Solvent-Mediated Enhancement of Additive-Controlled Crystallization

Abstract

Soluble additives are widely used to control crystallization processes, modifying the morphologies, sizes, polymorphs, and physical properties of the product crystals. Here, a simple and versatile strategy is shown to significantly enhance the potency of soluble additives, ranging from ions and amino acids to large dye molecules, enabling them to be effective even at low concentrations. Addition of small amounts of miscible organic cosolvents to an aqueous crystallization solution can yield enhanced morphological changes and an order of magnitude increase of additive incorporation within single crystalsa level that cannot be achieved in pure aqueous solutions at any additive concentration. The generality of this strategy is demonstrated by application to crystals of calcium carbonate, manganese carbonate, and strontium sulfate, with a more pronounced effect observed for co-solvents with lower dielectric constants and polarities, indicating a general underlying mechanism that alters water activity. This work increases the understanding of additive/crystal interactions and may see great application in industrial-scale crystal synthesis.

Kinetic control of competing nuclei in a dimer lattice-gas model

“…Formation of nuclei with different structure from a multi-component solution is often observed in nature. A system studied extensively by experiment is calcium carbonate 14,15 . Under conditions where a CaCO 3 solution is supersaturated with respect to both calcite and aragonite, the relative abundance of these two polymorphs within a population of post-critical crystallites cannot be predicted a) Electronic mail: dipanjan.mandal@warwick.ac.uk b) Electronic mail: d.quigley@warwick.ac.uk purely from their relative bulk stability.…”

Recent progress on strategies for the enhancement of crystal growth process

“…Some researchers believe that the mechanism by which additives can significantly enhance crystal growth lies in their obvious interference with the molecular self-assembly process. [32][33][34][35][36] Generally, additives could regulate the crystal shape by inhibiting the growth of crystal faces or promoting growth in certain directions. Additives can selectively be adsorbed on specific crystal faces and affect their growth rate, so crystals with the desired morphology and size can be designed and obtained.…”

Phase transformation of calcium carbonate in acetonitrile/H2O mixed solvents: effects of water content and dielectric constant

“…8,12 Apart from additives, solvents also play an important role in regulating crystal growth. 13 Organic co-solvents can yield enhanced morphological changes and an order of magnitude increase of additive incorporation within calcium carbonate, which cannot be achieved in pure aqueous solutions at any additive concentration. 13 In addition, metastable vaterite and aragonite phases form at relatively high ethanol/water cosolvent ratios.…”

“…13 Organic co-solvents can yield enhanced morphological changes and an order of magnitude increase of additive incorporation within calcium carbonate, which cannot be achieved in pure aqueous solutions at any additive concentration. 13 In addition, metastable vaterite and aragonite phases form at relatively high ethanol/water cosolvent ratios. 14,15 Besides, nanomaterials can be prepared by using a solvothermal method, which can be used in solar cells, tumor treatment and other fields.…”