Obituary of Edward Francis Casassa

Edward F. Casassa passed away on June 19, 2009, at age 84. A Professor Emeritus of Carnegie Mellon University in Pittsburgh, PA, his research publications on the statistical mechanics of polymer solutions are widely known, including work on the concentration dependence of the light scattering from dilute polymer solutions, the thermodynamics of multicomponent polyelectrolyte solutions and the basis for size exclusion chromatography. He was a Fellow of the APS.

After receiving a B.S. from the University of Maine in 1945, Ed joined the Buffalo, NY, laboratories of E. I. du Pont de Nemours&Co. before matriculating in graduate studies at MIT in 1949, working in the laboratory of Walter H. Stockmayer, alongside co‑grad student Marshall Fixman. Ed’s Ph.D. dissertation, accepted in 1952, presaged his future research interests, comprising a combination of experimental light scattering studies on dilute polymer solutions to characterize the dependence of the second virial coefficients A2 on molecular weight M and chain length polydispersity, and an approximate theoretical treatment giving the third virial coefficient A3 in terms of A2 for linear flexible chain polymers. In addition, during his graduate student years he developed his lifelong interest in the cello, an interest that led to his meeting and successfully courting a co‑student Ethel Zaiser, who would become his wife. His interests in light scattering shifted to dilute solutions of fibrinogen during a Post‑Doctoral fellowship in the laboratory of John D. Ferry at the University of Wisconsin from 1952–1956.

Ed’s experiences with Stockmayer and Ferry came to the attention of Hershel Markovitz, then in charge of a Fellowship at the Mellon Institute in Pittsburgh, PA. Markovitz recruited Ed to join the group as a Fellow in 1956 to work on topics involving dilute solutions. Ed became a Senior Fellow in the Fellowship in 1959, and a Professor of Chemistry in Carnegie Mellon University in 1966 on the merger of Mellon Institute and the Carnegie Institute of Technology. In 1959 Ed and Hershel began collaboration on a statistical mechanical model of A2 for linear flexible chain polymers, to develop an approximate relation for the dependence of A2 on M that differed significantly from the prior expressions developed by P. J. Flory and coworkers, with improved representation of experimental data. This led to a long series of papers on A2 for linear and nonlinear polymers (branched and ring shaped), and related work on the effects of increasing concentration on intermolecular interference effects in light scattering.

Ed had a fruitful collaboration with Henryk Eisenberg in the early 1960’s at Mellon Institute, in which they formulated the thermodynamics of dilute multicomponent polymer solutions, with applications to the experimental methods used to characterize polymers (e.g., light scattering, osmometry, sedimentation, etc.). Their results are of particular relevance in studies on polyelectrolytes, including naturally occurring macromolecules.

In addition to his statistical mechanical calculations related to the light scattering of dilute polymer solutions, beginning in the late 1960’s, Ed contributed seminal papers in the early development of size exclusion chromatography. He realized that in the absence of adsorption, the partitioning of the polymer in solution between the pores in a stationary phase and the mobile fluid phase would depend on constraints on the polymer conformation in the confined space in the pore. On that basis, he employed the random‑flight statistical model to calculate the partition function for the separation in the pores as a function of the polymer chain length, for a variety of pore shapes and polymer configurations (linear, branched, ring).

In addition to his research in polymer science, Ed served the polymer science research community for 27 years in various editorial capacities with the Journal of Polymer Science and its descendants, beginning as an Assistant Editor in 1965, and culminating as co‑Editor with GC Berry until both stepped away from that responsibility in 1992. Ed brought his deep understanding of polymer science and belief that the Journal should maintain the highest standards of scholarship to his editorial tasks. He spent a substantial fraction of his time on his editorship, perhaps too willing to spend hours suggesting revisions to help authors sharpen their language and presentation, to the benefit of us all. The Journal files reflect the gratitude of many authors for his extra degree of dedication and effort to help them present their work in the best way possible.

Casassa is survived by his three children, David, Anne C. Jones and Michael, and three grandchildren, Matthew, Timothy and Mark. His generous spirit and scientific acumen live on with those who knew him.