Mechanistic Design and Understanding of Fully Polymeric Antifreezing and Tough Hydrogels

About This Grant

NON-TECHNICAL SUMMARY: Icing is a natural phenomenon that plays a crucial role in sustaining life on Earth, but unwanted icing can cause severe economic, environmental, and life-threatening consequences. Conventional antifreezing materials, such as icephobic water-free organics or hydrophilic hydrogels containing antifreezing additives, often suffer from weak mechanical properties under subzero temperatures, which limits their practical applications. To address this issue, this research will explore a design strategy for developing a new class of fully polymeric hydrogels that possess inherent antifreezing properties and enhanced mechanical strength without requiring antifreeze additives. A successful project could pave the way for a new family of antifreezing hydrogels with diverse structures and other built-in functions for different applications under subzero temperatures, including flexible supercapacitors, soft robotics, electronic skin, and wearable devices. The research is multi-disciplinary and will provide a valuable learning experience for undergraduate/graduate students and high-school teachers in the areas of polymer chemistry/physics, molecular simulations, and engineering design. Additionally, the PI will also introduce experimental and computational components to the curriculum to enhance student learning of engineered materials and promote the field of hydrogel-based materials by organizing international conferences, special journal issues, and STEM student activities. TECHNICAL SUMMARY: The overarching goals of this research are twofold and aim to (1) develop and engineer a new family of fully polymeric hydrogels with intrinsic antifreezing and enhanced mechanical properties and (2) gain a fundamental understanding of antifreezing/toughening mechanisms of these hydrogels at different spatial and time scales ranging from atomic to macroscopic levels by using a combination of polymer chemistry and molecular simulations. The design strategy for these antifreezing hydrogels is to integrate strong water-binding polymers with tightly crosslinked and highly interpenetrating double-network structures, allowing to enhance polymer-water interactions for competitively inhibiting ice nucleation and growth, as well as to activate multiple energy-dissipation pathways for improving hydrogel mechanical properties. Parallel to experimental works, multiscale molecular simulations with new polymerization algorithms will be developed to study water structures, dynamics, and interactions around polymers confined in networks at both resting and stretching states, as well as at different subzero temperatures. Computational study allows to reveal different but correlated antifreezing and toughening mechanisms at atomic levels. Finally, experimental and computational data from the benchmarking hydrogel systems will be compared and correlated to better understand the complex composition/structure-dependent antifreezing and mechanical performance of such hydrogels. This will lead toward an optimal design of antifreezing hydrogels in an iterative way by investigating changes in polymer chemistries, pendant groups/crosslinkers, network structures, and water behavior. Overall, the development of new antifreezing hydrogels with enhanced properties could impact areas such as improved energy efficiency, environmental protection, biomedical treatments, and industrial applications. . This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.