**1. Introduction**

Layered Na+-titanosilicate (Na4Ti2Si8O22·4H2O) [1-5] has interesting potential applications. It contains titanosilicate layers composed of tetrahedral SiO4 units and square pyramidal TiO5 polyhedral [3]. The interlayer surfaces are composed of five-coordinated titanium (IV), and thus, are less coordinated than the octahedrally-coordinated microporous and layered titanosilicates [5]. The existence of five-coordinated titanium (IV) in interlayer surface makes Na+-titanosilicate a promising material for oxidation catalysis. Each layer is separated by water molecules solvated around interlayer Na+ ions [4]. Furthermore, this layer structure allows the intercalation of large organic and inorganic molecules.

Roberts et al. [3] synthesized Na+-titanosilicate using Ti-alkoxide, and Ferdov and coworkers [5] described an effective means of producing Na+-titanosilicate using TiCl4 as a titanium source without an organic template. Kostov-kytin and co-workers [6] also investigated on the phase transition of Na+-titanosilicate during heating at 300-700 oC. However, studies of Na+-titanosilicate are still in the early stage. For industrial applications, in which Na+-titanosilicate is used as a catalytic support, studies on surface chemistry, surface area, and porosity are needed, and on the relations between its surface properties and basic intercalation chemistry.

The galleries are normally occupied by exchangeable cations such as Na+, Ca2+, and Mg2+. They happen easily an ion exchange reaction with quaternary ammonium ions or other organic cation in water [7]. The acid treatment of Na+-titanosilicate can also produce Si-OH groups in interlayer surface by an ion exchange of exchangeable cations for H+. Si-OH groups can offer an excellent bonding site for an organic base or alkoxysilane compound.

Pillaring of metal oxides in layered silicate, such as, natural and synthetic layered silicate is being increasingly studied [8–13]. In general, pillaring is achieved by the direct introduction of bulk inorganic (polyoxocations) or organic precursors (metal alkoxides) between the interlayers of layered silicate. Pillaring processes that use metal alkoxide are facilitated by a

preswelling step where by interlayer regions are exposed to quaternary ammonium [8,9,13]. However, preswelling procedures are problematic because they are complex, nonquantitative and require reagents. Recently, we reported a method of introducing metal alkoxides or organic precursors into H+-layered silicates without a preswelling step [14–18].

Layered materials have been often used to design and construct organic–inorganic nanomaterials because of the ease and variety of modifications possible by the introduction of organic and inorganic compounds into the interlayer space [19–27]. In recent years, the chemical modification into the interlayer surface of layered materials has become the focus of increased research. Ruiz-Hitzky and Rojo [28,29] grafted trimethylsilyl groups to the interlayer silanol groups of H+-magadiite starting with intercalation compounds from polar organic molecules. Shimojima et al.[30], Okutomo et al. [31], Ogawa et al. [32] and Yanagisawa et al. [33] reported on the trimethylsilylation, diphenylmethylsilylation and octyldimethylsilylation of magadiite, kenyaite and kanemite using the quaternary ammonium-exchanged form of silicates as intermediates. Thiesen et al. [34] also reported on the silylation of H+-kenyaite using alkylamines together with a silylating agent.

We now report on the silylation of organic functional groups in the interlayer surface of a layered material. Functional organo-layered silicates with a functional group silylate in the interlayer surface can offer new opportunities for designing nanocomposites with the desired function because of their highly accessible interactions with various chemicals. In polymer–clay nanocomposite, physical properties depend on the interaction between exfoliated clay surfaces and the polymer. Interlayer surfaces bonded chemically by functional groups can interact with active groups in the polymer [35]. In particular, attached amine groups in the surface can chemically bond with epoxy [36], nylon [37], and urethane polymers [38], creating a bridge between the exfoliated layered surface and the polymer [35]. Their expanded gallery of functional groups can also store expensive reagents, such as drugs or enzymes. Layered materials with attached amine groups may be used to adsorb heavy metal ions for photosensitive species.

Here, we found that the H+-titanosilicate (formed by proton exchange of Na+-titanosilicate) produced H+-titanosilicate/DDA (dodecylamine)/TEOS (tetraethylorthosilicate) intercalation compounds in DDA–TEOS solution. In these intercalation compounds, the long chain amine DDA appears to act as a gallery height expander and as a base catalyst during TEOS hydrolysis. Furthermore, it also appears to act as a liquid crystal template that forms surfactant-like molecular assemblies in galleries. The physical properties of the SPT derivatives produced were investigated by XRD (powder X-ray diffraction), BET (Brunauer, Emmett and Teller)-surface area, and SEM (scanning electron micrographs), and these investigations confirmed that SPT derivatives are mesoporous materials with large surface areas, highly ordered gallery structures, and high thermal resistances.

Intercalation and silylation were easily achieved by entropy differences between the interlayer gallery and the outside, which were caused by vaporizing the relatively more volatile ethanol. The ethanol on the outside vaporizes more rapidly than that in the interlayer gallery. DDA can also have a role as gallery expander and silylation catalyst. Ethanol can quantitatively control the amount of OTES (octyltriethoxysilane) and DDA needed for gallery silylation, and the residual water from vaporization catalyzes the silylation reaction. This process was achieved by a quantitative procedure under atmospheric conditions without consumption of expensive reagents or an effluence of waste liquid. Our method is a promising route in leading to the preparation of new functional nanomaterials to bond with a variety of functional groups in the interlayer surface of layered materials.
