Synthesis of polymeric materials derived from abundant natural feedstocks using non-toxic heavy metals

Synthetic polymers are ubiquitous materials in the modern world. The vast majority are derived from petrochemical feedstocks and are unable to degrade in natural environments. It is estimated that by the end of 2015, 78% of all ever produced plastic waste was discarded in landfills or natural environment, whereas only 9% was recycled. The persistence of commodity polymers has resulted in severe land and marine pollution. A viable strategy to address this issue involves replacing petroleum based polymers with sustainable polymers derived from abundant natural feedstocks. Catalysis is key to enabling the transformation of natural resources into polymeric materials capable of competing with existing synthetic polymers in terms of both performance and cost. Suitable catalyst systems can improve the efficiency of synthetic processes and can tune polymer properties for target applications.
This project falls within the EPSRC Manufacturing the Future theme. The project aims to develop novel catalysts featuring non toxic heavy metals (such as bismuth, indium and lanthanides) for the synthesis of sustainable polymers. The initial focus of this project is on bismuth, as one of the most environmentally-benign heavy metals. The developed systems will be tested as catalysts in a series of synthetic methods to produce sustainable polymers using natural feedstocks. One of these is the ring opening polymerisation of lactide monomers derived from starch-rich biomass. This produces poly(lactic acid), a biodegradable and biocompatible polymer that has already found applications in medicine, packaging and fibre technology. Currently, poly(lactic acid) is industrially produced in harsh conditions using a catalyst containing a toxic tin metal. The use of more environmentally benign catalyst systems is of great interest as a means of preventing toxic residues in final polymer products. Although catalysts containing heavy metals have been studied scarcely compared to lighter elements, they have shown potential for unique reaction pathways and enhanced activity.
The developed catalyst systems will also be investigated for the conversion of carbon dioxide, a major environmental pollutant, into polycarbonate polymers. While a traditional synthesis of polycarbonates relies on hazardous petrochemical raw materials, carbon dioxide could be used to replace up to 50% of a polymer's mass, thereby offering an opportunity to both reduce the carbon footprint and turn an industrial waste into high value chemicals. The optimisation of new heavy metal based catalyst systems could broaden the scope of viable catalytic strategies used to produce sustainable polymers and afford new insights into rational polymerisation catalyst design.

The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.