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Using chemistry to help reach sustainability goals is becoming an increasingly attractive research area. From solving global plastic pollution to improving the performance of rechargeable batteries found in electric cars, ‘green chemistry’ is a truly promising topic.

This article was researched and written by Isabel Williams, a former Masters Student at Oxford University’s Department of Biology.

Tackling the plastic pollution problem

Synthetic plastics do not break down easily, causing them to be a major pollutant in natural environments. Image credit: mbala mbala merlin/ Getty Images.

But why is plastic such a problematic material? To find out why and to begin to tackle these problems, one needs to look at the material’s chemistry.

Plastics are made from synthetic ‘polymers’. Polymers are made from small molecular building blocks, called ‘monomers’, forming a large molecule resembling beads on a string. In plastics, these monomers are usually derived from non-renewable sources such as petrochemicals, making the production of plastic polymers highly unsustainable since they rely on fossil fuels. Additionally, due to the strong bonds between their monomers, synthetic polymers can persist and pollute the environment for hundreds of years before breaking down.

The solution: replacing plastics with ‘greener’ polymers

Dr Matilde Concilio (left) and Dr Gregory Sulley (right). Photo credit: Dr Gregory Sulley

Researchers at the University of Oxford’s Department of Chemistry are utilising a green chemistry approach to tackle plastic pollution. The aim? To phase out existing polymers and plastics and replace them with greener, more sustainable alternatives.

One avenue being explored is the production of polymers from renewable, bio-derived materials, rather than petrochemicals. Dr Matilde Concilio, a Postdoctoral Research Associate in Professor Charlotte Williams’ laboratory, works on making bio-derived polymers from commercially available resources. By using chemicals already commercialised, safety-checked, and approved, the hope is that any products or processes developed in this way will be swiftly accepted and adopted by industry. With bio-derived plastics accounting for only 1.5% of global plastic production in 2021, there is enormous potential for these materials to upscale and ultimately replace their less-sustainable competitors.

I’m convinced that polymers are the future, but only if you do it in a sustainable way.

 

Dr Matilde Concilio, Department of Chemistry

Dr Concilio’s bio-derived polymers are not only made from renewable sources but are also more sustainable from a processing standpoint. Usually, monomers need to be purified many times to achieve a high-quality final product. This is both energetically costly and expensive.

‘So, to make it more sustainable, what I’m trying to do is use monomers that don’t need to be purified’ Dr Concilio explains. This way, less energy, time, and money are spent on the polymerisation process.

Key to the development and uptake of these new polymers is ensuring that their material properties are as good as, if not better than, current petrochemically-derived options. This is essential if these new materials are to be adopted at scale within plastics industries.

Ultimately, what we want to do is phase out [the current plastics], so that our plastics, which we’re quite heavily reliant on as a society, come from renewable sources.

 

Dr Gregory Sulley, Department of Chemistry

‘One of the main targets for us is to try and property-match to the incumbent materials,’ says Dr Gregory Sulley, another Postdoctoral Research Associate in Professor Charlotte Williams’ laboratory. ‘Ultimately, what we want to do is phase out [the current plastics], so that our plastics, which we are quite heavily reliant on as a society, come from renewable sources.’

With continued work and collaboration, hopefully, sustainable plastics will go on to replace their more unsustainable alternatives, making plastic pollution a problem of the past. With any luck, the sight of plastic in our landfills, oceans, and beaches will soon be a distant memory.

Tailor-made polymers for energy storage solutions:

Similar green chemistry approaches are being applied to solve problems in energy storage. For instance, rechargeable batteries require their components to be in contact with one another to function. However, this is complicated by the fact that some of the components change volume as the battery is charged and discharged. With these batteries used in electric cars, solar panels, and wind turbines, overcoming this problem is a huge priority to help reach Net Zero emission targets.

So, how do you solve this problem? Enter polymers.

Dr Georgina Gregory. Photo credit: Royal Society.

This application-driven design is integral to Dr Gregory’s work to improve the design of polymers so that they can overcome the current limitations of rechargeable batteries.

‘The polymer, in some respects, comes in as a way of holding it all together’ Dr Gregory explains. This means the polymer needs to be:

1. Adhesive: to stick everything together in the battery;
2. Slightly flexible: to accommodate the changes in volume;
3. Ionically conductive: the polymer needs to allow ions (electrically-charged atoms) to flow through the battery.

With these three properties in mind, the researchers set out to precisely design a polymer for use in batteries. By specifically selecting building blocks possessing these properties, and utilising their ability to tightly control the polymerisation process, they were able to tailor the product to the problem.

A sustainable solution

The major global problem is replacing the plastics that we currently have. They are in absolutely everything, even things that you don’t even know they’re in.

 

Dr Georgina Gregory, Department of Chemistry

You would think with these many criteria, sustainability would fall to the back-burner. However, sustainability is still central to Dr Gregory’s tailor-made polymers.

‘I’m always trying to pick building blocks that are bio-based, so polymers won’t have a negative impact at end-of-life.’ Dr Gregory is referring to the fact that bio-derived polymers, in contrast to traditional synthetic polymers, can be quickly broken down using water. Consequently, the material doesn’t remain in the environment for as long, and degrades at a faster rate into smaller, non-toxic parts.

Additionally, the bio-derived polymers lend themselves to chemical recycling. Here, you ‘unzip’, or ‘depolymerise’ the polymer back to the monomers, or original building blocks, then use these monomers to make new polymers. Therefore, the tailor-made, bio-derived polymers don’t contribute to the global issue of plastic pollution.

This ability to produce ‘tailored’ polymers is a special skill, one that is enabling University of Oxford chemists to tackle the crucial engineering challenges that are currently holding back the key technologies we need to achieve Net Zero.

Diagram made by Isabel Williams using Canva.

Taking the hazards out of a hazardous production process

Sometimes, it isn’t so much the end product but the production process that creates environmental problems. Take fluorochemicals, for instance. This group of chemicals have a wide range of important applications – including polymers, agrochemicals, pharmaceuticals, and the lithium-ion batteries in smartphones and electric cars – and had a $21.4 billion global market in 2018. But currently, all fluorochemicals are generated from the toxic and corrosive gas hydrogen fluoride (HF) in a highly energy-intensive process. In addition, even with the best safety precautions, HF spills have occurred numerous times over the last decades, sometimes with fatal accidents and severe environmental impacts.

Thankfully, this may not be the case in the future, thanks to a new, safer approach developed by a team of University of Oxford chemists, alongside colleagues in Oxford spin-out FluoRok, University College London, and Colorado State University. The innovative method takes inspiration from the natural biomineralization process that forms teeth and bones.

Normally, HF itself is produced by reacting a crystalline mineral called fluorspar (CaF₂) with sulfuric acid under harsh conditions, before it is used to make fluorochemicals. In the new method, fluorochemicals are made directly from CaF₂, completely bypassing the production of HF: an achievement that chemists have sought for decades.

This advance builds on decades of research from the laboratory led by Professor Véronique Gouverneur FRS at the University of Oxford. ‘The direct use of CaF₂ for fluorination is a holy grail in the field, and a solution to this problem has been sought for decades’ she says. ‘The transition to sustainable methods for the manufacturing of chemicals, with reduced or no detrimental impact on the environment, is today a high-priority goal that can be accelerated with ambitious programs and a total re-think of current manufacturing processes.’

By commercialising this technology, we aim to enable the development of safe, sustainable, and cost-effective synthesis of fluorocarbons worldwide. We hope that this study will encourage scientists around the world to provide disruptive solutions to challenging chemical problems, with the prospect of societal benefit.

 

Professor Véronique Gouverneur FRS, Department of Chemistry

In the novel method, solid-state CaF₂ is activated by a biomineralization‑inspired process, which mimics the way that calcium phosphate minerals form biologically in teeth and bones. Professor Véronique’s team ground CaF₂ with powdered potassium phosphate salt in a ball-mill machine for several hours, using a mechanochemical process that has evolved from the traditional way that we grind spices with a pestle and mortar.

The resulting powdered product, called Fluoromix^TM, allows over 50 different fluorochemicals to be made directly from CaF₂, with yields of up to 98%.

Calum Patel, a DPhil student in the Department of Chemistry, and one of the researchers leading this work, says: ‘Mechanochemical activation of CaF₂ with a phosphate salt was an exciting invention because this seemingly simple process represents a highly effective solution to a complex problem; however, big questions on how this reaction worked remained. Successful solutions to big challenges come from multidisciplinary approaches and expertise, I think the work really captures the importance of that.’

The process represents a paradigm shift for the manufacturing of fluorochemicals across the globe, and led to the creation of spin‑out company FluoRok in 2022. With the method being suitable for both academic and industrial applications, the research team hope it will ultimately lead to significant impacts in minimising carbon emissions (e.g. by shortening supply chains) and increasing the reliability of fluorochemical supply chains.

An artistic illustration of the ball-milling process behind the newly developed method for generating fluorochemicals. Image credit: Calum Patel.

As Professor James Naismith, Head of the Mathematical, Physical and Life Sciences Division at Oxford University, says, these examples demonstrate how Oxford is leading the way to develop innovative solutions to our most pressing challenges. 'It is only through innovation that we can both improve the quality of life and stop damaging the planet' he says. 'Chemists at Oxford are leaders in green chemistry; the science behind sustainability. The range of work highlighted here includes materials from biology that could replace the fossil fuel-derived polymers modern life depends on, zero impact materials for lithium batteries, and replacing the use of waste-generating hazardous processes for chemicals which we can’t yet do without. The future is being made in Oxford by our talented researchers and students; this is a global effort with partnerships spanning the world.'

Green chemistry, also called sustainable chemistry, is defined as ‘the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances’ by the European Environmental Agency (EEA). Interest in this area has been increasing since the 1990s, with the US Environmental Protection Agency and the Royal Society of Chemistry’s journal, Green Chemistry, playing an important role.

Professor Andy Hector describes a unique living resource, Wytham Woods, and how this contributes to the distinctive and immersive learning experience for students at Oxford. 

Four miles northwest of Oxford’s city centre lies 1000 acres of woodland and grassland – an outdoor living lab for Oxford’s students and academics. Owned and maintained by the University since 1942, Wytham Woods is home to over 500 species of plants, a wealth of woodland habitats, and 800 species of butterflies and moths.

Professor Andy Hector at Wytham Woods (c) Monica Gujral

Now entering its eight year of data collection, the project, he says, relies heavily on Oxford’s students: “The Masters and the PhD students in particular, are really key to keeping the research going. Of course, it does mean projects need to be fairly unique. We can't just keep repeating the same things over and over, so it does pose the challenge of coming up with new ideas, and they have to be ones that the students are also interested in.”

PhD student Sara Middleton at the field site (c) Steven Pocock/Wellcome Collection

Equally, Professor Hector says, Wytham is important for PhD students who in general have relatively limited time and resources: “If you’re at a university that’s lucky enough to have an outdoor laboratory, which is what Wytham is to us, then we can have these long-running studies. The students can come in and hit the ground running and take advantage of all the past investment and long-running studies undertaken there.”

One of those students is Sara Middleton, a doctoral researcher in plant ecology and drought, who has been focusing her research on one specific species of grass within the ecosystem and is currently writing up her PhD thesis.

Undergraduate biology students on their orientation day (c) Monica Gujral

From 2020, the Department of Biology has offered an optional research-focused fourth year as part of an integrated masters and many choose to complete their field-based work at Wytham Woods.

So, what do students think when they visit Wytham? “Students react in different ways to Wytham”, says Professor Hector. “The undergraduate biology degree at Oxford is incredibly broad so you will have students with an interest in genes and cells to those who are more interested in organisms, whole ecosystems and conservation. Some people haven’t spent a lot of time outdoors, which can be challenging if the weather is not good. For others you can tell that they are delighted they can take advantage of this outdoor lab right on our doorstep, and interestingly by having a go some people might reconsider what appeals to them.”

What’s the best time of year there? “So as an outdoorsy person, I actually like Wytham at all times of the year! Even in February, with the leaves off the trees you can really see further through the vegetation. If I had to pick - June or July - before the hay is cut and it’s really looking at its best with most of the flowers in bloom”.

Find out more about Wytham Woods here.

- Randomised control trials in Kenya, show cash payments most effective at delivering aid where it is needed

- Based on the research, during pandemic, the South African government used cash payments to reach 28 million people - far more than possible with food parcels

- Researcher Dr Kate Orkin, who led the trials, which saw 5.5 million kept out of food poverty, has been nominated for an ESRC Impact Award. 

Nearly 10 million South Africans were going to bed hungry in the early chaotic days of the COVID-19 pandemic. With a hard lockdown in place and some three million people thrown out of work, it was proving impossible for the government to deliver adequate food parcels to the overwhelming majority of those in need. The logistics involved were simply unfeasible.

But based on some new university research, led by Oxford’s Dr Kate Orkin, the South African government did the unthinkable: they gave cash to those in need, and not just a little amount, but large sums of money to support families over the months of the crisis.

There is a stereotype of how people in poverty behave. But, studies have found, this is simply not accurate. People think really hard about the best way to spend the money

Dr Kate Orkin

Not only did the resources reach those in need, it enabled them to buy food, plan for the future and for children’s education.

It was an enormous success and Dr Orkin and her team have been nominated for a prestigious ESRC impact award – for social science research which makes a difference in the world. And it did make an enormous difference.

Together, the team’s recommendations in terms of cash payments influenced spending of ZAR 97.5bn (£4.87bn) which reached 28.5 million people in South Africa, helping to avert a national disaster. Research has shown recipients were both able to provide for today and plan for tomorrow – buying food, setting up businesses, finding new work.

It had been widely believed food parcels were the best way to alleviate urgent need – especially in the developing world. The argument went that, if you gave cash to people in need, they would simply squander it. 

But Dr Orkin’s research, based on formal randomised control trials in Kenya, showed that, far from squandering cash, poorer people used it carefully and wisely to improve their lives. And it had wider benefits, even helping those who did not receive the cash, because the money was spent locally.

Dr Orkin says, ‘If you give people the money, it gives them autonomy and they use it for the things they need, including food and healthcare.

The South African government was able to reach more people more quickly...Food parcels can end up being the wrong food and they are so difficult to provide in huge numbers and they can undermine local vendors

Dr Kate Orkin

‘There is a stereotype of how people in poverty behave. But, studies have found, this is simply not accurate. People think really hard about the best way to spend the money.’

She explains, ‘Many people made long term investments – putting a steel roof on their house – or starting a business. The trials we had run in Kenya had shown this to be the way to deliver aid, rather than food parcels.’

‘The South African government was able to reach more people more quickly,’ she says. ‘Food parcels can end up being the wrong food and they are so difficult to provide in huge numbers and they can undermine local vendors.’

According to Dr Orkin, similar trials had been conducted elsewhere internationally and similar programmes were run in various locations, including Colombia and now aid agencies, including UNICEF and ICRC are adopting the same approach.

‘It wasn’t all us,’ she laughs. ‘There is strong evidence from other trials as well.’

‘It was a big shift for the South African government, though,’ says Dr Orkin. ‘They switched to cash emergency aid and reached more people immediately. Previously, they had delivered one million food parcels in a week. The cash reached more than 28 million in five weeks and kept 5.5 million people out of food poverty.’

It was a big shift for the South African government...Previously, they had delivered one million food parcels in a week. The cash reached more than 28 million in five weeks and kept 5.5 million people out of food poverty

Academic research has previously been recognised to provide answers and solutions to many great scientific questions and problems. But the ESRC award is to recognise that social science researchers can also provide real-life impact. In this case, it put paid to a widely-held and long-lasting belief. Randomised control trial evidence transformed lives in the most difficult circumstances. 

This summer, 127 students from across the UK came to Oxford to participate in UNIQ+ - the university's flagship graduate access  programme that provides students from underrepresented or disadvantaged backgrounds with the opportunity to experience life as a graduate research student.  The 7-week programme sees students undertake a research project and attend training skills and information sessions, as well as meeting and working with Oxford researchers, academic staff, and graduate students.

Here we hear from UNIQ+ supervisor David Gavaghan, Professor of Computational Biology at Oxford, and his 2023 UNIQ+ interns, Talal and Kamil, to find out more about their experience of the programme.

How are you involved in UNIQ+? 
I’m Chair of the Graduate Access Working Group at Oxford, which has been going for about four years now. One of its first initiatives was UNIQ+, to support underrepresented groups and socio-economically disadvantaged undergraduate students from the UK. This is our fourth iteration of the internship programme. We started with thirty-three students in 2019 and then Covid happened, so the second year was a scaled back digital programme and we had about 115 students. In 2021, we ran a mostly online internship programme, then in 2022 and 2023 we’ve been able to open the programme to 130 students.  

You’ve also been supervising two UNIQ+ interns this summer. What have you been working on? 

Professor Gavaghan and UNIQ+ 2023 intern Kamil

They’re interested in machine learning applications in biology, so they really wanted to learn how some of these techniques work. One of the postdocs on the team suggested a historical data set that they might find interesting - one of a bubonic plague outbreak in Bombay in the 1870s - that allowed them to learn some of the techniques that we use to model the spread of an epidemic.  Everyone knows about R numbers these days, so how do you approximate things like the spread of the epidemic and what’s the size of the infected population and things like that.   

UNIQ+ 2023 intern Talal

Had you been to Oxford before?  
Talal: No, this is actually the first time. I think I visited Oxford when I was quite young on a year 9 or 10 trip, but this is the first time I've come to Oxford by myself and explored the city. 

Has anything particularly surprised to you about UNIQ+ or about Oxford itself? 
Kamil: There's a lot of support by the supervisors. They all clearly know their field very well.  Some of the concepts are hard to grasp, which I expected, but it's definitely doable. 

UNIQ+ supervisor David Gavaghan and interns Kamil and Talal

Talal: I think I was just surprised about how big Oxford University actually is and it's really nice how it's incorporated within the city. You have access to so many libraries. However you’re feeling you can always find a different place to study, which I really like because I was used to just having one library to go and study.