Have a think about how you started your day. Maybe you made some eggs in a frying pan that nothing sticks to, or made instant oats from an easy-to-go paper sachet. It started raining, so you put on a jacket that makes water bead off its surface to keep you dry. Perhaps it was a little cold on the way to work, so you stopped for a coffee in a paper takeaway cup from your local café. 

Now, there is nothing particularly exciting about this sequence of events. However, that is simply the point, chemistry has made many parts of your morning possible. Modern life has been built around convenience to such an extent that we rarely stop to think about why the products we use every day work so well. Why was your jacket able to keep you dry in the rain? Why, despite paper normally absorbing liquids, did your coffee stay inside its cup rather than soaking straight through?

Chemistry and chemical engineering allow us to change the properties of materials, creating products with specific characteristics that make our lives easier. Simple materials can be modified, combined or coated to become resistant to water and grease, withstand heat, prevent degradation or remain durable for long periods of time. These are impressive solutions to practical problems. Whilst we have become exceptionally good at designing materials to do exactly what we want them to do, such as resisting degradation during use, we haven't always considered what happens to those chemicals after use. The problem is not that we have learned how to make materials last, it’s that the chemical properties that make them last are not always ‘switched off’ when their useful life ends. This is where the convenience of chemistry can start creating pollution. 

Case Study: PFAS

Chemicals that are designed to be durable don’t suddenly break down in the environment, they persist and accumulate. Some chemicals readily break down through natural processes such as radiation exposure, microbial activity or chemical reactions. Others are much more resistant to these processes. Their chemical structures allow them to persist in the environment long after the product they were used in has disappeared.

Per and polyfluoroalkyl substances, better known as PFAS, are a great example of how something previously brought around as a tool for us has become a widespread issue. PFAS are a large group of compounds that contain a strong carbon-fluorine bond that provides strong water/oil resistance and chemical stability [1]. These incredibly useful qualities allowed them to be used since the 1940s for various industrial, commercial and consumer applications [2]. One familiar application is the non-stick coating on cookware, specifically Teflon pans by DuPont [3] . Suddenly, food that once stuck stubbornly to a pan could slide away with barely any effort due to the magic properties of PFAS. The applications only grew from there, as we started using it in clothes for waterproofing, takeaway containers for durability and much more (Figure 1). PFAS obviously does not know where it is being used. Its chemical properties do not disappear when a product is discarded and thus can pose major risks impacting ecosystems [4]. Whether it is on a jacket, in a river, in a popcorn bag or in soil, the underlying chemistry is still there. This is where the problem with designing for convenience becomes clear. The same properties that make PFAS useful during the life of a product can make it difficult to remove once that product is no longer useful.