Hydrogels are porous, cross-linked networks of hydrophilic polymers. Because of their ability to absorb large amounts of water and swell, or conversely, to release water and shrink, they are widely used in agriculture, biomedical, manufacturing, and sustainability applications. These unique materials are usually studied in uniform settings with emphasis on their intrinsic material properties; however, in many applications, hydrogel swelling/shrinking takes place in more complex environments with confinement, adhesion to surfaces, and temperature and humidity gradients.

Our lab combines synthesis, imaging, and poroelasticity theory to disentangle how polymer chemistry, gel microstructure, internal fluid transport, and these external constraints jointly control how hydrogels deform, fracture, and potentially even self-heal. Our main thrusts and research questions include:

Swelling/shrinkage in complex environments

By directly visualizing hydrogel swelling in 3D granular media akin to soil, our lab established that the spatially non-uniform stress imposed by the solid grains can hinder hydrogel water absorption and even cause fracture [Science Advances 2021, Soft Matter 2021, Soft Matter 2023, Soft Matter 2024]—rationalizing prior measurements that had puzzled the soil science community, and providing guidance for effective use of hydrogels in soil for sustainable agriculture.

In another advance, building on our prior work probing mechanical instabilities in soft materials [Physical Review Letters 2012], we showed that the coupling between hydrogel deformability, capillary forces, and internal water transport regulates how hydrogel assemblies crack during drying [Physical Review Letters 2019, Soft Matter 2019]—yielding ways to control and even reverse this process in diverse materials.

Building on these advances, we continue to investigate: How do obstructions and boundary constraints influence the morphology and integrity of swelling hydrogels? How do the hydrogels in turn influence their surroundings? And how can we use these insights to design hydrogels whose swelling and mechanics are optimized for use in a given environment?

Designer multifunctional hydrogels

Their versatility makes hydrogels attractive for use in diverse applications that require gel properties to be predictable and controllable. We are working to translate the fundamental insights derived from our research into applications, such as using hydrogels as sorbents for water harvesting and filtration [Advanced Materials 2021, ACS Central Science 2023, JACS Au 2023]. Building on these advances, we continue to investigate: How can we leverage methods from soft materials chemistry to develop design principles for multifunctional hydrogels that can e.g., harvest water from air in an energy-efficient manner, or deform in programmable ways?

This research program is expanding current understanding of gel swelling to more complex environments and modes of deformation. Ultimately, our goal is to develop fundamental principles that inform the use of gels in agriculture for water management in soil, in formulations for the development of functional coatings, and for environmental water harvesting.

In addition to reading our papers, you can find out more about some of this research in this short video presentation on using hydrogels for sustainability.