Paul Flory

Paul Flory
Flory in 1973
Born	Paul John Flory (1910-06-19)June 19, 1910 Sterling, Illinois,U.S.
Died	September 9, 1985(1985-09-09)(aged 75) Big Sur, California,U.S.
Nationality	America
Alma mater	Manchester University (Indiana)andOhio State University
Known for	Polymer chemistry Polymer physics Flory convention Flory–Fox equation Flory–Huggins solution theory Flory–Rehner equation Flory–Schulz distribution Flory–Stockmayer theory Random sequential adsorption Star-shaped polymer Self-avoiding walk
Awards	Nobel Prize for Chemistry(1974) National Medal of Science(1974) Priestley Medal(1974) Perkin Medal(1977) Elliott Cresson Medal(1971) Peter Debye Award(1969) Charles Goodyear Medal(1968) William H. Nichols Medal(1962) Colwyn medal(1954)
Scientific career
Fields	Physical chemistryofpolymers
Institutions	DuPont,Stanford University,Carnegie Mellon University,Cornell University
Doctoral advisor	Herrick L. Johnston

Paul John Flory(June 19, 1910 – September 9, 1985) was an American chemist andNobel laureatewho was known for his work in the field ofpolymers,ormacromolecules.He was a pioneer in understanding the behavior ofpolymersin solution, and won theNobel Prize in Chemistryin 1974 "for his fundamental achievements, both theoretical and experimental, in the physical chemistry of macromolecules".

Biography

Personal life

Flory was born in Sterling, Illinois, on June 19, 1910 to Ezra Flory and Martha Brumbaugh. His father worked as a clergyman-educator, and his mother was a school teacher. His ancestors wereGermanHuguenots,who traced their roots back toAlsace.He first gained an interest in science from Carl W Holl, who was a chemistry professor atManchester College, Indiana.In 1936, he married Emily Catherine Tabor. They had three children together: Susan Springer, Melinda Groom and Paul John Flory, Jr. His first position was atDuPontwithWallace Carothers.He was posthumously inducted into theAlpha Chi SigmaHall of Fame in 2002.Flory died on September 9, 1985, following a heart attack.His wife Emily died in 2006 aged 94.

Schooling

After graduating fromElgin High SchoolinElgin, Illinoisin 1927, Flory received a bachelor's degree fromManchester College (Indiana)(now Manchester University) in 1931 and a Ph.D. from theOhio State Universityin 1934. He completed a years of master's study in organic chemistry under the supervision of Prof. Cecil E Boord,before moving into physical chemistry. Flory's doctoral thesis was on the photochemistry of nitric oxide, supervised by Prof. Herrick L. Johnston.

Work

In 1934 Flory joined the Central Department ofDupont and Companyworking withWallace H. Carothers.After Carothers' death in 1937, Flory worked for two years at the Basic Research Laboratory located in the University of Cincinnati. During World War II, there was a need for research to develop synthetic rubber, so Flory joined the Esso Laboratories of theStandard Oil Development Company.From 1943 to 1948 Flory worked in the polymer research team of the Goodyear Tire and Rubber Company.

In 1948, Flory gave the George Fisher Baker lectures atCornell University,and subsequently joined the university as a professor.In 1957, Flory and his family moved to Pittsburgh, Pennsylvania, where Flory was executive director of research at theMellon Institute of Industrial Research.In 1961, he took up a professorship at Stanford University in the department of chemistry. After retirement, Flory remained active in the world of chemistry, running research labs both in Stanford, and IBM.

Research

Career and polymer science

Flory's earliest work in polymer science was in the area ofpolymerizationkineticsat theDuPont Experimental Station.Incondensation polymerization,he challenged the assumption that the reactivity of the end group decreased as the macromolecule grew, and by arguing that the reactivity was independent of the size, he was able to derive the result that the number of chains present decreased with size exponentially. Inaddition polymerization,he introduced the important concept ofchain transferto improve the kinetic equations and remove difficulties in understanding the polymer size distribution.

In 1938, after Carothers' death, Flory moved to the Basic Science Research Laboratory at theUniversity of Cincinnati.There he developed a mathematical theory for the polymerization of compounds with more than two functional groups and the theory of polymer networks orgels.This led to theFlory-Stockmayer theoryof gelation, which was equivalent topercolationon theBethe latticeand represents the first paper in the percolation field.

In 1940 he joined theLinden, NJlaboratory of theStandard OilDevelopment Company where he developed a statistical mechanical theory for polymer mixtures. In 1943 he left to join the research laboratories ofGoodyearas head of a group on polymer fundamentals. In the Spring of 1948Peter Debye,then chairman of the chemistry department atCornell University,invited Flory to give the annual Baker Lectures. He then was offered a position with the faculty in the Fall of the same year. He was initiated into the Tau chapter ofAlpha Chi Sigmaat Cornell in 1949.At Cornell he elaborated and refined his Baker Lectures into his magnum opus,Principles of Polymer Chemistrywhich was published in 1953 byCornell University Press.This quickly became a standard text for all workers in the field of polymers, and is still widely used to this day.

Flory introduced the concept ofexcluded volume,coined byWerner Kuhnin 1934, to polymers. Excluded volume refers to the idea that one part of a long chain molecule can not occupy space that is already occupied by another part of the same molecule. Excluded volume causes the ends of a polymer chain in a solution to be further apart (on average) than they would be were there no excluded volume. The recognition that excluded volume was an important factor in analyzing long-chain molecules in solutions provided an important conceptual breakthrough, and led to the explanation of several puzzling experimental results of the day. It also led to the concept of thetheta point,the set of conditions at which an experiment can be conducted that causes the excluded volume effect to be neutralized. At the theta point, the chain reverts to ideal chain characteristics – the long-range interactions arising from excluded volume are eliminated, allowing the experimenter to more easily measure short-range features such as structural geometry, bond rotation potentials, and steric interactions between near-neighboring groups. Flory correctly identified that the chain dimension in polymer melts would have the size computed for a chain in ideal solution if excluded volume interactions were neutralized by experimenting at the theta point.

Among his accomplishments are an original method for computing the probable size of a polymer in good solution, theFlory-Huggins Solution Theory,the extension of polymer physics concepts to the field of liquid crystals, and the derivation of theFlory exponent,which helps characterize the movement of polymers in solution.

The Flory convention

seeFlory conventionfor details.

In modeling the position vectors of atoms in macromolecules it is often necessary to convert fromCartesian coordinates(x,y,z) togeneralized coordinates.The Flory convention for defining the variables involved is usually employed. For an example, a peptide bond can be described by the x,y,z positions of every atom in this bond or the Flory convention can be used. Here one must know thebond lengths$l_{i}$,bond angles$\theta _{i}$,and thedihedral angles$\phi _{i}$.Applying a vector conversion from the Cartesian coordinates to the generalized coordinates will describe the same three-dimensional structure using the Flory convention.

Awards and honors

Flory was elected to the United StatesNational Academy of Sciencesin 1953 and theAmerican Academy of Arts and Sciencesin 1957.In 1968, he received theCharles Goodyear Medal.He also received thePriestley Medaland the Golden Plate Award of theAmerican Academy of Achievementin 1974. He received the Carl-Dietrich-Harries-Medal for commendable scientific achievements in 1977.Flory received theNobel Prize in Chemistryin 1974 "for his fundamental achievements both theoretical and experimental, in the physical chemistry of the macromolecules."Additionally in 1974 Flory was awarded theNational Medal of Sciencein Physical Sciences. The medal was presented to him by PresidentGerald Ford.This award was given to him because of his research on the "formation and structure of polymeric substances".

Bibliography

• Flory, Paul. (1953)Principles of Polymer Chemistry.Cornell University Press.ISBN0-8014-0134-8.
• Flory, Paul. (1969)Statistical Mechanics of Chain Molecules.Interscience.ISBN0-470-26495-0.Reissued 1989.ISBN1-56990-019-1.
• Flory, Paul. (1985)Selected Works of Paul J. Flory.Stanford Univ Press.ISBN0-8047-1277-8.

References

• Paul J. Flory – Facts. NobelPrize.org. Nobel Media AB 2019. Wed. 19 Jun 2019. <The Nobel Prize in Chemistry 1974>
• Somsen, Geert. Paul J Flory. Encyclopædia Britannica. June 15, 2019.Paul J. Flory | Nobel Prize-Winning American Chemist | Britannica
• Paul John Flory. Stanford Chemistry.[1].

External links

• Chemistry Tree:Paul J. Flory Details
• Paul Floryon Nobelprize.orgA short autobiography of Paul Flory
• Nobel lecture by Paul Flory
• Mangravite, Andrew (2001)."Finding Aid to the Paul J. Flory papers, 1931–1985 bulk 1950–1978".Science History Institute.RetrievedMarch 27,2018.Click on 'Paul J. Flory papers finding aid' for full finding aid.
• Paul J. Flory papersat theHoover Institution Archives
• National Academy of Sciences Biographical Memoir