Plastics are critical materials for broad swaths of society, including healthcare, food storage, packaging, and transportation, among others. However, managing end-of-life plastics must be improved, as the life-cycle of most materials currently end in landfills or an incinerator. Therefore, there is an urgent need to develop technologies to manage the environmental and economic consequences of end-of-life plastics. Unfortunately, the options available to compete with disposal are limited. Mechanical recycling is the most common current technology, but requires separation of a mixed waste stream to provide pure polymer as most polymer pairs produce ill-defined mixtures with inferior properties. The development of novel and effective polymeric surfactants can improve the properties of mixed plastic waste streams that are ubiquitous in polymer recycling. This research program will therefore provide a foundation to develop novel polymeric modifiers that are required to enhance current polymeric recycling. Notably, these results enable the development of materials that will have near-term benefits allowing the efficient reclamation of plastics currently in the environment. As such, the identification of these molecular design principles provides a bridge between emerging chemical recycling, new materials design efforts, and current technologies to mechanically recycle plastics. Workforce development and training of the next generation of scientists and engineers who are prepared to tackle the grand challenges in mitigating the economic, environmental and societal effects of the end of life of plastics will be realized through this research program and also by engaging public high school students in hands-on research experiences. Additionally, an online clearinghouse for curriculum modules focused on sustainable materials will be established and made available to the public.
The overarching goal of this research program is to provide a foundation from which optimal polymeric compatibilizers for mixed plastic waste streams may be designed. As crystalline polymers dominate polymer recycling, research efforts will provide fundamental information that delivers molecular design characteristics for effective compatibilizers of phase separated crystalline polymer blends. Initial experiments will seek to identify crucial molecular characteristics that enable the co-crystallization of compatibilizers and homopolymers in phase separated crystalline polymer blends, thereby strengthening weak interfaces. These studies will be coupled with efforts to intercept telechelic intermediaries in the chemical recycling of polymers that may be used as value-added materials, such as their use as feedstocks to synthesize multiblock copolymers that compatibilize polymer waste stream-derived phase separated blends. The targeted molecular characteristics of these optimal compatibilizers will be informed by the molecular design efforts described above. The efficacy of these building blocks to form optimal compatibilizers in both passive and reactive processing schemes will be studied, with the goal of providing routes to jointly utilize chemical and mechanical recycling in developing improved materials from end-of-life plastics. This portion of the research program will therefore have an amplified environmental impact as it links and improves both chemical and mechanical recycling of polymers. .
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.
