High Selectivity and Activity Catalysts to Deliver Sustainable Polymers

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Polymers are highly versatile materials and essential in our everyday lives with applications in every sector. Modern medicine, consumer products, packaging, construction, textiles, electronics, and transportation are all dependant on polymers. The majority of materials used to make plastics are derived from unsustainable depleting petrochemical or fossil fuel sources. Manufacturing of plastics has increased exponentially over the past several decades, and the pervasive nature of plastic has led to intense pollution globally.Recent efforts in research have focussed on sustainable plastics made from renewable or bio-derived resources, such as plant extracts or carbon dioxide, but matching mechanical and thermal properties to fossil fuel derived polymers has been challenging. Properties can be modified and improved by making block copolymers, this is where two chemically distinct segments of monomers are attached to each other. Current research has focussed largely on polymers with either 2 or 3 block segments. In 2014, a new type of catalysis was discovered which enables facile preparation of block copolymers with precise sequencing of the monomers and allowing multi-block sequences. These block polymers had good properties and were easily recycled or biodegraded after use, however, further property improvements are required.This project addresses both better polymer properties and catalysis used in manufacturing. The catalysis will be applied to compare properties of block polymers featuring different monomer sequences, including tri-, penta- and hepta-block polyesters and polycarbonates. The project will uncover the optimum manufacturing methods, polymer chemistry structure-performance relationships, and assess recycling options. In a second phase, polymer ionomers will be investigated by addition of a very low quantity of earth-abundant metal ions (e.g. zinc, magnesium, or calcium ions) to provide transient chain cross-linking and moderate properties. Polymer properties, like strength, toughness, stiffness, and elasticity will be tested for all polymers made. The end-of-life options through re-processing, recycling, and degradation will also be assessed. Through a collaboration with the engineering department, modelling of the materials will be employed to further optimise the mechanical properties. In the final part, the self-healing properties of the polymers will be assessed by understanding dynamic covalent interactions, i.e. where reversible metal ion coordination chemistry is exploited.Ultimately, this project aims to utilize renewable resources to produce sustainable plastics with thermal and mechanical properties that match current commercial polymers. This project falls within the EPSRC 'manufacturing the future' research area.