Taki Matsumoto

Synthesis of ion-exchangeable layered polysiloxane by sol–gel reaction of aminoalkyltrialkoxysilane: a new preparation method for layered polysiloxane materials

An ion-exchangeable layered polysiloxane containing alkylammonium groups was synthesized by sol–gel reaction of 3-aminopropyltrimethoxysilane (APTMOS) catalyzed by hydrochloric acid; the present reaction system provides a new method for the preparation of layered polysiloxane materials.

Preparation of higher-ordered inorganic–organic nanocomposite composed of rodlike cationic polysiloxane and polyacrylate

The preparation of inorganic–organic polymer nanocomposites is an extensively investigated area in materials chemistry. For developing new functions and applications, the preparation of new types of nanocomposite is considered important. In the present study, we prepared a higher-ordered nanocomposite composed of a rodlike polysiloxane with ammonium groups and polyacrylate by an ion-exchange reaction. Based on IR spectroscopy, we confirmed that the nanocomposite consisted of both inorganic and organic polymers. On the basis of the CHN elemental analysis, the ratio of the functional groups of the two polymers, i.e., NH3+ and COO−, was calculated to be ca. 1 : 1. The XRD profile of the nanocomposite showed three peaks with the d-value ratio of 1 : 1/√3 : 1/2, indicating that the nanocomposite has a hexagonal phase. The TEM image of the nanocomposite showed a striped pattern, indicating an ordered arrangement. The present material is a new type of inorganic–organic nanocomposite with a higher-ordered structure; namely, an inorganic core part surrounded by organic polymers forming a hexagonal phase.

Monte Carlo simulation of the sol-gel process for the hydrolysis and polycondensation of tin tetra-n-butoxide

Abstract The sol-gel process for the hydrolysis and polycondensation of tin tetra-n-butoxide in butanol was followed by viscosity measurements. The precipitation of tin-containing ultrafine particles was observed without any variation in the solution viscosity in the absence of diethylene glycols, while the viscosity increase was made without any precipitation by the addition of diethylene glycol. The induction period and the rate of the viscosity increase after the induction period was independent of the diethylene glycol content but depended upon the water content. The Monte Carlo simulation data were consistent with data for the viscosity experiment. The simulation was based on a kinetic model of the slow hydrolysis of tin tetra-n-butoxide, the reverse reaction of hydrolysis, and the polycondensation of the hydroxy derivatives.

Synthesis of water-soluble silicon oxide material by sol-gel reaction in tetraalkoxysilane-aminoalkyltrialkoxysilane binary system

A series of water-soluble silicon oxide materials was synthesized by the sol-gel reaction of tetramethoxysilane (TMOS)/3-aminopropyltrimethoxysilane (APTMOS) mixtures catalyzed by hydrochloric acid with varying TMOS/APTMOS ratios. Increase in TMOS composition made the products less water-soluble, and the richest TMOS composition for the water-soluble silicon oxide materials was found to be TMOS/APTMOS = 7/3 (mol/mol). Ultraviolet-visible spectroscopy of a 10 wt% aqueous solution of the product with TMOS/APTMOS = 7/3 showed a high transmittance in the visible region. Its infrared spectrum showed an absorptionband attributable to the Si–O bond, and the 29 Si dipole decoupled/magic angle spinning–nuclear magnetic resonance spectrum exhibited signals in the regions of T 3 , Q 3 , and Q 4 , indicating a dense siloxane network structure. A peak due to an ordered structure with a 1.76 nm periodicity was observed in the x-ray diffraction profile, and a stripe pattern was observed in the transmission electron microscopy image. These results indicate that the rodlike silicon oxide macromolecules with a 1–2-nm diameter stack parallel. Thus a silicon oxide material with nano-ordered structure was successfully formed and such a structure produced the water solubility.

Preparation of a transparent and flexible self-standing film of layered titania/isostearate nanocomposite

A titania-based self-standing film with high transparency and flexibility was successfully prepared via a sol-gel process, in which a titanium tetraisopropoxide/isostearate complex (precursor), n -hexylammonium isostearate (catalyst), and o -xylene (solvent) were used. The sol obtained by the sol-gel reaction was floated on a water surface to form an unsupported film. This film was composed of a titania/isostearate nanocomposite with ordered layer structure. The basal spacings of the nanocomposites depended on the chain length of the carboxylate modifier.