Interlamellar Esterification of H-Magadiite with Aliphatic Alcohols

Magadiite, a layered sodium polysilicate, was organically modified by esterification of interlayer silanol groups with various aliphatic alcohols. Methanol was directly reacted with H-magadiite (acid-treated magadiite) by refluxing. The methanol-treated product showed an increase in the basal spacing and the 13 C NMR signals due to methyl groups. The 2 H NMR spectrum of CD 3 OD-treated H-magadiite showed Pake doublet patterns of quadrupole coupling constants of 43 and 48 kHz and asymmetry factors of 0, indicating the fixation of the C−O axis. When aliphatic alcohols with the carbon chain length longer than 4 were used, an H-magadiite/ N -methylformamide (NMF) intercalation compound was used as an intermediate for esterification. The basal spacing of butanol-treated H-magadiite was 1.40 nm, the value of which was smaller than that of H-magadiite/NMF (1.63 nm) and larger than that of H-magadiite (1.15 nm). 13 C spin−lattice relaxation times ( T 1 ) of butyl groups showed a low mobility of the α carbon. Other alcohols (C n H 2 n +1 OH ( n = 2−16) and (CH 3 ) 3 COH) were also reacted with the silanol groups. The differential thermal analysis (DTA) curves of the products showed exothermic peaks. The alkyl chains are apparently lying parallel to the inner surface because almost constant basal spacings were observed despite the variation in the alkyl chain length. The butanol-treated H-magadiite was dispersed in toluene and cast, resulting in the formation of a transparent nanocomposite film.