrids by Self-Assembly of Hydrolyzed Organoalkoxysilanes with Long Organic Chains

“…In these systems, hybrid films were prepared by cohydrolysis and polycondensation of CnTMS (n 8, 10, 12)-TMOS THF H 2 0-HCl mixtures, followed by spin-coating on glass substrates [15]. As shown in figure 5 Alkyl chain length (n) The structural models for the hybrid films are schematically illustrated in figure 7.…”