The replacement of current petroleum-based plastics with sustainable alternatives is a crucial but formidable challenge for the modern society. Catalysis presents an enabling tool to facilitate the development of sustainable polymers. This review provides a system-level analysis of sustainable polymers and outlines key criteria with respect to the feedstocks the polymers are derived from, the manner in which the polymers are generated, and the end-of-use options. Specifically, we define sustainable polymers as a class of materials that are derived from renewable feedstocks and exhibit closed-loop life cycles. Among potential candidates, aliphatic polyesters and polycarbonates are promising materials due to their renewable resources and excellent biodegradability. The development of renewable monomers, the versatile synthetic routes to convert these monomers to polyesters and polycarbonate, and the different end-of-use options for these polymers are critically reviewed, with a focus on recent advances in c...

Catalysis as an Enabling Science for Sustainable Polymers

Chemically recyclable polymers: a circular economy approach to sustainability

Polyethylene (PE) and isotactic polypropylene ( i PP) constitute nearly two-thirds of the world’s plastic. Despite their similar hydrocarbon makeup, the polymers are immiscible with one another. Thus, common grades of PE and i PP do not adhere or blend, creating challenges for recycling these materials. We synthesized PE/ i PP multiblock copolymers using an isoselective alkene polymerization initiator. These polymers can weld common grades of commercial PE and i PP together, depending on the molecular weights and architecture of the block copolymers. Interfacial compatibilization of phase-separated PE and i PP with tetrablock copolymers enables morphological control, transforming brittle materials into mechanically tough blends.

https://science.sciencemag.org/content/sci/355/6327/814.full.pdf

Combining polyethylene and polypropylene: Enhanced performance with PE/iPP multiblock polymers.

Transition-metal-catalyzed copolymerization of olefins with polar monomers represents a challenge because of the large variety of substrate-induced side reactions. However, this approach also holds the potential for the direct synthesis of polar functionalized polyolefins with unique properties. After decades of research, only a few catalyst systems have been found to be suitable for this reaction. Some major advances in catalyst development have been made in the past five years. This Minireview summarizes some of the recent progress in the extensively studied Brookhart and Drent catalyst systems, as well as emerging alternative palladium and nickel catalysts.

Emerging Palladium and Nickel Catalysts for Copolymerization of Olefins with Polar Monomers.

The introduction of even a small amount of polar functional groups into polyolefins could excise great control over important material properties. As the most direct and economic strategy, the transition-metal-catalyzed copolymerization of olefins with polar, functionalized monomers represents one of the biggest challenges in this field. The presence of polar monomers usually dramatically reduces the catalytic activity and copolymer molecular weight (to the level of thousands or even hundreds Da), rendering the copolymerization process and the copolymer materials far from ideal for industrial applications. In this contribution, we demonstrate that these obstacles can be addressed through rational catalyst design. Copolymers with highly linear microstructures, high melting temperatures, and very high molecular weights (close to or above 1 000 000 Da) were generated. The direct synthesis of polar functionalized high-molecular-weight polyethylene was thus achieved.

Direct Synthesis of Functionalized High‐Molecular‐Weight Polyethylene by Copolymerization of Ethylene with Polar Monomers

All-Polyolefin Composites Markus Stürzel,† Shahram Mihan,‡ and Rolf Mülhaupt*,†,§ †Freiburg Materials Research Center (FMF) and Institute for Macromolecular Chemistry, Albert-Ludwigs-University Freiburg, Stefan-Meier-Strasse 31, D-79104 Freiburg, Germany ‡Basell Polyolefine GmbH, Catalyst Systems, Industriepark Hoechst, D-65926 Frankfurt am Main, Germany Sustainability Center Freiburg, Ecker-Strasse 4, D-79104 Freiburg, Germany

Shahram Mihan

Papers

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites