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Dichroic Calcite Reveals the Pathway from Additive Binding to Occlusion

Green, DC; Darkins, R; Marzec, B; Holden, MA; Ford, IJ; Botchway, SW; Kahr, B; ... Meldrum, FC; + view all (2021) Dichroic Calcite Reveals the Pathway from Additive Binding to Occlusion. Crystal Growth & Design , 21 (7) pp. 3746-3755. 10.1021/acs.cgd.1c00068. Green open access

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Abstract

Organic additives play key roles in controlling the precipitation of calcium carbonate in the environment, industry, and biology, where they can direct polymorphism, alter crystal morphologies, and sometimes even become occluded, modifying bulk properties. However, significant questions remain regarding the pathway from adsorption on crystal surfaces to occlusion. Here, the optical properties of calcite crystals grown in the presence of the dye Congo red are used to characterize the organization of the additives within the crystal. Complemented by the analysis of surface adsorption through in situ atomic force microscopy (AFM), molecular simulations, and changes in crystal morphologies, we show that the occluded dye molecules are randomly oriented under fast growth conditions, but that slow growth engenders ordering of the dye within islands, whose orientation is determined by the dye/terrace interaction free energy. The islands are subsequently overgrown such that their internal structure is preserved. These results reveal that the occlusion of organic macromolecules into calcite can be understood by thermodynamics operating at the adsorption stage. This new insight will ultimately enable the design of additives to give specific material properties.

Type: Article
Title: Dichroic Calcite Reveals the Pathway from Additive Binding to Occlusion
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acs.cgd.1c00068
Publisher version: http://dx.doi.org/10.1021/acs.cgd.1c00068
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Dyes and pigments, Crystals, Crystallization, Calcite, Optical properties
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: https://discovery.ucl.ac.uk/id/eprint/10130575
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