Wallace Carothers

Who Built The Giant Molecule · Chemist · 1896–1937

The chemist who proved that polymers are genuine, very large molecules by building them on purpose, and who drew the distinction between addition and condensation polymerisation that the subject still uses.

Who was Carothers?

Wallace Carothers was born in Iowa in 1896 and was teaching organic chemistry at Harvard when DuPont made him an unusual offer: an industrial laboratory with a mandate to pursue fundamental research rather than products. He took it in 1928 and settled one of the live arguments of the day. Chemists disagreed about whether the substances called polymers — rubber, cellulose, the early plastics — were true molecules of enormous size, as Hermann Staudinger insisted, or merely aggregates of small molecules clinging to one another. Carothers' answer was to build them deliberately, from known starting materials, by reactions whose chemistry was already understood, and then to measure what he had made. He also drew the classification that organic chemistry has used ever since: addition polymerisation, where monomers containing a double bond join with nothing lost, and condensation polymerisation, where each new link expels a small molecule such as water. Polyesters came out of the second — a dicarboxylic acid and a diol, joined over and over — and in 1930 his colleague Julian Hill found that a molten polyester could be drawn out into a fibre that kept stretching. Neoprene followed in 1931 and nylon, the first entirely synthetic fibre, in 1935. Carothers lived with severe depression throughout his adult life and died in 1937, aged forty-one, two years before nylon reached the public.

Major achievements

• Proved polymers are true macromolecules by synthesising them deliberately
• Distinguished addition from condensation polymerisation
• Made the first synthetic polyesters, in 1930
• Invented neoprene, the first commercially successful synthetic rubber, in 1931
• Invented nylon in 1935, the first wholly synthetic fibre

Life in brief

• 1896 — Born in Burlington, Iowa: Studies chemistry at Tarkio College and Illinois.
• 1926 — Harvard: Teaches organic chemistry, and begins thinking about large molecules.
• 1928 — DuPont: Takes a laboratory with a mandate for fundamental research.
• 1930 — The first polyester fibre: Julian Hill draws a molten polyester into a filament that keeps stretching.
• 1931 — Neoprene: The first commercially successful synthetic rubber.
• 1935 — Nylon: A diamine and a diacid give the first wholly synthetic fibre.
• 1937 — Dies aged forty-one: After a long struggle with depression, two years before nylon is sold.

Explore the life of Carothers — five chapters

1. An Unusual Offer — An industrial laboratory with a mandate for fundamental research
2. What Is a Polymer? — Real molecules, or clumps?
3. Addition and Condensation — The classification every syllabus uses
4. Neoprene and Nylon — Two materials, and a problem of melting point
5. The Illness That Nothing Touched — Philadelphia, April 1937

Read the five-chapter life of Wallace Carothers →

Where Carothers appears in your course

Wallace Carothers has a genuine claim on 4 lessons of the Pearson Edexcel International GCSE science course built into Incandio:

• Alkene Reactions And The Bromine Test — Chemistry: This page shows a double bond opening once, to take on two bromine atoms. Carothers' work rests on what happens when the same thing occurs millions of times over and the bond opens onto another molecule of the same alkene instead of onto a bromine. He established that the giant molecules formed this way are genuine single molecules rather than clumps, and he separated this kind of joining, in which nothing is lost, from the kind in which a small molecule is expelled. He is the right figure to ask what a reaction that has been demonstrated in a test tube can become at industrial scale.
• Esters And How To Make One — Chemistry: The reaction on this page joins one alcohol to one acid and expels one molecule of water. Carothers asked what would happen if each molecule had TWO reactive ends instead of one, so that every product could react again — and the answer was a polyester, a molecule thousands of links long that can be drawn out into a fibre. He also drew the distinction this page relies on, between joining that expels a small molecule and joining that expels nothing. He is the right figure to ask what separates a laboratory curiosity from a material.
• Addition Polymers — Chemistry: This page asserts something a learner has no way to check: that a piece of poly(ethene) contains single molecules tens of thousands of atoms long. When Carothers began, that was disputed — many chemists held that polymers were merely clusters of small molecules clinging together, since nothing so large had ever been shown to exist. He settled it by building polymers deliberately, from known starting materials by reactions already understood, and measuring what he had made. He also named the distinction between addition and condensation that the next page depends on.
• Condensation Polymers — Chemistry: The polymer on this page is Carothers' own invention. Working at DuPont in 1930 he set out to build a giant molecule deliberately, from a diol and a diacid, precisely so that every product could react again — and his colleague Julian Hill, touching a glass rod to the molten result, found it drew out into a filament that kept stretching far beyond what anyone expected. That accident revealed that the chains were aligning as they were pulled, which is why a synthetic fibre is strong. Nylon followed five years later on the same principle.

Begin

• Start a conversation with Carothers — a dramatised, historically grounded AI portrayal
• Read the Historical Brief
• Explore the life of Carothers — five chapters
• Find your exam topics · Meet all 208 figures