Polyethylene terephthalate (PET) is a semicrystalline thermoplastic with a dense network of ester linkages shielded by aromatic terephthalic units. The thermoplasticity allows for ease in thermomechanical reprocessing, and post-consumer PET can be easily recast into user-end products. Albeit cost-effective, mechanical recycling leads to undesirable hydrolysis and oxidative aging of PET, resulting in the 2<sup>nd</sup> generation of PET with inferior performance properties. This loss in performance properties makes it an imperfect process. At the same time, chemical disassembly of PET requires mandates for chemically corrosive environments at elevated temperatures and pressures, balking large-scale industrial adoption. This calls for devising a strategy that allows selective yet facile depolymerization of PET. This study aims to incorporate chimeric comonomers that respond rapidly to triggers at the monomolecular scale with the anticipation of the effect being mirrored at macromolecular scales. One such moiety has been carefully crafted with amide functionalities juxtaposed to benzylic ester groups. The presence of the neighboring amides to benzylic esters predisposes the molecule to intramolecular cyclization. The acidic protons of amides are readily abstracted by a base proceeding through a stable imide intermediate while ejecting alcohol from the ester. The polymer formulation comprising these chimeric moieties replicates the process at random centers at the chain resulting in a quick depolymerization cascade susceptible to milder alkaline hydrolysis. These units are also likely to equilibrate in the amorphous domains of the polymer, making them readily accessible to chemosensitive triggers. The cyclized isolates can be reintroduced in the chain by ring opening it with a nucleophile and copolymerizing with BHET (Bis(2-Hydroxyethyl) terephthalate). This establishes near-perfect circularity as desired for a true molecular recycling process for PET.

Anchimerically assisted depolymerization of chimeric polyethylene terephthalate

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