Catalytic production of monomers for sustainable polymers from carbon dioxide and diols

Polymers, better known as plastics, are widespread in modern society as they are light, strong, and cheap. Their demand is dramatically increasing and in 2013, 299 megatonnes of plastics were produced worldwide, a 46.5% increase compared to 2002 (source: plasticseurope). However, polymers are regarded as unsustainable as they are environmentally persistent and their production is dependent on finite fossil-based resources. In 2013, 99.5% of plastics were still produced from oil (source: europeanbioplastics). There is therefore an urgent need for further research into the production of sustainable plastics.

Additionally, in 2014, 32.3 gigatonnes of waste carbon dioxide (CO2) were released into the atmosphere (source: International Energy Agency). Therefore, polymers made from a cheap and renewable resource like CO2 are highly desirable products.

The aim of this proposal is to utilise CO2 as a raw material in the synthesis of cyclic carbonate monomers, which are the building blocks of polycarbonate polymers. Polycarbonates are furthermore promising materials for numerous applications, including as thermoplastics, binders for photovoltaics, polymer electrolytes, adhesives, tissue engineering scaffolds and drug delivery carriers.

The current method used to produce cyclic carbonate monomers employs phosgene, a toxic and energy intensive reagent. Replacing phosgene by CO2 is an exciting scientific challenge that has the potential to transform the economy and impact the environment. Building on our published preliminary results and using an experimental and computational approach, this project will develop catalysts for the synthesis of cyclic carbonate monomers directly from CO2 and diols, abundant molecules that can be sourced from nature. These catalysts will ultimately be used to transform carbohydrates from biomass and food waste into new monomers that cannot be accessed using traditional phosgene reagents. This process will provide a vital step towards the valorisation of CO2 and the derivatisation of renewable feedstock like carbohydrates into novel sustainable materials that could generate significant wealth within the UK.

This project will benefit many stakeholders by meeting the urgent requirements of CO2 utilisation and providing a safe route towards novel sustainable polymer architectures.

Exploiting waste CO2 and sugars to form essential monomers for the creation of sustainable novel materials will positively impact on the UK's economic, environmental, research and industrial agendas in the medium and long term.

A safe and environmentally benign method to access cyclic monomers and sustainable polymeric materials will not only serve the synthetic chemistry community, but will help to advance materials and biomedical sciences too. In particular the health sector will benefit from new polycarbonate materials that have displayed promising properties as drug delivery systems and supports for tissue engineering, and that could dramatically improve our quality of life.

There is a high consumer demand for useful bio-based plastics for niche applications, including portable electronics. The project could generate new products and companies focusing on the derivatisation of food waste and biomass to produce high-value advanced monomers and polymers, which would create a significant amount of wealth.

Our research will lead to the improvement of existing processes that currently use phosgene derivatives. Replacing this hazardous chemical by CO2, a non-toxic waste from many industries, will have a positive impact on the environment by reducing the energy consumption associated with the production of phosgene, and by marginally contributing to greenhouse gas emission mitigation. This will also make the plastic industry a safer and less polluting working environment. Additionally, the environmental impact of our research will include the development of monomers for commodity and speciality polymers that are biodegradable thanks to a carbohydrate backbone.

Finally, this project will be an excellent opportunity to showcase how physical sciences can address environmental and societal problems. The recycling of waste CO2 gas, reusing food waste and the production of degradable polymers are all areas that capture the public interest and support. This interest will allow the PI to further engage the general public and young audiences in the concept of sustainability and raise the awareness of the potential of physical sciences.