Earth Week Chemsplainer: Plastic is not your enemy

Paul Chirik shifts into high-energy mode when the subject of plastic arises, as it so often does these days. Particularly with the 2024 Earth Day theme of “Planet vs. Plastics.”

For Chirik, the Edwards S. Sanford Professor of Chemistry and a longtime researcher on methods that could dramatically improve chemical recycling, Earth Day provides an opportunity to introduce another perspective, one that focuses on the benefits of plastic and the real issue that lies behind its accumulation: better recycling methods.

Here, in celebration of both Earth Day and real solutions, is Chirik’s take on what we should know about plastic.  

This year’s Earth Day theme is “Planet vs. Plastics.” Does that strike you as hitting the wrong note?

Absolutely. I would say that plastic has done far more good for the planet than bad. For example, your car is filled with various plastics. The idea is that the lighter you make trucks, cars, airplanes, ships—anything that moves—the more energy you save. The key recognition here is that the energy you save is the equivalent of energy discovery. So, if you save a barrel of oil on a more efficient car, you discover a barrel of oil that you didn’t have before. Plastic has enabled that hundreds of thousands if not millions of times since its widespread adoption in the 1950s.

Should we get rid of plastic?

The bulk of the plastics around you are polyolefins – polyethylene, polypropylene, and polystyrene. They’re in just about everything you use on a daily basis, from your phone case to your sneakers to airplane parts to your hip joint implant. It’s hard to imagine a world without them.

The thing that I think that gets lost in all this is, if you ban plastic completely you have to replace it with something. Wood, metal, glass. Each of these weighs more. They are more energy intensive to make. They are more environmentally contaminating to make. So, if you look at this agnostically and say, what’s the best material based on C0₂ consumption, energy input, mass, volume, and lightweight end-product … you immediately land on plastic. This is why we as a society have used plastics for 75 years. It’s inconceivable that you could get rid of them.

How would you recast the challenge?

The real issue is an end-of-life issue – how do we throw plastics away? We’re not good at that, and that’s not the fault of the plastic. That’s the fault of us. But it’s complicated. Polyethylene comes in a huge number of forms, and the chemistry and engineering and physics that go into recycling each of those is different. It’s a huge problem, but also a great and inspiring problem because it’s fundamental chemistry. It’s engineering. It’s human behavior.

So how should we think about plastic?

If you step away from this “Planet vs. Plastic” idea and just look at it as a chemist, the same atoms—C and H—make all these different products. Car bumpers. Yogurt containers. Plastic bags. Face masks. That’s just two atoms. It’s an unbelievable triumph of chemistry. That’s where we’ll find the solution.

The conclusion is: we should not use less plastic; we should use better plastic. What do I mean by that? I mean plastic that can be recycled not one time but a hundred times, or a thousand times. And that means you need to figure out new chemical structures and how to synthesize them, and how to do it inexpensively and in a way that’s carbon neutral. What it comes down to is, how do you design a plastic for recycling? That was not thought about much during the polyolefin revolution in the 1950s. That has to be our focus now.