Paul Flory
American chemist and Nobel laureate in polymer physical chemistry.
He was a pioneer in understanding the behavior of polymers in solution and won the Nobel Prize in Chemistry in 1974 for his fundamental achievements, both theoretical and experimental, in the physical chemistry of macromolecules.
- died
- September 9, 1985, following a heart attack
- field
- Physical chemistry, polymer science
- nationality
- American
- known_for
- Pioneering work in polymer physical chemistry, Flory-Huggins solution theory, excluded volume concept, theta point, Flory-Stockmayer theory of gelation
Lore & Background
His doctoral thesis, supervised by Prof. Herrick L. Johnston, was on the photochemistry of nitric oxide. After retirement, he remained active, running research labs at Stanford and IBM.
Reader's Guide
Paul Flory's significance lies in his foundational contributions to the physical chemistry of macromolecules. He challenged the assumption that end-group reactivity decreases as polymer chains grow, deriving that chain number decreases exponentially with size. He introduced the concept of chain transfer in addition polymerization and developed the Flory-Huggins solution theory for polymer mixtures. His recognition of excluded volume—that one part of a long chain cannot occupy space already taken by another part—was a conceptual breakthrough, leading to the theta point concept where excluded volume effects are neutralized, allowing measurement of short-range molecular features. His 1953 book 'Principles of Polymer Chemistry' became a standard text. Flory also extended polymer physics to liquid crystals and derived the Flory exponent for polymer movement in solution. His legacy endures in polymer science, where his theories remain widely used.
Did You Know?
- Flory's doctoral thesis was on the photochemistry of nitric oxide, supervised by Prof. Herrick L. Johnston.
- He introduced the concept of chain transfer to improve kinetic equations for addition polymerization.
- The Flory-Stockmayer theory of gelation is considered the first paper in the percolation field.
Frequently Asked Questions
What is Paul Flory most famous for?
He is best known for creating a mathematical framework that describes how long-chain molecules behave in solution, including concepts like the excluded volume effect and the theta point where a polymer chain adopts an ideal random-coil shape. His gelation theory, developed with Wallace Stockmayer, also predicted the critical point at which a cross-linking reaction produces an infinite network.
Why did Paul Flory win the Nobel Prize in Chemistry?
The Royal Swedish Academy awarded him the 1974 Nobel Prize in Chemistry to recognize his combined theoretical and experimental breakthroughs in the physical chemistry of macromolecules. The citation highlighted that his work gave the field a rigorous, quantitative language for describing polymer solutions and networks.
What is the Flory-Huggins solution theory?
It is a statistical-thermodynamic model that treats a polymer dissolved in a solvent as a lattice of segments and predicts when the mixture will separate into two phases. The theory introduced a dimensionless interaction parameter that remains a standard tool for estimating solubility and blend compatibility in polymer engineering.
How did Paul Flory's life end?
Flory suffered a fatal heart attack on September 9, 1985, at the age of 75. He was survived by his wife and children, and the polymer-science community marked his passing as the loss of one of the field's founding architects.
More in Physicists And Chemists Of The 20Th Century 1-19
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