Nov 13 2019
For many centuries, crystals have been studied and are omnipresent in the everyday life of humans. They are found in human bones, the food humans eat, and the batteries they use. Still, researchers haven’t been able to fully understand the way crystals grow, or find ways for the efficient manufacture of crystals.
Local fluctuations allow molecules to leave the solvation shell and integrate into the crystal surface. Image Credit: Meenesh Singh.
Consequently, there have been very little scientific efforts to enhance a broad array of crystalline materials, from solar panels to self-healing biomaterials.
Scientists from the University of Illinois at Chicago have come up with a solution to part of this mystery. The UIC team used computer-based simulations to study the movement of atoms and molecules in a solution.
They determined a general mechanism that governs crystal growth. This mechanism can be leveraged by researchers while developing new materials.
In particular, they discovered that when a solvent (for example, water) surrounds crystal-forming molecules, the solvent molecules create a shield, known as a solvation shell. Fluctuations in this shield lead to breaking up of molecules, which then form crystals.
The team also demonstrated that the fluctuation of the shell is affected by the number of solvent molecules, type of the solvent, and temperature. The study outcomes have been published in the journal Proceedings of the National Academy of Sciences.
For the first time, we have shown what happens when a molecule leaves a solvent to form a crystal. Under the right conditions, the shield ‘dances’ around and allows molecules to break free and integrate into the crystal surface. The fluctuations in the solvation shell are key molecular events that explain how crystals form—knowledge of this mechanism has been missing since the inception of crystallization research.
Meenesh Singh, Study Senior Author and Assistant Professor of Chemical Engineering, UIC College of Engineering
According to Singh, gaining insights into this mechanism will offer researchers with increased ability to manipulate molecules to create crystals for particular shape, size, and structure. “This will allow us to make better materials for a wide class of products used in daily life,” he added.
He further stated that some examples are more stable lithium batteries, bone implants that support biomineralization, enhanced semiconductors and agricultural chemicals, and better drug delivery systems.
The molecular insight gained from this study will also help save money in various chemical industries by reducing the need for hit or miss techniques in thousands of trials. With the help of this study, we can now design systems that can crystallize the desired solute molecule without so many trials.
Anish Dighe, Study Co-Author and Graduate Student, University of Illinois at Chicago
This research was partially funded by the National Science Foundation (CBET-1706921).