Crystallization Kinetics of Amorphous Carbonates in Confinement

Metastable precursors are integral to the biosynthesis of mineralized tissues with intricate architecture and emergent properties.[1] They are also used in bio-inspired syntheses of structures and compositions far from equilibrium.[2-4] While simulations predict the structures of myriad materials with highly desirable properties, the ability to synthesize lags behind significantly. The difficulty often lies in determining accurate transformation rates between competing metastable phases. I will report on recent progress towards solving this problem by studying phase transformations of amorphous carbonates in confinement. Specifically, I will discuss insights into the crystallization of amorphous calcium carbonate (ACC) in the absence of additives that were gained using a microfluidic droplet assay;[5] the switch from constant to highly dynamic barriers to nucleation as a function of barium concentration in the barium-calcium-carbonate-water system,[6] and the polymorph-specific scaling of the nucleation rate of calcium carbonate with the radius of the confining droplet.<br/><br/>1. De Yoreo, J. J.; Gilbert, P. U.; Sommerdijk, N. A.; Penn, R. L.; Whitelam, S.; Joester, D.; Zhang, H.; Rimer, J. D.; Navrotsky, A.; Banfield, J. F.; Wallace, A. F.; Michel, F. M.; Meldrum, F. C.; Colfen, H.; Dove, P. M., Science 2015, 349 (6247), aaa6760.<br/>2. Kondrat, S. A.; Smith, P. J.; Wells, P. P.; Chater, P. A.; Carter, J. H.; Morgan, D. J.; Fiordaliso, E. M.; Wagner, J. B.; Davies, T. E.; Lu, L.; Bartley, J. K.; Taylor, S. H.; Spencer, M. S.; Kiely, C. J.; Kelly, G. J.; Park, C. W.; Rosseinsky, M. J.; Hutchings, G. J., Nature 2016, 531 (7592), 83-7.<br/>3. Whittaker, M. L.; Joester, D., Adv. Mater. 2017, 29 (26).<br/>4. Whittaker, M. L.; Smeets, P. J. M.; Asayesh-Ardakani, H.; Shahbazian-Yassar, R.; Joester, D., Angew Chem Int Ed 2017, 11 (56), 16028-16031.<br/>5. Cavanaugh, J.; Whittaker, M. L.; Joester, D., Chemical Science 2019, 10 (19), 5039-5043.<br/>6. Whittaker, M. L.; Sun, W.; Duggins, D.O.; Ceder, G.; Joester, D. Crystal Growth & Design 2021, 21, 8, 4556-4563.