STTR Phase I: Dynamic Covalent Polymers for Transition to Circular Plastics Economy

The broader/commercial impact of this Small Business Technology Transfer Research (STTR) Phase I project is reducing society’s reliance on hard-to-recycle plastics and transitioning towards a more circular plastics economy. 400M metric tons of virgin plastic is produced each year, <10% of which is recycled. 12% of global virgin plastic productions are thermosets which have a recycling rate of nearly 0%. In the US alone, 2% of energy consumption is dedicated to manufacturing virgin plastics, polymer resin, and synthetic rubbers. By enabling closed-loop plastic recycling with an infinitely recyclable material, waste can be reduced, costs can be lowered, energy consumption can be cut, and greenhouse gas emissions can be drastically reduced. This technology may enable plastic material recovery and significantly mitigate the volume of plastics ending up in landfills and the broader environment, ultimately curtailing a massive source of environmental microplastics that threaten human health. Incorporating commercially viable bio-based inputs will lower the environmental impacts of plastic production by upcycling agricultural waste and using plant-based feedstocks, providing domestically sourced and sustainable inputs. Overall, the technology is positioned to enable and incentivize plastic material recovery, mitigating the plastic waste issue that has allowed plastics to infiltrate water resources, the environment, and the food supply. The technical innovation of this project lies in the unique features of Enamine Covalent Adaptable Networks (ECANs). These networks have the potential to revolutionize handling of hard-to-recycle plastics, enabling closed-loop lifecycles and significantly reduced waste. ECANs are a platform polymer technology that produces a variety of resins for manufacture into films, sheets, foams, fibers and textiles, adhesives, composites, elastomers, and other high-value raw materials. Unlike conventional polymers, ECANs are dynamic covalent polymers that can undergo associative dynamic bond exchange reactions. ECANs are chemically recyclable and can be quickly recovered and remanufactured into next-generation ECANs. Platform development will occur through the following objectives: 1) develop new pathways for the synthesis of environmentally friendly and cost effective ECANs, 2) develop a platform of ECANs with controllable properties meeting the needs of diverse customers and applications, and 3) validate recyclability over multiple lifecycles. Production of resins with tunable properties will be examined through combinations of small molecules, triketones, polyamines, plasticizers, solvents, and colorants using various synthetic and processing conditions. Thermo-mechanical and rheological measurements will be performed on each newly formed ECAN to determine performance through each new generation. Extrusion and other existing plastics manufacturing processes will be employed for customer ease of adoption of ECAN resins. Recycling parameters will be optimized to increase purity, yield while decreasing cost, energy, and CO2 emissions. 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.