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Structural and stereochemical relationships between Langmuir monolayers and calcium carbonate nucleation


Mann, S and Heywood, BR and Rajam, Sundara and Walker, Justin BA, Structural and stereochemical relationships between Langmuir monolayers and calcium carbonate nucleation, Journal of Physics D: Applied Physics, 24, (2) pp. 154-164. ISSN 0022-3727 (1991) [Refereed Article]

DOI: doi:10.1088/0022-3727/24/2/011


The structural and stereochemical factors involved in the oriented nucleation of CaCO3 under compressed Langmuir monolayers have been studied by optical and electron microscopy, and X-ray and electron diffraction. The effect of headgroup charge, stereochemistry and changes in supersaturation have been investigated. At total (Ca)=9 mM, monolayers with carboxylate headgroups induce the oriented nucleation of calcite with the (11.0) axis perpendicular to the organic surface. At (Ca)=4.5 mM, oriented vaterite with the (00.1) axis normal to the monolayer, is deposited. The common features of these interactions are: Ca accumulation at the stearate headgroups, geometric matching of lattice distances (calcite only) and stereochemical correspondence between carboxylate and carbonate groups at the monolayer/crystal interface. In contrast, nucleation under positively charged octadecylamine monolayers was independent of (Ca) and gave vaterite aligned either along the (00.1) or (11.0) crystallographic axes. Although Ca binding is absent on these films, there is the possibility of stereochemical matching between bidentate binding of bicarbonate and the corresponding anions in the (00.1) and (11.0) crystal surfaces. Crystals (calcite and vaterite) grown under liquid-phase stearate monolayers were of increased size and uniformity in particle size distribution compared with those nucleated under fully compressed films. CaCO3 crystallization under octadecanol monolayers was inhibited and crystals grown in the presence of cholesterol films were the same as in the control experiments.

Item Details

Item Type:Refereed Article
Keywords:films, calcium compounds, electrons, diffraction, microscopic examination, X-rays, diffraction
Research Division:Chemical Sciences
Research Group:Macromolecular and materials chemistry
Research Field:Structure and dynamics of materials
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the chemical sciences
UTAS Author:Heywood, BR (Professor Brigid Heywood)
ID Code:104361
Year Published:1991
Web of Science® Times Cited:99
Deposited By:Research Division
Deposited On:2015-11-10
Last Modified:2015-11-12

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