Modification of Hexagonal-Type Mesoporous Silica via Intercalation of PVA and Its Adsorption Properties

Abstract

Modification of hexagonal-type mesoporous silica via intercalation of PVA and its adsorption properties were investigated. The hexagonal-type mesoporous silica was formed from Si (OC₂H₅) ₄ and self-assembly of C₁₆H₃₃N (CH₃) ₃Br. In order to intercalate PVA, the produced mesoporous silica was dipped into PVA aqueous solution with stirring, followed by firing at 300-800°C in N₂ atmosphere for immobilization of PVA. Thickness of PVA layer in intercalated mesoporous silica was evaluated from its composition and thermogravimetry. The thickness of around 0.1 nm was found to decrease with elevating the firing temperature and the carbonization fraction of the layer increased linearly. The adsorption properties were investigated by using O₂ and N₂ gases at 25°C. The ratio of adsorption volume, O₂/N₂, decreased apparently depending on firing temperature. Since the decrease of the ratio was in agreement with the amount of PVA that was not carbonized yet, the adsorption ability of O₂ was considered to be attributed to organic species.