Diamond Annual Review 2023/24

54 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 3 / 2 4 Soft CondensedMatter Science Highlights Fromgreenhouse gas to green synthesis: CO2 as a rawmaterial for next-generation polymers Our modern lifestyles can have detrimental effects on the environment, including producing an overabundance of carbon dioxide (CO2) that is fuelling climate change and a mountain of plastic waste that is proving challenging to recycle. Turning to green synthesis that uses CO2 and biomass as inputs allows us to make more sustainable plastics. Polymers are chemically bonded long chains of repeat units (monomers). Carbon dioxide is an attractive raw material - overabundant and cheap. With worldwide polymer production emitting 1.8 gigatonnes of CO2-equivalent every year, copolymerisation of CO2 with epoxides could become a useful carbon-capture and utilisation (CCU) technology, allowing existing manufacturing plants to turn waste products into sustainable polymers. Researchers from the University of Oxford describe new types of CO2- derived thermoplastic elastomers (TPEs) and investigate using a metal ion coordination strategy to augment tensile mechanical strength and Young’s modulus. They conducted Small-Angle X-ray Scattering (SAXS) at room temperature, using the mail-in service available for labSAXS. Diamond’s EPSRC funded offline facility offers Small- and Wide-Angle X-ray Scattering (SAXS/ WAXS) for high-end characterisation of materials on the nanoscale and in situ and operando experiments under process and synthesis conditions. The results showed that all the TPEs exhibited hexagonally packed cylindrical morphologies, allowing comparisons of the influences of different metals without altering their phase-separated microstructures. The team was then able to move on to mechanical testing of the TPEs, assess the stress- strain relationships and explore how the mechanical properties changed with metal–carboxylate coordination chemistry. Their results show significant benefits to using low quantities of metals, suggesting that these materials have the potential to replace petrochemical polymers in high-growth fields such as medicine, robotics, and electronics. Poon, K.C. et al. DOI:10.1002/adma.202302825. Figure: SAXS and mechanical properties of CO2-derived triblock copolymer elastomers. A) Room-temperature small-angle X-ray scattering (SAXS) profiles showing principle scattering peaks (q*) and higher-order peaks (q/q*). B) Representative stress–strain curves (10 mmmin−1 extension rate).