title: Intercalation of n-alkyltrimethylammonium ions into layered calcium octyl phosphates thermally treated in vacuo.
abstract: Layered calcium octyl phosphate (CH3(CH2)7OPO3Ca.1.6H2O: CaOP), which is composed of a multilayer alternating bilayer of octyl phosphates and a dicalcium phosphate dihydrate (DCPD)-like phase, was thermally treated in vacuo and the intercalation of n-alkyltrimethylammonium ions into the materials was examined. The octyl groups in the layer were eliminated by outgassing above 250 degrees C to give the amorphous calcium phosphates. Further, the specific surface area was steeply increased and mesopores with a diameter of ca. 2.0 nm were formed. IR results indicated that the surface P-OH groups were generated by outgassing at 250 degrees C. When the CaOP outgassed at 250 degrees C was treated with n-alkyltrimethylammonium ion solutions (carbon number of alkyl group, n=14-18), three XRD peaks reappeared below 2theta=15 degrees and the d-spacing ratio of these peaks was 1:1/2:1/3. These facts indicate that the n-alkyltrimethylammonium ions were intercalated into the amorphous calcium phosphate phases.
authors.affiliation: Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan. hidekazu@riko.shimane-u.ac.jp
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Koji
authors.initials: K
authors.lastname: Oomori
authors.forename: Ryozi
authors.initials: R
authors.lastname: Hino