(538o) Methanolysis of PET As a Model Chemical Recycling Method for Heterochain Polymers

The global issue of plastic pollution is widely known and remains prevalent as production, and thus waste, continues to grow. The key issue is that it is common to discard single-use plastic products, such as packaging and textiles. A plastic that is prominent in both of these industrial sectors is polyethylene terephthalate (PET), a derivative of fossil fuels. Chemical recycling provides a closed-loop process to yield chemical feedstocks from plastic that can be used without compromising quality. Chemical recycling of PET is feasible because of its heteroatom backbone structure. A promising avenue for PET recycling is catalytic methanolysis. Our work is converting PET through transesterification to produce high yields of the PET monomer dimethyl terephthalate (DMT). Previous research has primarily focused on the use of metal salts and ionic liquids for PET recycling, yet more recent studies have gained interest in the use of organic catalysts. Our work uses N-methylpiperidine (NMP) as an organocatalyst to facilitate the depolymerization of PET. We have demonstrated that temperatures of 140°C are required for converting PET into the monomers. Additionally, higher conversion is achieved through grinding of the materials to increase the surface area.

The methods will be extended to a polymer that is similar in structure and function to PET that is polyethylene furanoate (PEF), which is considered an important bio-derived polymer. PEF has similar synthesis methods and some superior properties that are desirable for applications like packaging. The goal will be to demonstrate similarities and differences in the recycling of PET and PEF. The ability to recycle plastic has significant applications for sustainable engineering design and the reduction of plastic waste streams.