NSF Award
2404030
With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Julia Kalow of Northwestern University will develop polymer networks controlled by light. Polymer networks are ubiquitous materials ranging from stiff, strong wind turbines, to stretchy rubber in tires and gloves, to soft gels in bandages. While all of these materials are based on interconnected polymer strands, a wide range of properties can be achieved by controlling the structure of the polymer strands, including controlling how densely they interconnect, and whether these interconnections are static or dynamic. The Kalow lab will combine dynamic bonds with molecular switches that change their structure in response to light. This combination is expected to provide for control over the number of bonds or how quickly they exchange with different colors of light, a widely available, precise, and tunable energy source. By incorporating these switchable dynamic bonds into a polymer network, the Kalow lab aims to create adaptable materials capable of on-demand changes in stiffness and flow. Potential applications of these materials include soft robotics, materials with on-demand recyclability, and tissue mimics. To improve accessibility in polymer education and outreach, the Kalow lab will also develop experiments and lesson plans for learners who are blind or have low vision, by collaborating with local organizations serving these individuals. These activities will allow learners to explore the polymer properties of edible gels by using touch and taste.<br/><br/>The Kalow lab takes a bottom-up approach to control polymer network mechanics by coupling photoswitches to dynamic crosslink reactivity. In principle, this approach will allow for the reversible photocontrol of mechanical properties such as stiffness and viscoelasticity. This research will expose students to physical organic chemistry, synthesis, polymer chemistry, and polymer physics. Specific objectives include the design of aqueous-compatible switchable crosslinks for hydrogels and switches that control crosslink exchange rate; these goals will be enabled by the development of high throughput methods for preparing and testing photoswitches. The expected outcomes of these studies are quantitative structure-property-reactivity relationships for photocontrolled dynamic networks, and viscoelastic hydrogels and reprocessable elastomers with targeted properties.<br/><br/>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.
