Cleaner, greener plastics

Each year, several million tonnes of waste plastics end up in the ocean, posing a serious threat to the ecosystem and human health. At Imperial College London, academic specialists in a range of disciplines are bringing their expertise to a new effort to address the problem. They are brought together by the multi-faculty Ocean Plastic Solutions Network.

Dr Arturo Castillo Castillo is a Research Fellow in the Centre for Environmental Policy and the network’s leader. He emphasises that there is no single solution to the problem of waste plastic. “The many functions of plastics and the many different products that contain them mean that we need to offer a plethora of solutions, not just one”, he says. “In place of a panacea, we advocate well informed interventions at every stage of the plastics value chain”.

Imperial is particularly effective, Dr Castillo Castillo adds, at understanding and influencing the trajectory of plastic before it reaches the ocean.

“We have very strong expertise in materials science, chemistry, product design and other parts that are upstream in the plastic value chain. This helps us work on interventions that prevent plastic from becoming waste. We also have strong expertise in chemistry, civil engineering and environmental policy that allows us to work on interventions to prevent the leakage of waste to the environment.”

Circular systems

Dr Marco Aurisicchio, a senior lecturer in the Dyson School of Design Engineering, is co-leader of the Ocean Plastic Solutions Network and co-investigator on Greener Plastic Future.

He is also supervising industry-funded research that explores how designers can consider the entire lifecycle of products and configure the systems to produce closed loop material flows.

Characteristically for the School’s researchers, he does not consider product design in isolation, but looks at systems like manufacturing, consumption and end-of-life that materials and products are embedded within, and investigates how these influence material resource flows. “We think about humans, infrastructure and technology in the design of systems”, he explains.

Anouk Zeeuw van der Laan is a PhD student working with Dr Aurisicchio on a project funded by Procter & Gamble. In a previous role, Ms Zeeuw van der Laan worked as a packaging technologist for another fast-moving consumer goods (FMCG) multinational. This sector produces low cost, non-durable items you might buy in a supermarket, including food products and items like disposable razor blades. The problem with these goods, she says, is that there is often a mismatch between the short lifespan of the product and the very long lifespan of the materials, including plastics, used to make them.

The project initially set out to identify more sustainable materials. “The first conclusion that we drew was that we can change the materials we use, but if we don’t change the way we use them we will still have the same problem”, she says. “For example, biodegradable materials will only biodegrade if we send them to the right places. So, instead, my research focuses on the design of consumption systems that get materials to those places.” Ms Zeeuw van der Laan studies product–service systems – business models that combine products with services, and have potential to achieve more sustainable outcomes.

“Take, for example, the disposable camera”, she says. “The camera is designed to give you 27 pictures and then the whole product becomes obsolete; but it still has a significant value for the consumer. To develop your photos, you have to take the obsolete camera to a photo developing service. What you, as a consumer, don’t realise is that by using this service you are closing the loop, allowing the company to intercept and re-use the camera’s components. Your incentive to return the components for re-use is hidden in the consumption of that system.”

Dr Aurisicchio and Ms Zeeuw van der Laan are looking at the role of consumers in product–service systems that involve take-back schemes offered for FMCGs. “You might expect incentives like money and discounts would make a difference. But there can also be implicit incentives such as increased convenience. Moreover, we found that the roles of consumers imply costs, which could be minimised by eliminating or alleviating the activities that constitute the role.”

In forthcoming work, the researchers will develop a tool to help companies like Procter & Gamble model the flow of resources in a consumption system. “A common approach is to look at the circular economy from a business perspective – what changes for my business – or what changes for a consumer”, she says. “Instead, we take a resource-centric approach in which we put the flow of resources first. Resources are always a part of circular economy research. But to put them above value creation is, I think, a novel approach.”

Understanding toxicity

Dr Theoni Georgiou, senior lecturer in Imperial’s Department of Materials, has a long track record working with polymers – the repeating chains of molecules that when malleable are known as plastics. As the incoming chair of Macro Group, which represents polymer chemists across the UK, she hopes to improve public understanding. “I would like people to understand that not all plastics are bad. There are bad ones and good ones”, she says.

Dr Georgiou’s research has always been oriented toward practical solutions. One example is drug delivery systems. The drugs used to treat brain conditions including cancer must, due to the blood-brain barrier, be injected directly into the brain. As liquid will not stay in the brain long enough for the drug to have an effect, the drugs need to be delivered through solutions containing specially created polymers that condense into gels at body temperature.

But this technique is not perfect, because the polymers are quite viscous even at room temperature, making them hard to inject. Dr Georgiou used her expertise to develop a now patented polymer that causes the solution to turn into a gel at one third of the concentration of those currently used, making the solution much easier to use.

Dr Georgiou is now turning her polymer expertise to sustainability. Recently, there has been a great deal of public attention to the fact that degraded plastic waste frequently finds its way into human bodies. Less understood are the health implications of ingesting plastic. “Many plastics can pass through our bodies harmlessly”, Dr Georgiou explains. “Others are not toxic themselves, but as waste plastics can pick up toxins and carry these to the body. When manufacturers develop plastic products that aren’t for consumption, such as airplane windows, they don’t usually examine whether the materials are harmful to ingest.”

Dr Georgiou is working with Professor Alexandra Porter, also in the Department of Materials, to investigate how small particles of plastic, like those that occur when plastic waste degrades, interact with bacterial cells. If the plastic kills the cell, this may indicate that it is toxic. If the plastic absorbs the cell, this may indicate it can transport toxins from the ocean to human bodies. If they do not interact, this makes it more likely that plastic particles of this type or size are not harmful to humans.

“This is the start of a new effort to help industry and policy-makers better understand the health consequences of choosing one plastic over another”, Dr Georgiou explains.

The right policy interventions

Dr Castillo Castillo’s own work in the Centre for Environmental Policy is at the interface with his colleagues’ scientific and engineering research into plastics across Imperial. In his work, he investigates policy interventions that most effectively incentivise positive changes such as reducing waste generation in the first place or improving recycling. “You can introduce guidelines, targets or mandates”, he explains, “but the question is what incentive, penalty and reward system you can use and in what time frame.”

“How do we build and position a policy proposal so it is taken up, and what is the right way of deploying existing policy tools, in terms of timing, testing, roll out, and monitoring?” There is also a question of unintended consequences. “We can provide deeper analysis into the effectiveness of different technical and policy interventions. For instance, we know that bans, such as a ban on plastic bags, can sometimes lead to illegal markets, equally polluting alternatives or other unintended consequences. Our aim is to provide the evidence base about not only environmental impacts but also societal and market effects, and potential unintended consequences, which will inform more sustainable policy decisions”, Dr Castillo Castillo says.

Dr David Silverman is Enterprise Communications Officer.

Infographic by Icographic. Photos by Thomas Angus, James Tye and Dan Weill.

This Imperial Story was produced by the College's Enterprise Division.

The Enterprise team helps businesses to solve their challenges by accessing Imperial's resources, talent and expertise, and helps academics and students find new ways to turn their expertise into benefits for society.