Synthesis of Organometallic Catalysts for Switchable Polymerisations Using Renewable Resources: Next Generation Sustainable Elastomers and Engineerin

Plastics are some of the most important materials we encounter in our everyday lives. From packaging to our clothes and our beloved electronic devices, plastic materials have become a cornerstone of modern society. These plastics are made up of a type of molecule called polymers. Polymers are long-chain molecules made up of lots of smaller building block molecules known as monomers. Both the type of monomers used and the order they are connected together in determine whether a plastic is hard or soft, brittle or tough. Therefore, chemists can control the properties of a polymer by deciding which monomers to include in the chain and how they are arranged. This allows for the creation of different plastics for various applications.
The majority of plastics we use are made up of monomers that are sourced from fossil fuels and are therefore unsustainable. Petrochemical derived polymers are also able to remain in the environment for incredibly long periods of time without degrading and the pollution they cause as a result can have potentially fatal consequences to many living organisms. This has led chemists to explore the possibility of making biodegradable polymers from bio-derived resources such as plant extracts or even carbon dioxide, the gas primarily responsible for global warming.
Unfortunately, polymers made of only one of these sustainable monomers have poorer mechanical and thermal properties compared to their fossil-fuel derived cousins. However, it has been shown that combining two or more bio-derived monomers together can result in the production of plastics with impressive properties. One option is to achieve these property improvements through the formation of block copolymers. These are a type of polymer containing chemically distinguishable segments of monomers that are joined together in one chain. In 2014, a new method of making sustainable block copolymers was discovered called switch catalysis. This new discovery allows for block copolymers to be produced easily and with a precise sequence of monomers.
Switch catalysis has since been used to produce a range of different sustainable polymers with better properties than either of the constituent blocks. However, if these new sustainable plastics are to truly compete with their petrochemical counterparts, new chemical strategies are still needed to make a broader range of materials and to improve the efficiency of the manufacturing process.
This project will investigate both the property improvements and the catalysis used to make them. In the first phase, a series of chemistries allowing for the modification of existing sustainable plastics made using switch catalysis will be explored. By introducing a small volume fraction of inexpensive and earth-abundant metal ions, it may be possible to network the polymer chains and provide further structural rigidity. These new materials are called ionomers and currently the potential for biodegradable ionomers is not well understood but this will be addressed through the current investigation.
This project falls within the EPSRC 'manufacturing the future' research area and will involve collaboration with the department of engineering to test the new types of plastic produced. The strength, toughness, stiffness and elasticity of all the materials will be compared within systematic series of polymers, ionomers and networks. These ionomers should also display the ability to self-repair or heal in the event of cracking or snapping due to the reversible nature of the polymer-metal bonds. Furthermore, unlike traditionally cross-linked polymers, such as rubber, it should be feasible to reprocess and recycle these materials. The self-healing behaviour and recycling potential will also be investigated in this project.
The overall goal is to deduce efficient manufacturing routes to bio-derived, recyclable and biodegradable products showing excellent mechanical properties and which may help improve sustainability of plastics

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.