Depolymerizable supramolecular polyethylene from bio-inspired nucleobase units

Given their manufacturing versatility, plastics have fundamentally changed commercial consumerism. Unfortunately, two of the largest drawbacks to current plastics on the market is their dependency on fossil fuels and their lack of circular recyclability. In this paper, the focus will be on the latter issue. Circular recyclability can be described as the idea of minimizing waste through its reformation back into a commodity. Currently, the primary method of recycling plastics, mechanical recycling, can only be achieved through melting and reshaping plastic for reuse. A significant drawback to this method is the reduction in chain molecular weight and subsequent loss of mechanical integrity through multiple reheating cycles. Chemical recycling provides an alternative where the polymer is broken down through chemically reactive sites, allowing the material to be recycled a theoretically infinite number of times and maintain its mechanical properties. Polyethylene, one of the largest classes of industrially produced plastic, does not have any commercially relevant chemically recyclable derivatives. The structure of polyethylene is primarily composed of long, nonpolar hydrocarbon chains that provide the material’s signature tough property. To make a material that can be depolymerizable for chemical recycling, polar ester functional groups must be added throughout the chain, allowing for chain scission by hydrolysis. Unfortunately, while the incorporation of ester functionality into polyethylene has been studied previously, material strength decreases as a result of this modification, sacrificing the integrity of the final product. Herein, I propose the incorporation of nucleobase pairings into the ester-containing polyethylene, which will add supramolecular hydrogen bonding reinforcements to improve the mechanical performance while maintaining chemical recyclability. This addition to the polyethylene backbone will be achieved by the synthesis of a ureido cytosine (UCy) diol, which contains 4 complementary hydrogen bonding sites for enhanced intermolecular forces between polyethylene chains.