NSF Award
2404007
With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Philip Costanzo and Daniel Bercovici of the Department of Chemistry and Biochemistry at California Polytechnic State University, San Luis Obispo, are developing synthetic approaches to prepare novel polymers that are responsive to externally applied temperature. Synthetic polymers or commonly referred to as plastics are widely used in our daily lives. The properties of these long chain macromolecules consisting of many repeating units linked with carbon-carbon bonds are controlled by their chemical structures which can be tailored for different applications. In this work, chemically distinct structures are imbedded into polymeric materials. These structures are incorporated into polymer chains at precise locations. Next, a directed chemical modification acts as a trigger, that upon heating, leads to breakage of the chain. This efficient strategy allows the design of polymer strands with chemical structures that can be pulled apart at one temperature and snapped back together at a different temperature. The chemistry associated with this award is broadly transferrable to many other polymerization systems and useful to materials chemistry or any other fields in which thermally responsive polymers are of interest. This research is having a broader impact by providing productive opportunities for undergraduate students to engage in frontline research training and education in organic and polymer chemistry. Apart from incorporating the results associated with this award into chemistry laboratory courses at the university, an outreach program called the Macromolecular Alliance of Community, Resources and Outreach (MACRO) is initiated. The goal of this program is to create a depository of outreach materials through which individuals can spread their passion and knowledge of science to the general population. <br/><br/>This work is focused on the development of dynamic-covalent linkages that can be incorporated into polymer systems to enable switchability in polymer topology and composition and bestow thermal responsive properties. Several studies will be carried out to achieve this goal. The first objective focuses on the development of Diels-Alder linkage systems with novel dienes and dienophiles and systematic understanding of the thermal stability of the prepared adducts. In the second objective, the unsaturated adducts are to undergo 1,4-addition or conjugate addition leading to adducts that are more susceptible to retro-Diels-Alder cleavage. Next these Diels-Alder linkages are to be incorporated within polymeric structures using copper-catalyzed atom transfer radical polymerization (ATRP), copper-mediate azide-alkyne cycloaddition chemistry and urethane-based strategies. The last aim will explore dynamic covalent chemistry effects on the polymer topology and physical properties with special emphasis on polymer processing for re/up-cycling of materials. Using nucleophiles such as thiols to modulate bond-cleaving temperature is applicable to a variety of other polymerization techniques and has the potential to generate a wide range of new smart materials of industrial importance.<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.
