(650g) Gates in the Impurity Fence: Controlling Crystal Growth and Latent Heat Release with Polymer Phase Transitions

It is well known that the presence of impurities in solutions of crystallizing material can slow the growth rates and affect the morphologies of the resulting crystals by adsorbing to exposed faces, kinks, and ledges, blocking the progression of the crystallization front.^[1–3] In this work, we characterize the crystallization of supersaturated salts in aqueous solutions and gels containing polymers that undergo phase transitions. We find that the polymers impede crystal growth significantly in expanded conformations, while they have little to no effect on growth rates in collapsed states. We apply this phenomenon to fast-crystallizing, stably supercoolable phase change materials used for thermal energy storage^[4] in order to use polymer phase transitions to modulate the kinetics and spatial patterning of latent heat release. Responsive moieties therefore enable the spatiotemporal coupling of a stimulus capable of inducing polymer collapse to the fabrication of crystalline materials and the activation of downstream thermally-mediated processes.

[1] N. Cabrera, D. A. Vermilyea, in Growth and Perfection of Crystals: Proceedings of an International Conference on Crystal Growth, Cooperstown, New York, August 1958 (Eds.: R.H. Doremus, B.W. Roberts, D. Turnbull), Wiley, New York, 1958, pp. 393–410.

[2] N. Kubota, J. W. Mullin, J. Cryst. Growth 1995, 152, 203.

[3] K. Sangwal, Additives and Crystallization Processes, John Wiley & Sons, Ltd, Chichester, UK, 2007.

[4] N. Beaupere, U. Soupremanien, L. Zalewski, Thermochim. Acta 2018, 670, 184.