Grant: Discovery Grants Program - Individual

Polymers that undergo degradation to small molecules in the environment or in the human body are of significant interest to both academia and industry for a wide range of applications from packaging to medical devices. Ideally, a polymer would be highly stable while performing its function, but would break down rapidly under the desired conditions. Currently available materials typically undergo degradation by random backbone scission and degrade gradually in a wide range of environments, limiting our ability to trigger and control this degradation. The proposed research program aims to develop a class of polymers that degrade specifically by an end-to-end depolymerization mechanism in response to the cleavage of a stimuli-responsive end-cap from the polymer terminus. New end-caps responsive to different stimuli such as changes in the concentrations of oxidizing or reducing species, heat, light and even multiple combinations of such stimuli will be developed, enhancing our understanding of their degradation behavior and demonstrating the potential to tune these polymers for a variety of applications. Through careful design of these end-caps, polymers composed of multiple blocks will also be prepared. The incorporation of new monomers will enable the properties of the polymers to be tuned, further chemical derivatization to be performed, and for new functions such as drug incorporation to be introduced. * The ultimate functions of these new depolymerizable molecules will be realized through their incorporation into 3-dimensional materials. Block copolymers will be incorporated into nanometer-sized assemblies including micelles and vesicles, which will be explored for their ability to encapsulate and release cargo such as anti-cancer drugs, therapeutic nucleic acids, and growth factors for tissue engineering in a controlled manner. The polymers will also be used to fabricate porous scaffolds for the growth of cells for tissue engineering. The ability to change the stimuli to which the polymers respond, simply by changing the end-cap, will offer a significant advantage over the current polymers in terms of our ability to prepare and study a wide range of new materials responsive to different stimuli. Furthermore, the ability to degrade an entire polymer chain following a single stimulus-mediated event can provide a significant amplification of the stimulus, enabling changes in material properties to occur at low, cell-compatible stimulus concentrations. Overall, this research will enable transformative advancements in our understanding of stimuli-responsive materials while at the same time affording new properties and functions for the target applications. *