Paul J. Flory


Paul J. Flory

I was born on 19 June, 1910, in Sterling, Illinois, of Huguenot-German parentage, mine being the sixth generation native to America. My father was Ezra Flory, a clergyman-educator; my mother, nee Martha Brumbaugh, had been a schoolteacher. Both were descended from generations of farmers in the New World. They were the first of their families of record to have attended college.

My interest in science, and in chemistry in particular, was kindled by a remarkable teacher, Carl W. Holl, Professor of Chemistry at Manchester College, a liberal arts college in Indiana, where I graduated in 1931. With his encouragement, I entered the Graduate School of The Ohio State University where my interests turned to physical chemistry. Research for my dissertation was in the field of photochemistry and spectroscopy. It was carried out under the guidance of the late Professor Herrick L. Johnston whose boundless zeal for scientific research made a lasting impression on his students.

Upon completion of my Ph.D. in 1934, I joined the Central Research Department of the DuPont Company. There it was my good fortune to be assigned to the small group headed by Dr. Wallace H. Carothers, inventor of nylon and neoprene, and a scientist of extraordinary breadth and originality. It was through the association with him that I first became interested in exploration of the fundamentals of polymerization and polymeric substances. His conviction that polymers are valid objects of scientific inquiry proved contagious. The time was propitious, for the hypothesis that polymers are in fact covalently linked macromolecules had been established by the works of Staudinger and of Carothers only a few years earlier.

A year after the untimely death of Carothers, in 1937, I joined the Basic Science Research Laboratory of the University of Cincinnati for a period of two years. With the outbreak of World War II and the urgency of research and development on synthetic rubber, supply of which was imperiled, I returned to industry, first at the Esso (now Exxon) Laboratories of the Standard Oil Development Company (1940-43) and later at the Research Laboratory of the Goodyear Tire and Rubber Company (1943-48). Provision of opportunities for continuation of basic research by these two industrial laboratories to the limit that the severe pressures of the times would allow, and their liberal policies on publication, permitted continuation of the beginnings of a scientific career which might otherwise have been stifled by the exigencies of those difficult years.

In the Spring of 1948 it was my privilege to hold the George Fisher Baker Non-Resident Lectureship in Chemistry at Cornell University. The invitation on behalf of the Department of Chemistry had been tendered by the late Professor Peter J.W. Debye, then Chairman of that Department. The experience of this lectureship and the stimulating associations with the Cornell faculty led me to accept, without hesitation, their offer of a professorship commencing in the Autumn of 1948. There followed a most productive and satisfying period of research and teaching “Principles of Polymer Chemistry,” published by the Cornell University Press in 1953, was an outgrowth of the Baker Lectures.

It was during the Baker Lectureship that I perceived a way to treat the effect of excluded volume on the configuration of polymer chains. I had long suspected that the effect would be non-asymptotic with the length of the chain; that is, that the perturbation of the configuration by the exclusion of one segment of the chain from the space occupied by another would increase without limit as the chain is lengthened. The treatment of the effect by resort to a relatively simple “smoothed density” model confirmed this expectation and provided an expression relating the perturbation of the configuration to the chain length and the effective volume of a chain segment. It became apparent that the physical properties of dilute solutions of macromolecules could not be properly treated and comprehended without taking account of the perturbation of the macromolecule by these intramolecular interactions. The hydrodynamic theories of dilute polymer solutions developed a year or two earlier by Kirkwood and by Debye were therefore reinterpreted in light of the excluded volume effect. Agreement with a broad range of experimental information on viscosities, diffusion coefficients and sedimentation velocities was demonstrated soon thereafter.

Out of these developments came the formulation of the hydrodynamic constant called theta, and the recognition of the Theta point at which excluded volume interactions are neutralized. Criteria for experimental identification of the Theta point are easily applied. Ideal behavior of polymers, natural and synthetic, under Theta conditions has subsequently received abundant confirmation in many laboratories. These findings are most gratifying. More importantly, they provide the essential basis for rational interpretation of physical measurements on dilute polymer solutions, and hence for the quantitative characterization of macromolecules.

In 1957 my family and I moved to Pittsburgh where I undertook to establish a broad program of basic research at the Mellon Institute. The opportunity to achieve this objective having been subsequently withdrawn, I accepted a professorship in the Department of Chemistry at Stanford University in 1961. In 1966, I was appointed to the J.G. Jackson – C.J. Wood Professorship in Chemistry at Stanford.

The change in situation upon moving to Stanford afforded the opportunity to recast my research efforts in new directions. Two areas have dominated the interests of my co-workers and myself since 1961. The one concerns the spatial configuration of chain molecules and the treatment of their configuration-dependent properties by rigorous mathematical methods; the other constitutes a new approach to an old subject, namely, the thermodynamics of solutions.

Our investigations in the former area have proceeded from foundations laid by Professor M.V. Volkenstein and his collaborators in the Soviet Union, and were supplemented by major contributions of the late Professor Kazuo Nagai in Japan. Theory and methods in their present state of development permit realistic, quantitative correlations of the properties of chain molecules with their chemical constitution and structure. They have been applied to a wide variety of macromolecules, both natural and synthetic, including polypeptides and polynucleotides in the former category. The success of these efforts has been due in no small measure to the outstanding students and research fellows who have collaborated with me at Stanford during the past thirteen years. A book entitled “Statistical Mechanics of Chain Molecules”, published in 1969, summarizes the development of the theory and its applications up to that date.

Mrs. Flory, the former Emily Catherine Tabor, and I were married in 1936. We have three children: Susan, wife of Professor George S. Springer of the Department of Mechanical Engineering at the University of Michigan; Melinda, wife of Professor Donald E. Groom of the Department of Physics at the University of Utah; and Dr. Paul John Flory, Jr., currently a post-doctoral Research Associate at the Medical Nobel Institute in Stockholm. We have four grandchildren: Elizabeth Springer, Mary Springer, Susanna Groom and Jeremy Groom.

From Les Prix Nobel en 1974, Editor Wilhelm Odelberg, [Nobel Foundation], Stockholm, 1975

This autobiography/biography was written at the time of the award and later published in the book series Les Prix Nobel/ Nobel Lectures/The Nobel Prizes. The information is sometimes updated with an addendum submitted by the Laureate.

Paul J. Flory died on September 8, 1985.

Copyright © The Nobel Foundation 1974

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