3. Plastics

Mr. McGuire: I want to say one word to you. Just one word.

Benjamin: Yes, sir.

Mr. McGuire: Are you listening?

Benjamin: Yes, I am.

Mr. McGuire: Plastics.

It’s from The Graduate, a very popular Mike Nichols film from 1967, just in case you don’t already know that. The screenplay is from Buck Henry and Calder Willingham and the movie made Dustin Hoffman a star.

Plastics are everywhere. The modern world is a plastic one. Plastics are made from hydrocarbons. They don’t have to be. You can make plastics from cellulose—rayon is a good example. You can make plastics from bio-molecules like starches and proteins. There are potato plastics and corn plastics and soybean plastics and whatnot.

But what we mean when we say “plastic” is the stuff made from oil and gas. In chemistry things that have a carbon-atom backbone are called “organic.” It was assumed for a long time that certain types of compounds—amino acids are a good example—could only be created by living things. Then a fellow named Wohler synthesized urea (a byproduct of protein metabolism in mammals, secreted in the urine) from “inorganic” compounds. Crushed rocks. Stuff not made of dead things. And people realized that a molecule was a molecule and its origin was not so important. Thus synthetic chemistry was born. People starting making their own molecules that mimicked “natural” ones. Plastics were born.

Plastics are polymers, just like starches. The most famous of all polymers is DNA. But it is the hydrocarbon polymers, mostly made with ethylene, that make up our plastic world. If you take “organic” chemistry in college you don’t learn about herbicide-free farming. You learn about polymers (and other stuff) and it matters not if they occur in nature or are made in a factory. Chemistry is chemistry is chemistry.

The plastics we make from petroleum have made our cars lighter and thus improved the gas mileage. That’s an environmental good. But most of the plastics are “one-use” and then they become garbage. That’s an environmental bad. All technologies are like this. There is no free lunch. Every decision we make about how to use a natural resource will come with consequences. It’s not about a consequence-free invention or innovation: that’s a fantasy. It’s about understanding and appreciating the consequences of our choices. It’s about making informed choices, and choices that value the future, and the well-being of all over short-term gains.

About 200 million metric tons of ethylene were produced worldwide in 2020 and that is expected to increase to 300 million tonnes by 2025. The US market alone is over 40 million tons. Again, ethylene can stand in as a proxy for the wealth of a nation. We’ve all heard of “polyethylene” plastics. Connect together many small ethylene molecules, like links in a chain, and you get poly-ethylene. Polyethylenes make up a third of the plastics market.

Spend your day looking around you. Think about all the different plastics you encounter. How many of them could you replace with something better? Chemists will continue to innovate and create new plastics. What do we want from these materials? And how do we get there?

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