title: Formation of calcite thin films by cooperation of polyacrylic acid and self-generating electric field due to aligned dipoles of polarized substrates.
abstract: We demonstrated the formation of calcite thin films on positively and negatively charged surfaces of a hydroxyapatite (HAp) electret coexisting with polyacrylic acid (PAA) and self-generating surface electric fields due to HAp electrets with electrically aligned dipoles. The cooperation of PAA and the self-generating surface electric field due to the electrets favored the formation of calcite thin films and acted remarkably on the negatively charged surface. Calcite thin films, 4-10 microm thick, with a shell-like microstructure were produced on the negatively charged surfaces with a small amount of PAA. In contrast, under other reaction conditions, calcite thin films with a fan-like structure in the cross section formed on the polarized substrates, and their thickness ranged from 2 to 7 microm. The films were composed of hemispheric- or flat island-shaped aggregates that were made of the calcite crystals that elongated along the c-axis. The morphology of the PAA-Ca(2+) complex assembly, which adsorbed onto the polarized HAp substrates, was controlled by the balance of the spatial charge distribution in its structure and the properties of the self-generating surface electric field, which led to the different morphologies of the calcite thin films. We proposed that the formation mechanism of the films formed coexisting with PAA and the self-generating electric fields.
authors.affiliation: Department of Applied Chemistry, Graduate School of Urban Environmental Science, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Wada
authors.forename: Miho
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yumi
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kanamura
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Yamashita
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization; D017886:Durapatite; D055672:Static Electricity
chemical_list: D000180:Acrylic Resins; C006903:carbopol 940; D017886:Durapatite; D002119:Calcium Carbonate