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The research presented in this paper offers insight into the availability of intermediates in the depolymerization of polyethylene terephthalate (PET) to be used as feedstock to create value‐added products. Monitoring the dispersity, molecular weight, end groups, and crystallinity of reaction intermediates during the heterogeneous depolymerization of PET offers insight into the mechanism by which the polymer chains evolve during the reaction. Our results show dispersity decreases and crystallinity increases while the yield of insoluble PET remains high early in the reaction. Our interpretation of this data depicts a mechanism where chain scission targets amorphous tie chains between crystalline phases. Targeting the tie‐chains lowers the Mnof the polymer without changing the amount of recovered polymer flake. Chain scission of tie‐chains and isolating highly crystalline PET lowers the dispersity (Đ) of the polymer chains, as the size of the crystalline lamellae guides the molecular weight of the depolymerized oligomers. When sufficient end groups of PET chains are converted to alcohol groups, the PET flakes break apart into highly crystalline and less disperse polymer. Our results also demonstrate that the oligomeric depolymerization intermediates are readily repolymerized, offering new opportunities to chemically recycle PET more effectively and efficiently, from both an energy and purification standpoint.
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This content will become publicly available on January 1, 2026
End‐To‐End FRET Enabling Direct Measurement of Oligomer Chain Conformations and Molecular Weight in Reaction Solutions
Abstract Förster resonance energy transfer (FRET) is an established tool for measuring distances between two molecules (donor and acceptor) on the nanometer scale. In the field of polymer science, the use of FRET to measure polymer end‐to‐end distances (Ree) often requires complex synthetic steps to label the chain ends with the FRET pair. This work reports an anthracene‐functionalized chain‐transfer agent for reversible addition‐fragmentation chain‐transfer (RAFT) polymerization, enabling the synthesized chains to be directly end‐labeled with a donor and acceptor without the need for any post‐polymerization functionalization. Noteworthily, this FRET method allows for chain conformation measurements of low molecular weight oligomers in situ, without any work‐up steps. Using FRET to directly measure the averageReeof the oligomer chains during polymerization, the chain growth of methyl methacrylate, styrene, and methyl acrylate is investigated as a function of reaction time, including determining their degree of polymerization (DP). It is found thatDPresults from FRET are consistent with other established measurement methods, such as nuclear magnetic resonance (NMR) spectroscopy. Altogether, this work presents a broadly applicable and straightforward method to in situ characterizeReeof low molecular weight oligomers and theirDPduring reaction.
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- Award ID(s):
- 2132144
- PAR ID:
- 10568695
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Macromolecular Rapid Communications
- Volume:
- 46
- Issue:
- 1
- ISSN:
- 1022-1336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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