Tandem synthesis of alternating polyesters from renewable resources

The vast majority of commodity materials are obtained from petrochemical feedstocks. These resources will plausibly be depleted within the next 100 years, and the peak in global oil production is estimated to occur within the next few decades. In this regard, biomass represents an abundant carbon-neutral renewable resource for the production of polymers. Here we report a new strategy, based on tandem catalysis, to obtain renewable materials. Commercially available complexes are found to be efficient catalysts for alternating polyesters from the cyclization of dicarboxylic acids followed by alternating copolymerization of the resulting anhydrides with epoxides. This operationally simple method is an attractive strategy for the production of new biodegradable polyesters

Advances in heterometallic ring-opening (co)polymerisation catalysis

Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts. This review describes advances in heterometallic RO(CO)P catalyst design, highlighting the overarching structure-activity trends and reactivity patterns to inform future catalyst design

Sustainable polymers from renewable resources

Renewable resources are used increasingly in the production of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manufacture of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymerizations and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers

Designing electrochemically reversible H2 oxidation and production catalysts

The most energy-efficient electrocatalysts mediate forward and reverse reactions at high rates with minimal overpotential requirements. Such electrocatalytic reversibility is commonly observed for redox enzymes and is an attribute that we have sought to bestow on synthetic molecules to realize highly active and robust catalysts for applications in renewable energy. The recent development of the first synthetic molecular catalysts that reversibly mediate H2???2?H+?+?2e? exploits an enzyme-inspired outer coordination sphere that works in concert with both first and second coordination spheres. In this Perspective, we discuss a series of molecular Ni catalysts for H2 production and oxidation that exhibit electrochemical reversibility. Study of these catalysts allows us to identify important first, second and outer coordination sphere features necessary for efficient conversions of H2 and provides direction for the rational design of electrocatalysts that operate on other small molecules.by Arnab.Dutta, Aaron.M. Appel and Wendy J. Sha