Materials of the last century shaped modern life, but at a price

Ingenuity and serendipity brought products that made life easier, with some unintended consequences

1920s science headline, “Ice cream from crude oil,” may best capture the era’s unbridled enthusiasm for chemistry. “Edible fats, the same as those in vegetable and animal foods … and equally nutritious … can be obtained by breaking up the molecules of mineral oil and rearranging the atoms,” exclaimed Science News Letter, the predecessor to Science News, in 1926. Synthetic ice cream was just one of the wonders that could lie around the corner.

Petroleum would become increasingly valuable, the article continued, “as a source of substances for which man has hither-to been dependent upon the chance bounty of nature.” A rash of potential products included aromatics, flavorings, nitroglycerin for dynamite, plastics, drugs and more.

Petroleum-based ice creams never became the new big thing, yet the last century has witnessed a dramatic leap in humans’ ability to synthesize matter. From our homes and cities to our electronics and clothing, much of what we interact with every day is made possible through the manipulation, recombination and reimagination of the basic substances nature has provided.

“The world is unrecognizable from 100 years ago,” says Anna Ploszajski, a materials scientist and author of the 2021 book Handmade: A Scientist’s Search for Meaning Through Making. And that, she says, is “simply because of the materials that we have around, let alone all of the new ways we use them.”

At the turn of the 20th century, organic chemists learned how to turn coal into a variety of industrial chemicals, including dyes and perfumes. Later, motivated by wartime demand, chemists honed their craft with poison gas, explosives and propellants, as well as disinfectants and antiseptics. As a result, World War I was often called “the chemist’s war.” And at a fundamental level, the new century also ushered in greater understanding of chemical bonds and the atom, its constituents and its behavior.

In the decades that followed, approaches in chemistry and physics combined with engineering to give rise to a new field, now called materials science. An extensive survey of the field, put together by the National Academy of Sciences in the 1970s and titled “Materials and Man’s Needs,” described the pace of research: “The transitions from, say, stone to bronze and from bronze to iron were revolutionary in impact, but they were relatively slow in terms of the time scale. The changes in materials innovation and application within the last half century occur in a time span which is revolutionary rather than evolutionary.”

Alongside this new science came new and improved scientific tools. Scientists can now see materials at a much finer scale, with the electron microscope making individual atoms visible. X-ray crystallography unveils atomic arrangements, allowing for a better understanding of materials’ structure. With equipment such as chromatographs and mass spectrometers, today’s scientists can untangle mixtures of chemicals and identify the compounds within. Francis Aston first took advantage of a mass spectrometer in his study of isotopes in 1919, but for a long time the tool was seen by some chemists as, according to a description by mass spectrometrist Michael Grayson, “an unexplainable, voodoo, black magic kind of a tool.”

Many new materials were birthed from basic curiosity and serendipity. But new techniques also made way for targeted innovation. Today, materials can be designed from scratch to solve specific problems. And explorations of the properties of solid substances — for instance, how matter interacts with heat, light, electricity or magnetism — along with iterations of design have further contributed to the stuff that surrounds us, giving way to transistors, eyeglass lenses that darken in sunlight, touch screens and hard disk drives. Explorations into how matter interacts with biological tissues have yielded coronary stents, artificial skin and hip replacements that include metal mélanges that are tough and nonreactive when they sit against bone.

The outputs of such efforts are all around us. Take air travel, and the global interconnectivity it introduced. It’s possible thanks to alloys that are lightweight and robust. And today’s personal connectivity — via smartphones and computers — came with transistors made of silicon. Their small size and low power requirements brought computing to our office desks, and then into our homes and pockets. An abundance of plastic housewares and comfy athleisure clothing options are made possible via improvements in polymers.

Yet innovation hasn’t come without consequences. For each tale of progress, there are stories of the marks people have left on this planet. While enabling humans to flourish, many new substances have become pollutants, from PCBs to plastics. However people go about addressing these environmental problems, other new materials will likely be part of the solutions.

Going places
It was the summer of 1940, the early days of the Battle of Britain. Nazi Germany’s air force, the Luftwaffe, began a months-long attack on the British Isles that eventually included the nightly bombing raids known as the Blitz. Going into the battle, the Luftwaffe believed it had the upper hand; in battles in France, the Germans had dominated in the air. Little did they know the Allies had a secret weapon — in their fuel tanks.

As Germans began flying over England, they were surprised to find the tables had turned. The British Spitfires and Hurricanes that the Germans had outmaneuvered in France could now climb higher and fly faster thanks to fuel made with a newly developed process called catalytic cracking.

Catalysts boost chemical reactions by reducing the energy needed to get them going. French mechanical engineer Eugene Houdry had developed a catalytic process in the 1930s to make high-octane fuel, which can withstand higher compression and allows engines to deliver more power. Simply increasing the octane rating of aviation fuel from 87 to 100 gave the Allies a crucial edge.

Houdry wasn’t the first to attempt using catalysts to bust the big molecules of heavy fuels into smaller ones to improve performance. But as an avid road racer, he had a special interest in high-quality gasoline. He studied hundreds of catalysts until he landed on aluminum- and silicon-based materials that could do the busting more efficiently than an existing process that relied on heat. When he tested his gasoline in his Bugatti racer, he reached speeds of 90 miles per hour.

In the following decades, catalytic cracking and improvements to the process Houdry pioneered would contribute to the reign of automobiles. Catalytic cracking still produces much of the gas that cars guzzle today.

But all that driving soon took a toll on the environment. When the hydrocarbon molecules in gasoline burn, the engine exhaust contains small amounts of harmful gases: poisonous carbon monoxide, nitrogen oxide that can cause smog and acid rain, as well as unburned hydrocarbons. Los Angeles and other car-packed cities choked on smog in the 1940s and ’50s.

Houdry looked again to catalysts to deal with the pollution that internal combustion engines caused. He designed a catalytic converter.

“When first considered, the problem seems simple,” Houdry wrote in a 1954 patent application. “A great number of catalysts can be used for the reaction. By simply placing one of these catalysts in the exhaust line under controlled conditions, the exhaust fumes can be cleaned.” The catalysts, precious metals such as platinum or palladium, provide docking sites for the harmful gases to hang onto; there, reactions involving oxygen convert them to less harmful forms.

In the 1950s, Houdry outlined a series of reactions, materials and conditions necessary for a working catalytic converter. But he was ahead of his time. For years, the adoption of catalytic converters in automobiles was stymied by leaded gasoline, which gummed up the catalysts’ surfaces. Finally, with the passage of the Clean Air Act of 1970, which led to requirements for catalytic converters and lead-free fuel, the air in cities began to clear.

For air travel to serve the masses, a different dilemma needed solving: lightening the load. The earliest airplanes gained lift at the turn of the 20th century on wings of fabric and wood, but to really soar, airplanes needed light but strong materials. The first aircraft designed for passengers — the Ford Trimotor, nicknamed the Tin Goose — took to the air in 1926 with help from aluminum alloys.

Alloys have existed since ancient times. Bronze Age artisans combined copper with arsenic or tin in crucibles to make tools, jewelry and more. From there, advances coincided with the ability to melt metals at higher and higher temperatures, eventually leading to steel. Scientists since have studied how materials’ structures and properties — including desirable features like strength, bendability and resistance to corrosion — vary with composition, temperature and processing.

The fuselage of the Tin Goose contained a newly developed alloy named duralumin, a contraction of “Dürener” (for the company that originally made it) and “aluminum.”

In 1926, Science News Letter described the promise of materials such as duralumin for safer dirigibles, which would carry large numbers of passengers into the air: “Of these sound materials, strong and light girders must be built. So light that a man can carry one of them in his hand and yet so strong that they will carry loads of thousands of pounds.”

Dirigibles and duralumin were just the beginning. The 20th century saw an explosion in the types of alloys and their applications, from stainless steel cutlery to the titanium alloys used in prostheses and pacemakers to crucial components of vehicles. Today’s jet engines are built of superalloys, which can withstand infernal temperatures.

Plastics and composites have also helped planes shed weight. Composites combine materials with very different properties — such as glass and plastic — by suspending one in the other or sandwiching them together, for instance. Because they can be tuned to be light and strong, composites have made their way into parts all over planes, from the engine to the wings. Boeing’s 787 Dreamliner, which debuted in 2007, is made up of 50 percent composites by weight.


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