Patterned crystal growth and heat wave generation in hydrogels
Abstract
The crystallization of metastable liquid phase change materials releases stored energy as latent heat upon nucleation and may therefore provide a triggerable means of activating downstream processes that respond to changes in temperature. In this work, we describe a strategy for controlling the fast, exothermic crystallization of sodium acetate from a metastable aqueous solution into trihydrate crystals within a polyacrylamide hydrogel whose polymerization state has been patterned using photomasks. A comprehensive experimental study of crystal shapes, crystal growth front velocities and evolving thermal profiles showed that rapid growth of long needle-like crystals through unpolymerized solutions produced peak temperatures of up to 45˚C, while slower-crystallizing polymerized solutions produced polycrystalline composites and peaked at 30˚C due to lower rates of heat release relative to dissipation in these regions. This temperature difference in the propagating heat waves, which we describe using a proposed analytical model, enables the use of this strategy to selectively activate thermoresponsive processes in predefined areas.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 11, 2022
- Source ID
- 10.1038/s41467-021-27505-z
Entities
People
- Joanna Aizenberg
- Thomas B. H. Schroeder
Organizations
- Army Research Office
- Swiss National Science Foundation
- United States Department of Energy