Catalytically Controlled Ring-Opening Polymerization of 2-Oxo-15-crown-5 for Degradable and Recyclable PEG-Like Polyesters

Fully recyclable and tough thermoplastic elastomers from simple bio-sourced δ-valerolactones

While a large number of chemically recyclable thermoplastics have been developed in recent years, technologically important thermoplastic elastomers (TPEs) that are not only bio-based and fully recyclable but also exhibit mechanical properties that can rival or even exceed those petroleum-based, non-recyclable polyolefin TPEs are critically lacking. The key challenge in developing chemically circular, bio-based, high-performance TPEs rests on the complexity of TPE's block copolymer (BCP) structure involving block segments of different suitable monomers required to induce self-assembled morphologies responsible for performance as well as the control and monomer compatibility in their synthesis and the selectivity in their depolymerization. Here we demonstrate the utilization of bio-sourced δ-valerolactone (δVL) and its simple α-alkyl-substituted derivatives to produce all δVL-based polyester tri-BCP TPEs, which exhibit not only complete (closed-loop) chemical recyclability but also excellent toughness that is 2.5-3.8 times higher than commercial polyolefin-based TPEs. The visualized cylindrical morphology formed via crystallization-driven self-assembly in the new all δVL tri-BCP is postulated to contribute to the excellent TPE property.

Recyclable and (Bio)degradable Polyesters in a Circular Plastics Economy

Polyesters carrying polar main-chain ester linkages exhibit distinct material properties for diverse applications and thus play an important role in today's plastics economy. It is anticipated that they will play an even greater role in tomorrow's circular plastics economy that focuses on sustainability, thanks to the abundant availability of their biosourced building blocks and the presence of the main-chain ester bonds that can be chemically or biologically cleaved on demand by multiple methods and thus bring about more desired end-of-life plastic waste management options. Because of this potential and promise, there have been intense research activities directed at addressing recycling, upcycling or biodegradation of existing legacy polyesters, designing their biorenewable alternatives, and redesigning future polyesters with intrinsic chemical recyclability and tailored performance that can rival today's commodity plastics that are either petroleum based and/or hard to recycle. This review captures these exciting recent developments and outlines future challenges and opportunities. Case studies on the legacy polyesters, poly(lactic acid), poly(3-hydroxyalkanoate)s, poly(ethylene terephthalate), poly(butylene succinate), and poly(butylene-adipate terephthalate), are presented, and emerging chemically recyclable polyesters are comprehensively reviewed.

Recent Advances in Biodegradable and Biocompatible Synthetic Polymers Used in Skin Wound Healing

The treatment of skin wounds caused by trauma and pathophysiological disorders has been a growing healthcare challenge, posing a great economic burden worldwide. The use of appropriate wound dressings can help to facilitate the repair and healing rate of defective skin. Natural polymer biomaterials such as collagen and hyaluronic acid with excellent biocompatibility have been shown to promote wound healing and the restoration of skin. However, the low mechanical properties and fast degradation rate have limited their applications. Skin wound dressings based on biodegradable and biocompatible synthetic polymers can not only overcome the shortcomings of natural polymer biomaterials but also possess favorable properties for applications in the treatment of skin wounds. Herein, we listed several biodegradable and biocompatible synthetic polymers used as wound dressing materials, such as PVA, PCL, PLA, PLGA, PU, and PEO/PEG, focusing on their composition, fabrication techniques, and functions promoting wound healing. Additionally, the future development prospects of synthetic biodegradable polymer-based wound dressings are put forward. Our review aims to provide new insights for the further development of wound dressings using synthetic biodegradable polymers.

Ring-Opening Polymerization for the Goal of Chemically Recyclable Polymers

A crucial modern dilemma relates to the ecological crisis created by excess plastic waste production. An emerging technology for reducing plastic waste is the production of "chemically recyclable" polymers. These polymers can be efficiently synthesized through ring-opening polymerization (ROP/ROMP) and later recycled to pristine monomer by ring-closing depolymerization, in an efficient circular-type system. This Perspective aims to explore the chemistry involved in the preparation of these monomer/polymer systems, while also providing an overview of the challenges involved, including future directions.