You've probably learned in your science classes that a water molecule is made of one oxygen atom and two hydrogen atoms. You've probably also learned about some other molecules, such as carbon dioxide, which is made of one carbon atom and two oxygen atoms.

Everything around you is made of molecules, not just water. But have you ever seen a drawing of a rubber molecule? What about a wood molecule or a cotton molecule? These things, which you see and use every day, are also made of molecules. But what are these molecules like? We know that a water molecule is made of one oxygen atom and two hydrogen atoms. What kinds of atoms, and how many atoms, are there in a rubber molecule?

Cotton: one of many mystery materials.

Over 100 years ago no one knew the answer to these questions. In the early 1900s, no one knew what rubber molecules were like. No one knew the molecular structure of the molecules that made up a lot of natural materials, like rubber, wood, cotton, silk, and some new artificial materials called plastics. Scientists called these mystery materials polymers.

These polymers did strange things that scientists didn't quite understand. One of the strangest things was their molecular masses. When scientists determined the molecular mass of water, they got an answer of 18. When they determined the molecular mass of carbon dioxide, they got 44. But polymers were just plain weird. When scientists tried to determine their molecular masses, they got huge numbers, in the thousands or higher! Nothing like this had ever been seen before.

Could these high molecular masses be for real? Some scientists thought that small molecules were clumping together in giant clusters called colloids. According to this theory, the high molecular mass was the combined molecular mass of all the molecules in the cluster.

There was a simpler theory, but not many scientists accepted it. This theory said that polymers were made of giant molecules, each containing thousands of atoms, all joined together by covalent bonds. According to this theory, the extremely high molecular masses were observed because the molecule in rubber, wood, and cotton really did have a molecular masses in the thousands or higher. One German scientist named Hermann Staudinger began to strongly support this theory sometime around 1917. He invented a name for his big molecules. He called them macromolecules.

Why would anyone care?

Why did anyone care about the molecular structure of polymers? What did it matter anyway? We knew how to use them, and that's what really matters, isn't it? Of course, the usefulness of any material is important. But the apparent high molecular masses of polymers challenged scientists' basic understanding of what kinds of molecules atoms could form. What's more, being able to understand the molecular structures of polymeric materials could help people trying to make new polymeric materials. Remember, a few new synthetic polymers had been discovered, but that was all by accident. Scientists wanted to know how to design and build new polymeric materials with better properties than the materials found in nature, or the few synthetic polymers that had been discovered accidentally. Knowing the molecular structures of polymers would give scientists a starting point to design and build new materials from the ground up, atom by atom.

Back to Staudinger...

Staudinger never could decisively prove to his peers that polymers were made of macromolecules, no matter how strongly he believed his theory was correct. He argued for years with other scientists in Europe about his theory. Then, across the ocean in the United States, far away from the debates and controversy, a scientist named Wallace Carothers had a plan to help settle the question of whether polymers were colloids or macromolecules.

Next: Testing the Theory