Chemically Recyclable Linear and Branched Polyethylenes Synthesized from Stoichiometrically Self-Balanced Telechelic Polyethylenes

Abstract

High-density polyethylene (HDPE) is a widely used commercial plastic due to its excellent mechanical properties, chemical resistance, and water vapor barrier properties. However, less than 10% of HDPE is mechanically recycled, and the chemical recycling of HDPE is challenging due to the inherent strength of the carbon−carbon backbone bonds. Here, we report chemically recyclable linear and branched HDPE with sparse backbone ester groups synthesized from the transesterification of telechelic polyethylene macromonomers. Stoichiometrically self-balanced telechelic polyethylenes underwent transesterification polymerization to produce the PE-ester samples with high number-average molar masses of up to 111 kg/mol. Moreover, the transesterification polymerization of the telechelic polyethylenes and the multifunctional diethyl 5-(hydroxymethyl)isophthalate generated branched PE-esters. Thermal and mechanical properties of the PE-esters were comparable to those of commercial HDPE and tunable through control of the ester content in the backbone. In addition, branched PE-esters showed higher levels of melt strain hardening compared with linear versions. The PE-ester was depolymerized into telechelic macromonomers through straightforward methanolysis, and the resulting macromonomers could be effectively repolymerized to generate a high molar mass recycled PE-ester sample. This is a new and promising method for synthesizing and recycling high-molar-mass linear and branched PE-esters, which are competitive with HDPE and have easily tailorable properties.

Synthesis, Characterization, and Application of High-Molecular-Weight Polyethylene-like Polycarbonates: Toward Sustainable and Recyclable Fibers

“…The long-chain polycarbonates and polyester possess PE-like solid-state structures and, therefore, present good mechanical properties, holding great potential for further applications. Despite the fact that significant effort has been devoted to the synthesis and degradation of PE-like materials, − a long-pursued target is to produce sustainable, inexpensive, and biobased PE-like materials to meet practical applications in a wide variety of fields. A prerequisite to realize this target is to establish a scalable, reliable, and economical synthesis strategy for PE-like materials, which is preferred if it is compatible with the current industrial synthesis process.…”

Oxidative Polymer Degradation via Cope Elimination

“…To address challenges in plastic persistence, it is vital to develop highly tunable, degradable materials. − With this in mind, poly(β-amino esters) (PBAEs) and poly(amido amines) (PAMAMs) have garnered interest in biomedical and materials science due to their facile synthesis, controllable degradation lifetime, and biocompatibility. − These materials are typically prepared via bulk aza-Michael polymerization of diacrylates/acrylamides with primary amines. , This combinatorial approach allows for the preparation of materials libraries with highly customizable backbone and pendent group chemistries without the need for purification. − Because of this structural diversity and ease of synthesis, PBAEs and PAMAMs have been extensively investigated as degradable polymeric platforms in gene delivery, ,, bioimaging, , three-dimensional (3D) printing, , and dynamic covalent networks. − …”