British TV presenter Hugh Fearnley-Whittingstall’s ‘War on Plastic’ documentary revealed that every minute of the day sees the equivalent of a garbage truck full of plastic emptied into the world’s oceans – prompting many businesses to pledge action on reducing the amount of plastic they use.
‘Zero plastic’ is a holy grail being sought by many brands globally, as consumers' awareness of the environment grows and their purchasing habits begin to shift. But is trying to eliminate our use of plastics to nothing a dangerous fantasy that could cause significant economic and societal damage?
The reality is that plastic is an integral part of modern life and its many benefits are often overlooked in the current scramble towards zero plastic waste. Cucumbers and a totemic example of this. Many people ask the question: ‘Why do supermarkets wrap cucumbers in plastic – surely, it’s unnecessary?’ The answer is straightforward - cucumbers last longer in plastic, meaning less food is wasted and more people can be fed, with less food required to be produced and transported. This creates additional benefits such as reduced water and fuel use.
From safe packaging and better agriculture to clothing and provision of clean water, plastics perform a valuable role in enhancing our lifestyles, economy, and health. However, the negative environmental impact of their poor disposal presents a massive global issue in their contribution to pollution.
With the environmental impact of single-use plastics recognised as one of biggest challenges facing humanity, Andrew Dove, Professor of Sustainable Polymer Chemistry at the University of Birmingham, has a clear vision of the future.
“We have to get beyond just focussing on packaging and look at the bigger challenge. We need to create opportunities to make plastics the solution rather than part of the problem – changing the global plastics economy with a Paris Agreement-style accord that challenges the thinking of the whole system and looks at the bigger picture, rather than focussing solely on short-term fixes that drive incremental change. We are potentially in a period of big change for plastics – we must break the cycle, but this requires a strategy for the next 50 to 100 years.”
Professor Dove’s team is looking at short-term recycling of current plastics, but their eyes are on the bigger, long-term prize of redesigning plastics, helped by their expertise in the field of stereochemistry.
Stereochemistry not only affords us an insight into how molecules are affected by the way their atoms are arranged in space, but allows us to change the properties of materials –different molecules made up from the same atoms and joined the same way, but arranged differently can behave in very different ways.
Depending on the orientation of molecular bonds, a material such as polypropylene exhibits different degrees of strength and ductility. This ability to manipulate a material’s characteristics is proving increasingly important in creating sustainable plastics. This gives us opportunities to create a diverse array of materials from a relatively limited pool of monomers. Nature already makes molecules in which stereochemistry dictates their properties – for example, limonene smells of orange or lemon depending on the stereochemistry of one bond, whilst carvone either smells of spearmint or caraway seeds.
“Stereochemistry fundamentally controls the application of plastics; by understanding how it affects the alignment of molecules changes a material’s properties we can engineer variations of a material that exhibit different characteristics – such as strength and flexibility,” explains Professor Dove. “Beyond this though, we need to consider all aspects of the plastic’s lifecycle and go beyond thinking about what they are made from and how they are made to what happens to them at the end of their useful life.”
The fundamental chemistry we use to create polymers will determine how plastic products end up being used. Recycling polyethylene (PE) and polypropylene (PP) uses huge amounts of energy and many plastics cannot be recycled through common processes. This means a lot of waste ends up going to landfill or incinerator - contributing further to environmental damage and climate change.
“Step-by-step changes to managing plastic waste will solve some problems, but we need a radical overhaul in the chemical design of plastics we use to create a sustainable plastic economy,” comments Professor Dove. “Integrating such polymers into current recycling streams poses a considerable challenge, but once separated from the mixed waste stream, the new plastic can be selectively and cleanly deconstructed into its building blocks.”
Professor Dove added that if we can evolve recycling systems in line with materials development, chemical recycling could become an integral part of our collective efforts to reduce the environmental impact of plastics.
“We’ve used petroleum as the basis of our plastic products for more than 50 years and they’ve performed well, but problems associated with their disposal mean we urgently need to find alternatives that have a minimal ecological impact. We must develop new materials that perform well as well as find a way to lower the environmental impact of the petrochemical-based plastics that we currently use,” he explains
Professor Dove’s vision is to create polymers that perform mechanically and physically like existing plastics, but can be efficiently recycled. However, he also acknowledges that not all plastics will get captured so even a perfect recycling system will still leak - those plastics must degrade in the environment back to molecules that are not toxic to life.
The Birmingham team is also exploring how to use chemistries such as depolymerisation to enable materials to be sorted more effectively at the recycling stage.
Depolymerisation breaks down a polymer into its monomeric components, but is typically not a selective process. By applying different catalysts during the depolymerisation process, the team have been able to develop processes that selectively react with single plastics within mixtures based on their different chemistries to return plastics to their small molecule state.
There is, however, a significant gap between what can be achieved in the laboratory and its implementation in the real world. Within the University of Birmingham, experts recognise that a multidisciplinary approach is essential to making that transfer of knowledge happen. The Birmingham Plastics Network brings together researchers from different disciplines across the University – economists, regulators, lawyers, business analysts, chemists and more. Whilst the road ahead is long, the intra-university collaboration brings together like-minded academics committed to understanding the context of plastics use and creating solutions that will gain traction and be welcomed in the longer term.
“We need to change the rules and develop legislation to get producers to make more sustainable plastics, but there are still many questions that need answers,” explains Professor Dove. “How do we change the status quo and create ‘positive prejudice’ in the context of plastics production?
“The Birmingham Plastics Network unites the usual suspects of chemical engineers, mechanical engineers and environmental scientists, but we don’t stop there. We enjoy valuable contributions from our colleagues in Birmingham Law School and the theologians, as well as creative arts, human and physical Geography.”
There are, of course, significant obstacles in creating a sustainable roadmap for the manufacturing, use and recycling of plastics, but the Birmingham team’s vision is clear; we must develop different solutions for different sectors. There are, for example, a distinct set of challenges for materials used in the healthcare sector given the need to factor in biological contamination such as viruses or bacteria.
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Other questions remain to be answered. In the construction industry, for example, almost all waste from building sites, bar plasterboard, goes to landfill. How can we sort these materials so that potentially useful plastic is extracted and recycled?
“In a time of potentially big change in plastics, we cannot ignore these questions and hope they go away,” says Professor Dove. “We have to develop a unique way of looking at the use of plastics around the globe – if we have better recycling in ‘northern’ countries, less of our waste will reach the Global South, but we must also understand what effect that might have on the economies and people that process waste plastics there. Birmingham’s Plastics Network wants to understand what the role of plastics should be in our society.”
There is one thing that experts at Birmingham are certain of - if we don’t know what the future should look like, how can we know what we’re aiming for?
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