Crystallization in Confinement

Abstract

Many crystallization processes of great importance, including frost heave, biomineralization, the synthesis of nanomaterials, and scale formation, occur in small volumes rather than bulk solution. Here, the influence of confinement on crystallization processes is described, drawing together information from fields as diverse as bioinspired mineralization, templating, pharmaceuticals, colloidal crystallization, and geochemistry. Experiments are principally conducted within confining systems that offer well‐defined environments, varying from droplets in microfluidic devices, to cylindrical pores in filtration membranes, to nanoporous glasses and carbon nanotubes. Dramatic effects are observed, including a stabilization of metastable polymorphs, a depression of freezing points, and the formation of crystals with preferred orientations, modified morphologies, and even structures not seen in bulk. Confinement is also shown to influence crystallization processes over length scales ranging from the atomic to hundreds of micrometers, and to originate from a wide range of mechanisms. The development of an enhanced understanding of the influence of confinement on crystal nucleation and growth will not only provide superior insight into crystallization processes in many real‐world environments, but will also enable this phenomenon to be used to control crystallization in applications including nanomaterial synthesis, heavy metal remediation, and the prevention of weathering.

Reversing the Irreversible: Thermodynamic Stabilization of Lithium Aluminum Hydride Nanoconfined Within a Nitrogen-Doped Carbon Host

“…As the results in this work indicate, the creation of such a "designed metal hydridefunctionalized scaffold composite" and the optimal tuning of its properties can address important materials science challenges in energy generation and storage and can lead to a better understanding of con nement effects in nanoscale volumes. 39 25 mg of puri ed LiAlH 4 was dissolved into 1.25 mL of dried diethyl ether obtained from a solvent puri cation system. The LiAlH 4 solution was ltrated by 0.45 μm syringe lter and added to 100 mg of the pretreated mesoporous carbon scaffolds (CMK-3 and NCMK-3).…”

NaCl-related weathering of stone: the importance of kinetics and salt mixtures in environmental risk assessment

“…Based on the precision of the measured temperature data, these correspond most closely with a w = 0.755 (at 10 °C for a saturated sodium chloride solution 6.135 mol kg − 1 ). It also remains important to keep in mind that crystallization is affected by a range of different factors (see [18]) and dissolution of salt crystals takes more time compared to crystallization. Furthermore, a threshold of 65.5% RH is considered as the RH eq of NaCl tends to shift in a mixture with other ions, thus representing a more realistic situation.…”

“…In contrast, the literature about stone in the built environment has focused on practical approaches to addressing stone conservation (e.g., [5][6][7][8]). Fundamental questions, such as the mechanisms of crystallization and the development of crystallization pressure in porous media, remain open questions and active areas of research (e.g., [9][10][11][12][13][14][15][16][17][18][19]). Nevertheless, there is consensus that repeated cycles of crystallization and dissolution of hygroscopic salts is controlled by changing conditions in relative humidity (RH) and that repeated crystallization leads to the degradation of porous stone through the resulting weakening of intergranular bounds in the substrate.…”

NaCl-Related Weathering of Stone: The Importance of Kinetics and Salt Mixtures in Environmental Risk Assessment

“…Based on the precision of the measured temperature data, these correspond most closely with a w = 0.755 (at 10 °C for a saturated sodium chloride solution 6.135 mol.kg − 1 ). It also remains important to keep in mind that crystallization is affected by a range of different factors (see (19)) and dissolution of salt crystals takes more time compared to crystallization. Furthermore, a threshold of 65.5% RH is considered as the RH eq of NaCl tends to shift in a mixture with other ions, thus representing a more realistic situation.…”

“…In contrast, the literature about stone in the built environment has focused on practical approaches to addressing stone conservation (e.g., (5)(6)(7)(8)). Fundamental questions, such as the mechanisms of crystallization and the development of crystallization pressure in porous media, remain open questions and active areas of research (e.g., (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)).…”