Designer Crystals:  Single Crystals with Complex Morphologies

Abstract

Biological systems are capable of remarkable control over crystal growth, producing morphologically complex single crystals with curved surfaces. We have previously demonstrated that crystals with identical morphological complexities can be produced synthetically using templating routes. This article provides a detailed investigation into the mechanism of this process, studying the relationship between the chemical environment provided by the template and the structure of the templated particles produced. A range of crystals were precipitated within the confines of macroporous polymer templates whose surface chemistries were varied by oxidation with an oxygen plasma, by modification with adsorbed polyelectrolytes, or by electroless deposition of a thin layer of gold and subsequent functionalization with ω-terminated self-assembled monolayers. The surface chemistry of the template was shown to play a crucial role in determining the structure of templated calcite particles, such that only non-charged surfaces directed the formation of single-crystal particles and polycrystalline particles being produced with negatively charged surfaces. Control of crystal morphologies is clearly fundamental to the development of many new functional materials and devices. This work therefore demonstrates how a templating methodology can provide a general and highly controllable route to synthesizing crystalline materials with defined morphologies and structures.

Confinement Increases the Lifetimes of Hydroxyapatite Precursors

“…4,56 A perfect example of a process which occurs in confinement is biomineralization. 7,8 Despite this, with the exception of control over morphology, [9][10][11][12] the effects of confinement on the formation of biominerals, or indeed inorganic substances has received little attention, possibly partly due to the experimental challenges associated with carrying out systematic studies of the precipitation of poorly soluble compounds in small volumes. Recent work has provided strong evidence, however, that confinement can also have significant effects on the precipitation of compounds such as calcium carbonate 13 and calcium sulfate, sometimes at surprisingly large length scales.…”

Growth modification of seeded calcite using carboxylic acids: Atomistic simulations

“…Calcite is a calcium carbonate (CaCO 3 ) polymorph important in many fields of science and technology ranging from being a component in animal skeletons [1][2][3], applications as fillers in polymers [4] or pigments in paints, and use as a catalysts [5] or substrates in chemical engineering. For many technological applications a precise control over the particle size, morphology and specific surface area would be highly desirable.…”

Biomimetic synthesis of calcium carbonate bilayers interfaced by a diblock copolymer template

“…From these, it can be imagined that by a proper choice of organic template and additives many more bilayered materials -if desirable composed of more layers and of different inorganic components -could be synthesized. In this respect the replicating concept of Meldrum and coworkers is of interest [48][49][50][51][52]. They demonstrated the formation of bicontinuous hybrids by filling a polymeric replica of a seaurchin plate with calcium carbonate, which after removal of the template leads to the reversed porous bicontinuous structure which in principle can be filled with another material.…”