Polymers are used everywhere in our daily lives in almost every application imaginable. After decades of research, it is still nearly impossible to directly see the shape of a single polymer molecule and how it moves in its native environment, because the typical sizes of polymer chains are too small. This project uses the next generation of optical techniques called super-resolution microscopy to achieve this goal of directly imaging how single polymers behave in the solid state. While these techniques have been explored in several biological applications for achieving tens of nanometer resolutions, their use in materials science has been much more limited. This work will focus on a specific class of polymers called bottlebrushes, which have attracted interest for photonic materials and drug delivery, and happen to be a perfect size to be imaged by super-resolution. This project will directly address the question of how the structure and behavior of single polymers connect to the properties of the material at everyday length scales. Beyond the fundamental understanding that this offers, it will also enable efficient design of new materials for societal benefit. In addition, the further application of super-resolution microscopy to materials science will make it easier for others in this community to adopt these methods to their own research problems. In line with this theme of nanotechnology and materials science, this project will also support new curriculum development for Junior Science Club, an afterschool activity for underrepresented youths of grades 3-5. Graduate students and volunteers across campus will mentor students weekly over new 6-8 week modules, which will be publicly available and ready for adoption by others offering similar programs.
The connection between single-chain behavior and macroscopic properties is a central tenet in our modern understanding of polymer physics. However, direct visualization of single polymers is difficult particularly in application-relevant configurations, because single polymer chains are typically nanometers in size. This project tackles the grand challenge of imaging the conformation and dynamics of single polymer chains within a bulk material. The experiments will utilize super-resolution microscopy, which can image structures at tens of nanometer resolution, both non-invasively and with chemical specificity through fluorescent labeling. The specific polymers in this study are bottlebrushes, exploring the conformational rigidity in the bulk vs. previous dilute solution results, and directly visualizing entanglement dynamics. The questions posed here can be directly answered by visualization of single chains, while other techniques such as scattering, rheology, and simulation can only probe these questions indirectly .
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.
