Search for: All records

Abstract We describe a methodology of post‐polymerization functionalization to enable subsequent bulk depolymerization to monomer by utilizing mechanochemical macro‐radical generation. By harnessing ultrasonic chain‐scission in the presence ofN‐hydroxyphthalimide methacrylate (PhthMA), we successfully chain‐end functionalize polymers to promote subsequent depolymerization in bulk, achieving up to 82 % depolymerization of poly(methyl methacrylate) (PMMA) and poly(α‐methylstyrene) (PAMS) within 30 min. This method of depolymerization yields a high‐purity monomer that can be repolymerized. Moreover, as compared to the most common methods of depolymerization, this work is most efficient with ultra‐high molecular weight (UHMW) polymers, establishing a method with the potential to address highly persistent, non‐degradable all‐carbon backbone plastic materials. Lastly, we demonstrate the expansion of this depolymerization method to commercial cell cast PMMA, achieving high degrees of depolymerization from post‐consumer waste. This work is the first demonstration of applying PhthMA‐promoted depolymerization strategies in homopolymer PMMA and PAMS prepared by conventional polymerization methods. 

The polymerization of N -carboxyanhydrides (NCAs) affords access to a vast array of synthetic polypeptides with tunable molecular weights, functionalities, and architectures. The use of light to achieve spatiotemporal control over these polymerizations could expand their applicability to a variety of areas, including 3D printing and photolithography. In this report we utilized 2-(2-nitrophenyl)propyloxycarbonyl (NPPOC) as a photoprotecting group to cage a primary amine initiator that is activated upon UV irradiation. NPPOC photocages underwent quantitative deprotection and afforded better polymerization control compared to previously reported photocaged amines for NCA polymerizations. Furthermore, the addition of a small equivalence of base enhanced the control and resulted in polymers with lower dispersities. Overall, this method advances photo-controlled polypeptide synthesis by demonstrating high chain-end fidelity, efficient chain extension, and the ability to synthesize block copolymers.